WW2 German prototypes

Maus II

Nazi Germany (1944) Super Heavy Tank – None built

The Maus is an easily recognisable vehicle, marking the largest and heaviest production tank of WW2. At nearly 200 tonnes, the Maus, fully loaded and ready for combat, was a feat of engineering which lacked a purpose by the time it was finished. Despite having been ordered into mass production, Allied bombing had slowed deliveries and then all but a few hulls and turrets were finished when the project was scrapped. Even though the Maus was effectively dead as a project by November 1943, the story for the vehicle and even for a possible follow-up ‘Maus II’ was far from over. Maus II would not be a new vehicle, but the improvement of the first design, most noticeably in the turret.


The first mention of a Maus II was in March 1943. At this time, production of the original Maus vehicle had already begun, with the project having been approved for mass production shortly beforehand. The rush to deliver the Maus meant that production began quickly by Krupp and was well underway by the summer of 1943. Following an Allied bombing raid of the Krupp plant on 4th August 1943, production of the Maus ground to a halt, with work on 30 hulls at various stages of completion. The result of this bombing was that there was an interruption in production which led to a scaling-down of production followed by the cancellation of the project in November 1943. This permitted just 2 hulls and a single turret to be finished.

At this time though, there were several Maus hulls in various stages of completion as well as armor plating in various stages of rolling, milling, and welding for dozens more Maus available at Krupp’s factory in Essen.

It is important to note, at this point in the understanding of the Maus II and what it would look like, that all of these Maus hulls were not the same. In May 1943, after production had started, it was realized that, due to manufacturing tolerances on the very substantial side armor plates, the first hulls were ‘out-of-gauge’, namely they were too wide for the standard rail width in Germany. Rather than scrap these vehicles, it was decided to modify them along with the ones moving through the production line to bring them back into gauge. What this meant was that, by the time of the August bombing attack on the Krupp works, there were several marginally different Maus in production at the same time.

By the time of the project cancellation, the partially completed plates, hulls and turrets were still at Krupp’s Essen plant and only one hull was actually operable. A second hull would follow later and would be paired up with a finished Maus-turm and be used for testing, but, for all intents and purposes, by the end of 1943, the Maus idea was dead in the water.

Spring 1944

Having considered that several vehicles were already in various stages of completion, Krupp had a lot of time, money, and material invested in the Maus project, as did Dr. Porsche, the designer. However, it was not until March 1944 that Hitler would intervene. That month saw Hitler demand an update from Wa Pruef 6 as to the status of the Maus program and demanded that the Maus which had been completed to undergo testing and further development. At this time, the Maus was still mounting a test-weight ‘turret’ known as the Einsatzgewicht to load the hull as if a turret was mounted. The second hull arrived at Böblingen around this time too and mounted the newly produced turret.

Following Hitler’s demands, an assessment at Krupp was clear that production could, in fact, restart and that hulls 3 to 7 had been welded up and were sat in the armor workshop. Post-war evidence also suggests that all of these hulls also had Maus-turm turrets welded-up ready for them, as these four hulls and turrets were found by Allied forces after the capture of Krupp’s factory and testing ground in 1945.

Maus II, therefore, was not a recycling of one of the original Maus-turms, but a new turret and this was mentioned by Porsche when he requested a ‘Maus-II turm’ from Krupp. At this time, the Maus II-turm did not exist outside of some sketches of the initial design, as a contract for the production of a 1:5 scale Maus model with Maus-II turm was not issued until 8th April 1944. This contract is important, as it was exactly a week after the assessment of resuming production at Krupp was delivered. That assessment had shown that a resumption of Maus production at Krupp would need an additional 200 workers per month and could deliver vehicles at a rate of just 2 per month, just a fifth of the 10 per month which had originally been suggested. This production though would be starting from hull number 8 (for which armor had been cut) onwards.

Maus II Turm (turret)

On 8th April 1944, a contract had been issued for an improved Maus turret to be modeled in 1:5 scale. The model was to have the same armament as the original Maus, a 12.8 cm gun paired with a 7.5 cm gun, but rather than being side by side with each other like on the original Maus, these were to be stacked: the 7.5 cm gun was to be mounted above the 12.8 cm gun. No plans seemed to consider the possibility of a 15 cm gun.

Bearing in mind that, when Porsche first saw the Maus-turm on the full-sized mockup in May 1943, he disliked the curved front, concerned that it could deflect shells into the hull roof, it should be no surprise that the Maus II-turm would look quite different. Dr. Porsche had made a series of suggestions to modify the original turret, including wholly impractical ideas for sub-turrets and anti-aircraft guns, but his primary suggestion of note was to change the front profile of the turret by turning the curve in the bottom half the other way.

A second change was the gun mounting, although it is not clear whose idea this was. The mount would go from a side-by-side mounting with the 12.8cm Kw.K. 44 L/55 gun on the left and the 7.5 cm gun on the right to an ‘over-and-under’ mounting with the smaller gun mounted on top. This was not the same 7.5 cm gun as used on the Maus-turm. The mounting of that gun had caused problems because the position it occupied meant that fumes from the muzzle after firing could be drawn down into the engine bay, meaning that instead of a 7.5 cm L/24 gun the barrel had to be lengthened to avoid the problem. The result was a 7.5 cm L/36 as the secondary armament on the Maus turm. By mounting the 7.5 cm gun above the primary armament, much of that problem was removed as the gun was much higher up and this meant that the original 7.5 cm L/24 could be used instead.

The general shape of this new turret was ready by 15th March, as the changes needed to the hull to accommodate it had to be worked on by Porsche. A month or so later, on 16th/17th April 1943, Krupp met with Wa Prüf 6 to discuss the improvements to the Maus-turm.

These were to include an improved ventilation system in the turret with a fume extractor directly over the 12.8 cm ammunition bin and a new breech for the 7.5 cm gun which opened horizontally rather than vertically, as this would make loading possible. Mounting the 7.5 cm gun on top of the 12.8 cm and with a vertical breech would leave it almost impossible to reload otherwise.

Most importantly, though, was the incorporation of Porsche’s concerns over the front shape. Gone was the curved front and it was replaced with a single flat plate angled back. This design had the advantage of preventing the possibility of deflected shots striking the hull roof, but also reduced the space available for the gun trunnions (the mounts for the gun), which were originally behind the front plate. Keeping this arrangement would, in fact, have reduced the space so much that the 12.8 cm gun would not have been able to fit in the turret properly.

Where the front-curve design had ensured these trunnions were protected, the shape of the front of this new design got around this problem by simply putting the trunnions on the outside of the plate. This kept the gun-forwards in the turret, maximizing space inside, and simply required a large rounded casting on the front to protect them. On top of this casting was a second large steel casting forming the mantlet around the gun.

The new turret was a significant improvement over the original Maus-turm, providing a better ballistic shape, being easier to produce (no more bending a 240 mm thick steel plate to form the front) and having improved ventilation, but in order to fit it to the hull, certain changes were needed.

On 15th May 1944, the contract for the 1:5 scale model of the Maus-II turm was changed to include an additional model in 1:10 scale to incorporate a new range finder (EM – entfernungsmesser), which was slightly narrower than the original one (1.9 to 2 m long instead of 2.1 m). Krupp’s work on this new turret was underway by August 1944 in both options (the 1:5 and 1:10 scale models with and without the new rangefinder, respectively), but to make them he was forced to scavenge parts from the original 1:1 scale model for the first Maus turret which was at Kummersdorf.

The only practical difference between the Maus II turm and the turret selected for the E100 design by Adler was that the armor on the turret was changed to reduce the weight. In this way, the E100 turm can be seen as a ‘light’ version of the Maus II turm. Visually, they would have been very similar, with only the slightly narrower rangefinder distinguishing the two from the outside. Obviously, any upgunning of the E100 turm to a 15 cm or 17.4 cm gun would cement the visual differences between the two.

Maus II Wanne (hull)

The outline of the new Maus turm was ready on 15th March 1944 in order to allow for necessary changes to be made to the hull in order to mount it. Firstly, the turret ring was to be enlarged on the hull to accommodate this new and improved turret, which would also make it more stable and make the vehicle less cramped. The original Maus turm was sat on a turret-race attached within a 2,959 mm diameter opening in the hull, allowing for the 2,388 mm diameter basket to rotate within it. The Maus II turm required a larger turret ring. This would mean that the turrets would not be interchangeable between the Maus and Maus II.

One of the Maus hulls found by 21 Army Group at Meppen in May 1945, showing the circular hole in the hull roof where the turret ring was mounted. It was made from four separate 60 mm thick sections welded together. Source: UK National Archives

Improved ventilation in the hull roof was also meant to be added, with improved or additional gratings which allowed for more air to be drawn in for cooling.

As of 4th August 1943, it is known that armor plates had been cut for Maus hulls 8 and 9, delivered from the armor works for hull 10, and another 20 Maus-worth of armor plate rolled ready for cutting. Bearing in mind the first 7 vehicles would in the event of a resumption of production clearly be finished as Maus with the Maus-turm, it is a fair assumption that plans for this second turret would be intended for hulls 8 onwards, with a potential to finish at 22 tanks in this manner using the armor already available (for the hulls). If that was the case, there would be 8 Maus I tanks and 22 Maus IIs potentially even before considering any new contracts for renewed mass production to the original Maus I levels.

One additional and rather speculative element to consider for a Maus II is the drive train. It is understood that the original Maus was, at one time or another, envisaged with a rather large variety of engines and options and that, whilst it eventually got a modified version of the Daimler-Benz MB 517 1,200 hp V-12 Diesel engine, it had suffered through using the less-powerful MB 509 1,080 hp V-12 Petrol due to shortages of engines. Given that the MB 517 was not available or installed prior to the end of 1944, it seems a fair assumption that either this engine or one of equivalent power would have been fitted to any Maus II or Maus tanks from vehicle 8 onwards. There were also numerous other ideas for even more powerful, lighter, smaller power plants for tanks, but so far as is known in the development of Maus II, the MB 517 is the most likely option.

Whether or not Maus II would have retained the electric transmission of the Maus or would have adopted a hydraulic or mechanical transmission is not clear, but given a demand to save weight and reduce the use of strategic materials (such as the copper in the electric transmission), a switch or at least consideration of a switch is also very likely. Evidence supporting this would come from a later plan envisaged for the E100 using the 8-speed Mekydro transmission – a mechanical/hydraulic type system.

One thing less considered is the suspension. It could be assumed that a new order for Maus production in the form of Maus II would have led to a replacement of the twin-bogie system. Dr. Porsche had always favored torsion bars and had adopted external horizontal torsion bars for his Tiger P/Elefant/Ferdinand. These had also been planned for the original Typ 205 from the end of 1942. As the weight of that design had steadily increased, Dr. Porsche had reluctantly gone to a spring suspension from his much favored torsion bar system. A new, larger and more resilient external torsion bar system could therefore easily be seen as a logical development in Maus II from Dr. Porsche if it had been ordered back into production. However, without drawings, plans, or documentary evidence, this remains speculative only.

Typ 205 from December 1942/January 1943 showing the distinctive and very large rectangular Maus turret. Note the use of a hull machine gun and the use of 5 pairs of road wheels for the suspension, copied as units from the Tiger (P), but reduced from the 6 pairs drawn in October 1942. Source: Frohlich


Just like the original Maus, the idea for Maus II was to partner the high velocity 12.8 cm gun (12.8 cm KwK.44 L/55, known as the ‘12.8 cm Kw.K. 44 (Maus)’) with a 7.5 cm gun. For the Maus, it was a long-barrelled (to avoid gas from the propellant entering the hull-roof vents when it was fired) 7.5 cm gun (7.5 cm Kw.K. 44 L/36), but this was not required on the Maus II as a shorter 7.5 cm gun could be used. Also unlike the Maus, which mounted these two guns side by side, the Maus II design was to mount them in an ‘over-and-under’ style, with the 7.5 cm gun mounted on top. The only major change this required was the switch to a horizontal breech for the 7.5 cm gun so it could be loaded from the side. The unusual arrangement had several considerable advantages over the former arrangement. Firstly, mounting the 7.5 cm gun higher up ensured no gases could go into the hull roof-vents even with the shorter barrel. Secondly, it reduced the width of the gun mounting in the turret face, which meant a lighter mounting as well as a narrower hole being cut in the turret face. More importantly, though, was that by sharing the same vertical axis, these two guns were now much easier to range for the new rangefinders being considered.

Original Krupp Maus turm (number 1) as fitted to the Maus (top), and the improved Krupp Maus II turm dated 23rd March 1944 (not to scale). Source: Jentz and Doyle

Maus II as envisaged by Jentz and Doyle.


The story of the Maus II, an improved version of the Maus, is a complicated one and one for which the entire story may never be known. Even after the original Maus hulls (3 to 6) were ordered scrapped in July 1944, work was continuing on models of the Maus II turret. This can be seen as confirmation that the Maus II was a viable new tank that needed a new hull – hence the non-reuse of the old hulls, or simply that the turret project had not been canceled or possibly was intended for the E100 or something else instead.

Likewise, the fact that hulls 3 to 6 for the Maus were not, in fact, scrapped has also been seen as evidence supporting the idea that Maus II was not much more than an improved turret for the original hull. Analysis of the information about this turret shows that this latter conclusion cannot be correct. The Maus II turret was too large for the original Maus hull and, at the very minimum, would have necessitated the removal of the original hull roof and replacing it with a ring large enough to take the new turret. Considering that hulls 3 to 6 had manufacturing tolerance issues and needed reworking just to fulfill the needs of the Maus, it is perhaps more likely that Maus II would simply have started from Maus hull 8 onwards, incorporating the manufacturing improvements needed to stay within gauge.

It is not even clear quite when Maus II was completely terminated, as work on the turrets was still going on in August 1944, a month after the spare Maus hulls were ordered scrapped. The relationship between the E100 turret and that for Maus II is almost equally as opaque. Whilst they are assumed to share a common turret-ring size (larger than that of the original Maus), and the same guns (12.8 and 7.5 cm over-and-under) and same general layout, they were not the same. The E100 turret offered much less protection than the Maus II turret and, at only 35 tonnes, significantly lighter than the 50+ tonne turret of Maus II. The E100 turret was announced as finished by 17th May 1944, yet work on Maus II turret was still continuing, suggesting further changes were still being considered, but after this date the project disappears. Likely, it was simply canceled by the end of the year as redundant. The Maus program had been canceled and those workers and resources were needed elsewhere. No Maus II was ever built and no turret finished.

The Maus II, featuring the new turret with an angled front, external trunions and an over-and-under gun arrangement. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon campaign.

Pz.Kpwg. Maus II specifications

Dimensions est. 10.085 long (9.034 without gun), 3.7 wide (series max.), 3.649 m high
Total weight, battle ready Est. 188 tonnes (50 to 55 tonne turret)
Crew 6 (commander, gunner, 2 x loaders, driver, radio operator)
Armament 12.8 cm Kw.K. 44 L/55
7.5 cm Kw.K. 44 L/24
7.92 mm M.G.34 machine gun
Armor Turret
Front – 220 mm @ 30 deg.
Sides – 200 mm @ 30 deg.
Rear – 200 mm @ 15 deg.
Roof – 60 mm @ 0 deg.
Hull – as Maus
Propulsion Est. Daimler Benz MB 517 V-12 Petrol 44.5 litre – 1,200 hp @ 2,500 rpm


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War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
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War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

WW2 American Prototypes WW2 British Prototypes

The Bechhold Tank

Light tank – Single partial prototype and design. (1938-41)
United Kingdom – None built


Many people interested in tanks have likely heard the name Walter Christie and are aware that he produced several prototype tanks during the period between WW1 and WW2. Whilst his vehicles had some good features, overall they were not a commercial success for Christie, who had amassed a lot of debt in developing and building them. The result was that some of his assets, his tank prototypes included, ended up being used to pay off his debts and his ‘high-speed tank’ was one of them.

Sold to pay off Christie’s debts, this vehicle ended up in the hands of a German-born American businessman, Siegfried Bechold. This new owner rebranded the tank, had some additional design changes made and then, at the start of WW2, tried to sell the ‘new’ design to both the Belgians and the British.

The Belgians needed tanks urgently but this design would come too late to help them. The British expressed interest as the light weight of the machine was suited to their need for a tank for airborne operations, and by 1940 the British Purchasing Commission was actively considering the vehicle for production. Nonetheless, the idea was over by 1941, when British attention switched to a vehicle with more armor and firepower than the ‘Bechold’ tank. Even so, this early design and the consideration of it adds to the story of how the British were trying to develop their own ideas for a new kind of mobile warfare and airborne operations.

The enigmatic Mr. Bechhold

The name Siegfried Bechhold means very little even to the most ardent tank enthusiast. However, just prior to WW2 and into its first years, Bechhold was one of the most prominent men involved in tank design and production in America, despite never having produced any tanks. This peculiar state of affairs takes some digging to get to the bottom of, as does the man himself, not helped by his name appearing variously as Bechhold, Bechold, and Buchhold.

Siegfried Bechhold appears to have been born in Bavaria, Germany in 1900, although a newspaper article from January 1941 puts his birthplace as Holland. This is likely one of those situations where people de-Germanized themselves to try and disguise their German ancestry, something which was a common occurrence at the time, especially with the switch from ‘Deutsch’ to ‘Dutch’ in terms of self-description. Another account of his early life (from April 1941) stated that he was born in Bavaria and lived in Germany until he was 11 – so maybe his family moved to Holland or maybe he was just hiding his background.

Bechhold recounted his story that, at the age of 16 (so ~1916), he was, like tens of thousands of other German boys, drafted into the German Army during World War One, although it is not known if he saw any active service or not. By 1922, with WW1 behind him but in a country ravaged by economic and social problems, he managed to make the transatlantic voyage to the United States, arriving in New York with just US$40 to his name.

His first jobs were very poorly paid but, by the late 1920’s, he was living as a tenant at 34 East 62nd Street between Madison and Park Avenues (this house was demolished in an explosion in July 2006). He had been learning English at night school and had managed to get a job as a salesman, which proved very successful for him. So successful was it, that this man, who had arrived in the USA just a few years before, could now afford to travel back and forth to Europe. He would later claim that he used these trips to pass on information about German rearmament efforts during the early 1930’s and that he believed that Germany was far ahead of other countries in weapons development, although this sounds more like his sales-speak for selling tanks than the serious recollections of an international spy.

What is known though is that during this time, he, like many others, saw the tanks of Walter Christie. These were very well covered in the newspapers and newsreels of the age with Christie’s penchant for publicity stunts. Seeing a potential business opportunity, Bechhold was interested in these tanks which were significantly faster than other tanks of the age, and in many ways the most advanced tanks in the USA at the time.

Bechhold later reported that he was encouraged in his interests by Congressman Ross Collins of Mississippi, although how these two men knew each other is unknown. It was, according to Bechhold, Collins who encouraged him to produce tanks in the United States but Bechhold was not a technical man nor an engineer despite being Vice President of the Bethlehem Engineering Export Corporation of Wall Street, New York. He was skilled in salesmanship and finance. He was, however, despite his lack of engineering skills, to be credited in the US press as coming up with the idea of putting lightweight aircraft engines into tanks in place of ordinary diesel or petrol engines, although this too sounds more like the pitch of a salesman, as Christie had already done this years beforehand.

As an aside to his tank work and to give a flavour of the way in which Bechold was trying to avoid being labelled as anything other than as a patriot, he embarked on a vigorous self-justification campaign in the media, making sure no one was in any doubt as to his loyalties. As a result, in June 1941, it was reported that Bechhold, a naturalized citizen and “intense” patriot, had refused to sell his tanks to the Russians at the time of the War against Finland. Furthermore, it was claimed that, in the new war against Hitler, he would only sell them when the Russians went to war with Hitler, even though there seems to be no evidence whatsoever for this claim.

The Tank Company

By the end of the 1930’s, Bechhold had his opportunity. Walter Christie, a man of undoubted technical gifts, was running short of investors who wanted to keep losing money on his tanks. One vehicle of his, a “high-speed tank”, had to be handed over to the partners of the Hempsted Welding Company of New York, William and Alfred Christ, as a lien against unpaid debts owed to them by Christie. Exactly which of Christie’s vehicles this was in unclear but as the M.1938 was later presented by a Mr. Bigley with some involvement from Christie suggests that Bechhold got hold of the M.1937 high speed tank from Christie as the basis of his design. However, whilst exactly which vehicle may not be known, Christie’s creditors were to be appeased with a tank available for purchase to pay his debts.

Bechhold had, through Bethlehem Engineering Co. been engaged in a commercial contract with Christie which started on 9th August 1938 whereby Bechhold and his company were granted exclusive rights to sell and manufacture the design from Christie for the princely sum of US$5,000 (just over US$91,000 in 2020 values). The idea of the partnership was simple. For this initial outlay of cash to Christie, Bethem Engineering would take the full blueprints of the design, market them globally and grant manufacturing licences for US$50,000 to each national licensee. This US$50,000 (US$915,000 in 2020 values) would be split 50:50 between Bethlehem Engineering and Christie for which the licence got not only the blueprints but also a master mechanic or draughtsman from Christie. This agreement simply fell apart not least in part to how appallingly badly written and complicated it was. In the words of the New York Second Circuit of Appeals in July 1939 ruling on whether to grant an injunction against Christie for breach of his contract:

“This contract is so obscure, and, strictly taken, so incoherent, that nobody can be sure of its meaning, but so far as we can spell it out, this is what it was. The defendants made the plaintiff its exclusive agent to sell licenses to prospective manufacturers of their tank in foreign countries — perhaps also in this country as well, though apparently it was not included. The plaintiff was not free to sell such licenses generally, but only for those countries where the parties thought it “practical” to do so. The minimum license fee was to be $50,000, but the plaintiff was to try to get more, and the parties were to discuss the amount in advance: probably this implied that they should agree upon it.”
105.F.2d 933 (2nd Cir. 1939)

With the case between them ending in confused acrimony, Christie and Bethlehem Engineering’s relationship was over. Christie had won that case due not least in part to how confusing the agreement was between them over rights and whilst he had retained his rights over his design he was also financially crippled.
Bechhold too had moved on and was no longer involved with the Bethlehem Engineering Expert Company and, instead, on 25th July 1939 (just 2 weeks after the ruling), formed the Armored Tank Corporation (A.T.C.), incorporated in New York. Initially, this company had just 100 shares of stock (30 Class A, and 70 Class B) at a value of US$50 each (Total nominal value US$5,000).

The purpose of the company was to acquire the Walter Christie high-speed tank from William and Alfred Christ. On 31st July 1939, this tank was purchased for an undisclosed sum along with 34 shares (Value US$1,700) in the new company (6 more were given to the attorney for their legal services). The Armored Tank Corporation (A.T.C.) of New York was now in possession of the Christie High-Speed Tank, the rights over which had fractured the relationship between Christie and Bethlehem Engineering. Bechhold now had the vehicle and also the more difficult task of making money from it.


Within a few months of formation of the company and the purchase of this High-Speed tank, Bechhold was recruiting a draughtsman. Between December 1939 and January 1940, A.T.C.’s draughtsman prepared blueprints and drawings of this Christie tank with some modifications. During this time, a license agreement for the production of this modified Christie high-speed tank was acquired in Belgium. The Belgium firm, Ateliers de Construction de Familleureux, paid an advance royalty of US$10,000 for this license. Whatever plans there were in Belgium for this vehicle though are unknown, as the nation was overrun by the Germans in May 1940, with no Christie tanks produced.

Super Tanks

By the end of 1940, the first glimpse of what A.T.C. was working on can be seen. In November-December that year, it was advertising ‘Super-Tanks’ in the US Army Ordnance Magazine as being “built in all weights” by the Armored Tank Corporation at 30 Church Street, New York. This was formerly the location of numerous businesses such as the National Manufacturing Company, American Locomotive Sales Corporation, and the New York Railway Club (close to the site of the World Trade Center Complex today and now the location of the Century 21 Department Store). The same advert appeared that same month as being constructed by the Pressed Steel Car Co. as well.

Image of a Bechhold Tank
Image of a Bechhold Tank dated 1940, published November/December 1940. Source: Army Ordnance Magazine

Although the tank was never built as shown, there is some information available from contemporary press reports too. Also, bearing in mind that the vehicle was based on the Christie design (purchased in 1939), and that it was advertised as being “Built in all weights”, a brief analysis of the vehicle shown is possible.

Advert for Bechold’s Armored Tank Corporation of New York.
Advert for Bechold’s Armored Tank Corporation of New York. Source: Army Ordnance Magazine

In December 1940, Bechhold was reported to have been producing ‘Medium Tanks’ for the British and had also submitted a design for an airborne tank. This tank was at the time being reported in the press as weighing 10 tons (9.1 tonnes), 14 ½ feet (4.42 m) long, fitted with armor one-inch (25 mm) thick with a single 37 mm gun and a machine gun. Also noted was that it would carry two sub-machine guns, suggesting a crew of just 2 or 3. A final note is that it was designed to be carried under “a Douglas plane”.

This description is immediately reminiscent of the Christie promotional idea of an underslung high-speed tank from 1936. In that artwork, a 3-wheel Christie turretless high-speed tank was pictured being carried under an Air Corps bomber.

The idea for the rapid deployment of tanks by aircraft
The idea for the rapid deployment of tanks by aircraft appeared in Christie designs as early as 1936. Source: Popular Mechanics. May 1936.

An idea of quite how a system for carrying a tank in this manner under a plane would work can be found in a May 1941 Patent. This was filed by Alfred Anderson, assignor to the Armored Tank Corporation for a ‘Hook-on-and-Release-Mechanism for Fighting Tanks’. This invention describes an invention for attaching tanks to aircraft, specifically slung below the plane, and for dropping the tank when in flight. This is a different system to the one from Christie – that one used a pair of scissor arms to grab and retract the tank.

Instead, four upside-down triangular fittings would be attached on the underside of the fuselage of the aircraft. Each held a hydraulically controlled actuator with a large stud pushed out on a spring. When hydraulic pressure was applied, this spring would compress withdrawing the stud back inside the actuator. This would release the tank, as these four studs were attached via holes into the body of the tank. These would not be disengaged simultaneously, but in pairs. The rear pair would disengage first, allowing the bottom of the tank to hang down as the carrying plane swooped in suicidally low over the ground. At a suitable point, the front studs would also then be disengaged releasing the front of the tank. The back end of the tank was then supposed to hit the ground first from a lower height, with the front end following. This method was intended to overcome the turning effect on the vehicle. The dangers to the vehicle crew and to the aircraft performing this maneuver cannot be overstated; this was really a system designed to get the plane and its tank shot down. Even if it did work and the tank was deposited safely to the ground, one wonders how long it would take the crew to become operational after such an experience.

Hook on and Release Mechanism for a Fighting Tank.
Hook on and Release Mechanism for a Fighting Tank. US Patent US2310887 of 1941
Christie M-1950
A depiction of the gantry arrangement on top of what is supposed to be the ‘Christie M-1950’ (albeit with a different number of road wheels). The gantry could not only attach a tank, but also raise it within the fuselage of the aircraft. Source: Steel Steeds Christie

The vehicle shown in that 1936 promotion art for Christie is different from the vehicle in the 1940 ATC advert though. For sure, ATC got a Christie High-Speed Tank but its vehicle is much closer to a vehicle the size of the M3 Stuart or even the M1 Combat Car. What can be seen from the advertising image is that it was a small tank with a distinctive rounded back end to the hull running on four closely-spaced Christie type wheels (and presumably Christie spring suspension too). No track guards or mud guards at all are shown. The track itself is very similar to the flat plate track of the Christie tanks.

The nose lacks any indication of the pointedness of the earlier Christie High-Speed tanks but is uniformly rounded leading to a long glacis sloping up to a slightly inclined driver’s plate. Where the glacis meets the driver’s plate, there are two structures that appear to be mounts for fixed hull machine guns. In 1940, it should have been obvious that fixed, forward-firing machine guns were utterly useless but it was an easy way to add what was thought of as additional firepower to a design and many tanks subsequent and independent of this one retained this feature, including the M3 Grant, M4 Sherman, and Canadian Ram.

The driver’s plate featured two rectangular hatches, each with a vision slit. Out of the front of the left hand hatch was what appears to be a heavy machine gun. From the position of the hatches and hull weapons, it would appear to have had a driver mounted on the right and hull machine gunner on the left. A third man, the commander, would most likely occupy the turret. The turret itself, as drawn, is very unusual, looking like an overturned cooking pot. On the roof was a full size (it occupies the entire roof) hatch in two parts, each opening sideways. A series of slits were placed around the exterior of the turret and at least two machine guns, one forwards and one to the left. In total, the firepower for this vehicle as drawn was 4 machine guns and one heavy machine gun.

Presumably, the part about being built in ‘all weights’ was to mean that different options in terms of fittings, armor, and weapons were potentially on offer. Certainly, the specifications and look of the vehicle were very up to date given the parlous state of US tank development at the time. The T4 medium tank, for example, from 1935/1936, was a very promising design but was 13.5 tons and capable of just 35 mph with 3 machine guns. The Bechhold tank was, at least on paper, better armed, better armored, smaller (about 50 cm shorter), and faster. No surprise then that it was an interesting prospect for investors interested in lucrative future army orders.

The 13.5 ton Medium Tank T4
The 13.5-ton Medium Tank T4 – at 13.5 tons (12.2 tonnes) this tank was armed only with machine guns and was not adopted. Source: Wiki


The potential of the A.T.C. tanks from Bechhold’s company had indeed gained attention. In June 1940, a British Purchasing Commission had arrived in the USA to look at the possibility of producing and purchasing tanks for the war effort. Great Britain had, of course, been at war since September 1939, and June 1940 was just after the evacuation of Dunkirk, a time when a lot of British armor had already been lost on the continent with the fall of France. Great Britain and its Empire now stood resolute against the Axis of Germany and Italy but it desperately needed tanks and arms to fight the war.

The same month, Bechhold managed to interest John MacEnulty, the President of the Pressed Steel Car Company, in tank production and a five-year contract (renewable for up to 2 years) was signed on 23rd July 1940. Under the terms of this contract, Pressed Steel would gain exclusive rights to the production of tanks from A.T.C. (notwithstanding that a non-exclusive Belgian production license had already been signed). Under the terms of the contract, Pressed Steel would pay A.T.C. a royalty of $750 for each vehicle of A.T.C.’s design ordered for production by the US or Foreign Governments at Pressed Steel. A.T.C. was to provide plans, drawings, technical advice and, if required, a skilled engineer to assist in production.

 John F. MacEnulty, President of Pressed Steel Car Company
John F. MacEnulty, President of Pressed Steel Car Company from 1937. Source: Railway Engineering and Maintenance Vol.34

On 25th October 1940. Pressed Steel entered into an agreement with the British Purchasing Commission for the production and delivery of 501 M3 Medium tanks. These were not tanks designed by A.T.C. but Bechhold did assist in the completion of the contract arrangement and the British sent an advance of US$500,000 to Pressed Steel. The next month, November 1940, Pressed Steel paid A.T.C. US$75,000 under the terms of the July 1940 contract with US$300,000 remaining to be paid.

It is not clear though why Pressed Steel paid this commission to A.T.C. as the vehicles being produced were Grant tanks and not the Christie-based tank design from A.T.C. Despite the huge sum paid to ATC, it was in trouble. Bechhold had finagled matters so that after October 1940, only he held all of the Class A shares in the company, and therefore had exclusive voting rights for A.T.C. He had also increased the number of shares available from 100 to 10,000 (3000 Class A and 7000 Class B) with a reduced value of just US$1 each.

British Interest

The desperate need for tanks meant that the British were rapidly building their own in industries repurposed from civilian work to war work, but they were also looking for American production too, as this would not be affected by the manpower shortage in Britain or by German bombing. As well as the order for the M3 tanks from Pressed Steel, various other options were being considered and the work of the Purchasing Commission continued into 1941.

One particular type of vehicle that the British were interested in was an airborne tank,namely a tank which could accompany parachute or glider-borne troops. The lightweight and compact Bechhold tank was obviously of specific interest. On 27th February 1941, on behalf of the British committee in charge of evaluating tank designs, a telegram was sent to the Consul General in New York regarding the tank situation. The British were clear on what they needed from an airborne tank:

3 man crew
37 mm gun and .30 calibre Browning in a 360 degree rotating turret (quite why a 37 mm gun was specified in preference to the 2 pounder which was already an excellent gun and fielded on the A.17 Tetrarch is unknown but it is probably to do with the 37 mm being easier to produce in the USA)
Space for a wireless
Maximum Speed 40 mph (64 km/h)
Radius of Action 200 miles (320 km)
Armor basis ‘preferably’ 40-50 mm on the front and turret. 30 mm thick sides
Weight about 9 tons (9.1 tonnes) (anything under 9 tons was felt to lack the fighting qualities required) (for reference: the A.17 Tetrarch weighed just 7.6 tonnes)
“Not very interested in dropping Tank from a height of two feet”

In other words, the idea of dropping the tank from a plane was not wanted at all. Either it had to be landed directly (some various schemes for adding wings to tanks were considered), or it had to be unloaded from an aircraft. Dropping it from underneath a plane was, quite rightly, seen as a terrible idea. These requirements exceeded those of the Bechhold tank from A.T.C. That vehicle lacked the armor and firepower required and was inferior to the available A.17 Tetrarch when what was wanted by the British was basically a better armored version of the Tetrarch. The British were also anxious to get an airborne tank as soon as possible and were hoping for interest from the USA in manufacturing the vehicle. The Bechhold tank was, therefore, not suitable for their needs as it was noted that a pilot model had not yet been built.

By the end of March 1941, British plans for “the Bechold [sic: Bechhold] Project” were over. Having analyzed the tank, the British reported that: “The tank will not have the essential fighting qualities for the operations in view” and would also divert production from heavy bombers. The matter was left in the hands of American authorities to pursue and oversee its development. In its place came consideration of a 9-ton (9.1 tonnes) tank to be carried by towed glider. A final comment on the matter, from 30th April 1941, was that it had become clear to the British that the “American War Department feel they have no capacity to devote to the development of air-borne tanks”. As the decision was that Bechhold’s tanks should be overseen in America rather than from Britain it was decided that no action be taken on the Bechhold tanks.

Sold Off

The British had not been convinced by Bechhold’s salesmanship. They had, after all, already been down the Christie suspension vehicle route with the purchase of a Christie M.1931 which became the A.13E1 in 1936/7 and they had extensive experience with light Cruiser type tanks already. They also had plenty of small light tank designs including the A.17 Tetrarch. They had been clear on what they wanted but Bechhold was either unable or unwilling to comply, or simply could not produce a prototype, which was required before a decision could be taken. With the British unconvinced and an already lucrative deal with Pressed Steel in place, Bechhold had other plans.

Shenanigans and Taxes

In February 1941, A.T.C. sold its original Christie tank for just US$3,500, (Bechhold had bought it for US$5,000 in 1939) and on 18th August that year, A.T.C. incorporated as a corporation in Delaware to avoid payment of New York franchise taxes. This was completed on 20th August and the shares changed to just 100 Class A and 9,900 Class B shares with Bechhold, of course, retaining all the Class A shares and the voting rights that went with them (he also held 6,400 of the Class B shares too). Between 2nd and 4th September 1941, A.T.C. signed over all assets and the July 1940 contract (with Pressed Steel) to a newly incorporated body in Delaware, meaning the New York ATC effectively disappeared, although it was not formally dissolved until 11th September 1941. Mr. MacEnulty of Pressed Steel wrote to Bechhold on 4th September 1941 informing him that the July 1940 contract was now canceled due to alleged misrepresentations by Bechhold and a legal fight ensued.

Bechhold was insistent that he was owed money from Pressed Steel and, despite being offered US$300,000 (the remaining balance from the British Purchasing Commission contract), Bechhold refused due to the tax liability involved. His counter-offer was US$1.5m and this was immediately rejected. Instead, Pressed Steel suggested it should buy all of the remaining shares of ATC for US$50 per share (10,000 shares at US$50 would mean a US$500,000 payday). This would mean the end of Delaware A.T.C, which would have to surrender all its designs including an “aero” (airborne) tank concept, a full size model of the hook and release mechanism for releasing a tank from an airplane, designs of various other tanks and flamethrowers, and cash. This offer was considered and changed on 3rd October 1941 with a value of US$37.50 per share (US$375,000), but this would be only the existing July 1940 contract, no other plans or designs. This was agreed to by the voting members of Delaware A.T.C., which was just Bechhold, who of course approved of this arrangement.

In order to facilitate this transaction, the Delaware incorporated A.T.C. was changed from any mention or use of Armored Tank Corporation to the ‘Illinois Tank Corporation’ (I.T.C.) on 14th October 1941. On this day, just as Armored Tank Corporation (Delaware) was bought out by Pressed Steel and changed to Illinois Tank Corporation, Bechhold started a new company in Delaware. He called this new company the ‘Armored Tank Company’ once more receiving all of the assets from the original A.T.C., other than the contract, which had now gone to I.T.C. The next day, the new A.T.C. handed over all of its shares to I.T.C. which was then distributed to the stockholders, which also included Bechhold.

From these corporate shenanigans, Bechhold netted himself a cool 100 Class A shares (100% of the voting power), and 6,400 Class B shares valued at US$243,750 in total. This 15th October 1941 payment of US$375,000 (tax year 1941-1942) was to have serious consequences for Bechhold and his creative accounting.

Following this 15th October takeover though, the original July 1940 contract was finished. Bechhold probably felt he had made enough money and the entire business of the Illinois Tank Company was wound up suggesting that what assets in terms of tank designs it might have had leftover had little to no value. I.T.C. formally dissolved on 22nd November 1941.


The substantial pay-off which Bechhold had received was classed as personal income. He, and the other stakeholders, were found to be personally liable for taxes of this income. If there is one certainty greater than death and taxes, then it is taxation in time of war. Taken to court for non-payment of taxes, Armored Tank Corporation admitted an error in its tax liabilities and was assessed to be liable for the sum of US$390,144.91 (including US$78,028.98 in tax penalties on top of its original 80% tax liability of US$312,115.93).

This was not the end of it either, for the individual shareholders of the Armored Tank Corporation/Illinois Tank Corporation were also found personally liable for back taxes and penalties. Stockholders Philip Steckler and Hamilton Allen were found liable for US$33,750, and US$22,500 respectively, and Max and Siegfried Bechhold were found liable for US$243,750 and US$45,000 respectively. A massive combined penalty of US$735,144.91 (over US$12.8m in 2019 dollars) for not paying taxes on that US$375,000 (US$6.5m in 2019 dollars) income demonstrated the danger of trying to dodge taxes in wartime.


A.T.C. did not just produce a tank design. One of the more unusual things it designed and produced was a trailer for vehicles. This design appears in a letter dated 19th May 1942 from the Office of the Chief of Ordnance to the Commanding General of Aberdeen Proving Grounds (A.P.G.). Confusingly though, the product in question was produced by the ‘Armored Tank Corporation’ of Jersey City, New Jersey, suggesting that Bechhold kept working on designs incorporated in a different state. It is unlikely to be a mistake as A.T.C. (NY) had ended in September 1941 and I.T.C. (DE) ended November 1941. It is undoubtedly the same firm reborn, however, as the person providing information to A.P.G. on behalf of A.T.C. (NJ) was none other than ’Mr. Bechhold’ himself.

Rota-Trailer Model 4
A.T.C.(NJ) Rota-Trailer Model 4 during testing at A.P.G., Summer 1941, hitched to the rear of a half-track. The tests did not go well. Source: The_Chieftain – WoT forum

The proposal to the military was not this time a tank, but a trailer capable of being used for hauling supplies, equipment, or fuel. According to Mr. Bechhold, the British were interested in this trailer and the report recommended that APG experiment with it over a 250 mile (402 km) course to assess its viability, showing it off to the army and British representatives respectively.

This trailer was known as the ‘ROTA-TRAILER’ and the name stenciled on the side during trials stated this was the ‘Model 4’, suggesting the other 3 models or designs were less well refined. This Model 4 trailer consisted of two large hollow wheels fitted with a 40 inch (101.6cm) rubber tire 5 inches (12.7cm) wide. The wheels were unsprung but could hold up to 60 imperial gallons (272.8 liters) of fuel, either petrol or diesel, and were covered in rubber to provide a ‘self-sealing’ effect if the wheel hub were punctured by ammunition up to .50 caliber. Between the two wheels was a large rectangular cargo compartment made from ⅛” thick (3.175 mm) thick welded steel. This large space inside could be fitted with an ammunition rack for tank or artillery shells (34 rounds of 75 mm or 108 rounds of 37 mm), small arms ammunition boxes, ration boxes, water or fuel cans, or other items that were required. A second, smaller compartment below this was specifically designed to hold four boxes of .30 ammunition.

Top-down view of the Rota-Trailer Model 4
Top-down view of the Rota-Trailer Model 4 from A.T.C. (NJ) with top cover open. It contained 3 specimen shells in a rack, two 5-US gallon (18.9 liter) ‘flimsies’ and three boxes of rations. Source: The_Chieftain – WoT forum

At the back of the trailer lay a third compartment, smaller than the first, and which contained a hand-operated fuel pump and supply hose long enough to feed the towing vehicle. Below this compartment lay a fourth compartment (just like the one at the front) which held stowage space for tools.

A.T.C.(NJ) Rota-Trailer Model 4
A.T.C.(NJ) Rota-Trailer Model 4 pictured during testing at A.P.G. Summer 1941. Source: The_Chieftain – WoT forum

Overall, the trailer was very complex containing many bespoke parts that made for complicated maintenance. The doors to access the items inside were fitted with wing nuts (butterfly nuts) but were overly laborious to unscrew to access the contents. This is something that could easily have been rectified in a production model.

Rear view of the Rota-Trailer Model 4
Rearview of the Rota-Trailer Model 4 from A.T.C. (NJ) with hand pump (top) and toolbox (bottom) open for inspection. Between the two is a towing hook for additional trailers. The narrow tires and very wide wheel hubs are apparent in this image. Source: The_Chieftain – WoT forum

The Rota-Trailer not only had these internal compartments for stowage but also the ability to have a multitude of items carried on top. A special frame was fitted which held three 5-US gallon (18.9 liter) oil cans, and various tie-downs allowed other accessories such as nets or tarpaulins or other stores to be lashed to the top of the trailer.


Despite looking good on paper, capable of extending the fighting range of a tank, the trailer had serious problems. It was tested by an M4 Sherman and two different half-tracks over a 26 mile (42 km) cross country course and 250 miles (400 km) of gravel roads and, whilst it was on a flat surface, like a road, it worked well with little bouncing. The trailer was heavy too: each wheel weighed 400 lbs (180 kg) empty and 800 lbs (360 kg) when full in addition to the weight of the other material carried. The weight of the trailer placed additional strain on the drivetrain of the towing vehicle and, during rough travel off-road, the stress and strain on the trailer risked serious damage. On top of this, the trailer reduced the maximum speed of the vehicle towing it because the instability of the load caused by the sloshing liquid in the wheels threatened to result in sideways skids at high speeds.

Even as it was, the semi-rough terrain traversed ended up with all of the cans of water inside or on top of the trailer becoming deformed and leaky but the trailer did at least provide self-floatation in mud due to the width of the fuel cells. Another downside was that the lower front compartment, just 8.75 inches (222 mm) from the ground had a tendency to become filled with mud which was forced into it.

A final problem with the trailer was that it made reversing more difficult. During testing with an M4, the trailer skewed to one side and the stress caused damage to the towing arm and the tank tracks rubbing against the trailer body.

Model 4 from A.T.C. (NJ) after testing, the twisted tow arm
View of the Rota-Trailer Model 4 from A.T.C. (NJ) after testing, the twisted tow arm and torn section of the front having been caused by contacting the tracks of the tank. Source: The_Chieftain – WoT forum

Overall, the tests of this A.T.C. product were a failure and the vehicle was not recommended for use. Its main faults were:
Difficult to reverse
Additional strain on the drivetrain of the towing vehicle
Reduces maximum possible speed of the towing vehicle
Too heavy to move easily by hand
Too little ground clearance
No suspension
Steel body is not resistant to small arms fire

None of these faults were to stop further ideas, designs, and experimentation with trailers for hauling fuel or stores by tanks, but the work from A.T.C. (NJ) on this matter was effectively dead. No more is known of A.T.C. after this time; possibly Bechhold’s resources had simply run out and this venture failed, although it is noteworthy that on 1st February 1943, despite the failings of the Rotatrailer, the British still ordered 600 of them anyway, although how many were finished or delivered is less clear.

In the Army

Siegfried Bechhold, aged 42, in October 1942 joined his second Army. His first was a German one in WW1, his second, an American one in WW2. He served as a private being sent to Camp Lee in Virginia. He is not believed to have been sent overseas.

Re-born once more?

The back end of the hull of the Bechhold Tank seen in the November/December 1940 advert is very similar to the vehicle shown to the US Army Ordnance Department in May 1942 known as the Bigley Gun Motor Carriage suggesting a possible link to that vehicle. Was, in fact, the Bigley GMC the M.1938 High-Speed tank from Christie, bought and modified by A.T.C. and then sold off, redeveloped and re-submitted by another firm? Or is it in fact the other Christie tank, the M.1937 sold off by his creditors to Mr. Becchold. On the balance of the evidence, the former case appears to be correct.

Bigley GMC seen in May 1942
Bigley GMC seen in May 1942. Source: US Army Ordnance

By the end of WW2, Bechhold had left the field of tanks and the complications of military work. By 1948, he was living in Florida where he headed the Ribbonwriter Corporation of America, selling parts for typewriters. Siegfried Bechhold died in California in 1956.

A rendition of Bechhold’s tank, as shown in the ad published in the November/December 1940 issue of the Army Ordnance Magazine. Illustration by Adrielcz, funded by our Patreon campaign.


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WW2 American Prototypes

Light Tank T3

USA (1936) Light Tank – 1 prototype

Light Tanks T3 Source: AGF

The Light Tank T3, made in the late 1930s, occupies a period of time in US tank development history best described not so much as a dark age but more of a grey age. Lots of failed and somewhat obscure ‘T’ number designs were being developed to fulfill an unclear and poorly considered set of strategic goals at a time when an isolationist America was unprepared to wage a modern war.

This relatively unknown and obsolete-before-it-was-even-finished tank is remarkable only for its unremarkableness, and that it was inferior in almost every way to tanks of other nations such as Italy, whose 2-man turretless light tanks were also identified as having serious failings in combat. Perhaps, the only thing to distinguish the Light Tank T3 is that it marks one small step in the process of development which eventually led to one of the most successful light tanks of WW2, the Stuart.

The design

The US Light Tank T3 started life in 1936 as an idea by Rock Island Arsenal (RIA) to produce a tank lighter than the Light Tank T2, which was due to go into mass production that fiscal year. At this time, weight was king. The US Secretary of State for War had decreed in the Spring of 1933 that 7.5 US tons (6.8 tonnes) was the maximum weight allowable for a light tank, so the goal was to keep the weight as low as possible. RIA had already dropped the British Vickers 6-ton-style suspension in favor of a double-wheel volute spring bogie from the Combat Car T5 for the Light Tank T2 in 1934. Thus, the suspension which was to form the basis of numerous American designs for the next several years had already been selected when the Light Tank T3 came along. With an attempt to be less than half the fully laden weight of the already light Light Tank T2 (weighing just 7.5 US tons to 9.7 US tons/6.8 to 8.8 tonnes depending on the variant), severe design compromises would have to be made.

The most obvious of these changes was the removal of the turret, followed by a significant overall reduction in size and the switch to a crew of just two instead of four on the Light Tank T2. The two crew were simply the driver on the front left of the hull, and the commander on the front right. The commander also had to operate the sole armament. In an effort to further reduce weight, some aluminum components were also used inside. Finished in March 1936, the vehicle was shipped to Aberdeen Proving Ground (APG) in Maryland in April that year. Here, on 23rd April, the Light Tank T3 was unveiled for comparative testing with the pilot model Combat Car T5 (a tank in all but name).

Pilot model of the Light Tank T2 (no armament fitted) Source: Hunnicutt
The 7.5 US ton (6.8 tonnes) Pilot Combat Car T5 (no armament fitted) Source: Hunnicutt


The Light Tank T3 was powered by a single V8 Ford car engine. Capable of delivering 83 hp at 3,800 rpm, with differential steering and a 4-speed transmission, the Light Tank T3 could manage a credible 35 mph (56 km/h) on a road.

This Ford V8 was later replaced with a Menasco air-cooled engine and as such was renamed Light Tank T3E1.


The Light Tank T3 used a pair of dual-wheel bogies with rubber volute springs of a very similar style fitted to a whole generation of US tanks in WW2. These volute spring units, however, were the result of comparative testing with an experimental rubber torsion suspension. Details on what that suspension actually looked like are unclear but it is known that it failed repeatedly during testing and would need redesigning to be usable. It was not and was abandoned. When the Light Tank T3 was upgraded with a Menasco engine as the Light Tank T3E1, the volute springs were finally selected as the preferred suspension.

The Armament

The Light Tank T3 was very poorly armed, just a single .30 caliber (7.62 mm) machine gun located in the front right of the hull. Mounted in a ball, the range of motion was acceptable but still ultimately as limited as other vehicles such as the Italian CV.3, it faced forwards so could not fire to the sides or rear.


As might be imagined in such a small and light vehicle, the armor was woeful. No part of the Light Tank T3 was thicker than ⅜” (9.5 mm), with most of the armor being just 3/16” (4.8 mm) thick, enough to protect against small arms from the front but vulnerable to even a burst from a machine gun or shot from an anti-tank rifle. With such poor armor, it is no surprise that an idea was floated to increase the armor thickness to an unspecified value in another variant known as the Light Tank T3E2, with the issuing of the tank to the National Guard in mind. This was never completed and the Light Tank T3E2 was never built. There was also a T3E3 version that got as far as a study but it is not known exactly what the study was about and whether it was armor or automotive related or something else.

US Light Tank T3 pictured during trials on 13th March 1936. No armament is fitted but it does have a very shiny single front headlamp on the glacis nose and what appears to be some kind of siren on the mudguard. Source: Hunnicutt


T3E1: upgraded T3 with a Menasco engine. 1 converted.
T3E2: T3 project with increased armor. None built.
T3E3: unknown study project


When the Light Tank T3E1 was abandoned, it was not wasted. Instead, the remaining vehicle was stripped of its armament and converted into an experimental tracked carrier named the Cross-Country Carrier T5. The sole contribution of the Light Tank T3 is perhaps to show the futility of a two-man tank armed with just a single machine gun. The cost of the vehicle and the poor combat potential meant that, despite moderately good mobility, it was still a failure. Of the variants attempted, the Light Tank T3E1 was at least an improvement with a better engine but the E2 with more armor was dropped before it began. The Light Tank Tank T3E3 got as far as a design study but how far and quite what they were even trying to study is not clear. The concept was a dead end. The vehicle was converted to a tracked utility carrier and quite rightly consigned to the dustbin of US tank design.

With a soldier for scale, the tiny Light Tank T3 shows really just how small it was. Source: Hunnicutt
The T3 light tank was tiny, armed with just a single machine-gun and seating two crew members in the front compartment. The rear rounded compartment housed the engine. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.


Dimensions 11.25’ x 6.75’ x 4.5’ (3.43 x 2.06 x 1.37 m)
Weight 3.54 US tons / (3.21 tonnes)
Crew 2 (Commander/gunner, and driver/radio operator)
Engine Ford V8 Petrol (T3), Menasco air-cooled (T3E1)
Max. speed 35 mph (56 km/h)
Armament 1 x .30 caliber machine gun
Armor ¼” to ⅜” (6.35 to 9.53 mm) (T3), slightly heavier armor (T3E2)


AFV Data Series
Crimson, F. (1992). US Military Tracked Vehicles. Crestline, USA
United States Army. The General Staff: Its Origins and Powers
AGF Board. (1947). Development of Armored Vehicles Vol.1: Tanks.
Hunnicutt, R. (1992). Stuart: A History of the American Light Tank. Presidio Press, USA

Coldwar American Prototypes

FMC Howitzer Improvement Program (HIP)

USA (1979-1983)
Self-propelled gun – Project only

FMC HIP design. Source: Janes

The SPG deficit

The United States had, by the 1970s, realized that the majority of their artillery was aging rapidly or just out of date. Open topped, slow, vulnerable, based on obsolete chassis, the existing self-propelled guns (SPG’s) in service were not suitable for a potential Cold War showdown with the Soviet Union, which had a more modern SPG force. Early development work took place under the program names Division Support Weapon System (DSWS) and Direct Support Armored Cannon System (DSACS). The DSWS had changed by 1979 into the Enhanced Self-Propelled Weapons System (ESPWS) program with the goal of producing a common platform for self-propelled artillery for the Army.

All of these programs were also grouped under the general name of the Howitzer Improvement Program (HIP). This development was to take multiple strands. One was work commissioned from the firm of Norden to study improvements to the existing M109 fleet as well as an examination of foreign systems in use or development. This included the French GCT and the multinational SP-70 project. The M109, a system developed in the 1950s and first fielded in 1963, was a prime candidate for upgrading or replacement. In 1980, the replacement for the M109, incorporating elements of the other programs, was underway and after 3 years of work several alternatives for replacement or modernization of the M109 had been evaluated as part of the Howitzer Improvement Program known as HIP.

HIP outline

With the multitude of acronyms involved before work had even begun, it is easy to become confused, but the HIP program laid general principles a future system would have to meet to be acceptable. Firstly and most importantly, the caliber was defined. It had to be a 155 mm gun with a barrel length not less than 38 calibers long (5.89 m) and not longer than 50 calibers (7.75m) capable of firing standard 155 mm shells to 25 km. HERA – High Explosive Rocket-Assisted – ammunition would be available in order to extend this range to 30 km. Shells would be loaded by means of an automatic loader system reducing the crew down to a nominal 4 with some optimism that it could be reduced to 3 and operated in an emergency by just 2 men.

Not less than 50 rounds were to be carried with a target of up to 75 shells which, working with the automatic loading system, could deliver between 8 and 12 rounds per minute. If the automatic loading system was omitted and a manual system retained, then the rate of fire would drop to just 4 rounds per minute, as well as impacting the number of crew required to operate the gun. The alternative consideration was a ‘halfway house’ of a semi-automatic system rather than manual or fully automatic with an estimated rate of fire of between 4 and 8 rounds per minute. The desire was for a state of the art system to meet the RAM (Reliability, Availability, Maintainability) requirements with computer-controlled and monitored systems. Fire control was to be by means of an onboard ballistic computer and computer-controlled gun motors. This combination allowed the system to fire, relocate to avoid counter-battery fire, and then fire again in under 1 minute. The ability to avoid enemy counter-battery fire was a significant improvement and step forward.

Protection was to be just of an ‘improved’ type over what (presumably) there already was in comparison on the M109 and the vehicle had to have an NBC overpressure system fitted as standard. A further note was that for self-defense the vehicle would be provided with a single .50 caliber heavy machine gun on the commander’s cupola. For mobility, the HIP required a new powerful engine capable of delivering not less than 20 horsepower per ton capable of propelling the various vehicles based on this chassis to a road speed of 60-75 km/h, to a maximum operational range of between 400 and 600 km. All vehicles had to be capable of transportation via a C-130 transport aircraft.

HIP Chassis family

Each SPG would have an associated and dedicated Ammunition Resupply Vehicles (ARV) with between 80 and 150 additional rounds of ammunition. This vehicle was to be based on the same chassis as the SPG itself, with a crew of 3 or 4 and the same level of protection.

Another vehicle would be the Battery Operations Center (BOC) also based on the chassis with a crew of 7 (in two shifts) and an Armored Maintenance Vehicle (AMV) with a crew of 2 (and 4 mechanics). Each AMV would carry spares, tools, and even a complete spare power pack for the chassis. The vehicles were to be assigned to a battery at the rate of one AMV per battery.

A battery would therefore consist of 3 SPG’s, 3 ARV’s, 1 BOC and 1 AMV for a total of 3 guns, up to 675 x 155mm shells, and between 28 and 45 men.

HIP was to be an integrated part of all Army divisions replacing the vehicles already in service at a rate of one battalion to each Army brigade

Battalion makeup for the HIP program. Source: Author

The FMC Proposal New Start

By 1984, FMC (Food Machinery Corporation) had made their own proposal to meet the demands of the HIP program as specified under the name ‘DSWS New Start.’ The basic arrangement of the proposal was an unusual-looking vehicle with a completely fixed superstructure on the rear of the chassis. The engine was mounted in the front and the ammunition (in drums) sat at the top rear of the casemate. The 155 mm gun mounted into this superstructure was not completely fixed and had the ability to move up to 5 degrees left or right. The driver sat forwards of the casemate, in a raised structure that extended back along the hull into the casemate. This would permit him to come back into the fighting space rather than be isolated in the driving position. The chassis itself was mounted on 7 road wheels with 4 return rollers and drive to the tracks delivered by a front-mounted sprocket. Power would be provided by an unspecified 700 hp engine.


The requirement was for a 155 mm gun 38 to 50 calibers long and FMC’s design was for a 45 caliber weapon which was under development at Watervliet Arsenal. The range required was 25km (30km with rocket assistance) but this FMC proposal gave the maximum range with standard (non-rocket-assisted) projectiles as 23km.

Shells would be delivered via a fully automatic system feeding from two large drums containing a maximum of 50 rounds divided equally, with one drum on each side of the breach. Fifty shells were the minimum required by the program but this FMC proposal could fulfill the other needs for full automation including fuze setting which was incorporated into the breach and was fully compatible with the existing 1 to 8 zone bag charge propellant system or the then newly proposed 5-zone modular propellant. Shells would be reloaded via the Ammunition Resupply Vehicle via two large hatches in the rear of the gun.

The end of the new start

The DSWS project was canceled by 1983. It was seen as being too expensive and too complicated. The focus would instead be on modernizing the existing M109 fleet and the HIP project would roll on sucking in more cash. For their part, FMC had produced a capable design whose biggest flaw was probably not the cost but the lack of a turret. They had met almost all of the requirements set by HIP and would try their hand at the M109 modernization instead, rolling much of their development work into a new M109.


Like many of these multi-year huge contracts in the US, this one is an enormous project of overlapping requirements. The HIP program didn’t end with the cancellation of the FMC DSWS New Start concept, it was still going on into 1991. This was the date by which the vehicles were meant to have been entering service yet development hadn’t even finished and only 8 prototype improved vehicles had even been made by 1989. The project was simply too large and phenomenally expensive. In 1989 alone, for example, the HIP program cost nearly US$28.5million and nearly US$10.5million the following year. It didn’t matter anyway for FMC. All work on a complete replacement for their project was terminated by 1984 with the decision being made at the time to simply modify the M109 fleet with new ammunition stowage and a longer range gun instead. The project was overall somewhat of a failure, no new vehicle was produced and a huge amount of money was spent. The opportunity for a new and more capable platform producing a new family of vehicles was lost.

Illustration of the FCM New Start Howitzer Improvement Program, showing the forward placed driver compartment connected to the rear fixed superstructure. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.

Specifications required for Future Self-Propelled Artillery System

Propulsion Advanced new engine delivering at least 20 hp/t
Top speed 60 to 75kmh (road)
Operational maximum range 400-600km
Armament 155 L38 to L/50 main gun, one cupola mounted .50 cal heavy machine gun
Ammunition All current and future compatible NATO 155mm shells, modular combustible case shells as well as guided, unguided and rocket-assisted shells.
Armor Unspecified ‘improved’ armor

FMC proposal ‘DSWS New Start’

Armament 155 L45 main gun, one cupola mounted .50 cal heavy machine gun
Ammunition 50 rounds in two 25 round drums with fully automatic feed capable of firing unassisted projectiles to 23km


GAO Report AD-A141 422 M109 to M109A5 Report, March 26th 1984
Janes Armour and Artillery 1984-5
US Army Tank Automotive Command Laboratory Posture Report FY 1982, US Army
Research Development and Evaluation Army Appropriation descriptive summaries, January 1990, US Army Congressional Report
Report ARLCD-CR-81053, Demonstration Prototype Automated Ammunition and Handling System for 155mm Self-Propelled Howitzer Test Bed, December 1981, US Army ARRADCOM

WW2 German prototypes

E100 (Entwicklung 100)

Nazi Germany (1942-45)
Super heavy tank prototype – 1 partially completed

The E100 was a project which is occasionally and somewhat erroneously referred to as a rival to Dr. Porsche’s Maus design. This is not strictly true, as the E100 came after the 130-tonne Tiger-Maus design from Krupp, which was the Maus-rival. When the Porsche-Maus was approved by Hitler on 3rd January 1943, the Krupp Tiger-Maus was abandoned. Shortly thereafter, Ernst Kniekampf (Panzer Kommission), without informing Krupp, gave work on the project over to the firm of Adler at Friedberg to build a simple prototype (E100 versuchs-farhgestell: Experimental 100-tonne test hull) for trials. This was done despite the lack of experience by the firm in the design or manufacture of tanks and turrets. According to Kniekampf, Krupp was already overburdened with other work, but it lay within Kniekampf’s general Entwicklungsreihe versuchs panzerkampfwagen (development series test armored vehicle) framework trying to rationalize tank development in different weight categories. It would be nearly a year later (after the failure of the Porsche-Maus production plans), that the failed Tiger-Maus, a vehicle which showed a large amount of promise in simplified production over the Maus, had shown any substantive progress.

Although Adler’s work on this 100-tonne hull project began at the end of June 1943, it would not be until spring 1944 that the program had progressed to the point of anything more than just an idea to produce a test hull (although some parts had started to be assembled at Paderborn). This means that the E100, strictly speaking, started after the Maus was approved and that it was not a rival to the Maus in any sense. It was not a copy of the Tiger-Maus, but a further development from it and was a promising step towards the rationalization of German tank production in WW2.


The Krupp 130-tonne Tiger-Maus had been a logical rival to the Porsche-Maus, using already available components from the Tiger II and Panther projects which had been designed and tested. From the engine to the suspension, the Tiger-Maus would be substantially heavier than both of those vehicles but would be much easier to produce, operate, and maintain than the Porsche-Maus because of those shared components. In contrast, the Porsche-Maus almost every element had to be designed from scratch. There was, by the end of 1942, when Krupp was seeking production orders, only 3 elements left to resolve for the Tiger-Maus. The first was the engine. A 700 hp Maybach HL 230 P30 had been selected for expediency, in the absence of the 1,000-1,100 hp* supercharged version promised to be ready in time for production by September 1943. The second was the transmission and steering. Although the L801 steering system from Tiger II could be used whilst the Tiger-Maus was still planned with the 700 hp HL 230 P30 engine, when the new engine (Maybach HL 234 delivering 1,000 – 1,100 hp*) was ready, the steering system and transmission needed to be strengthened to deal with the additional stresses. Work on that element was also underway and would be ready in time for the production of the vehicles. Finally, the least of the problems with the Tiger-Maus was the desire for a lighter turret. The original had weighed 45.5 tonnes and constituted an excessive proportion of the weight of the tank due to its heavy armor. Wa Pruf 6 had pressed for a much lighter turret, although by the end of 1942, this does not appear to have progressed, as the vehicle was still weighed just shy of 130-tonnes.

(*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)

If Krupp had started to play around with ideas for reducing the weight of the turret, this would have to have involved a significant reduction in the armor protection offered. This is due simply to the fact that the steel armor of the turret was the single largest contributor to its overall weight. Reducing the turret weight to between 25 – 30 tonnes would have meant that the vehicle would weigh around 110 tonnes. Coincidentally, when the 130-tonne Tiger-Maus was resurrected in 1943, it was in the class of a 100-tonne tank (Entwicklung 100 – Project tank 100 tonnes).

Projected Hull and Turret Weight Percentage Comparisons

Component 130-tonne Panzer 130-tonne Panzer with lightened turret per Wa Pruf 6
Hull Weight 83.4 tonnes 83.4 tonnes 83.4 tonnes
Turret Weight 45.5 tonnes 25 tonnes* 30 tonnes*
Overall Weight 128.9 tonnes 108.4 tonnes 113.4 tonnes
Hull as a % of overall weight 64.7 % 76.9 % 73.5 %
Turret as a % of overall weight 35.3 % 23.1 % 26.5 %
Notes For comparative purposes, the Serienturm on the Tiger II represented 21.9 % of the vehicle’s overall weight.
* Estimates for the purposes of illustrative analysis ONLY shown in italics.

The first mention of this new 100-tonne project was on 18 March 1944, when Krupp’s representative (Obering Woelfert) learned that a wooden model of this new tank was going to be inspected by the end of the month by representatives from Wa Pruf 6. This was after Director Jenschke from the firm of Adler in Frankfurt had handed over the drawings, presumably Krupp’s drawings from the previous January. At a meeting at the end of May 1944 between Krupp and Kniekampf, it was confirmed that the E100 was essentially just the 130-tonne Tiger Maus with a modified suspension.


Adler had been working on the E100 hull project since 30 June 1943 and had slowly been assembling parts at Paderborn, but little had really been done until the spring of 1944 when Krupp was to learn of the project. Krupp representatives, rather understandably, appear to have been annoyed by what they saw (quite correctly) as their hull design (for the 130-tonne Tiger-Maus), a design which was rejected in January 1943, given to another firm (with no experience in making such things) for development (in secret away from Krupp). It could be speculated that the reason for the involvement of Krupp was that someone had to assemble the hulls and they were the only firm able to take the armor plates and weld them together to produce a hull on which those parts could be assembled.

Regardless of being circumvented, Krupp appears to have fulfilled whatever obligation was being asked of them regarding the E100 Fahrgestell (test hull) and by 15th January 1945 assembly of the hull was well underway at Hauestenbeck (near to Paderborn).

At this time (15 January 1945), the hull was awaiting its spring suspension to be fitted (the springs were made but were shipped to the wrong location by mistake) and the assembly of the fuel lines (which had not arrived). Other than those parts, the majority of the automotive elements had been installed and the track guard sections (all 6 of them) had been delivered. There was also a stock of the transport tracks (transportkette) on hand although the combat tracks (gefechtskette) had not arrived. The rest of the internal components in the fighting compartment were in the process of installation, after which the final drive-train components, such as the steering system, brakes, final drives, and driveshaft would be installed.

The report on the production status of this test hull also requested information about the turret (or similarly-shaped test weight) so that a means of mounting it onto the hull could be arranged. Further work on the assembly continued through these first months of 1945, but with the war situation collapsing, the vehicle remained unfinished when the site was captured by Allied troops in May 1945.

What the Allies found was a hull with the engine (700 hp Maybach HL 230 P30), transmission (Maybach OG 40 12 16 B) and steering system (Henschel L801) fitted. The combat tracks missing in January 1945 had arrived and the springs had been fitted, but the drive-sprocket toothed-rings were still missing.


The E100 followed the same path in automotive terms as the work on the 130-tonne Tiger-Maus which preceded it. It was initially to use a Maybach HL 230 P30 engine delivering 700 hp at 3,000 rpm, although on the 130-tonne vehicle this would have delivered an anaemic power to weight ratio of just 5.4 hp/t. What it did mean was that it could use an existing transmission and steering system and still manage a top speed of just over 20 km/h. This would overstress the Henschel L801 steering system, but was an expedient option to try and produce this test hull quickly. The transmission selected was the 8-speed Maybach Olvargetriebe OG 40 20 16 B which was limited to being able to handle 800 hp, but a new system would be required to handle more power from a new engine. The fact that Wa Pruf 6 and Krupp were both wanting a system capable of handling up to 1,200 hp for the Tiger-Maus as far back as November 1942 adds yet more credibility to this thought.

This led to the second scheme for the drive train for the E100. This scheme used a 1,200 hp Maybach engine (a supercharged version of the HL 230 known as the HL 234) connected to an 8-speed ‘Mekydro’ mechanical/hydraulic-type transmission and steering unit combined. Working together, this new engine and new transmission would have allowed this new E100 design to have an improved power to weight ratio and manage 40 km/h. Unlike the original E100 scheme which retained the common front-wheel-drive system on German tanks (engine at back, transmission at the front), this scheme would place the transmission at the rear, with the engine compartment becoming longer and further forwards. In turn, this would have brought the turret further forwards which would have resulted in a very different-looking E100. Sadly, no drawings remain of this layout as Adler destroyed many of their drawings at the end of the war. Indeed, the only reason the general layout of the E100 with the modified Maus II turm is known at all it because the Allies had draughtsmen from Adler redraw them after the war from partially burnt originals.


The only substantive differences between the 130-tonne Tiger-Maus and the E100 was the suspension. Gone on E100 was the Tiger II-style torsion bar suspension. Instead, the tank was to adopt an external Belleville-washer-type suspension system omitting the torsion bars under the hull floor. This would save weight, improve simplicity, and reduce space being wasted inside the hull, meaning the hull could be lower. Further, it allowed for an escape hatch to be fitted into the floor, which would have been difficult with a torsion bar design. The Belleville-washer system relied upon coiled springs, although delivery of them to the E100 prototype was delayed as they had been shipped by train to the wrong location in January 1945 and by the middle of the month had still not arrived. This system had been developed by Dr. Lehr of M.A.N. (the parent firm of the Panther) and was better than the torsion-bar system, as it reduced the pitch rate of the vehicle, making it more stable on the move.

The Belleville-Washer system used a pair of overlapping wheeled guide lugs which were suspended on the outside of the hull by a pair of double spiral coil springs. On the inside of the hull, there was very little space used up as only the shock absorbers for the system impinged on the crew space.


It is surprising for a very heavy vehicle like the Tiger-Maus that the turret was relatively poorly protected. The hull of the E100, just as the Tiger-Maus before it, was extremely well protected with 200 mm of armor angled at 60 degrees at the front on the glacis, sides 120mm thick (vertical) with additional, heavily armored demountable side sections and 150 mm at 30 degrees at the back. The turret, in contrast, provides less protection on all sides to the hull with a front 200 mm thick angled at 30 degrees, sides just 80 mm thick at 29/30 degrees and a rear 150 mm thick at 15 degrees. The turret sides, therefore, were only the same thickness as the sides of the Tiger I, albeit with some shallow angling. The same protection for the turret sides on this substantially larger turret was provided for on the Tiger II serienturm, but providing a much smaller target. It could be questioned why the rear armor was 150 mm thick on the turret but heavy armor on the turret rear obviated two problems. The first was reducing the chances of mistaken friendly fire from behind destroying the tank, and the second was that it added a lot of weight to the back to help counterbalance the enormous weight of the front of the turret (armor and guns).

NotesThe turret structures are essentially the same save for reduced thickness for the E100 turret, but the sides of the Maus II turm were 30 degrees yet are given as 29 degrees for the E100 turm. This is likely an error in production rather than a design difference.
* Ring diameter for Maus II lies between 2,388 and 2,959 mm
** Maximum possible diameter of ring
+ Consideration also given to a 15 cm and 17.4 cm gun
++ Drawing 021A38300 retained many early Maus turm-features such as the crew hatch on the rear)

Comparison between Maus II turm and E100 turm

Maus II turm Maus II turm
(mit neue entfernungsmesser)
E100 turm
Date <15th March 1944 15th May 1944 <17th May 1944++
Drawing No. Bz 3269 Bz 3250 021A38300++
Front 220 mm @ 30 deg. 220 mm @ 30 deg. 200 mm @ 30 deg.
Sides 200 mm @ 30 deg. 200 mm @ 30 deg. 80 mm @ 29 deg
Rear 200 mm @ 15 deg. 200 mm @ 15 deg. 150 mm @ 15 deg
Roof 60 mm @ 0 deg. 60 mm @ 0 deg. 40 mm @ 0 deg.
Hull Weight HullWeight HullWeight HullWeight
Turret Ring Diameter (mm) 2,388 > ? < 2,959* 2,388 > ? < 2,959* 2,910 (internal)**
Weight 47 – 50 tonnes 47 – 50 tonnes 35 tonnes
Armament 12.8cm Kw.K. 44 L/55 and 7.5 cm Kw.K. L/24
Rangefinder 2.1 m wide Improved 1.9 to 2 m wide 2.1 m wide

For all of the heavy armor protection on the E100, it is perhaps remarkable that the turret sides were left so poorly protected compared to the rest of the vehicle. The heavy armored side plates, for example, could have been scrapped from the design to save weight to make the sides of the turret thicker to match the protection levels of the hull sides, but instead, a vehicle whose armor everywhere else was all but immune to the majority of Allied tank guns was otherwise remarkably vulnerable on the turret sides, a flaw identified already on the Tiger II.


Obering Rabe of Porsche reported on 17 May 1944 that the turret for the planned E100 weighed just 35 tonnes (a loss of just over 10 tonnes from the original Tiger-Maus plans) and marks a reduction in armor from the Maus II turret. This can be confirmed as being the basic design of the Maus II turret by considering a timeline of the events of the Maus turm development

Maus / E100 turret key dates

Date Turret Note
12/1/1943 Maus turm Modifications to Maus turm (Type 205)
May 1943 Maus turm Full-sized mockup of original Maus shown – Porsche suggests reshaping front of turret to avoid shot-trap
Sept/Oct 1943 Maus turm Version with improved roof armor for bunkers considered – abandoned
14/3/1944 Maus II turm Drawings sent from Krupp to Porsche
23/31944 Maus II turm Slope-fronted with 7.5 cm gun over 12.8 cm gun
8/4/1944 Maus II turm Contract to Krupp for 1:5th model to be made
16-17/4/1944 Maus II turm Krupp and Wa Pruef 6 meet to discuss turret improvements for Maus II
15/5/1944 Maus II turm Contract amended for additional turret design incorporating new range finder
17/5/1944 E100 turm Slope fronted with 7.5cm gun mounted over 12.8 cm gun – this is a version of the Maus II turm with less armour.
35-tonne turret adopted for E100
12/8/1944 Maus II turm Work underway by Krupp of two Maus II turret models

When, in 1945, the Allies captured Adler’s works, they found many files had been burned. Under their supervision, drawing 021A38300 was redrawn from the burnt scraps of the original. That drawing showed the original Maus-shaped turret from the Typ 205 dating back to the end of December 1942/January 1943, rather than the Maus II turm which was the turret intended. The reason for this is fairly clear, the Adler workers were simply working off the left-overs from the Tiger-Maus program and this was the Krupp turret shown on that hull when they redrew it with their suspension changes. This accounts for why the turret retains so many early Maus features, such as the side viewports, rear crew hatch, and the lack of coincidence rangefinder. That turret weighed in excess of 50 tonnes and was abandoned long before E100 was even a glint in Heydekampf’s eye. E100, in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work down to just 35 tonnes. Depictions of the E100 therefore with this turret are incorrect even though they are shown in the recreated original drawing. Adlerwerke employees, after all, were not contending themselves with turret design, but with the completion of the hull for trials and awaiting a turret which was a separate development.

Typ 205 from December 1942/January 1943, showing the distinctive and very large rectangular Maus-stye turret. Drawing 021A38300, redrawn post war showed this turret on the E100 hull (see below) Source: Frohlich

E100 turret
Original Krupp Maus turm (number 1) as fitted to the Maus (top), and the improved Krupp Maus II turm dated 23rd March 1944 (not to scale). Source: Jentz and Doyle

E100 blueprint
Inverted-colour blueprint for the completed E-100 showing the Typ 205 (December 1942/January 1943 Maus-style turret per drawing 021A38300) on a hull with a new type of overlapping-wheel suspension.


The report from Rabe (Porsche) on 17 May 1944 confirms that the turret selected for the E100 was the Maus II turm Krupp was designing with the improved range finder. That turret was to have the sloped front with the armament mounted on trunnions on the outside rather than the inside and with the guns stacked – the 7.5 cm gun Kw.K. L/24 over the 12.8 cm Kw.K. L/55.

There was, at the end of May 1944, a discussion between Krupp and Kniekampf on a change in the planned armament for this experimental 100-tonne tank with the focus moving from the 12.8 cm/7.5 cm partnership carried over from the Maus and back to consideration of a 15 cm gun. The Porsche Maus had originally been intended for an option for a 15 cm gun as well, but this had been effectively dropped on the Maus II as the 12.8 cm gun was, after all, available, (unlike the 15 cm gun) and highly effective at what was required from it, namely penetrating enemy structures and armor.

Recovery and Fate

The partially completed E-100 hull was uncovered by the British and shipped back to the UK in 1945 for examination. The sheer bulk of the hull alone created problems and slowed the shipping, indicating perhaps just how impractical a 100+ tonne tank would have been for Germany in 1945.

Back in the UK, the vehicle was thoroughly examined and sadly was later disposed of, chopped up for scrap in the post-war austerity of a nation which had bankrupted itself to defeat Germany.


The development of the E-100 was a drawn-out and complex affair. Like other German heavy tank projects, the E-100 was heavier and more complicated than originally planned as the size, shape, and features of the tank had to be made to conform to the rail gauge. As the suspension, and in particular, the turrets were changed from one project to another.

The redrawn blueprint certainly has caused some confusion post-war but the idea of a 1944/45 tank project using a turret from 1942 remains a conundrum. Regardless of whether it had that Type 205 turm or the Maus II turm though, the project was a failure that did not address the fundamental weakness in German tank design or armor theory.

No single design or single vehicle was going to deliver a victory for Germany in WW2 and whilst we can, with the benefit of history admire some of the technical achievements for making such a large and heavy vehicle, we should also consider that Germany was abandoning vehicles half its weight when they broke down for lack of being able to recover them. With crippling fuel shortages adding a new, bigger, and thirstier, vehicle and one which surpassed any easy means to recover in combat if it was immobilized the E-100 was merely a distraction to the general German war effort.

The E100 with the correct Maus 2-like angled front turret and showing the rounded detachable side plates. It mounts the 12.8 cm gun with the 7.5 cm on top. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon campaign.

Panzerkampfwagen E-100 Specifications

Dimensions 11.073 m long (8.733 m without gun) x 4.48 m x 3.375 m
Total weight, battle-ready 123.5 tonnes combat loaded (turret 35 tonnes, hull 88.5 tonnes)
Crew 6 (commander, gunner, 2 x loaders, driver, radio operator)
Propulsion Maybach HL 230 P30 V-12 Petrol delivering 700 hp
Maybach HL 234 V-12 Petrol delivering up to 1,200 hp
Speed (road) 23 km/h (HL 230), up to 40 km/h (HL 234)
Trench 2.9 m
Main Armament 12.8 cm Kw.K. 44 L/55 interchangeable with 15 cm
Secondary Armament 7.5 cm Kw.K. 44 L/24
7.92 mm M.G.34 or M.G. 42 machine gun
Turret Armor Front – 200 mm @ 30 deg.
Sides – 80 mm @ 29/30 deg.
Rear – 150 mm @ 15 deg.
Roof – 40 mm @ 90 deg.
Hull Armor Front Glacis – 200 mm @ 60 deg.
Lower front – 150 mm @ 50 deg.
Sponson floor – 30 mm @ 89 deg.
Side – 120 mm @ 0 deg.
Rear – 150 mm @ 30 deg.
Floor front – 80 mm @ 90 deg.
Floor middle and rear – 40 mm @ 90 deg.
Roof – 40 mm @ 90 deg.


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British Intelligence Objectives Sub-Committee. (1945). BIOS report 1343: German Steel Armour Piercing Projectiles and Theory of Penetration. Technical Information and Documents Unit, London.
British Report on ‘Experimental Super Heavy Tank ‘Mouse’ (Pz.Kpfw. Maus)’ – May 1945
CIOS Final Evaluation Report 153. (28th June 1945). Interrogation of Herr Stiele von Heydekampf.
Datenblatter für Heeres Waffen Fahrzeuge Gerät W127. (1976).
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Ogorkiewicz, R. (1991). Technology of Tanks. Janes Information Group, Surrey, England
Sawodny, M., Bracher, K. (1978). Panzerkampfwagen Maus und andere deutsche Panzerprojekte. Odzun-Pallas-Verlag, Friedberg, West Germany
Spielberger, W. (1998). Spezialpanzerfahrzeuge des Deutschen Heeres. Motor Book Verlag
Spielberger, W., Milson, J. (1973). Elefant and Maus. AFV Weapons Profile No.61.
US Army. (1953). Technical Manual TM9-1985-3 German Explosive Ordnance (Projectiles and Projectile Fuzes)
US Army. (1946). Intelligence Bulletin March 1946. The German Mouse.
US Navy. (September 1945). Technical Report 485-45 – German Powder Composition and Internal Ballistics for Guns. US Naval Technical Mission in Europe Report.
War Office. (25th October 1944). 12.8cm A.Tk. Gun Pak.44 on Pz.Jag. Tiger (Pz.Kpfw. Tiger B Chassis) Sd.Kfz.186 JAGDTIGER. Appendix D War Office Technical Intelligence Summary, No.149 1944.
War Office. (25th April 1945). Technical Intelligence Summary Report 174 Appendix C
War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
War Office. (27th June 1945). Technical Intelligence Summary Report 180 Appendix D
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F and G
War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

Cold War British Prototypes

Vickers Mk.4 Valiant

United Kingdom (1977-1985)
Cold War MBT – 1 built

The Chieftain tank replacement?

The final decades of the Cold War saw a generational change in Western tanks as they faced off against the armies of the Warsaw Pact across Central Europe. The Soviet-led forces were dominated by tanks such as the T-55, T-72 and variants of both, and there were continuing concerns over even newer Soviet tanks with improved armor and firepower. The Western tank armies of NATO were dominated by an older generation of tanks in a long and slow process of improvement and replacement: the British wanted a replacement for the Chieftain, the Americans were replacing the aged M60 with the new M1 Abrams, and the Germans were replacing the Leopard I with the Leopard II. Much of that Western generational change from tanks based on steel armour had come about as a result of the British development of a new type of armor, announced in June 1976 as ‘Chobham’. A whole new level of protection for Western tanks promised to provide a true qualitative edge in protection over their Soviet contemporaries. With this new armor, and a need for a replacement for Chieftain urgently required, there was a clear opportunity for a large and lucrative contract for a new main battle tank for the UK, and potentially for export.

Vickers Mk.4 Valiant (Ground Defence International No.70 December 1980)

Based in Newcastle-Upon-Tyne in the northeast of England, engineers at the British firm of Vickers, with decades of tank building experience, were, at this time, developing a new ‘conventional’ tank for the export market: the Mk. 3. Using the availability of this new Chobham armor, they applied that knowledge to their Mk. 3 to produce one of the first of this new generation of tanks moving away from tanks reliant solely on steel armor, analog fire control and ranging to a new era of enhanced protection and digital fire control. Originally simply referred to as the Mk. 4, it soon gained a much more marketable name, the Valiant.

Vickers Mk.3 MBT
Vickers Mk.3 MBT – a conventional tank reliant on steel armor was the apex of conventional steel tank design for Britain with good mobility and excellent protection on the turret. The arrival of Chobham provided a qualitative step-change in protection available to tanks. (Source: Foss and McKenzie)
Vickers Mk4 Valaint
Vickers Mk.4/Valiant during early trials. (Source: Vickers)


The Valiant followed a conventional layout with the driver in the center of the front of the hull, the turret roughly central, and the engine in the back. On top of the hull was the large rectangular turret with vertical sides and an angled front made from flat panels. The gun, located centrally on the front of the turret, was flanked by a pair of smoke dischargers, and on the roof were two circular hatches for the commander on the right, and the loader on the left. A rectangular sight was provided on the front right of the turret roof for the gunner who, in keeping with British general tank-layouts, was located on the right, in front of the commander.


Work on the Valiant began in earnest at the end of 1977 and progress began on manufacture from March 1978 through November that year and the initial turret was finished in September 1979.

A working prototype was being put through mechanical trials in June 1979, meaning it had taken less than 2 years to go from drawing board to the testing ground. Those automotive trials ended in September with some problems identified and the vehicle was returned to the factory for modifications in December. There, it was taken apart and thoroughly examined and the improvements started. Reassembled and improved, it was ready for unveiling to the British Army as a potential replacement for the aging Chieftain.

Vickers Mk.4 Valiant during early trials
Vickers Mk.4 Valiant during early trials. Note the single periscope for the driver. (Source: Vickers)

When the British Army received this tank in March 1980 at Bovington Camp in Dorset, it was faced with a tank unlike anything it had seen to that point. Gone was the highly sloped casting of the Chieftain to try and deflect incoming shells. Instead, this was replaced with a very rectangular turret made up of a series of flat faces, the defining characteristic of a tank made with Chobham technology and a general shape for which this new Western tank-generation would exploit.

Trials of this new tank began immediately to check for automotive performance and firing trials over their course. The formal public unveiling took place at the British Army Exhibition at Aldershot in June 1980 along with its formal new name ‘Valiant’. This new development was made possible by the formulation of an international sales consortium with Societe de Fabrication d’Instruments de Mesure (SFIM) (responsible for the panoramic stabilized commander’s sight), Vickers Instruments (gunners, telescopic, and unitary sights), Marconi Radar UK (gun stabilization and fire control), Philips and Odelft of Netherlands (panoramic stabilized thermal imager), and Simrad of Norway (laser range finders for the commander and gunner) each of whom invested financially in the project.

With these new partners, the redevelopment of the turret unveiled in 1980 was progressed and manufacture commenced at the Elswick, Works of Vickers, in 1981 followed by a demonstration of the finished product in the British Army Exhibition at Aldershot in 1982. British Army trials were completed by late 1982 after the tank had covered over 4,500 km of automotive and operator trials with few problems.

Still bearing Trade Plates VRM 447 BB the Valiant
Still bearing ‘Trade Plates VRM 447 BB’, the Valiant, with turret reversed is put through its paces. The single periscope for the driver dates these images to 1982.

British Army officers inspect the Valiant during trials
British Army officers inspect the Valiant during trials. (Source: GDI)

Following the 1982 unveiling, a promotional video was created at Long Valley, Aldershot, with the vehicle painted in a very-non-standard camouflage scheme for dramatic purposes. The goal was not to show some new style of camouflage, but simply to be noticed despite the non-military emulsion paints used and not to be confused with the Chieftain 900 project: an armor and mobility upgrade option offered for the old Chieftain.

Fitted with the L11A5 120 mm rifled main gun
Fitted with the L11A5 120 mm rifled main gun and sporting a very fancy non-standard camouflage, the Valiant is put through its paces at Long Valley, Aldershot. (Sources: Janes)
The Chieftain 900 shows little resemblance with the Valiant hull
The Chieftain 900 shows little resemblance with the Valiant hull although the general shape of the new turret led to a desire to visibly differentiate the Valiant. (Source: fighting


The commander was provided with a slightly raised cupola consisting of 6 fixed x1 magnification non-reflecting Heliotype viewers. Sighting for the commander was provided by the French SFIM VA 580-10 2-axis gyro stabilised panoramic (360 degree) sight. This sight had two magnification modes, x3, and x10 and incorporated a Nd-YAG-type laser rangefinder and had been added to the design in 1979 following a tour of the plant by Derek Rile and Patrick Michon of SFIM as part of their UK-wide sales tour. In addition to this was a PPE Condor-type 2-axis gyro-stabilised image intensifier (Phillips UA 9090 thermal sight) displayed on a 625-line television monitor for the gunner and commander alike.

The gunner had a x10 magnification Vickers Instruments L30 x10 telescopic laser sight with Barr and Stroud LF 11 Nd-YAG-type laser rangefinder fitted with a projected reticle image (PRI) for ranging. This was mounted coaxially with the main gun, directly on the rotor for the gun eliminating mechanical error. In addition to this, the gunner was provided with a Vickers Instruments GS10 periscopic sight for target acquisition mounted on the roof. The loader was provided with a single AFV No.10 Mk.1 observation periscope. The driver was well equipped with optical equipment too, including his own image intensifier, a PPE Badger Jenno viewer.

Through the clever use of electronics, the commander could access the imagery from both the gunner’s 2-axis gyro-stablised day-sight (and independently operate it), as well as the driver’s optics. Originally, the driver was provided with just a single wide-angle AFV No.44 Mark 2 modified periscope, but this was supplemented by the end of the 1982 trials with an additional periscope on each side of the original. The range of the night vision was limited to 1,200 m for the gunner and commander and 500 m for the driver.

Tidworth 1982. The Vickers Valiant strikes an imposing image next to the shorter Chieftain
Tidworth 1982. The Vickers Valiant strikes an imposing image next to the shorter Chieftain. (Source:

Tracks and Suspension

The original tracks and running gear from the Vickers Mk. 3 were changed out in December 1979 for a wider track on which the Mk. 4 was running by March 1980. Running on six large rubber-tyred road wheels, similar to those on Chieftain, each wheel station was, however, attached to a trailing arm connected to a torsion bar. Additional secondary torsion bars were mounted inside the trailing arms for the arms of wheel stations 1, 2 and 6. During operation over particularly rough terrain, these secondary bars could be released to provide additional shock absorption. In addition to this, stations 1, 2, and 6 also had hydraulic shock absorbers. With the adoption of the Universal Turret for the 120 mm gun and the additional weight this brought about an improvement whereby all wheelstation-trailing arms were fitted with the secondary torsion bars. Later this type of suspension was changed to a hydrogas suspension system on a vehicle designated as Valiant 2.

The track, like that of the Mk.3, was a manganese steel single connector type. It was 558 mm wide, having replaced the original 520 mm wide track from the Vickers Mk. 3 and provided additional ground contact on which to spread the weight of the vehicle, reducing ground pressure to between 0.81 kg/cm2 and 0.83 kg/cm2. On its return run, the track was supported by 3 small rubber-tyred return rollers. Each side of the tank required 98 track links, each of which was fitted with a removable rubber pad to reduce road damage. Interestingly, Vickers’ own performance figures for the Valiant in its later form state a ground pressure of 0.92 kg/cm2 with a wider body (explained by the switch to wider side skirts with improved protection), a longer gun length (explained by the switch to a 120 mm gun), and a faster top speed (explained by the switch to the German MTU engine). All these modifications added weight and is the likely explanation as to why this ground pressure figure is higher.

testing at Aldershot
Jimmy Nichol, Geoff Newcomb, and Brian Dillon from Vickers take a break during testing at Aldershot. (Source: Vickers)


The emphasis on the maneuverability of the Valiant was not to focus on top speed, but on acceleration. This meant an emphasis on the available torque from the engine. Trials were done using the derated Rolls Royce CV12TCA Condor diesel engine delivering 1,000 hp at 2,300 rpm to roughly match the very similarly sized General Motors 12V71T diesel engine delivering 915 hp at 2,500 rpm which was also tried. Ideally, the goal was the use of the Condor delivering its normal power output of 1,200 to 1,500 hp. There was sufficient space in the engine bay for engineers at Vickers to also contemplate the use of the German MTU 872 1,200 hp diesel engine. Operating with the RR Condor at 1,000 hp, the vehicle was capable of 51 km/h on the road with a range of 380 to 603 km depending on weight and engine from a fuel tank holding just 1,000 liters. Later figures state 1,150 liters. Vickers’ performance figures for the Valiant give the top speed as 70 km/h presumably quoting a top speed for the most powerful engine option.

The 17.41 liter RR Condor engine made at the Rolls Royce plant in Shrewsbury was a V12 (60 degrees) diesel engine with a 135 mm bore and a stroke of 152 mm with a low compression ratio and turbo-chargers. The V12-1200A, as used on the Valiant, weighed just 2,638 kg complete with water-filled radiators and coolant and rated at 1,000 hp was eventually selected to power the Challenger MBT, Chieftain 900, the Indian Vijayanta and even a re-engined Chieftain project.

The engine was matched to an automatic gearbox with mechanical speed gear as well as a centrifugal clutch as the TN12-1000 gearbox. The TN12-1000 was developed from the one used on the Chieftain and Mk. 3 providing gear-change efficiency improvements. The TN-12-1000 cross-drive transmission was produced by Self-Changing Gears Limited, Coventry, and weighed 1,361 kg, the same as the earlier TN-12 but was able to handle greater torque, specifically 3,660 Nm compared to 2,509 Nm of torque on the TN-12. The TN-12-1000 was also used in the Chieftain 900 and was able to manage engines up to around 1,200 gross hp.

This system provided 6 forward and 2 reverse gears. The important change was the elimination of the torque converter which reduced wasted torque from the power system, allowing for up to 150 hp of power available which would otherwise be wasted.

The vehicle was also fitted with an electrohydraulic differential which provided ease of steering and braking for the driver who, like on the Mk. 3, steered using a very simple yoke system instead of tiller bars. The steering, by means of handlebars, little different to a bicycle, used a twist-grip throttle control, a simple handle for the brakes, and a button which served as an override for the gearchange to prevent the gearbox from the automatic change down for improved performance for example during cornering or when firing on the move.

The Valiant being put through its pace
The Valiant being put through its paces and providing a view of the Chobham armor packs fitted to the sides of the turret as well as the NBC pack at the back. The two corner sections are simple stowage bins. (Source: GDI)


Underneath the square-cut appearance lay a tank similar to the Vickers Mk. 3. The regular armor of the Mk. 4 provided protection against small arms and cannon fire but was insufficient to protect against direct fire from Soviet tanks, unsurprisingly, as without the Chobham, it weighed just 30 tonnes. The primary way in which this weight was kept so low was the use of an all-welded all-aluminum alloy armor for the main structure of the hull. The type of alloy used was developed from 7039 series aluminum armor produced by Alcan Specialty and Aerospace Limited of Birmingham, England to produce a material more resistant to corrosion, ballistically stronger, and with better resistance to stress. Chobham technology had been made available to Vickers by the Ministry of Defence when it was announced in 1976 and two company directors from Vickers served on the Chobham Armour Committee, so they were well aware of its potential.

The turret, on the other hand, was primarily made from steel with the Chobham armor packs added across the front and sides. The adoption of aluminum for the hull differed from the Mk. 3, which had a conventional all-welded rolled armor steel hull. The turret itself followed on internally from the lessons of the Mk.3 using a cast steel front to produce a good ballistic shape which could not be matched in aluminum, and then with steel sections welded to the sides and rear in much the same fabrication manner as that used on Chieftain. It is not known, however, if when the turret was modified to take the universal mounting if this form of cast/weld steel was retained or if there was a switch to an all-welded steel plate turret underneath to simply manufacture.

With the addition of the Chobham armor, the appearance was changed, as was the weight, an additional 16.3 tonnes, with the likelihood that in the future, as armor technology improved, more weight could be added. Across the frontal 60-degree arc (30 degrees from centerline each direction), the Valiant, with this new armor, offered ballistic protection above that of the then in-service 56-tonne Chieftain, a design which had started in the 1950s.

An important additional consideration for the tank was the ‘future battlefield’ of the 1980s and 1990s seeing a potential large-scale use of nuclear or chemical weapons. Crew protection, therefore, was supplemented by a built-in nuclear, biological, and chemical warfare air filtration system made by Westair Dynamics and located on the back of the turret. This NBC filter system was mounted externally which made replacement and maintenance easier and consisted of a multi-stage high-efficiency filtration process and worked to create an overpressure inside the tank which served not only to keep gases out of the tank but also to evacuate fumes from the weapons.

Inside the vehicle was the Graviner Firewire CO2-based automatic fire fighting system, although these CO2 cylinders could be switched for an alternative gas like Halon if required.

The turret design itself had the same diameter ring as that of the Chieftain and was supported on a ball race with a semi-type basket. The turret crew were situated on a turntable that rotated with the turret.


The Valiant, using a clever design, was able to offer a choice of guns with either the tried and trusted Royal Ordnance L7A3 105 mm rifled gun or, in a new mounting in the Universal Turret, with the L11 120 mm rifled gun. In order to potentially fulfill the NATO need for a common 120 mm smoothbore gun, the Rheinmetall 120 mm gun could also be fitted, a gun finishing development for use in the M1E1 and Leopard 2 at the time. When it first appeared, the Valiant mounted the 105 mm gun, but this was quickly exchanged for the superior L11A5 120 mm rifle instead. The advantage of the Universal Turret mounting being that the main gun could be removed in one piece from the front of the turret through the trunnions without having to remove the turret. This was achieved by using a wide-diameter gun rotor with pre-loaded trunnion bearings and extended cradle bearings. Not only did this allow for different guns to be mounted easily but also for good stability and thereby accuracy from the gun.

The Vickers team taking a break during testing of the Valiant on Ridsdale Ranges
Alec Keiler, Tony McNally, Robin Lyon, and John Codling from the Vickers team taking a break during testing of the Valiant on Ridsdale Ranges. Note the VRM is now VV001. (Source: Vickers)

Loaded manually, the rate of fire was given as 10 rounds per minute (1 every 6 seconds). A Vickers muzzle reference system (MRS) on the end of the barrel added information into the computer system and the barrel was clad in a rigid thermal sleeve (a patented Vickers design) made from a material called Fibrelam Vickers developed with Ciba-Geigy of Duxford. This sleeve reduced distortion and was used on the Valiant, the Mk. 7 vehicle and even had a 105 mm gun version for the Mk. 3. That sleeve was thoroughly tested at Fort Halstead by the Royal Armament Research and Development Establishment (R.A.R.D.E.) and found to offer a significant improvement in reducing barrel sag in hot weather.

 Patented Vickers thermal sleeve made from Fibrelam
Basic outline of the Patented Vickers thermal sleeve made from Fibrelam. (Source: US Patent US4628713(A))

The fire control and gun stabilization system was an all-electric system developed by Marconi. This had a built-in laser rangefinder and a brand new ballistic computer to improve the chances of a first-round hit against static and moving targets as well as for supporting firing on the move. This system used the SFCS 600 computer derived from the GCE 620 system installed on the Vickers Mk. 3 with some improvements, known as the Marconi Radar systems Centaur 1 system.

The Centaur 1 fire control system (FCS) was a state of the art solid-state system designed specifically for Valiant which completely integrated all of the different sightings and optics. The gun itself had a 2-axis gyro-stabilized mounting located underneath the breach and with the Centaur 1 FCS the gun could be directly slaved to either the commander’s gyro-stabilized day or thermal sights. Further, these balancing systems interfaced with the 3 primary sighting systems: the gunner’s telescopic laser sight, the commander’s gyro-stabilized panoramic laser sight, and the thermal imaging system. The ballistic computer took range data from the laser range-finders, manual values, and tracking data (for a moving target) and calculated a firing solution with supporting data from a tilt-sensor measuring the tilt-axis on the trunnion, with manually entered data such as ammunition type, barrel wear, and charge temperature. The Centaur system then superimposed a mark over the gunner’s sight graticule and tracked the target with the pressing by the gunner of the laser button. The gun was then ready to fire within 3 seconds of the tracking starting.

The elevation range for the 105 mm L7 gun was -10 to +20 degrees and it was capable of firing all commonly available 105 mm rounds. Storage was provided for up to 56 rounds of 105 mm, 44 rounds for the 120 mm Rheinmetall smoothbore, or 52 rounds for the L11A5. Rounds could be carried in the turret, in the basket as ready rack ammo and in a space alongside the driver as well.

Vickers Mk 4 Valiant Interior
Vickers Mk 4 Valiant Interior Interior showing the simplicity of the driver’s controls on the right and the stowage for 30 105 mm shells on the left. Note the single periscope for the driver indicating this is the early version. (Source: Pengelley)

The RO L11A5 120 mm gun made by Royal Ordnance, Nottingham, was 7.34 m long and weighed 1,782 kg. It featured improvements over the earlier designs by using a forged upstand for the muzzle reference system and featured a smaller volume and lighter fume extractor than the L11A2. As a result of these changes, the gun was out of balance, so 7.7 kg of additional weights had to be added to counterbalance it.

Secondary armament included a single 7.62 mm machine Hughes chain gun mounted coaxially with the main gun and a second 7.62 mm machine gun (L37A2) in a remote-control mount next to the commander’s cupola, on the roof. In total, 3,000 rounds for these could be carried. Both of these weapons were interchangeable with a variety of commercially available 12.7 mm machine guns.

Advertising image shown by Vickers for the British Arms Export Exhibition of 1980
Advertising image shown by Vickers for the British Arms Export Exhibition of 1980. Note that at least two of the figures are shown in NBC suits and respirators. Source: Vickers

Firing trials at Lulworth took place at the end of 1982 against simulated targets using APDS at 1,500 m range and found to be excellent. By early 1983, the vehicle, refitted with the Universal Turret mount, was showing off the 120 mm L11A5 to potential Middle Eastern customers. Marketing literature from Vickers at the time sub-divided the configurations for potential buyers as Configuration 1 with the 105 mm L7A1, 60 rounds, of APDS or HESH, Configuration 2 with the 120 mm L11A5 with 44 rounds (different from the earlier plan for 52) of APDS or HESH, or Configuration 3 with the Rheinmetall 120 mm smoothbore with 44 rounds of APDS and HESH (MP).

The Vickers Universal Turret
The Vickers Universal Turret, as it would later be advertised for the Mk.7/2, fitted with the Rheinmetall 120 mm smoothbore gun. Note the storage for 15 rounds in the turret bustle. (Source: Lobitz)
Promotional shot of the Valiant taken at Ridsdale Ranges
Promotional shot of the Valiant taken at Ridsdale Ranges. Source: Ogorkiewicz


Other than the British Army there was other interest in the Valiant, specifically in the Middle East but also from some European nations including Spain who at the time were seeking a new tank. Vickers may have hoped for some success here as, after all, they had already sold a number of their Mk.3 tanks to Kuwait in the 1970s. In order to try and gain interest, the Valiant was packed up and shipped out to Doha, Qatar, a 3-month trip. This tour involved showing off the Valiant to Qatar, Jordan, Abu Dhabi (United Arab Emirates), and finally Egypt. The Valiant did its tour of prospective users offering these nations a tank objectively better in many ways than certainly the British Challenger. Sent with British Army crews, the Valiant, Challenger 1, and Stormer painted in desert colors performed a variety of trials whilst the team from Vickers traveled separately to talk about the technology. On one occasion, in Bahrain, there was a ‘mishap’ where the Vickers team got lost on the way to the firing trials and accidentally found itself driving past the targets on the firing range, something on which to focus the mind.

Despite these trials, there were no orders from this tour, and other than the sale of a single gold-plated Sterling SMG, was unsuccessful, although it had led to an invitation to participate in desert trials in the United Arab Emirates in July and August 1983.

In the desert outside Abu Dhabi
In the desert outside Abu Dhabi, a Chieftain ARV provides support to the Vickers Valiant. Note the two-tone desert camouflage scheme. (Source: BAE)

Those trials in the UAE were to involve comparisons of the British Challenger 1, the French AMX-40, and the Vickers Valiant. Here, the lighter weight and automotive power of the Valiant was impressive leaving the other two contenders behind. During an off-road trial, however, the Valiant suffered a small disaster. A drain plug in the final drive had come out. This led to sand getting into the unit as well as a loss of lubricant and causing the unit to fail.

A new one had to be flown out from the UK delaying Valiant for two days but it was back operational to take part in firing trials where once more it outperformed the other two vehicles. It was not the only one of the three to suffer mechanical problems. The AMX-40 suffered a severe set of problems with the automotive system and was out of use for over a week. In fact, the only one without major problems was the Challenger 1. The UAE, however, bought the Leclerc instead.

The Fall of the Valiant

The Valiant had been a strong performer. Automotively powerful albeit it still a little underpowered but with a world-beating fire control system. The British had gone with the Challenger 1 MBT and there were no orders for the Valiant. The Valiant 2 was to improve on the Valiant with planned automotive improvements in the engine and suspension but whilst at Larkhill, the Valiant slipped off the low loader during transport and rolled into its roof. The optics were damaged but repairable, the hull was twisted and had to be scrapped. The Valiant was dead and all that could be salvaged was the significant investment in the turret. With no hull on which to make a Valiant 2 and with a large sum of money invested in a failed project, Vickers was in trouble. A review of automotive options for a new chassis were considered and would eventually lead to the attempt to use the Leopard 2 which created a whole new tank: the Vickers Mk.7/2.

An unfortunate accident
An unfortunate accident which occurred during testing and evaluation when the Valiant fell off a low loader during transport. Landing on its roof, significant damage was done to the chassis. (Source:


Had the Valiant received orders, Vickers was planning a series of variants, specifically a bridge layer, an armored recovery vehicle (ARV) version and a self-propelled gun. Options also all available for the Vickers Mk.3.

The ARV was to be fitted with a 30-tonne direct-line pull capstan winch capable of up to 75-tonne of pulling by multi-reeving of the rope. A hydraulic crane was also available with an auxiliary 3-tonne winch.

The 13.4 metre long bridge laying version was to carry a class 60 bridge. The self-propelled gun variant was simply designed to take the universal 155 mm howitzer turret developed by Vickers Shipbuilding and Engineering. None of those three vehicles were ever built, however.


The Valiant, despite its good features, was not a success. It received no orders despite a lot of interest from the British and even being shortlisted by the Spanish in 1985, but Vickers would not give up. The turret was the biggest selling point, as a Universal Turret was able to offer a wide range of firepower and optical options. The turret would live on and was modified once more. It would go on to be tested on the Leopard 2 hull to create the Vickers Mk.7/2, having a maneuverability boost from its MTU engine. That vehicle would fail too, but the lessons learned would eventually lead to the turret contract for Brazil for their EE-01 Osorio.

The Vickers Valiant Main Battle Tank prototype failed to get any orders and was unfortunately lost in an accident. The vehicle is pictured with the 105 mm L7A3 gun. Illustration by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

Vickers Mk.4 Valiant Specifications

Length 29.53 m long (with 105 mm gun)
10.62 m long (with 120 mm gun)
8.47 m (gun to the rear)
Width 3.3 m wide (with side skirts)
3.6 m with improved skirts
Height 3.24 m high (turret roof)
Weight 46.3 tonnes Combat laden (with Chobham)
41 tonnes Unladen (with Chobham)
30 tonnes (without Chobham)
Track length on ground 4.47 m
Ground Clearance 0.46 m
Trench Crossing 3 m
(without preparation)
0.91 m
Vertical Obstacle 3 m
Main Armament RO L7A3 105 mm rifle or L11A5 120 mm rifled main gun
or Rheinmetall 120 mm smoothbore
Secondary Armament coaxial 7.62 mm or 12.7 mm machine gun
roof-mounted remote-control 7.62 mm or 12.7 mm machine gun
Crew 4 (driver, gunner, loader, commander)
Propulsion Rolls Royce CV12TCA Condor diesel engine 1,000 hp at 2,300 rpm or normally rated for 1,200 hp. Possible to uprate to 1,500 hp.
General Motors 12V71T diesel engine delivering 900 hp at 500 rpm.
German MTU 872 1,200 hp diesel engine
Speed 51 to 61 km/h (road) depending on engine (Vickers state 70 km/h)
Suspension Torsion bar
Production Armor
All aluminium alloy hull with Chobham across front 60 degrees. All steel turret with Chobham armor across front and sides.
Total production 1 prototype


Ground Defence International #69. November 1980
Ground Defence International #70. December 1980
Janes. (1985). Arms and Artillery. Janes Defence Group
Ogorkiewicz, R. (1983). Vickers Valiant. Armor Magazine March-April 1983
Lobitz, F. (2009). Kampfpanzer Leopard 2. Tankograd Publishing, Germany
Foss, C. & McKenzie, P. (1988). The Vickers Tanks. PSL.
BAE. (2012). The Tank Factory.
American Patent US4638713A, Thermal sleeve for gun barrels. Filed 25th November 1985, granted 27th January 1987
Pengelley, R. (1980). The Vickers Valiant Main Battle Tank. International Defense Review

WW2 American Prototypes

Barnes Two-Man Heavy Tank

U.S.A. (1938)
Heavy Tank Design – None Built

Lt. Colonel Gladeon M. Barnes from the US Army’s Ordnance Department casts a long shadow over tank development in the USA in the period around the start of WW2. Barnes was an interesting man, but some of his ideas and designs were demonstrative of a disconnect between his thinking and military reality.

One such example came in 1938 with the idea for a small heavy tank armed with a single machine gun. Quite what role such a vehicle was meant to fulfill is hard to imagine years after other users of such vehicles had already accepted the serious inherent limitations of a similar type of vehicle.


Somewhat oddly, the inspiration for this idea came from the Spanish Civil War. Section G-2 (the department responsible for Intelligence in the US Army) examined that conflict for lessons in a report titled ‘Tank Lessons from the Spanish Civil War’. They concluded that tanks were too poorly armored, used in too few numbers, and that they were not maneuverable enough.
In that war, the primary tanks being used were the German-supplied Panzer I, the Italian CV.3 series light tank, and the Soviet-supplied T-26 light tank. During that war, as G-2 correctly pointed out, tanks tended to be used in small numbers or alone and both the CV.3 series and T-26 had thin armor, around 14 to 15 mm maximum, meaning both were just bulletproof.

The T-26 had an advantage over the CV.3 in the addition of a turret-mounted weapon, whilst the CV.3 was stuck with its only armament in a mounting on the front left of the hull facing forwards. Neither tank was able to demonstrate much speed even though the CV.3 was faster, just under 30 miles per hour (48 km/h) compared to just under 20 miles per hour (32 km/h) for the T-26, although the overall effect was slight. Both tanks were too slow, both suffered from narrow tracks and a relatively underpowered engine. Any reasonable and objective assessment of the use of tanks in the Spanish Civil War would reflect this.

The Italians, for example, understood from the conflict the severe limitations of the CV.3 for tank vs tank combat and undertook work on turreted light tanks with some urgency. The Germans and Soviets likewise looked and learned. Why then did the US see a solution lying in a vehicle with the same sort of layout as the CV.3 but with less armament is difficult to comprehend.

The outline of Barnes’ concept for a 2-man heavy tank.(Source: Armor Magazine)

The design

Barnes’ concept was for a small light tank, just 7 US tons (6.35 tonnes) or so and just 11 feet (3.35 m) long. For reference, the Italian CV.3 was less than half the weight, shorter, narrower, and lower, and the Soviet T-26 was heavier and slightly longer, wider, and taller.

With a crew of just two, both men would have their work cut out for them. One man had to drive the tank and operate its radio, almost certainly sat on the left just like on the Light Tank T3. The other crew member would have to both command the tank and operate the armament and would sit on the right, alongside the other man. This is a very similar arrangement to the Italian CV.3, except the crew position/roles were reversed. It could be considered that these reductions in size and capability were, in fact, simply the means to get the most tank possible for the least money. However, here Barnes trips-up once more. He provided a cost estimate of US$20,000. In 1938, US$20,000 was a huge sum of money, equivalent to over US$350,000 in 2020 values, or roughly half the cost of a far more potent and useful Sherman tank.

Comparison between Barnes’ design and the primary Spanish Civil War Tanks

The 2-man heavy German Pz.I Italian CV.3 Soviet T-26
Crew 2 2 2 2
Armament 1 x 37 mm / 1 x .30 cal MG 2 x 7.92 mm machine guns 2 x 6 mm machine guns 1 x 45 mm & 1 x 7.62 mm MG
L / W / H
11’ x 6.5’ x 4.5’
(3.35m x 1.98m x 1.37m)
4.02 x 2.06 x 1.72
3.03 x 1.4 x 1.2
4.65 x 2.44 x 2.24
Weight 7 tons (US)
(6.35 tonnes)
5.4 tonnes ~3 tonnes 9.6 tonnes
(off road/on road)
20 mph / 35 mph
(32 km/h / 56 km/h)
25 km/h / 37 km/h 42 km/h 42 km/h
F / S / R
(38 mm)
7 – 13 mm 14 / 8 / 8
15 / 15 / 15
Note No turret Turreted No turret Turreted

The Armament

The drawing of Barnes’ vehicle shows a single machine gun and the annotation states this to be a single .30 caliber (7.62 mm) weapon with 60 degrees of traverse, presumably 30 degrees to each side. An alternative armament was also proposed, a 37 mm gun. Once more, this was to be mounted in the front, seriously limiting its potential effectiveness. On top of this failing, operating a gun is a lot of work to load, aim and fire and, perhaps because of this, Barnes did propose that it could be automatically fed. Thus, the commander would have to ‘only’ command the tank, aim and fire the gun. Even so, the tank, limited by the traverse of its gun, would still be inferior to the Soviet T-26.


If the CV.3 and T-26 were unsuitable, with armor only 15 mm at most, then the goal would be to have more, presumably to make the tank protected against automatic cannon fire such as the potent 20 mm Breda cannon which was a proven armor-killer in Spain. It would also mean anti-tank rifles would be less useful against tanks, so more armor was not an unreasonable goal. Barnes wanted up to 1.5 inches (38 mm) of armor on this small heavy tank. For the purposes of reference, the Czech LT vz. 35 (better known as the Panzer 35(t) in German service in WW2), a tank which is possibly the preeminent and most modern turreted tank of the era, had just 25 mm across the whole front. What Barnes was indeed proposing was a tank the size of the diminutive American Light Tank T3, a little larger than the Italian CV.3 light tank, but with armor heavier than most of the tanks then in European service. All that, just to carry a single and rather limited machine gun, a task the even smaller CV.3 did more effectively with two machine guns mounted together.

tiny Light Tank T3
With a soldier for scale, the tiny Light Tank T3 shows really just how small it was. (Source: Hunnicutt)


The speed and agility of the vehicles in the Spanish Civil War were seen as a failure because they were insufficient. Therefore, Barnes should have been looking for a vehicle able to exceed the speed of the CV.3. Instead, he managed to make a vehicle which even under ideal circumstances was larger, heavier, and slower.

The power to weight ratio of this design was to be 20 to 25 horsepower per ton and, with an estimated 7-ton (6.35 tonnes) weight, that would mean an engine of 140 to 175 hp. Ideally, this would mean a top speed of 20 mph (32 km/h) on a slight slope and 35 mph (56 km/h) on a road. On paper, this all sounded good, but paper-designs are like that and a magic engine can be produced from thin air with imaginary performance. When the design meets reality, things change and this is exemplified by the Light Tank T3.

Although Barnes did not specify which engine was going to be used, the Light Tank T3, produced two years earlier in 1936 gives a good idea of the problems. Both vehicles clearly use a pair of volute-sprung bogies, each with two wheels and a front-mounted drive sprocket meaning the transmission was in the front. The Light Tank T3 is very similar in size, suspensions, armament, and appearance to Barnes’ idea and was fitted with a 221 cubic inch (3.62 litre) Ford V-8 engine. Despite being slightly over 3.54 US tons (3.21 tonnes), this vehicle had half of the armor Barnes was proposing and yet had the same top speed. The Light Tank T3 was the same size as Barnes’ idea, with half the armor and half the weight, and yet the same desired performance meaning whatever engine Barnes was considering would have to be significantly more powerful and yet fit in the same space as available in the T3. This was no small order, although the Combat Car T5 of 1933 had managed to cram a 235 hp air-cooled Continental R-670 radial petrol engine inside, all for 6.29 US tons (5.71 tonnes), albeit with armor around just ½” to ⅝” thick (12.7 to 16 mm).

US Light Tank T3 of 1936
US Light Tank T3 of 1936. (Source: AGF)

The closest vehicle, perhaps to Barnes’ idea, was not the Light Tank T3, but the Light Tank T6. Built in 1939, one year after Barnes’s 1938 concept, the Light Tank T6 departed from the suspension of the Light Tank T3, using just a single 2-wheel bogey with a volute spring and the large on-ground trailing wheel at the back along with a separately sprung half-bogey. Once more, the driver was to be on the left in another two-man tank but this vehicle was not armed at all. With armor up to 1” (25 mm) thick and weighing in at 9.75 US tons (8.85 tonnes), the Light Tank T6 was roughly the same size and gives a good idea of a potential power plant for Barnes’s tank, namely a pair of 8-cylinder Buick petrol engines. However, even so, it was more than 2 tons heavier and still had armor no thicker than 1” (25 mm) and, importantly, no armament. Comparing Barnes’ idea to both Light Tanks T3 and T6 shows how unrealistic it really was.

US Light Tank T6
US Light Tank T6. (Source: AGF)

Comparison between Barnes’ design and the Light Tanks T3 and T6

Light Tank T3 The 2-man heavy Light Tank T6
Date 1936 1938 1939
Crew 2 2 2
Armament 1 x .30 cal MG 1 x 37 mm / 1 x .30 cal MG unarmed
L / W / H
11.25’ x 6.75’ x 4.5’
(3.43m x 2.06m x 1.37m)
11’ x 6.5’ x 4.5’
(3.35m x 1.98m x 1.37m
Approx. 11.25’ x 6.75’ x 4.5’
(3.43m x 2.06m x 1.37m)
Weight 3.54 tons (US)
(3.21 tonnes)
7 tons (US)
(6.35 tonnes)
9.75 tons (US)
(8.85 tonnes)
Engine Ford V8 Petrol unstated Twin Buick 8-cylinder Petrol
(off road / on road)
? mph / 35 mph
(? km/h / 56 km/h)
20 mph / 35 mph
(32 km/h / 56 km/h)
? mph / 30 mph
(? km/h / 48 km/h)
F / S / R
¼” to ⅜”
(6.35 to 9.53 mm)
(38 mm)
⅜” to 1”
(9.53 to 25 mm)
Note No turret No turret No turret


It is hard to see any merit in Barnes’ idea. The armor certainly would have provided excellent protection from the relatively small caliber weapons then in service on a lot of tanks, but those were the previous generation. Against a 37 mm anti-tank gun, like the type used in numbers in Spain to good effect, even 38 mm of armor was not going to be much help, although it would certainly have made the little tank impervious to infantry which did not have access to a cannon. What then was Barnes’ really proposing? A small lightly armed and heavily armored tank may have some utility against infantry but, with the only armament in the front it would, as the Italians found to their cost, prove untenable. If, however, Barnes was really considering a small tank destroyer then why bother with the armor at all. Concealment and maneuverability would have been of far more use and he could reasonably have mounted the gun on top in an open-setting for a wider arc of fire and more space to carry ammunition.

Both ideas were also stymied by the selection of just two crew. There was simply too much for two men to do in combat, so a slightly larger chassis would also have allowed a third or fourth man to operate the gun, but would also have severely increased the weight and decreased the mobility.

Finally, Barnes’ concept of mobility was flawed. There was no way he was going to get even more armor and an automatic 37 mm anti-tank gun into a vehicle no bigger than the 9-ton Light Tank T6, along with a larger engine and still have the same performance. Likewise, he could not have allowed the weight to go over 7.5 tons (6.8 tonnes), as this was the limit set in 1933 by the Secretary of War for light tanks, suggesting a reason behind the ‘heavy’ part of the name, and that is before the eye-watering price-tag for the vehicle was considered.

Illustration of Barnes Two-Man Heavy Tank illustrated by Yuvnashva Sharma and funded by our Patreon campaign.

Barnes 2-man Heavy Tank specifications

Weight 7 tons (6.35 tonnes).
Crew 2 (Commander/gunner, and driver/radio operator)
Propulsion Type unknown, 140-175 hp desired
Desired Speed 20 mph off-road / 35 mph on road (32 km/h / 56 km/h)
Trench Crossing 4 feet (1.22 m)
Armament 37 mm gun or .30 caliber machine gun
Armor up to 1.5 inches (38 mm)
Total production None


Bellinger, J. American Hetzer. AFV news Magazine 37(2)
AFV Data Series
Crimson, F. (1992). US Military Tracked Vehicles. Crestline, USA
United States Army. The General Staff: Its Origins and Powers
Christie, J. (1985). Steel Steeds Christie. Sunflower University Press, Kansas, USA
AGF Board. (1947). Development of Armored Vehicles Vol.1: Tanks.
Hunnicutt, R. (1992). Stuart. Presidio Press, USA

WW2 German prototypes


Nazi Germany (1942-45)
Superheavy tank – 141 ordered

This article was first published on 19th October 2019. It is now being republished with a brand new, far more accurate illustration and with its Youtube video series.

It is impossible to consider the Maus and not be impressed by the machine as a feat of engineering. At 188 tonnes, it is the heaviest operational tank ever made by any nation at any time in any war and was made despite the shortages of raw materials, industrial capacity, and manpower at the time in Nazi Germany. Yet, despite the impressive achievement of making this rolling behemoth, the vehicle stands as a testimony to the total waste taking place in the German industry and the inefficiencies inherent in the way in which tank development was carried out. By the time the Maus was finished in 1945, it was a boondoggle. No amount of awe at the size, weight, firepower, or armor on this beast could disguise the incredible waste of resources it accounted for, nor could it make any difference to the outcome of the war. The Maus, as a weapon, was simply useless, yet the lessons learned from its development did find use in other programs and the very existence of such an enormous machine has inevitably drawn a significant amount of attention. Drawing both awe and fascination in equal measure, the Maus is a complex tank with a lengthy development.


Following the invasion of the Soviet Union on 22nd June 1941, the German army had quickly gained huge swathes of territory and destroyed, captured, or killed large quantities of Soviet troops, supplies and equipment. Yet, despite this success, the German army was unable to deliver a knock-out blow against the Soviets or to capture Moscow. By January 1942, with Moscow saved by an increasingly stubborn Soviet defense, it was clear that the conflict on the Eastern Front was going to be very long and very bloody. As Soviet tanks of increasing quality, armor and firepower started to reach the front lines through 1942, it was clear that in order for German forces to maintain an edge in tank combat, they would need a tank that was bigger, more heavily armored, and better armed than anything that had gone before. There was also the need for a heavy tank capable of assaulting heavily defended enemy positions and since nothing in the German arsenal in Spring 1942 was capable of meeting these requirements, long term plans were being put into place.

The origins of the Maus began around this time as, on 5th March 1942, a directive was issued to Fried Krupp A.G. of Essen for the development of a new heavy tank in the 100-tonne class to replace the previous concept of a 72-tonne tank, which originated as a project by Rheinmetall started in 1938. The goal was to have an operational trial vehicle for this 100-tonne vehicle in the shortest possible time and to be ready to show it off in the spring of 1943. Two weeks later, on 21st March, Dr. Ferdinand Porsche was given a separate and independent contract for exactly the same goal, a 100-tonne tank.

Thereafter, requirements for this 100-tonne tank started to fall into line, with demands for a heavy gun, and at least one machine gun. The hull machine gun could be eliminated as long as there was a separately controllable machine gun, as this would simplify the design and eliminate the hole in the front armor needed to accept a hull machine gun. By May 1942, however, the 100-tonne limit was being seen as too conservative and a 120-tonnes weight was permitted with priority placed on achieving the heaviest possible armor and firepower. Speed was not an important factor.

Initial drawings were completed on 4th June 1942 by Porsche’s designers at Zuffenhausen. The project was named ‘Sonderfahrzeug IV’ (special purpose vehicle), but identified as the Project Typ 205. Completed drawings from Porsche for this 120-tonne vehicle mounting a 15 cm gun were ready by 23rd June 1942 and approved by Hitler. As an indication to the heavy armor proposed, the hull floor alone was to be 100 mm thick, the same thickness as the front armor that would be used on the Tiger I. Hitler approved the design, selecting a 10.5 cm L/70 gun and discounting the idea for a secondary turret with a 7.5 cm gun, as the tank was to be supported by other tanks. The priorities for the design had changed. In May, these had the armor on top, followed by firepower and speed in this order, but, in June, this changed to firepower, followed by speed and armor.

A contract was then issued on 17th July 1942 to Krupp to design a turret for this new tank under the name ‘Pz.Kpfw. Mäuschen’ (Tank: Little Mouse). This new turret, weighing 57 tonnes, was to be incredibly heavily armored, with armour 250 mm thick at the front (not including a large cast gun mantlet), 200 mm thick on the sides and 80 mm thick on the roof, and was to mount two guns (a 15 cm Kw.K. L/31 and a 7.5 cm Kw.K. L/24). Design work then proceeded on taking this enormous turret and firepower and producing from them a conceptual vehicle that could fit within the normal limits of the German rail gauge.

The enormous size of the Maus turret is evidenced here in 1945 by these Allied soldiers examining captured unfinished turrets. Source: UK National Archives

From August through September, work at Porsche continued on creating what was inevitably going to be a box-shaped vehicle in order to fit within the tight limits of the rail gauge. Combined with the work of Krupp on the turrets, it must have been considered to show significant promise too as, at the end of September, the turret being designed by Krupp was selected to replace the earlier 10.5 cm gun turret on the Löwe program and thus, Krupp received the contract for this too.

October 1942 – a design revealed

Between conceptualization in March 1942 and October 1942, it had been fairly plain sailing for both Porsche and Krupp, despite some general disagreements within the German establishment over a preferred gun or guns for the tank. On 5th October, the new design was ready under the name Typ 205A and had options for either a 15 cm L/37 or for a 12.8 cm gun to work alongside the 7.5 cm Kw.K. L/24.

The dominant feature of what was little more than an enormous brick with pointed ends fore and aft was the enormous rectangular turret roughly half the length of the entire tank. The engine was mounted ahead of the centerline but delivered drive to the sprockets at the rear via an electrical drive. The entire vehicle was to be mounted on 12 pairs of double road wheels running along a 1 m-wide track, although a pair of 500 mm wide tracks were also considered. All told, this Typ 205A was going to weigh some 150 tonnes and, in keeping with common design practice, was still to retain a front-mounted machine gun in the hull on the right-hand side.

Power for this 150-tonne vehicle was to be provided by a single 44.5 liter, 12-cylinder Daimler-Benz water-cooled diesel delivering 1,000 hp at 2,400 rpm. This was connected to an electrical generator which, in turn, delivered the electrical current to a motor on each side at the back, each connected to a 918 mm diameter drive sprocket. This arrangement would allow the Typ 205A to reach a top speed of 20 km/h. An alternative engine, the 41.5 liter Typ 205/2 Porsche air-cooled diesel was also shown in October 1942 as an option. This was labeled as design ‘Typ 205B’ and could deliver 780 hp at 2,000 rpm.

A review of the Typ 205 A and Typ 205B Mäuschen took place in November 1942 by the Panzerkommission and resulted in Krupp and Porsche being ordered to make another design with the turret at the back.

The result was a 170-tonne proposal from Porsche for a rear-turreted version using the same Daimler-Benz 603 water-cooled petrol engine as before, but with the addition of a compressor. It was also to use the electrical transmission taken from the Panzerkampfwagen VI P (Tiger (P)). Consideration at this time was also given to the production of a Sturmgeschutz version of this rear-turreted Mäuschen, but this was rejected by Obert Thomale from Waffen Prüfungsamt 6 (Wa Prüf 6), the branch of the German ordnance department responsible for motorized vehicle design.

Typ 205 from December 1942/January 1943, showing the distinctive and very large rectangular Maus turret. Note the presence of a hull machine gun and the use of 5 bogey units with two pairs of road wheels each for the suspension, copied from the Tiger (P), but reduced from the 6 pairs drawn in October 1942. Source: Frohlich

When this work was presented to Hitler at the start of December 1942, he was supportive and ordered the production of a trial vehicle to be ready for operation in the summer of 1943, with a production of 5 vehicles each month thereafter assembled by Krupp. It is important to note that at this time the Porsche design was known as the ‘Maus’ and the Krupp design as the ‘Tiger-Maus’, but a dose of reality was also setting in.

From an original 100-tonnes to ‘maybe-if-necessary’ 120-tonnes, the weight had ballooned to 170-tonnes and so some weight needed to be stripped off. The easiest way to achieve this was to reduce the amount of steel in the vehicle, which meant reducing the level of protection it offered from 250 mm at the front and 200 mm on the sides to ‘just’ 225 mm and 180 mm on the front and sides respectively. With the Krupp designed ‘Tiger-Maus’ being judged to be the lesser of the two designs, it was terminated on 15th December 1942, with the Porsche design being selected, albeit with significant changes.

Further changes to the hull to accommodate the removal of the turret collar and allow for a tunnel for the driver and radio operator at the front to get to the turret without getting out were making the design process difficult. Even as these changes and other minor changes were discussed, a decision was made on production. Hitler met with Albert Speer (Armaments Minister) on 3rd January 1943 and ordered the Maus to be produced between three manufacturers. Porsche would design it, Krupp produce the armored segments, and Alkett would assemble these components into a functional tank. Hitler was adamant that the production of the tank should be able to begin by the end of that year and deliver the Mäuschen at a rate of 10 tanks per month.

January 1943

By January 1943, the preliminary ideas for the Mäuschen were out of the way and a decision was made that the proposal from Porsche, rather than the design from Krupp, was to be selected. Several key design decisions had been made regarding the layout of this tank. Firstly, there was to be no hull machine gun at all. It weakened the frontal armor and added another element of complexity to the design it simply did not need. Secondly, the idea of a connecting tunnel to link the driver and radio operator at the front to the rest of the crew was abandoned – these men would remain physically isolated from the others, but connected via intercom. One additional note here is that there was a 20 mm thick armored bulkhead behind the driving compartment, so that, in the unlikely event of that compartment being breached by a shell, the drive system would still be protected. Likewise, in the event of a fire in the engine bay, those men in the front would be protected. A small access hatch in this bulkhead was provided for maintenance purposes.

The massive turret was to go at the back with the engine in front of it, the electrical components underneath it and the motors behind it, while the armor specifications had been decided at the start of January 1943. With that, a full-sized wooden model was ordered to be shown to the Panzer-Kommission on 21st January.

The full-sized wooden model of the Maus as seen in May 1943, dwarfing the members of the military and industry representatives examining it along with Hitler (in the light-colored trench coat). The fitting at the back on the corners is the flamethrower system which was later dropped, saving 4.9 tonnes in weight. Note that the mockup still retains the large cupola. Source: Frohlich

Here, under the eagle-eye of representatives from Porsche, Alkett, Daimler-Benz, Skoda, Wa Prüf 6, the Army, and Krupp, various changes were suggested, including:

  • Larger crew hatches in the hull (Wannen-Ausstiegsluke)
  • A new lighter type of track (Laufkette)
  • A machine gun mounting next to the hull crew hatch (MG-Kuppel)
  • A 100 mm thick track guard (Kettenschutz)

In February 1943, the engine for the Maus became the focus of attention. A big tank, after all, required a powerful engine. Maybach had originally been offering Porsche a supercharged V-12 engine capable of delivering 1,000 hp, but that engine turned out to be a pipe dream and was dropped. As to Porsche’s preferred engine, the 36.5 liter Simmering-Graz-Pauker Sla 16 (X-16), this was not ready.

Instead, Porsche selected a vehicle-version of the new DB 603 aircraft engine, a 44.5-liter V-12 petrol engine known as the MB 503A. Fuel-injected, this engine could produce 1,200 bhp at 2,300 rpm, but could only deliver 1,080 hp of that power due to having to run engine accessories. The alternative engine available was the MB507C, a diesel version of the engine capable of producing up to 1,000 hp.

This engine was connected to a pair of Siemens direct current (DC) dynamos, each producing 400 kW at 2,800 rpm (total combined DC output was 720 kW, 240 volts, 3,000 amps) that were a reverse of the layout in the Ferdinand/Elefant. In that vehicle, the dynamo was (single dynamo in the Ferdinand and two dynamos in the Maus) in front of the engine; here, they were behind. This electric drive was selected primarily because it required less development time than a mechanical drive but also because it made deep fording much simpler. A key departure for the Maus from previous German designs was the placement of the final drives at the back of the tank.

One thing commonly forgotten or otherwise not paid attention to is engine maintenance. There were, obviously, removable hatches in the roof of the hull, but there was an additional hatch in the floor of the engine room, measuring 1,295 mm x 216 mm in the 50 mm armored floor rather than the 100 mm thick floor proposed back in June 1942.

One of the Maus hulls found by 21 Army Group at Meppen in May 1945. It shows the points of access to the engine, with a hatch in the 20 mm bulkhead to the driving compartment, the sections for the three large engine hatches, and the letterbox-shaped access in the hull floor. Note that the hull roof, where the turret is mounted, is made from four separate sections 60 mm thick, welded together. Source: UK National Archives

Engines for Mäuschen up to October 1942

Date ~June 1942 to October 1942 October 1942
Manufacturer Maybach Simmering Daimler-Benz Porsche
Name HL-230 P30* X-16 MB503A Type 205/2
Fuel Petrol Diesel Petrol Diesel
Cylinders V-12 16 V-12
Capacity 23 liter 36.5 liters 44.5 liters 41.5 liters
Cooling Type Water Air Water Air
Power Output 900 to 1,000 / 1,200 hp** 720 hp @ 2,000 rpm 1,000 hp @ 2,400 rpm to 1,200 hp @ 2,300 rpm+ 780 hp @ 2,000 rpm
Installed no no no no
Notes Not ready Not ready
Porsche’s preferred engine
Unable to supply engine, November 1942 Unable to supply engine, November 1942 – MB 509 selected instead

* When modified to run on ‘special fuel’ at an increased compression (Bosch fuel injection) and supercharged this was known as the HL 234
**In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp – well short of the 1,000 to 1,200 planned
+ 1,080 hp available after driving engine accessories
MB = Mercedes-Benz

Engines for Mäuschen November 1942

Manufacturer Daimler-Benz Maybach Daimler-Benz
Name MB501 HL230 TRM P45 MB 507C
Fuel Diesel Petrol Diesel
Cylinders V-20 V-12 V-12
Capacity 134.4 litres 23.88 litres 42.3 litres
Cooling Type Water Water Water
Power Output 1,200 to 1,500 hp 700 hp @ 3,000 rpm 800 hp @ 2,000 rpm
850 hp @ 2,300 rpm
1,000 hp @ 2,400 rpm
1,200 hp @ ?
Installed no no Maus no.1
Notes 40-degree Offered as a temporary replacement if another suitable engine could not be found or supplied in time
MB507 selected as a short-term solution instead
Modified and downrated from Flugmotor DB603
MB503 converted to run on diesel

Intention to rationalize a common engine for Maus in line with R1 and R2 projects from Krupp
MB = Mercedes-Benz

Engines for Maus after November 1942

Date February 1944 December 1944
Manufacturer Daimler-Benz Daimler-Benz
Name MB 509 MB 517*
Fuel Petrol
(Min. 77 Octane)
Cylinders V-12 V-12
Capacity 44.5 liters 44.5 liters
Cooling Type Air Water
Power Output 1,080 hp @ 2,300 rpm** 1,200 hp @ 2,500 rpm
Installed Maus no.2 Maus no.2
Notes Modified (and downrated) from Flugmotor DB603A
Required installation upside down, requiring an additional gear train
At 2,300 rpm the engine absorbs 78 hp for fans and 5 hp for gearing
(total efficiency loss 7.5 %)
Modified motor-boat engine (installed upright)

* MB 517 engine converted from running on petrol to diesel
** A British Report of 1945 states that the MB 509 could deliver 1,540 bhp for 5 minutes at 2,500 rpm and 1,375 bhp continuously at 2,300 rpm using 87 octane fuel and that 74 octane fuel reduces engine power by 200 hp. The 1,375 hp @ 2,300 rpm figure is repeated in German documents from November 1942 detailing Maus development.
MB = Mercedes-Benz
DB = Daimler-Benz

MB 507 engine. Source: Frohlich

All of these changes had swollen the weight of the Maus by about 10 tonnes, mainly as a result of a 3% thickness tolerance on the armor plate and the addition of a Flammenwerfer Anlage (flamethrower system). This 10-tonne burden was further increased by additional ammunition stowage demanded by Hitler in May and a Gasschützanlage (gas protection system) in June.


The goal of the entire project was to create a heavy tank all but immune to enemy fire. The Krupp turret design from 17th July 1942 had armor 250 mm thick at the front, with a large cast steel mantlet in front of that. The side armor was to be 200 mm thick and it was to have a roof 80 mm thick. By the start of December 1942, the need to shed some weight had brought the suggested turret armor down from 250 mm on the front and 200 mm on the sides to 225 mm on the front and 180 mm on the sides, and, by the end of the month, it was reduced yet further. By the end of December 1942, therefore, the hull (Wanne) armor for the Mäuschen Typ 205 was also reduced, down to 200 mm on the front. The sides were to be the same thickness as would be used on the Tiger II, with 80 mm on the inner hull sides except that on this vehicle they would have an additional 100 mm outer skirt layer over the top. The rear was to be 150 mm thick with the roof of the hull 100 mm thick at the front and 50 mm thick at the back, although British measurements in 1945 of a scrap hull say that the space was for a plate 60 mm thick. The hull floor had been reduced from 100 mm across the full length to ‘just’ 100 mm under the front of the hull and 50 mm at the back.

In January 1943, the design from Porsche had won out over the design from Krupp and the armor, the source of a lot of debate and redesign, had been determined. A full-size wooden model of the ‘Maus’ was ordered, as it was now being known, which combined the Porsche Typ 205 hull with the Krupp Maus Turm.

* figure based on calculated value suggested by Porsche’s 10% reduction
** Jentz/Doyle claim the July 1942 turret weighed 57 tonnes but also that Porsche’s plan to reduce the weight was to take it from 47 down to 43 tonnes (a 10% reduction) – this suggests a 10-tonne weight loss between July and November 1942 otherwise unaccounted for.
+ Estimated value
++ A confusing note from 10th April 1943 states that the original plan for the Maus was to use 80 mm side walls doubled over the upper sides to 160 mm with a weight of 150 tonnes, suggesting a different ‘Typ 205’ armor scheme was considered

The armor was to remain effectively unchanged from the acceptance in 1943, as any major changes would affect the wheelbase of the tank. In January 1943 though, it was proposed to make the side walls in one piece by ‘simply’ using one 180 mm thick plate and milling out 80 mm of the thickness for the bottom half. This would have the advantage of improving protection, as the armor would be all in one piece, but Krupp, the manufacturer of the armored hulls, had a different idea. It wanted 60 mm of the armor to be milled out to provide plate 120 mm thick over the wheels instead, but this could not be achieved without affecting both the wheelbase and the inner face of the armor, which was supposed to be made from softer steel than the exterior armor. Krupp however, did not give up, as the plan to make the sides in one piece and milling out what would be 4.5 tonnes of steel from each side plate was not an attractive one from a production point of view, as it was laborious, difficult, and wasteful of steel. Instead, Krupp proposed making it in two pieces, one 80 mm thick for the hull side and an outer layer 100 mm thick bolted to it. A further suggestion was to abandon the solid side plate altogether and to use a pair of plates. The idea was to not attach them together to be a homogenous panel of steel but to space them 30 to 40 mm apart on bolts. This, however, would involve a redesign of the tank, and the first Krupp alternative proposal also had to be rejected. Making the armor from two separate plates was complex due to the need to ensure they could fit and would reduce the protection from enemy fire due to the weakness of the bolts which might be used.

These ideas for changing how the side armor was to be made could not be executed at the time and still keep the production schedule for the Maus on track, but were not abandoned. They, along with another ‘spaced armor plan’ where the 100 mm and 80 mm plates were held just 10 mm apart (instead of 30 to 40 mm), and a plan for the entire side to just be a single 180 mm thick panel, were to be subjected to firing trials.

These potential improvements were confirmed in April 1943, when Porsche announced that it had improved the suspension system for the Maus so that it no longer relied upon a mounting on the inner face of the outer armor skirt. So simple was this solution that the lower section of the side armor could be made thinner (just 60 mm) and simply welded to the upper section. This was approved as a change for Wanne #7 onwards from the total of 120 tanks to be produced. This order was increased to 135 in May 1943.

Maus side armor proposals January to April 1943
(not to scale)

Scheme Image* Upper Side Lower Side Inner Hull Note
Milled armor
January 1943
180 mm 100 mm 60 mm Original scheme for Maus hull # 1
Krupp’s suggestion (Reduced Milling)
January 1943
180 mm 120 mm 60 mm Not possible as it interfered with the wheelbase
Double plates
March 1943
100 mm + 80 mm 100 mm 60 mm Complex to machine plates to fit exactly and difficult to secure together
Spaced armor scheme
March 1943
100 mm + 30 mm (air) + 80 mm 100 mm 60 mm Would increase width beyond rail gauge limits and/or involve redesigning the interior
Spaced armor scheme
March 1943
100 mm + 40 mm (air) + 80 mm 100 mm 60 mm Would increase width beyond rail gauge limits and/or involve redesigning the interior
Spaced armor scheme
March 1943
100 mm + 10 mm (air) + 80 mm 100 mm 60 – 80 mm Outer 100 mm plate and inner 80 mm plate spaced 10 mm apart but not bolted together to ease machining burden
Single piece – no milling
March 1943
180 mm 180 mm 60 mm Single piece of armor for the side with no milling – required new means of supporting the wheels
New suspension scheme
April 1943
180 mm 60 mm 120 mm With new suspension not connected to the outer armor, the lower plate could now be welded to the upper plate – reinforced inner hull
Arrangement selected for Maus hull #7 onwards

* Source – Author
Plate thickness manufacturing tolerance is +3 to +5%

So, the first six Maus hulls were planned to be made with a single 180 mm thick side plate which was milled down to 100 mm thick in the lower part but, after that, production would be greatly simplified by virtue of the improved suspension design. The side armor would still be 180 mm over the upper sides but the lower part could simply be welded on as the suspension was now connected only to the inner hull of the tank rather than spread to the side skirt. This is a good lesson in how a small design change in one component can deliver a significant improvement in manufacturing.

In February 1943, the armor for the Maus was, once more, under discussion. This meeting, held on the 4th, was not about methods of construction or proposed thicknesses required but on the material itself. In order to make sure the armor was as good as possible, it was suggested that instead of using the current standard type of armor plate, they should switch to using naval armor plating (marine platten) which had been made available and was considered to be of better quality than the standard-type plate. There was, however, a problem with the plates – not the weight or material, but the size. In order to be used, these giant slabs of steel would have to be rolled down to 2 m x 2.3 m and 200 mm thick.


Krupp met with representatives of Wa Prüf 6 in the middle of January 1943 to discuss the turret for the tank. Known as the ‘Maus Turm 12.8 cm’, the gun to be used was, unsurprisingly, a 12.8 cm piece. Back in April 1942, the 12.8 cm gun considered was an L/50, with additional thought given to using a longer gun of either 60 or 70 calibers. That was reiterated later with thought given to using a 61 caliber-long gun firing shaped charge ammunition or types of sabotted projectiles. In January 1943, the 12.8 cm selected by Wa Prüf 6 was an L/55 gun as it, combined with the new ammunition, would provide the performance required. Therefore, modifications would need to be made to Krupp’s turret design in order to accommodate this longer gun. Even so, there was the option of switching out that gun with a 15 cm L/38, and both were to be partnered with a 7.5 cm gun too.
January to February 1943 was a time of flux for the turret design. The idea of mounting a flame projector in the turret had been dropped but in its place were ideas for a 2 cm Flak anti-aircraft gun in the front as well as possibly a new type of range-finder (EM – Entfernungsmesser).

2 cm Flak MG151/20 anti-aircraft mounting as designed for the front of the Maus-Turm February 1943. Source: Frohlich

Between March and July 1943, four types of range-finders were considered: horizontal, vertical, T-shaped, and V-type. The 1.73 m horizontal type was impossible to use, as the position of the guns prevented it from being installed. A 1.0 m vertical-type range finder would have to be mocked-up in wood on the mockup Maus turret to assess whether or not the loader (or gunner) could even use it. The T-shaped range-finder was experimental and required a new housing measuring 80 cm x 20 cm on the turret roof which would allow the gunner to range and fire on his own but would also restrict the commander’s visibility and would be less accurate at long range. The final type, the V-type range finder, was in common use already but was discounted as it was required (after July 1943) to be protected by armor and operable when the tank was buttoned down in combat.

Welded Maus turret and behind it a completed Maus hull. Note the supporting pins used in the construction of the turret are still sticking out of the front left of the turret and have not yet been ground off. Source: Milsom
Close-up of the interlocking plate with supporting system – this photo shows the edge of the glacis after the explosion inside has blown off the side armor and broken the weld.

Adding to this growth in armament was a growth in protection, as the commander’s cupola (Kommandantenkuppel) was significantly uparmored to match the rest of the turret and the crew hatch (Einsteigklappe) was increased to 60 mm thick. With Wa Prüf 6 insisting on a small petrol/electric generator being added as well, the weight and complexity had increased although, as a plus-point, the vision ports (Ausblichluken) and empty cartridge ejection ports planned in the side of the turret (which would mean boring through the armor) were abandoned. The vision ports would be replaced with new periscopes (Schwenkspiegel) in the turret-roof and the spent casings could be tossed out of the ammunition hatch (Munitionsluke).

“The turret is a really massive structure being particularly high in relation to its width and length and in relation to the hull”
British examination report 1945

Even with dropping those ports, however, the weight of the Maus Turm (Turm Typ 205 ‘Maus’) had, by February 1943, crept over the strict 50-tonne limit set by Dr. Porsche in order to keep the total vehicle mass to no more than 180-tonnes. Changes followed through April 1943 with the addition of ports for machine-pistols in the side walls (Machine-Pistol-Luke) on a ball-mount (Kugelblende).

After the full-sized wooden mockup was shown to Hitler in May 1943, Porsche became very concerned about the shape of the front of the turret, as the inwards curve could lead to shells ricocheting into the roof of the hull. Porsche suggested that this could be obviated by inverting the lower curve to make it curve outwards rather than inwards. That change might add some additional room within what was becoming an increasingly cramped turret. So cramped that, when in May 1943 it was decided between Dr. Porsche and the Waffenamt to add a machine gun into the front of the turret, Krupp had to inform them that there was not enough room.

This was not the only design change proposed by Porsche that was making the life of Krupp difficult, as he [Dr. Porsche] had already been asked a couple of weeks earlier to stop modifying the turret or making new openings in the base (in that case for access to the crawl space) as they were weakening the structure of the tank. Even so, it should be borne in mind that the turret basket of the Maus Turm remained 55 mm thick and the floor plate was 93 mm thick.

Underside of the three Maus turrets found by Allied forces on the Meppen range in 1945 showing the heavily protected inner turret basket, 55 mm thick, and the 93 mm thick turret floor. Source: UK National Archives

Other problems would remain, however, such as the commander who had to turn to his left to avoid being hit by the recoil from the 7.5 cm gun and could not sit down when the vehicle was moving or in combat without being hit by the breech of the 12.8 cm gun or recoil guard for the 7.5 cm gun. Even standing, the commander had a problem as he was in the way of the loader when loading the 7.5 cm gun, so some shuffling around was needed to operate that gun in combat. Some shuffling of the turret-crew positions was implemented in July 1943, with the right-side loader moved to the back of the turret, where he would sit just inside the bustle. Combined with the removal of the ammunition loading assist system (Munitionstransportanlage), space could be freed up within the turret, reducing some complexities associated with this loading system, as well as allowing the loader to freely operate the smoke grenade launchers (Nebelwurf Gerät). The commander would be moved over to the position occupied by the loader and this simple change got him out of the way of the breech of the 7.5 cm gun as well as allowed him to operate the range finder. The gunner could also be moved, as his legs were in an awkward position. Moving him back to the position occupied by the left-side loader removed this problem and allowed him to not only operate the turret rotation mechanisms but also the machine gun in front of the turret. That loader was simply moved to the rear of the turret with the other loader.

This crew-shuffling was simply a result of too much crammed into the turret, which although massive on the outside, was significantly smaller on the inside, as the majority of the space was occupied by the breeches of the guns and their associated ammunition. Yet, despite these difficulties, there seemingly was no discussion of the obvious solution – remove the 7.5 cm gun.

At the same time as Porsche was suggesting the front curve being inverted, he also had the idea of adding a 3.7 cm anti-aircraft gun in an anti-aircraft turret (fliegerabwehr Kuppel) on top of the primary turret, capable of 360 degree traverse seemingly in contradiction to the fact that the turret was already at or just over the 50-tonne limit Porsche had personally imposed that February. Despite the difficulties with the turret design and ignoring Dr. Porsche’s concerns over the front curve and his less than stellar idea for an AA gun turret on top of the primary turret, a mockup was ready by July 1943.

The finished Krupp Maus-turm provides a good view of not only the enormous size of the turret and its massive cast mantlet around the primary gun, but also the interlocking armour and supporting rods at the armor joint on the rear. The hole in the side is the machine pistol ball-mount (MP-kugelblende) and in the rear is the loading port with machine pistol port (Munitionsluke mit MP-stopfen). Source: Frohlich (left) and Jentz and Doyle (right)

Primary Maus turret armor/design changes June 1942 to January/February 1943

Project Mäuschen
Name Krupp Maus Turm Krupp Maus Turm Krupp Maus Turm for Typ 205 Turm Type 205 ‘Maus’ 12.8 cm
Date ~1942 July 1942 November 1942 January – February 1943
Mass (tonnes) u/k 57 43** 49.5 / 51*
Front 250 mm required
(232-241.5 mm actual)
250 mm + mantlet 225 mm
Side 200 mm required
(204.4 – 205.4 mm actual)
200 mm 180 mm
Rear 200 mm required
(205.5 – 205.8 mm actual)
200 mm 200 mm
Roof 90 mm required
(90.8 – 91.5 mm actual)
80 mm 72 mm
Hatches 50 mm + 50 mm + 60 mm
Notes Tolerances for plates as follows:
Front: -3.4% to -7.2%
Sides: +1.75 to +2.9%
Rear: +1.75% to +2.15%
2 cm Flak added, improved cupola armor

* 49.5 tonnes in January 1943, given as 51 tonnes in February, exceeding the 50-tonne limit imposed by Dr. Porsche that month
** Jentz/Doyle claim the July 1942 turret was 57 tonnes but also that Porsche’s plan to reduce the weight was to take it from 47 down to 43 tonnes (a 10% reduction) – this suggests a 10-tonne weight loss between July and November 1942 otherwise unaccounted for.

Primary Maus turret armor/design changes after February 1943

Project Mäuschen Maus
Name Maus Turm
(Porsche suggestion)
Maus Turm Type 205 with Maus Turm
Date May 1943 October 1943 December 1942

January 1943
Front 220 / 205 mm*** 225 mm
Side 200 mm
Rear 200 mm
Roof 60 mm
Notes Reshaping of the front to avoid the lower curve on the front
Addition of 3.7 cm AA turret
Curved front Curved front

+ Estimated value
*** The 220 mm thick plate used for the turret front was only 205 mm thick after being bent into shape, although a post-war US intelligence report erroneously reported the thickness as 240 mm.

Armor Testing

As development and discussions over the fabrication of the armor for the hull were taking place with the newly designed suspension in January 1943, the work on the turret had also progressed. Krupp, the armor manufacturer for the turret and hull, was issued a contract for a single blank turret and two hulls for firing trials. These two hulls were not only testing the resistance of the plates to attack but also the strength of the welds joining what was to be the thickest armor ever mounted on a tank at that time. The standard method of fastening heavy plates together involved cutting interlocking joints in them and then welding over those joints. Other methods included simple welding of one plate to another and the supplementing of welded seams with a bolted joint-piece which could then be over-welded, as was done on the side hulls of the Tiger I. For the Maus, however, boring holes for a bolted support plate was not practical and the joining of the armor plates had to rely on welds supported by pins instead.

Hull number one (Model 1) was to have the interlocking parts of the armor plating cut by means of being milled out, whereas the second hull for firing trials (Model 2) was to have these sections cut out by means of a flame-torch. Cutting by means of the torch was faster and easier than milling out large pieces of heavy armor plate, but was considered to produce an inferior product than milling due to the accuracy of the surface a milled-cut would produce. A decision on which method was to be used would not be made until after the firing trials had been completed at Hillersleben in June 1943. Regardless of which method of cutting was to be used, the interlocking sections were to be supported by the use of 100 mm diameter connecting pins (Verbindung Bolzen) between these plates. The joint and pins would then be welded together, with the pins providing additional strength to the joint. These pins were important to the construction of the hull to support the welds, but were an additional burden on construction as they had to be bored out and were also considered to marginally weaken the overall armor protection where they were used. Their use was essential to the hull fabrication process but to reduce any effect on weakening the armor, they were reduced after June 1943 to just 80 mm in diameter.

Diagrammatic representation of the use of the verbindung bolzen (connecting pins) to add strength to the joint between two armor plates. Left to right: Plates cut and shaped, put together and holes bored, supporting pins (pink) fitted, and the edges are all-welded over. Source: Author


Even before a finished design was ready or approved, Hitler, in November 1942, ordered that 5 Mäuschen were to be built and a timetable set by Wa Prüf 4 to achieve this. Turret and hull drawings were to be ready and approved by March 1943 and then 5 vehicles built within just 6-7 months- an ambitious and unrealistic schedule, as this also called for trials by 5th May 1943. The Heereswaffenamt (Army Ordnance Department) arranged for Colonel Haenel to help ensure timetables for the Maus were adhered to by going from firm to firm to press them to meet production requirements and, if necessary, assess severe penalties for missing deadlines.

Krupp received a contract in December 1942 for a complete prototype Maus turret (Versuschsturm) followed a month later by a contract for a hull. An agreement between Krupp and Porsche in the middle of January 1943 stated that assembly was to take place at the Alkett works by September 1943. Several firms were actually involved in the production of the Maus:

Primary firms connected with Maus production and development

Company Responsibility
Porsche Design and overall construction/development
Krupp Hull and turret fabrication
Daimler-Benz Engine development
Siemens-Schuckert Electrical apparatus
Škoda Suspension, tracks, and gearing
Alkett (Altmärkische Kettenfabrik) Assembly
Alkett Design and specification of tracks

The initial drawings for the turret and hull which were due in March were actually ready on 21st January 1943 and the production of 120 vehicles was ordered on 10th February.

Maus track link (top), track pin (bottom) and removable ice cleats (center) weighed 29 kg and measured 1,100 mm wide, 263 mm long, and 127 mm thick when complete. Each side of the Maus used 160 individual plates (4.64 tonnes per side). Seen here on the outside of the link (left) and the inside (right). Source: Frohlich and UK National Archives respectively

Production of the first Maus hulls had started very quickly after the design was authorized and, for this reason, it was too late to make the change to the improved side armor scheme for the first vehicles. By the end of May 1943 though, a problem had been identified. The tolerances on the armor plates of 3% meant that those 180 mm thick side panels could actually be up to 185.4 mm thick each, meaning an additional 11 mm or so in potential width. As the original design was exactly 3,700 mm wide, the maximum limit for the German rail gauge, any additional width created a huge problem as the tank would be ‘out of gauge’. As a result of the first four hulls already having been welded together that month, they were allowed to be finished as long as the width was kept to 3,715 mm, as even this ‘out of gauge’ width was just about manageable.

This width problem had to be addressed and, in order to guarantee that the maximum width would not be exceeded, after hull number 5 the outer 180 mm armor was to be milled down even more than before. An extra 10 mm was to be shaved off the outside, effectively doubling the amount of machining that was needed on those plates, as well as reducing the armor to 170 mm thick (upper) and 90 mm (lower). This was to be a temporary solution to the problem, rectified from hull number 14 onwards, where the plates were to be rolled 170 mm thick to begin with. The fact that in May they could only implement this change for hull 14 onwards strongly suggests that at least 13 hulls were already in preparation by 26th May 1943 when the order was delivered, with the first 4 nearly finished hulls undergoing assembly. Thus, before even the first vehicle was finished, there would effectively be 3 slightly differently made Maus – the consequences of not producing prototypes.

Exactly a month after this debacle was uncovered, in an effort to reduce the time required for welding, Porsche requested Krupp to mill the side plates of hulls 3 and 4 to match those scheduled for 5 to 13.

Maus Side Armor/Width and Manufacturing Differences

Hull (Wanne) Number Side Armor Maximum Width
1 180 mm (upper), 100 mm (lower) plus 3% allowable manufacturing tolerance
(185 mm / 103 mm max. thickness respectively)
Left side (upper) 191 mm, Right side (upper) 186 mm**
3,717 mm
2-4* 180 mm (upper), 100 mm (lower) plus 3% allowable manufacturing tolerance
(185 mm / 103 mm max. thickness respectively)
3,715 mm
3-4 180 mm (upper), 100 mm (lower) milled down to 170 mm (upper) and 90 mm (lower) 3,700 mm
5-13 180 mm (upper), 100 mm (lower) milled down to 170 mm (upper) and 90 mm (lower) 3,700 mm
14+ 170 mm (upper), 90 mm (lower) plus 3% manufacturing tolerance
(175 mm / 93 mm max. thickness respectively)
3,690 mm

* The order of May 1943 to keep hulls 1-4 ‘out-of-gauge’ was changed in June 1943 with hulls numbers 3 and 4 ordered to also be milled down to 170 mm like hulls 5 to 13.
** Hull number one was 11 mm out of tolerance on the left-hand side, and 6 mm out of tolerance on the right-hand side when it was assembled in July 1943

Further changes to the hulls were far less drastic than milling off 10 mm from each side. Through the summer of 1943, amendments to the hull were dominated by the boring of towing holes.

The only firm in all of Germany with a machine capable of milling these enormous plates was at Krupp’s factory and any damage to that machine would, therefore, cripple fabrication. Ensuring a system whereby the side armor needed no milling meant that production was not reliant upon a single machine. This was achieved by a reduction of side armor to allow for manufacturing tolerances to still stay within the rail gauge and the change to a type of suspension not dependent upon the side skirts to support it.

The production schedule was a tight one as well, with an order in May 1943 for the initial 120 tanks increased to 135, with the first two vehicles expected to be ready for November that year. Production of hulls, therefore, was supposed to be 5 the following month (December 1943) then 8 in January 1944 with production becoming streamlined and up to full speed with 10 per month from February 1944 onwards. The 120 production target, therefore, would deliver the last Maus hull (assuming things stayed on schedule) in January 1945 and the 135th Maus by April 1945. Turret production was expected to keep pace with the hulls, albeit to trail them by one month, with the 135th turret to be delivered in May 1945. The Waffenamt, however, had issued contracts for production of 141 Maus (6 experimental hulls and 135 serial production vehicles) by June 1943 and production of the main sections of armor had already begun when Generaloberst Guderian (General Inspekteur der Panzertruppen) overruled this order and reduced the order to just 5 in order for them to be tested under real combat situations before a full order was placed.

In the back and forth around production, the Panzerkommission changed this reduced order from a total of 5 to just 5 per month instead on 1st July. Eleven days later, the six experimental chassis already in hand were given official production serial numbers 351451 to 351456 (6 vehicles) with serial numbers assigned to production vehicles from 351457 to 351591 (135 vehicles).

When, less than a month later, Krupp’s plant in Essen was bombed by the Allies, the concerns about the single milling machine were proven to be justified. Production ground to a halt with a delay of a month to clear the rubble away, leaving 30 Maus in various stages of production. A previous bombing raid in March 1943 had not affected hull production but had caused an estimated 2-month delay in turrets as the wooden mockup had been burned. Thus, the first trial turret was not going to be available until the middle of November, a month behind schedule, and now two months behind the scheduled delivery of the first hull.

Maus Hull (Wanne) Production

Hull (Wanne) Group Hull (Wanne) Number Serial Number Status as of 4th August 1943
1 – 4* 1 351451 Hull welding finished 7th July 1943
Delivery delay for 4 weeks
2 351452 In Wagen Werkstatt (workshop) Delivery delay for 3 days until when rail lines are restored
3 – 4 351453 – 351454 In Wagen Werkstatt (workshop)
5 – 13 5 – 6 351455 – 351456 At Panzerbau (construction shop) – awaiting crane repair before they can be delivered for welding
7 351457 At Panzerbau (construction shop) – awaiting crane repair before they can be delivered for welding
8 – 9 351458 – 351459 Armor panels cut and at Panzerbau
10 351460 Most armor plates delivered by Panzerplatte Walzwerk (armor fabricators)
11 – 13 351461 – 351463 Most armor plates rolled but buried under rubble
14 + 14 – 30 351464 – 351481 Most armor plates rolled but buried under rubble
31 + 31 – 141 351181 – 351591 No work

* The order of May 1943 to keep hulls 1-4 ‘out-of-gauge’ was changed in June 1943 with hulls numbers 3 and 4 ordered to also be milled down to 170 mm like hulls 5 to 13.
Green highlight indicates Versuchs (experimental) series, Blue highlight indicates serial production

With production delays caused by bombing, Krupp, seemingly without any warning, received orders on 27th October 1943 that, instead of 120 vehicles, just 1 Maus was to be completed instead. All of the unused armor plates were ordered to be transferred to the Sturmgeschütz program at Harkort-Eicken instead, excluding those already prepared for use in Maus construction.

More bad news for Krupp followed, with an order to cancel further development of the tank and cancellation of orders for series production of the turrets and hulls. On 5th November, another order clarified the situation, changing the initial batch of 6 prototype turrets to just one. A week later the contract for 6 prototype hulls was changed to just 2.

With work canceled, there seemed little point in finishing hull number 1, which still needed some machining work done but was otherwise finished. It was sent from Krupp to Alkett on 26th September 1943, where it was fitted with the internal components and drive train. This was completed on 22nd December and then ordered to be shipped to the testing grounds at Böblingen on 10th January 1944. When it left for Böblingen the next day via railway, the vehicle was able to move under its own power and load itself, but work on the hull was otherwise incomplete inside. The journey to Böblingen took 3 days.

The second Maus hull arrived at Alkett on 8th January, but work stopped by the middle of the month with a focus on Sturmgeschütz assembly instead. After about a fortnight of lying idle, it was decided to ship the partially assembled hull (fitted with just suspension and mechanical brakes) to Böblingen to finish the work.

Maus hull number 2 on its 27 m railcar, 10th March 1944. Source: Jentz and Doyle

The single turret which had been ordered to be completed did not fare much better. It was not finished until the middle of April 1944, several months behind schedule – no doubt as a result of being a low priority project as serial production had been canceled.

Engineer Karl Gensburger from Alkett takes the Maus for a preliminary test drive around the factory, December 1943. Source: Ludvigsen

It was then inspected by Wa Prüf 6, which made several changes to the design to rectify some minor deficiencies, but neither Krupp nor Alkett were going to implement them at their primary factories. The Maus project was all but over and this single turret was to be sent directly to Böblingen instead, where technicians from Krupp could finish work on it. Arriving at Böblingen on 3rd May 1944, Turret number 1 was finally mounted on Hull number 2 during the night of 7th to 8th June 1944.

Maus hull number 2 mated with turret number 1 at Böblingen, June 1944. Note the towing eyes which have been added and that there are two additional shell deflectors on the hull roof. Hull number 1 did not have these deflectors. Source: Frohlich


The most critical element in a tank edging up towards 200 tonnes was how it was to be carried. Somewhat impressively, the designers of the various Mäeuschen never seem to have considered the ‘easy’ solution of adopting plain rollers, as was adopted on the much lighter TOG-2 in the UK. Instead, the design had originally planned to simply copy the suspension from the Tiger but, as the weight of the design ballooned from 100 tonnes to around 150 tonnes, even a strengthened form of Tiger suspension had to be abandoned. Instead, the designers from Porsche focussed their attention on multiple small wheels to spread the load and these were arranged in groups of bogies running on a very wide track to spread the weight. This was fine in theory, except that no one had attempted to make an effective suspension system for a tank of this weight before.
The original ideas for the suspension back in October 1942 had 12 double road wheels per side using units copied directly from the Tiger (P) but, by January 1943, this was down to just 10 sets. These pairs of road wheels were suspended between the inner hull and the outer skirt of armor on a large support pin (Tragzapfen). This was the primary reason the side armor had to be made in one piece until the suspension was redesigned. When, in March 1943, a new system of Laufwerk (suspension and road wheels) was adopted, it took the loading off the side armor, allowing for the manufacturing process to the improved (notwithstanding the fact that the first vehicles were too wide). That system came too late for the first 6 hulls but, as hull 7 had not yet been assembled, the changes could be adopted from number 7 onwards.
Further suspension improvements followed in April 1943 with the previously welded suspension supports (Trägerstützen) being replaced with ones that bolted onto the hull instead. However, this meant boring holes through the armor plate in order to accommodate longitudinal supporting arms for the torsion bar suspension.
The design for the track which was shown on 21st January 1943 differed from the earlier work on suspension for the tank to take into account the growing weight of the machine. Developed by Dr. Porsche, the system was unique with no compatibility with the suspension from any other tank. This new suspension system (neue Laufwerk) had removed the need for the side skirts to bear some of the suspension load and also allowed for an additional set of bogies to be added to the design. Running on a new design of track 1,100 mm wide, this arrangement allowed for a better distribution of weight to the track which in turn allowed for improved crossing of soft ground. Not only did this new compact design allow for an extra bogie, it also reduced weight by a significant 4 tonnes. These new suspension units (designed by Porsche) were not to be built by Porsche or Krupp, but by Škoda as a subcontractor.

Improved volute suspension units fitted in March 1944, replacing the earlier type in which the internal rubber rings had failed during testing in January 1944. These units were all made by Škoda. Source: UK National Archives and Frohlich
The wheels, fitted with a steel tire, contained a heavy rubber ring within them as a shock absorber and were identified, even before testing, as a weak point. They were a hang-over from the urgent need to change from torsion-bars to volute spring suspension in February 1943 in order to create space for the flame projector system. Dr. Porsche always preferred torsion bars and this was the original and favored system for the Maus, but with the flame-projector requirement forced upon him at very short notice, he complained that he lacked the time to test a new type of heavier torsion bar system and reluctantly agreed to what he considered to be an inferior system of volute springs. Tested in January 1944, the internal rubber rings in these wheels failed after only a short distance and were replaced with an improved type of wheel in March 1944.

Replacing the original road wheels with an improved design (shown being fitted) in March 1944 involved jacking up the Maus by means of 3 large hydraulic jacks. During this time, the engine, generators, motors and final drive were all removed and inspected. Each of these new units weighed 800 kg. Source: Frohlich
The first hulls, which were in the process of being made, were to have holes for the bracing arms (Streben) bored into the hull sides and side skirts – a lengthy process. This redesign meant that holes would still have to be bored out of the inside of the side skirts and in the hull, but they would only be bearing the load of the bolts for the horseshoe-shaped sections (Träger Stütze – suspension supports) for holding the Streben, meaning that the lower side skirts could be made thinner and could be welded onto the upper section. The ends of the bolts holding those horseshoe-shaped mounts for the Streben are visible along the bottom edge of the side skirt.

Original method (left) of holding the bracing arm (Streben) for the external torsion-bar suspension (laufwerk) involving boring holes at both ends, and modified method (right) (February/March 1943) of holding the bracing arm for the volute spring suspension. Not to scale. Source: Author

Cross-section of the sponson area with the track-run below. Clearly shown is the Streben for the support of the suspension unit and the new type of horseshoe-shaped mounts holding it to the hull and outer armor. Source: US Army Intelligence Bulletin March 1946

Pair of incomplete Maus hulls stacked on top of each other (the bottom one is upside down) found by the Allies in 1945 showing the holes bored through the lower side armor for the horseshoe-shaped supports for the Streben. Source: UK National Archives

Composite image edited to show the upside-down horseshoe-shaped holders for the ends of the Streben on the inside of the side skirts. Source: Jentz and Doyle, and Frohlich


Right from the start, the goal was to create a 100-tonne tank with a heavy gun and, on 14th April 1942 (a month after the program started), the gun in question was identified as the 15 cm L/40. This gun used unitary (single-piece) cartridges instead of a shell with separate bagged charges. The desire was to be able to fire 4 to 5 times per minute, but during the development of this weapon, it was decided to reduce the desired shell weight from 43 kg to 34 kg and to compensate for this with an increase in muzzle velocity to 845 m/s.
Just as with the early concept for the vehicle which became the Jagdtiger, there was an initial expectation for the tank to be able to operate in indirect fire mode, which is to act as field artillery. This is evidenced by the fact that, although the elevation limits for the gun were -8 to +15 degrees, it was desired that the gun should also be able to be elevated to +40 around its entire arc of rotation (360 degrees). There could be no reason for this except to act in an indirect fire capacity and this turret was to be offered to Porsche for use in its VK 100.01 by the middle of May, leaving just 3-4 weeks to design it. Krupp’s engineers planned another turret design based around a different gun, the 12.8 cm L/50, which could fire a slightly lighter 29.3 kg shell at 810 m/s.
By the middle of May, it was expected that even these guns were not going to be able to deliver the anti-armor punch which was desired of this new tank and caliber lengths of L/60 and L/72 should be considered even though, as of that time, those guns did not exist. A month later, the guns had changed again, with Porsche suggesting a 15 cm L/37 or 10.5 cm L/70 gun, with Hitler selecting the 10.5 cm gun for reasons of improved ammunition stowage and a better rate of fire. At this time, Hitler was against the adoption of a second turret with a 7.5 cm gun.
In July 1942, Krupp was issued a contract by Wa Prüf 6 for the June design under the name ‘Pz.Kpfw. Mäuschen’ to mount a pair of guns in a single mounting in a single turret. The guns in question, despite Hitler’s selection of a 10.5 cm gun, were the 15 cm KwK. L/31 and the 7.5 cm Kw.K. L/24. The combination of these guns would allow the Mäuschen to deliver effective indirect high-explosive shellfire, but also direct fire against armored targets. Both guns were to be able to achieve an elevation of -7 to +25 degrees, although a British examination in 1945 states elevation was limited to +23 degrees.
At the start of December 1942, Hitler ordered a trials vehicle to be ready for summer 1943 but wanted information on the performance of the 15 cm gun, the 12.7 cm Naval gun, 12.8 cm Flak gun, and a new (as yet unbuilt) 12.8 cm gun with a longer length.
When, on 3rd January 1943, Hitler met with Armaments Minister Albert Speer, he ordered the Mäuschen into production by the end of the year but was still debating what the final gun was to be. The candidate guns were essentially the same as before, albeit the 12.7 cm Naval gun idea was dropped. Hitler was still favoring the 12.8 cm gun option, although a 15 cm gun option was to be projected too and the secondary 7.5 cm gun was still being retained.
By January 1943, the gun for the Maus had been selected. It was to be a 12.8 cm gun, 55 calibers long and capable of firing new ammunition to achieve the performance required against enemy armor. An option was retained to switch out the 12.8 cm gun with a 15 cm L/38 gun to provide additional high-explosive firepower and both options could be fitted on the same carriage, making exchange simple. Whichever gun was used, it was to be paired with a 7.5 cm L/36 gun. Originally, the secondary armament was intended to be a 7.5 cm Kw.K. L/24, but this was changed out prior to January 1943 with the slightly longer version. The ammunition remained unchanged but the addition of the slightly longer gun meant a small increase in anti-armor performance. An additional weapon planned in January 1943 was a 2 cm Flak gun built into the turret.
In December 1942, before the design of the Maus was even approved, a supplemental system to protect the tank from enemy infantry and to attack enemy positions was proposed and Porsche was ordered to add this to his design on 2nd February 1944 by Col. Haenel. At a meeting held in Stuttgart on 10th February, representatives of all of the manufacturers complained about this late addition to the design and that the added complications would slow down production. This Flammenwerfer Anlage (flamethrower system) was based on the Gross–Flammenwerfer (heavy flamethrower) system which had been installed in a Panzer III, but a long-range of 150 to 200 m was wanted for the flame-projector on the Maus.
The Gross-Flammenwerfer as used on the Pz.III was made by Hermann Koebe of Feuerwehr-Geräte-Fabrik of Berlin, a manufacturer of fire-fighting equipment, and they were asked if they could make this new long-range flame-projection system. They responded that they could not, as even a 100 m range necessitated a flame-nozzle (Spritzkopf) 22 mm wide and used 33 liters of fuel per second propelled by a 30 hp engine driving a pumping system. To project a flame even further would require a narrower (12-14 mm) nozzle, but to add an additional layer of complexity the Maus was not to have one flame-projector nozzle but two, one on each side. Consideration had actually been made to mount those nozzles in the turret (abandoned to keep turret-weight down) and at the front of the tank’s hull, which would assist with the range, although it would prevent the use of flame to keep enemy troops from the sides of the tank. Mounting the system on the front would require additional armor protection to prevent damage to the nozzles and to the fuel system of the tank but even at the back, they were still substantially armored under a 150 mm thick cowling. Altogether, this system weighed an extra 4.9 tonnes, and added significant complexity to the design of the tank, not least of which was directing the flame projectors. That was to be done by an indicator for the radio operator in the front of the hull to control the direction and use of the flame projectors, but this complexity and the added weight was simply an unnecessary complication for the tank. Despite an attempt to reduce the weight to just 2 tonnes by reducing the armor over the projectors from 150 mm to just 30 mm on the front, the problems of the system, the already tight space requirements and the growing weight of the Maus made this device highly impractical.
In May 1943, the entire flame projector idea was rightly abandoned. It had caused one other key change in the design of the Maus which was to make it a lot heavier. The torsion bar suspension of the original design needed an additional bogie to bear the weight, but with a lack of space for it, the torsion bars were replaced with a volute spring-type suspension instead.

Front crew station for the driver (left) and radio operator (right). Note the escape hatch in the floor in front of the radio operator’s seat. Source: Frohlich
Redesigning the turret to maximize space created almost as many problems for the main armament as it solved. The main armament was decided for the Maus around a simple 3-weapon standard. The main gun was a 12.8 cm gun which was to be interchangeable with a 15 cm gun, a secondary 7.5 cm gun (long enough so that gases from the muzzle did not enter the air intakes on the hull roof below), and a forward-facing machine gun. These gun choices had come about as a result of needing to perform particular roles and had been variously modified in order to avoid technical problems (the lengthening of the 7.5 cm gun), to increase muzzle velocity (longer gun options), and to allow for the use of saboted ammunition (removal of the muzzle brakes).
The ammunition was modified to support these changes through the adoption of unitary ammunition (single-piece cased ammunition rather than two-piece ammo with shell and a separate propellant).
However, the 7.5 cm gun used the same ammunition as an L/24, which was predominantly hollow-charge ammunition (HL-Granate). The general high explosive 7.5 cm shell (Granate) was considered unsuitable and even the armor-piercing Panzer-Granate (Pz.Gr.) 39 shell was considered poor. More than 50 mm of penetration was required of the L/36 and it was expected that using the Pz.Gr.39, this longer 7.5 cm gun would be able to achieve that. Shells which were of ‘second quality’ (not good enough for the 7.5 cm Pak 40) could, therefore, be used for this gun.
Whilst existing shells were available for the 7.5 cm gun, new shells were needed for the 12.8 cm gun and, by March 1943, development of shells for this gun included a full-calibre armor-piercing shell APCHE-T (Vollkaliber-Panzer Granate), saboted armor-piercing shells (Treibspiegel Panzer-Granate), hollow-charge high explosive (HL-Granate), smoke (Nebel-Granate), anti-concrete shell (Be-granate), high-explosive (Sprenggranate), Brand-Granate, incendiary (L’spur mit brandsatz), and a leuchtgeschoss. All of the rounds were to be fitted with a tracer (L’spur) able to provide tracing of the shell out to 3,000 m. Another full-caliber 12.8 cm anti-armor shell, a ballistic-capped armor-piercing shell, would follow later on (APBC-HE-T).
An important note on the 12.8 cm gun is that, right from the start of the development of a main gun for the project, preference had been given to the use of unitary ammunition – a case and shell combined into a single piece. Firing tests conducted on 29th April 1943 compared the rates of fire between unitary and two-piece ammunition (case and shell separate) for a 12.8 cm gun (in this case the 12.8 cm Flak 40) in a wooden model of the turret to evaluate the differences. The results of firing just 15 rounds of each confirmed that unitary rounds were preferable. On 29th June 1943, unitary ammunition was ordered for the 12.8 cm Kw.K. (Maus) L/55, but only for 300 rounds, with 100 to be delivered by 15th July 1943. The reason for this low number of rounds was due to production problems associated with the cases (Patrone Huelsen) for the shells and plans were put into place for two-piece ammunition to be used after this date for the 12.8 cm Kw.K. (Maus). This also meant that later vehicles would need modifications made to the ammunition stowage arrangements. By the end of 1943, with the serial production cancelled, the Maus became a low priority and, although the 12.8 cm Kw.K. 44 (Maus) gun was fitted as planned, the unitary ammunition did not join it. Instead, the Maus was fitted with racks for two-piece shells, with the shells stowed separately from the propellant-containing cartridges at the back of the turret. Shells (unitary) for the 7.5 cm gun were stowed in the front right of the turret, just to the right of the gun.

The breach of the 7.5 cm Kw.K. 44 L/36 on the right-hand side of the turret looks minute next to the enormous bulk of the 12.8 cm gun (left). The ammunition for the 7.5 cm gun is located conveniently next to the gun. Source: Jentz and Doyle
Ammunition for the 15 cm gun was not as complicated, with high-explosive (Sprenggranate), hollow-charge (HL-Granate), armor-piercing (APCBCHE-T), semi-armor piercing (SAP)(Halbpanzergranate), and an anti-concrete shell (15 cm Granate 19 Rot Beton.). The requirements for the anti-concrete shell for the 12.8 cm gun (and by extension for the 15 cm gun) were that it should be able to breach a reinforced concrete wall up to 4 m thick, a substantial demand but one which would enable to Maus to attack even the heaviest infantry and gun positions and knock them out. This focus on anti-concrete performance and the ability to fire sabotted shells shows that the purpose of the primary armament was to take out bunkers and heavy enemy armor, whilst the 7.5 cm secondary gun was for light targets only, reducing waste of the larger shells. Production of the 15 cm Kw.K. L/38 for the Maus was slow and, on 8th June 1944, the contract for production was canceled, with only two gun tubes completed.

Weapon Role Performance
Machine gun
(M.G. 34 or M.G. 42)
Anti-infantry n/a
7.5 cm KwK. 44 (Maus) Light-targets and open positions 50 mm with Pz.Gr.39
12.8 cm Kw.K. L/55 Anti-heavy armor / anti-concrete 4 m concrete with anti-concrete shell
245 mm @ 1,000 m / 30 deg. with 8.8 cm Triebspeigel-Geschoss mit H-kern at 1,260 m/s
15 cm Kw.K. L/38 Anti-heavy armor / anti-concrete >4 m concrete with anti-concrete shell*

* Estimated anti-armor performance of the 15 cm anti-concrete shell

The primary armament, the massive 12.8 cm Kw.K. 44 (Maus), was, in spite of its huge size, a good fit for the turret and able to elevate between +24* degrees and – 7. (* British examination in 1945 of the gun cradle showed the elevation limit to be 23 degrees). Mounted to the left of the secondary armament was a mount for an M.G.34, although Wa Prüf 6 requested an M.G.42 instead. Stowage for ammunition was a large task. 85 rounds of ammunition for the 7.5 cm gun were carried, as an additional stowage for 26 rounds was added between June and July 1944.

M.G. 34 mounted on the left of the 12.8 cm and 7.5 cm guns. It was mounted independently. Source: Jentz and Doyle

Summary of Guns considered from April 1942 onwards

Gun Approximate Date Range Note
Primary Armament 10.5 cm L/70 June 1942 to September 1942 Hitler’s choice June 1942
12.8 cm L/50 April 1942
12.8 cm L/55 January 1943 Using special ammunition can achieve 250 mm of penetration at 1000 m / 60 deg
12.8 cm L/60 April 1942
12.8 cm L/61 Shaped charge ammunition, 8.8 cm Tungsten core, saboted 10.5 cm penetrator, and various propellants to be tested to find suitable anti-armor ammunition
12.8 cm L/70 Shaped charge ammunition, 8.8 cm Tungsten core, saboted 10.5 cm penetrator, and various propellants to be tested to find suitable anti-armor ammunition
12.8 cm L/71 April 1942
12.8 cm L/? October 1942 to
December 1942
Type 205 concept drawing
12.7 cm Naval December 1942
12.8 cm Flak December 1942 Sectional gun which could not be used without modification
Alternative Primary Armament 15 cm Kw.K. L/31 July 1942 to December 1943 16 km range
190 mm / 30 deg. /1000 meters
15 cm Kw.K. L/37 June 1942 to
October 1942
Slow rate of fire, inadequate space for ammunition
Typ 205 concept drawing
15 cm Kw.K. L/38 January 1943 Alternative mounting to 12.8 cm L/55 on the same carriage in Maus-Turm
15 cm Kw.K. L/40 April 1942 Unitary ammunition
Secondary Armament 7.5 cm Kw.K. L/24 July 1942 to
December 1942
Secondary armament – 7 km range
7.5 cm Kw.K. L/31
7.5 cm Kw.K L/32
7.5 cm Kw.K. L/33
December 1942 Made longer than L/24 to avoid gasses entering the engine and cooling gratings on the hull roof
7.5 cm Kw.K. L/36 Prior to January 1943 Same ammunition as the 7.5 cm L/24
Other Guns 2 cm Flak January 1943 Built-in anti-aircraft gun
3.7 cm Flak May 1943 Additional mini-turret on top of the primary turret with 3.7 cm AA gun
Flammenwerfer Anlage (flamethrower system) December 1942 to May 1943 Improved (longer range, 150-200 m) version of the Gross–Flammenwerfer (heavy flamethrower) system on the Pz. III. Consideration given to mounting it in the turret, front of hull, and rear of hull.

The 7.5 cm L/36 was only rifled to L/32 length due to fabrication limits on the rifling in 7.5 cm gun tubes – an extension was added 4 calibers long to extend the barrel from L/32 to L/36.
British examination in 1945 of the 7.5 cm L/36 gun showed it to actually be 7.5 cm L/36.5

Specifications for shells for 12.8 cm Kw.K. 82 (L/55)

Shell Weight (kg) Muzzle Velocity (m/s)
12.8 cm Pz.Gr. 43 (Medium charge) 28.3 kg 750 m/s
12.8 cm Pz. Gr. 43 (Full charge) 28.3 kg 920 m/s
12.8 cm Spr.Gr. Flak 40 (Medium Charge) 26 kg 750 m/s
12.8 cm Spr.Gr. Flak 40 (Full Charge) 26 kg 920 m/s
12. 8 cm Spr.Gr. L/5 (Medium Charge) 28 kg 750 m/s
12.8 cm Spr.Gr. L/5 (Full Charge) 28 kg 920 m/s


With all work on Maus development over by the end of 1943, all that was left of the program was a contract for a pair of hulls (one unfinished) and for a single turret (finished but needing modifications, along with half a dozen unfinished armored hulls.
The completed hull, now at Böblingen for trials, was not going to wasted despite the serial production being canceled. A program for these trials was set on 1st November 1943, but without a turret, a weighted mockup would have to be used to simulate the loading on the hull. This mockup turret (Ersatzgewicht) was a crude affair, roughly similar in shape and size to the Maus Turm but unable to rotate and held in place by cross pieces which were simply tightened up against the underside of the 2,959 mm diameter opening in the hull for the turret ring* to hold it in place.
(*A British examination of the hulls and turrets in 1945 found the opening in the hull for the turret ring to be 2959 mm in diameter and the actual basket of the turret to be 2,388 mm in diameter)

Maus hull 1 with Ersatzgewicht ‘turret’ during trials at Böblingen. Source: Jentz and Doyle
Trials started extremely well on 15th January, with a 2 km off-road trip showing the extreme ease and accuracy of steering. During travel off-road on soft clay soil, despite its enormous bulk, the Maus only sank 50 cm into the ground, yet still managed to steer and drove through it successfully.
Work at Böblingen to finish the interior took place in the second half of January 1944. After that it undertook its first successful trial and was then back on trial on 31st January. Here, during this test, the first problem was found. The rubber rings within the wheels – something which had already been identified as a weak point, started to fail under the load after just a 14 km journey, of which the 9.4 km on a hard surface were likely responsible. New and improved road wheels were already on order despite the existing orders for no further development on the Maus to take place. Here though, Porsche may have been a little bit disingenuous with the high command as, whilst the ‘Maus’ was now effectively dead, he was calling the vehicle by his original designation of Type 205 once more. The driving system from Porsche had been proven effective with the ease of steering and this was reinforced on 3rd February when the turning of this massive vehicle was tested. It could turn both within its own length, by reversing one track and driving the other forwards, or in a minimum radius of 14.5 m for a full 360 degree turn when driving forwards on just one track.
Dr. Porsche must have been very proud of his design work, as it had proven itself to work very well and the final work on the hull, such as welding on towing eyes, was completed during February 1944 with a 2-day off-road trial personally conducted by Dr. Porsche on 8th and 9th February 1944.
During this time, the otherwise grey-colored Maus hull and Ersatzgewicht ‘turret’ were painted with a rough three-tone camouflage scheme consisting of a base coat of Dunkelgelb RAL 7028, over which green (Olivgrun RAL 6003), and red-brown (Rotbraun RAL 8107) stripes were painted, along with a small backwards Soviet hammer and sickle motif on the sides of the hull, possibly to confuse any observers about the origins of this machine. It was painted in this way that Type 205/1 (Type 205 hull number 1) became stuck in very soft swampy ground on the testing ground. That area of the ground was avoided by all tanks but the driver, not knowing his way around, stumbled into it and the hull sank to about half its height in the soft mud. Extricating this enormous tank was easier than might be imagined, as it required only for the mud at the back to be dug out and some timbers placed under the tracks for it to free itself under its own power.
Despite this, the photos of the Maus stuck in the mud and subsequently being cleaned appear regularly in books and online (incorrectly) as evidence as to why the Maus was a failure, as it would sink into the ground.

15th to 17th March 1944. The notorious ‘stuck’ photo (left) and being cleaned (right) are frequently disingenuously used as evidence for why the Maus was a failure despite this taking place months after the contracts for production were canceled and in spite of successful tests. Source: Jentz and Doyle

Hull number 2 with turret number 1 (unpainted) during tests at Böblingen. Source: Jentz and Doyle
Tests on and improvements to the turret were carried out throughout July 1944 and the finished machine was an imposing sight. It should be noted at this point that there were both external and internal differences between the two Maus hulls at Böblingen. Hull 1 had three shell deflectors on the roof of the hull to help eliminate the shot-trap which Porsche had previously complained about. Hull number 2 only had the single wide deflector on the hull. The second difference is the engine. Both vehicles had originally been fitted with the Daimler-Benz MB 507 engine but, in February 1944, hull number 1 was refitted with the Daimler Benz MB 509 motor.

The completed No.2 vehicle with turret number 1 painted in its 3-tone camouflage pattern during testing at Böblingen. Source: Jentz and Doyle
The tests were, on the whole, highly successful. The Maus could be driven easily and with a fine degree of control, ground pressure and traction were acceptable and the drive system, in contrast to many other German heavy vehicles like the Tiger II and Jagdtiger, was more than sufficient for the job, especially after the improved engine had been fitted. There had been problems, the sort of thing expected from trials, requiring changes to a few features such as periscopes to improve visibility, the driver’s seat, ammunition stowage, the traversing mechanism, and those original wheels which had failed. The engine had also not worked as well as was wanted and was suffering valve damage although it is not clear if this was a manufacturing problem or as a result of stress on the engine during testing.
On top of this, the original 1,100 mm wide flat-plate track (plattenkette) had proven unsuitable and was replaced with a new track plate with removable ice cleats which were produced by Škoda (Griffigere Gleiskette). On the whole, there was nothing out of the ordinary for testing and the vehicle was able to move and maneuver adequately under its own power yet, despite this, on 19th August 1944, all work on the Type 205 (both vehicles) was stopped and the Krupp workers were diverted to more urgent work.

Both Mäuse seen together with V.2 and Turm 1 closest to the camera. V.1 with the E-Turm is in front of it. Source: Jentz and Doyle
Despite this order, some work continued to be done on the Maus, including on the new engine, which had proven to be problematic. On 1st December that year, Daimler-Benz had acknowledged that a new engine for the tank, the MB 517, was nearly ready. It had been ordered by OKH but then canceled and left unfinished – 2 weeks’ work would see it operational but Daimler-Benz was reticent about giving the engine away. Obtaining that MB 517 engine for the Maus would at least mean that both tanks had the same engine. Both vehicles, Hull 1 with the E-turm amd Hull 2 with Turret 1 were taken from Böblingen and sent to Kummersdorf in the second half of 1944. Here, at the end of the war, Vehicle 2 with Turret 1 was blown up. When Soviet forces captured Kummersdorf and the blown-up Maus hull, as well as the complete but E-turreted second vehicle, were found, they conducted some firing trials on the second vehicle. At least seven hits were obtained on the side of the second vehicle, including two on the sides of the E-Turm, some or all of which were using shaped charge ammunition. The front of the hull was also subject to being fired at with at least 10 hits of the glacis, lower front, and track guards respectively.
After these seemingly impromptu trials, the Soviets recovered the turret from the wrecked vehicle and installed it on the first hull (still bearing the scars of the firing trials) and shipped it back to the Soviet Union for further examination. There, it eventually had all of the interior stripped out, and the engine, motors, and transmission were all removed, leaving an empty armored shell. The vehicle, thankfully, survives to this day and is on display at the Patriot Park Museum at Kubinka near Moscow.

Soviet troops using captured German halftracks to recover the turret of the Maus. Source: Unknown

Maus (hull number 1, turret number 1) as rebuilt by the Soviets, heads to its new home at Kubinka circa 1946, still on its spezial Transportwagen. Ahead of it on the train is the no less special prototype Sturmtiger. Both vehicles survive to this day at Kubinka’s Patriot Park exhibition. Source: Unknown

Maus Timeline – Key Events

Date Hull (Wanne) Turret (Turm) Event
5/3/1942 100- tonne Panzer contract to Krupp
21/3/1942 100-tonne Panzer contract to Porsche
23/6/1942 Initial drawings from Porsche
17/7/1942 Pz.Kpfw. Mäuschen turret contract issued
5/10/1942 Type 205A
November 1942 Hitler orders 5 vehicles
December 1942 Maus Turm contract issued to Krupp
15/12/1942 Krupp Tiger-Maus terminated
3/1/1943 Trio-production agreement between Porsche, Krupp, and Alkett
21/1/1943 Full sized mockup shown
21/1/1943 Turret and hull drawings ready (ahead of schedule which was March 1943)
2/2/1943 Order to add heavy flame-projector system
10/2/1943 120 vehicles ordered
10/2/1943 Complaints from manufacturers over the late addition of the heavy flame-projector system
Late February 1943 Abandoned external torsion bar suspension and adoption of volute spring suspension
6/4/1943 Albert Speer inspects full-sized Maus model
May 1943 Suggestion to adopt ZF electromagnetic gearbox instead of electric drive system is not adopted
May 1943 Order increased to 135. First 2 to be ready by November 1943
End of May 1943 Manufacturing tolerances tightened to avoid oversize
May/June 1943 Contract issued for 135 series production vehicles and 6 prototypes (141 total)
June 1943 Gen. Guderian adjusts order to just 5 tanks (total)
1/7/1943 Order amended to 5 Maus per month (a production speed cut of 50%)
July 1943 Complete turret mockup ready
7/7/1943 1 Armored hull welding complete
12/7/1943 Serial numbers issued for production
16/7/1943 Daimler-Benz MB509 engine arrives at test laboratory for testing. Modified to run inverted and on low octane fuel.
1/8/1943 2 Second hull ordered – will be fitted with Daimler-Benz MB517 engine
4/8/1943 Allied bombing of Krupp (Essen) slows production
26/9/1943 1 Hull number 1 transferred from Krupp to Alkett for fitting of drivetrain – some machining still required
27/10/1943 all all Development of Maus cancelled with order for 120 changed to a single vehicle
1/11/1943 1 – 2 1 Trials programme set
5/11/1943 all all Series production cancelled
5/11/1943 1 Contract for 6 turrets reduced to complete just a single turret
12/11/1943 1 – 2 Contract reduced from 6 to 2 hulls
22/12/1943 1 Finished at Alkett
28/12/1943 1 Test drive at Alkett
8/1/1944 2 Shipped from Krupp to Alkett
10/1/1944 1 Ordered to be shipped to Böblingen for tests
11-13/1/1944 1 Shipped from Berlin to Böblingen via railway on a 14-axle Spezial Transportwagen
14/1/1944 1 Unloaded at Böblingen and drove 5 km to the workshops without problems
15/1/1944 1 E First trials of hull number 1 (Typ 205/1) – very successful
Mid. January 1944 2 Assembly work at Alkett halted
16-30/1/1944 1 E Assembly and fitting of other interior components
31/1/1944 1 – 2 n/a Component parts (armored periscope housings and gratings for hulls 1 and 2 (Typ 205/1 and 205/2)) delivered to Alkett by Krupp
31/1/1944 1 E Off road trials – travels 14 km including 4.6 km off road. Failures found in rubber rings in the road wheels.
3/2/1944 1 E Further driving trials restarted. Wa Prüf 6 representative in attendance
4-25/2/1944 1 E Vehicle completed including addition of towing eyes
7-8/2/1944 1 E Off-road driving trials for Dr. Porsche for 6.4 km (64 km total).
7/2/1944 2 Assembly work ordered transferred to Böblingen
8/2/1944 1 E Daimler-Benz MB509 engine installed
7-10/3/1944 2 Shipped to Böblingen for completion
10/3/1944 2 Hull number 2 (Typ 205/2) arrives at Böblingen – towed by hull number 1 to the workshops (~5 km) involving a 12% incline and icy road – successful
13/3/1944 Assessment at Krupp that production could restart
18/3/1944 3 – 7 Hulls 3 – 7 available at the armor workshops – welding complete
20/3/1944 1 E Improved road wheels fitted
23/3/1944 2 Porsche requests second turret from Krupp
1/4/1944 Production, if restarted, could deliver 2 vehicles per month
1/4/1944 3 – 7 2 – 7 Can be completed due to bodies already finished
15-17/4/1944 1 E Trials crossing 1 m deep streams and traversing 45% slopes – successful
Vehicle later became stuck in a swampy area and had to be partially dug out – freed itself under its own power
New road wheels fitted
Mid. April 1944 1 Assembly at Krupp finished
3rd May 1944 1 Shipped from Krupp to Böblingen for modification and mounting – turret arrives bare with guns and fittings separate
4th May 1944 1 Unloaded at Böblingen
7-8/June 1944 2 1 Turret number 1 mounted on Hull Number 2 at Böblingen
June 1944 2 1 Work on turret interior
June 1944 Daimler-Benz MB517 engine arrives at Böblingen
9/1/1944 1 Turret number 1 assembly finished
23/6/1944 to 2/7/1944 2 1 Under repair – improved ammunition stowage
10-17/7/1944 2 1 Tests on electrical turret traverse
July 1944 2 1 Driving trials – tears up cobblestones
25/7/1944 3 – 7 2 – 7 Wa Prüf 6 gives permission to scrap leftover turrets and hulls
19/8/1944 1 – 2 1 All work on Maus ordered to stop
September 1944 Tests on MB517 show it is superior to MB509
Late 1944 1 – 2 1 – E Both vehicles moved to Kummersdorf
February to March 1944 2 1 MB509 installed in vehicle number 2 started and breaks crankshaft due to bad alignment of engine when fitted
Mid March 1945 2 1 Replacement MB517 engine sent to Kummersdorf for vehicle number 2 to replace broken MB509 engine – technicians from Porsche attend Kummersdorf to fit engine
April 1945 2 1 Blown up at Kummersdorf
After May 1945 1 E Firing tests against Maus and E-turm at Kummersdorf
March to April 1946 1 1 Turret 1 mounted on hull 2 by Soviets and shipped to USSR
4/5/1946 1 1 Arrival at Kubinka

Typ 205/1 is hull number 1
Typ 205/2 is hull number 2
‘E’ is the ‘Einsatz Gewicht Turm’ used to simulate the weight of the actual turret

Allied soldiers at the captured Krupp factory in May 1945. Behind him are the hulls of two Maus tanks and two turrets. The turret directly behind the soldier is serial number 351452, the second Maus turret. The other turrets belong to Tiger Is and are not part of the Maus program. Source: Frohlich (left) and Jentz and Doyle (right)

Maus hull serial number 351453 (Number 3 hull) laying unfinished at the Krupp plant in 1945. Source: Jentz and Doyle

Maus Redux

A final element in the story of the Maus is a report dated 13th March 1944, 4 months after serial production had been canceled, by Dr. Muller of Krupp stating that production of the Maus hulls and turrets could be restarted if required. Five days later, on the 18th, Krupp reported that 7 Maus hulls had been finished by the armor workshops (Panzerbau) and that it had enough armor plate on hand to finish another 8 hulls.

On top of this, the order to send unused armor to the Sturmgeschütz program back in October 1943, immediately prior to the Maus program being canceled, seems to have been interpreted fairly liberally, as there was clearly a lot of armor plate still available. There were enough, in fact, for about another 30 hulls and turrets as well as 15 more hulls and 9 turrets’ worth of cut plate. Those 30 hulls and turrets’ worth of armor should have been sent away to the Sturmgeschütz program, but having retained them at Krupp for whatever reason, in spite of no orders for them, Krupp now had enough material to fabricate 45 Maus hulls and 39 turrets from that material plus the 7 finished hulls and armor prepared for 8 more, a total of 60 or so hulls and 39 turrets. On 23rd March 1944, despite the program having been canceled, Wa Prüf 6 was under orders from Hitler to accelerate testing and to resume development of the Maus.

Porsche contacted Krupp around this time to request not only delivery of the second turret for the existing Maus hulls (two hulls one turret), but also for a follow-on design of a turret known as Maus II.

On 1st April 1944, when looking at restarting Maus production, it was determined that an additional 200 workers would need to be allocated and that even then the rate would be just one or two tanks per month. This would be restarting production from vehicle 8 onwards as, by this time, 2 hulls had been finished and shipped out leaving 6 partially completed hulls awaiting scrapping. Approval to scrap hulls 3 to 6 was given on 27th July 1944. There were to be no more Maus completed, 2 had been built and were going to be tested.
The left-over pieces though were not scrapped. A British report from 1945 shows that three Maus hulls and turrets were found at Meppen (Krupp’s proving ground) with the hulls on their sides and turrets upside down. The examination showed the highest number found to be number 6. A complete 12.8 cm Kw.K. 44 monobloc gun with coaxially mounted 7.5 cm Kw.K. 44 monobloc gun (on the right) was found on the same range a few miles away. The British examination of records at the range showed that this 12.8 cm Kw.K. 44 (Maus) had been rechristened ‘12.8 cm Kw.K. 82’ and that ammunition (and presumably that gun) had been delivered in November 1943 and that ammunition was there by at least 3rd January 1944.

12.8 cm gun and 7.5 mm gun on dual mount (left) and what is believed to be the 15 cm gun (the muzzle has been sabotaged) with 7.5 cm gun on dual mount (right) as found on a cradle at the Krupp firing range, Meppen, 1945. Source: UK National Archives

The three recovered hulls and turrets found by the 21st Army Group at Meppen in 1945. It is interesting to note that the turrets had not yet had the roof plates holes cut out for the cupola and hatches. Source: UK National Archives


Sturmgeschütz (15/17 cm Sturmgeschütz auf Mausfahrzeug)

This was a brief idea from May 1944 to consider how and if a 15 cm or 17.4 cm gun could be mounted on the chassis of a Maus to compete with the same idea based on the E100 hull. Less than a month after being floated as an idea, it was discounted in favor of considering the E100 hull-project instead. No Sturmgeschütz (15/17 cm Sturmgeschütz auf Mausfahrzeug) was ever built and no drawings are known to survive.

Maus bunkers

One of the more unlikely off-shoots of Maus development was the consideration, in late September/early October 1943, to use series-production Maus turrets as static defensive structures. The situation had been forced upon Speer (the Armaments Minister) by a lack of steel-casting capacity for the 12.8 cm and 15 cm Panzerturm (armored fortress turrets) and, as the Maus was designed to be able to mount a 15 cm gun, these turrets might be a solution to the fortress-turret shortage.
The result was that Krupp was asked to prepare a design for such an installation and duly, on 2nd November 1943, it did just that, providing a drawing of a Maus turret (with a reinforced roof) for use on a bunker (Turm ‘Maus’ für ortsfesten Einsatz – Maus turret for a fixed installation). With the cancellation of the Maus turret production just 3 days later on the 5th, the idea became impossible and was abandoned, although quite how realistic the idea was anyway is debatable.

Turm ‘Maus’ für ortsfesten Einsatz (Maus Turmstellung) 2nd November 1943. Source: Jentz and Doyle


John Milson, writing in 1973 about the Maus, questioned just how much the men responsible for the design of vehicles like the Maus really believed in the value of such a machine as a weapon of war. He doubted that they really believed in these projects and, whilst certainly they may have denounced them post-war as ludicrous and wasteful, their actions during the war belie this. Porsche, in particular, was pressing hard for the Maus project right from the start, and even after it was canceled, in order to restart it – hardly the actions of a man who felt it was pointless.
It was clearly felt by many in the industry that manufacturing a technical solution was possible to ensure dominance over the increasingly better armored, better-armed enemy tanks that were being encountered in superior numbers. Dr. Porsche also no doubt reveled in the engineering of the vehicle he had designed and made full use of his political connections to gain and maintain support for the Maus long after its perceived utility was over.
As a piece of engineering, the Maus is impressive in the challenges it created and the solutions presented. However, the size, armor, and firepower were simply an extravagance Germany did not need and could ill afford in terms of time, money, and material. There is no realistic consideration that the Maus, even if produced in numbers, could have made any substantial effect in a campaign or the war. It is far more likely that the ignominious fate which awaited the single finished vehicle would have been shared by any others that were built: namely, being abandoned when it ran out of fuel or broke down and then being blown up by its own crews, a fate which befell many other German heavy tanks. Yet the Maus is still around, preserved at Kubinka and marking the top-end of what a tank could really be in terms of armor and firepower during the Second World War.

Maus Typ 205/2 hull mounting the number 1 turret during tests. Illustration by Pavel ‘Carpaticus’ Alexe.

The 1st Maus hull mated with the 1st Maus turret as it stands today at the Kubinka tank museum in Russia. While the tank looks complete on the outside, it is almost completely gutted on the inside. Photo by Craig Moore


Porsche, F. Bericht Uber die Werksorprobung des Typ 205/1 in Böblingen von 11.1 – 3.2.1944
British Intelligence Objectives Sub-Committee. (1945). BIOS report 1343: German Steel Armour Piercing Projectiles and Theory of Penetration. Technical Information and Documents Unit, London.
British Report on ‘Experimental Super Heavy Tank ‘Mouse’ (Pz.Kpfw. Maus)’ – May 1945
CIOS Final Evaluation Report 153. (28th June 1945). Interrogation of Herr Stiele von Heydekampf.
Datenblatter für Heeres Waffen Fahrzeuge Gerät W127. (1976).
Frohlich, M. (2016). Panzerkampfwagen Maus’. Motor Buch Verlag
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
Koebe, H. (8th April 2019). Luckenwalde Local History – Koebe factory founded 140 years ago. Maz
Ludvigsen, K. (2018). Professor Porsche’s Wars. Pen and Sword Publications
Ogorkiewicz, R. (1991). Technology of Tanks. Janes Information Group, Surrey, England
Sawodny, M., Bracher, K. (1978). Panzerkampfwagen Maus und andere deutsche Panzerprojekte. Odzun-Pallas-Verlag, Friedberg, West Germany
Spielberger, W. (1998). Spezialpanzerfahrzeuge des Deutschen Heeres. Motor Book Verlag
Spielberger, W., Milson, J. (1973). Elefant and Maus. AFV Weapons Profile No.61.
US Army. (1953). Technical Manual TM9-1985-3 German Explosive Ordnance (Projectiles and Projectile Fuzes)
US Army. (1950). Project 47: German Tank Losses. Historical Division European Command. US Army.
US Army. (1946). Intelligence Bulletin March 1946. The German Mouse.
US Navy. (September 1945). Technical Report 485-45 – German Powder Composition and Internal Ballistics for Guns. US Naval Technical Mission in Europe Report.
War Office. (25th October 1944). 12.8cm A.Tk. Gun Pak.44 on Pz.Jag. Tiger (Pz.Kpfw. Tiger B Chassis) Sd.Kfz.186 JAGDTIGER. Appendix D War Office Technical Intelligence Summary, No.149 1944.
War Office. (25th April 1945). Technical Intelligence Summary Report 174 Appendix C
War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
War Office. (27th June 1945). Technical Intelligence Summary Report 180 Appendix D
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F and G
War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

Maus specifications

Dimensions 10.085 (9.034 without gun) x 3.7 x 3.649 m
Total weight, battle ready 188 tonnes (50 to 55 tonne turret)
Crew 6 (commander, gunner, 2 x loaders, driver, radio operator)
Propulsion V1 – Daimler-Benz MB 507 V-12 Petrol
V2 – Daimler Benz MB 517 V-12 Petrol 44.5 litre – 1,200 hp @ 2,500 rpm
8 hp auxiliary petrol engine providing power to create overpressure inside, air conditioning, gas filtration, heating, battery charging and for snorkelling
Fuel consumption 3.5 litres per km
Speed (road) 22 km/h
Trench 3.5 m
Fording 2 m (without preparation), 7.9 m (submersible) with snorkel tube fitted
Turret Armor Front – 215 mm rounded
Sides – 205 mm at 30 deg.
Rear – 205 mm at 10 deg.
Roof – 60 mm at 90 deg.
Basket walls – 55 mm
Floor- 93 mm
Hull Armor Front Glacis – 205 mm at 55 deg.
Lower front – 205 mm at 35 deg.
Track guards – 100 mm at 10 deg.
Sponson floor Front – 50 mm at 75 deg.
Sponson floor Middle – 50 mm at 90 deg.
Sponson floor Rear – 50 mm at 85 deg.
Sides Upper – 173 mm at 0 deg.
Sides Lower (skirt) – 105 mm at 0 deg.
Sides hull inner – 80 mm at 0 deg.
Rear Upper – 153 mm at 40 deg.
Rear Lower – 153 mm at 30 deg.
Floor front – 100 mm at 90 deg.
Floor middle and rear – 50 mm at 90 deg.
Roof Front – 103 mm at 90 deg.
Roof Middle – 60 mm at 90 deg.
Roof Rear – 60 mm at 90 deg.
For information about abbreviations check the Lexical Index
Cold War Yugoslav AT weapons WW2 British AT Weapons WW2 German AT Weapons WW2 Italian AT Weapon WW2 Japanese AT Weapons

Sticky and Magnetic Anti-Tank Weapons

Infantry taking on tanks is a real challenge. Infantrymen are, after all, mainly equipped with weapons primarily intended for killing enemy infantry. Anti-tank guns are large, cumbersome, and heavy and so, right from the first days of the tank in WWI, the goal has been to produce a man-portable anti-tank weapon. One of the first, the Mauser Panzergewehr M1918 was little more than a scaled-up rifle designed to defeat relatively modest armor. More anti-tank rifles followed in the decades afterward up to the first years of WW2, but they all suffered from the same drawbacks. The rifles were so large and heavy they would take at least one (often two) men to carry without being able to carry the usual accouterments of infantry work. On top of this, the performance was relatively modest. Only thinly armored vehicles were vulnerable and anything with armor about 30 mm thick was relatively impervious to them.

Smaller devices, the sort of device which could be issued to a standard soldier making him capable of knocking out a standard enemy tank were, and still are, the gold standard for infantry anti-tank weapons. Grenades, small explosive devices, were useful but were primarily to spray fragments over an area to target infantry. Their effect was relatively limited against armored vehicles unless you could get the explosives in direct contact with the tank and one way to do this was to make the explosive ‘stick’ to the vehicle. Tanks, being made of steel, lent themselves to an obvious thought, why not make the explosive charge magnetic?

Here, there are two distinguishing elements: throwing and placing. Grenades, as throwing weapons, are advantageous for the soldier as they permit the user to maintain a distance from the target. The smaller and lighter (to a point) the grenade, the further it can be thrown. This also means that the features of an effective grenade against armor are also challenged. The size of the charge used is inherently going to be small with larger charges being harder to throw and therefore of shorter range. The next is accuracy, the further an item being thrown, the lesser the chance of hitting the target. Of course, a smaller grenade is also easier to carry and deploy.

A charge, on the other hand, such as an attachable mine, has to be placed on the target. This allows for the significant advantage of a large charge, shaped if possible to optimize anti-armor performance, but which would not lend itself to being thrown. A further advantage of the placed charge is also the obvious one, it guarantees a ‘hit’ because it does not have to be thrown and risk hitting and bouncing off the target. The disadvantages are equally obvious; the man has to expose himself to enemy fire to place the charge, has to be uncomfortably close to the enemy tank, and they are also larger and heavier than a grenade to contain enough explosives to do effective damage, meaning fewer of them can be carried.

All of the various attempts to develop either a hand-placed charge or thrown charge suffered from these problems and none adequately managed to overcome them.


Such a relatively simple idea, though, was far easier to imagine than it was to turn into a functional weapon. Some experience in the area could be drawn from naval warfare. There, a magnetically attached charge had been developed by the British as a means of sabotaging enemy ships: the Limpet mine. A relatively small explosive device, adhering to the steel of a ship’s hull could burst a seam or plate and cause enough damage to put it out of action until it was patched. The power of the charge was magnified if it was placed below the waterline, as the pressure of the water helped to magnify the explosive power of the charge and, obviously, a hole above the waterline was less useful at crippling a ship.


For the British, the work on the underwater anti-ship charges found its way both in style and name to a land weapon. The ‘Clam’, as it was called, originally came with a light steel body (Mk.I), later replaced with a Bakelite (plastic) body (Mk.II) with four small iron magnets, one in each corner. Resembling a large bar of chocolate, this charge contained a modest charge of just 227 grams of explosive. This charge was a 50:50 mix of Cyclonite and T.N.T. or 55% T.N.T. with 45% Tetryl. Although the device was magnetic, the charge was not shaped nor specifically designed for breaching armor plate. The utility of the mine was for sabotage. Enemy infrastructure, vehicles, railway lines, and storage tanks made excellent targets for this mine. The ‘Clam’ was able to breach just 25 mm of armor, offering little compared to far simpler anti-tank weapons such as the No.82 ‘Gammon’ bomb or No.73 Grenade, aka the ‘Thermos Bomb’. Both of these were weapons that could be thrown from a safe distance, exploded on impact, and were far simpler to make.

The British No. 82 and No. 73 Anti-Tank Grenades. British Explosive Ordnance, 1946

The ‘Clam’, therefore, found a role in sabotage, where it was very effective. Large quantities were produced in Britain and shipped to the Soviet Union for exactly that purpose.

The British ‘Clam’ and Limpet Magnetic charges. The circular Limpet (Mk.III) used a ring of magnets in a flexible fitting allowing for fitting to a contoured surface and capable of breaching 60 mm of steel plate. Source: Wikimedia Commons

The most famous, or infamous, Anti-Tank Grenade is probably the British ‘sticky bomb’. Although not magnetic, the ‘sticky bomb’, officially known as the ‘No.74 S.T. Mk.1 HE’, was constructed from a glass sphere containing 567 grams of nitro-glycerine and covered with a stockinette fabric to which an adhesive was applied. Once the protective steel shells around the grenade had been removed, it could be thrown at an enemy tank. When the bulbous glass ball at the end struck the tank, it would break causing the nitro-glycerine inside to ‘cow-pat’ on the armor and remain stuck there by the glued stockinet until it was detonated. The weapon was not a success, but was also made in large numbers and saw service in North Africa and Italy against German and Italian forces.

The No.74 S.T. Mk.1 HE ‘Sticky Bomb’. Source: British Explosive Ordnance, 1946

Video of a British No.74 Grenade being demonstrated rather badly by American forces in Italy 1944. The thrower did not manage to break the glass bulb, resulting in it falling off before it exploded.

German Weapons

Probably, the most famous magnetic anti-tank device was the German Hafthohlladung (handheld hollow charge). These came in different sizes, although the most common weighed in at 3 kg. This Hafthohlladung mine used three large magnetic feet to adhere to the armor of a vehicle. Each permanent horseshoe-shaped magnetic foot, made from Alnico-type alloy (VDR.546) had an adhesion strength of 6.8 kg-equivalent, meaning over 20 kg of force-equivalent would have to be used to remove a well-adhered mine and also that only a single foot was needed to ‘stick’ the mine to a steel surface. The 3 kg Hafthohlladung contained a simple 1.5 kg shaped charge consisting of PETN/Wax.

A still from a German wartime training film showing the correct method of use of a Hafthohlladung mine against the side of a Soviet T-34 tank. Source: Wikimedia Commons

Placed by hand on the target, the position of the magnets ensured that the shaped charge, when detonated, would strike the armor perpendicularly and at an optimal stand-off distance to maximize its anti-armor potential. According to British tests in 1943, the 3 kg charge could perforate up to 110 mm of I.T. 80 D armor plate or 20 inches of concrete, meaning that it could defeat any Allied tank then in service almost regardless of where it might be placed.

A later, and slightly heavier model of this mine weighing 3.5 kg contained up to 1.7 kg of 40% FpO2 and 60% Hexogen explosive which was capable of defeating over 140 mm of armor. A post-war British report stated that versions of this type of grenade were known in 2, 3, 5, 8, and even 10 kg versions.

3.5 kg bell-shaped variant of the Hafthohlladung, and (right) alongside the conical 3 kg Hafthohlladung. This version used the projectile from the Panzerfaust 30. Source:

A German soldier in spring 1944 prepares himself for the run out of cover to place a Hafthohlladung on a target either during training or on the Eastern Front. Such a run from cover exposed the user to enemy fire. Source: Bundesarchiv.
An extremely nervous-looking German soldier making a mess of applying a Hafthohlladung against the suspension of a captured French Renault R35 during training. Considering the mine is capable of piercing the armor at any place, it is wholly unclear what he is trying to achieve. Source: Wikimedia Commons

An even larger version of the Hafthohlladung was made for the German Luftwaffe, known as the Panzerhandmine (P.H.M.), or sometimes as the Haft-H (L) ‘Hafthohlladung-Luftwaffe’. This device had the appearance of a small wine bottle with the base cut off to make room for six small magnets. Larger than the Hafthohlladung, the P.H.M.3 still had to be applied by hand.

German Panzerhandmine. Source: TM9-1985-2 German Explosive Ordnance and Intelligence Bulletin May 1945

A small, spiked steel ring was fixed to the bottom of the magnets so that the charge could be stabbed onto a wooden surface too. In order to fasten to a steel surface, all that was required was the removal of this ring. First appearing in about 1942, the P.M.H.3 (a 3 kg version) contained a shaped charge made from 1.06 kg of T.N.T. or a 50:50 Cyclonite/T.N.T. mix. Against a steel target, this charge was sufficient to pierce up to 130 mm, making it a very serious threat against a tank. A 4 kg version (P.H.M.4) was also developed with a performance of up to 150 mm, although details are very limited.

A Hafthohlladung being attached to the back of a tank after having passed over the trench. Showing a Russian soldier, this image illustrates a far safer means of attaching the mine to a tank, obviating the need to stand alongside the vehicle. Even so, the soldier needs a heart of steel to be this close and is still exposed to enemy troops following the tank. Source: Fedoseyev via survincity

German ‘sticky’ shaped charge – the Panzerhandmine S.S.. Details of this version are scarce. Source: Tech. Report No.2/46

A variant of this mine also had a sticky ‘foot’ with different mixtures of explosive compositions. The sticky versions had the advantage of being able to stick to any solid surface regardless of whether it was magnetic or not. In this way, it was emulating the British idea of an adhesive-impregnated fabric behind a thin steel cover. Containing a 205 gram filling of 50% RDX and 50 % TNT, the entire charge weighed just 418 grams, just over a pound. Able to penetrate an I.T. 80 homogenous steel plate 125 mm thick, this small mine was a very effective weapon in terms of penetration although how many were made or used is unknown. A further variation of this grenade allowed it to be thrown, relying on the stickiness to attach to the armor with an instant fuse and small streamer behind to ensure it landed sticky-side down. No other details are known.

Thrown version of the hollow charge German sticky grenade. Source: and Tech. Report No.2/46

Another variation for a hand-placed sticky charge from the Germans was more complex than just an adhesive-impregnated fabric. This version featured the same sort of thin protective cover but with the detonator as part of the sticky process. Here, once the detonator was pulled, it would create an exothermic reaction melting the plastic on the face to make it ‘sticky’. It was, at this point ‘live’, so had to be applied or discarded as it would then blow up. No known use of this particular device or live examples are known.

German handheld Haftmine featured a usual self-melting element allowing it to stick to any hard surface regardless of whether it was magnetic or not. Source: Federoff & Sheffield

One further German magnetic charge was the 3 kg Gebalte Ledung (Eng: Concentrated charge) demolition charge which was little more than a large box with magnetic panels on each side. The interior was filled with cubes of explosives and had the additional advantage of being throwable. Even if the magnets failed to adhere to the steel of the tank, the 3 kg charge was sufficient to cause a lot of damage and possibly cripple the vehicle. However, as it was not a shaped charge, the anti-armor performance was relatively poor. Even so, it was more than capable of knocking out the Soviet T-34 and capable of sticking on the target even when thrown, but few other details were known.

German 3 kg demolition slab ‘Geballte Ladung’ with magnetic plates at each end, fitted with the B.Z.39. Friction Igniter. Source: Department of Tank Design

Many of these German shaped charge devices were made by the firm of Krümmel Fabrik, Dynamite AG which, after a lot of trials, found that the best mix for shaped charges was the explosive Cyclotol which was made up of 60% Cyclonite and 40 % T.N.T. with other mixtures producing less efficient results. Under ideal conditions, they found that a 3 kg shaped charge with this explosive could penetrate up to 250 mm of armor, although ideal conditions were rarely to be found on the battlefield. Either way and despite numerous attempts at both magnetic and ‘sticky’ anti-tank weapons, the Germans did not deploy them in significant numbers. One British report of late 1944 even confirmed that they had, to that point, yet to confirm that even a single Allied tank had been knocked out by a magnetic mine, the far bigger threat being the German ‘bazooka’, the Panzerfaust.


The Japanese, like the Germans and to a lesser extent, the British, had experimented with magnetic anti-tank weapons. Unlike both of them though, Japan was successful. The primary magnetic anti-tank weapon was the deceptively simple Model 99 Hakobakurai ‘Turtle’ mine. Reminiscent in shape to a turtle with four magnets sticking out like feet and the detonator looking like the head, this canvas-covered circular mine was a potent threat to Allied tanks in the Pacific theater of operations.

Japanese Type 99 Hakobakurai anti-tank mine. Source: TM9-1985-4

Appearing on the battlefield from 1943 onwards, the Hakobakurai weighed just over 1.2 kg and was filled with 0.74 kg of cast blocks of Cyclonite/T.N.T. arranged in a circle. Placed against thin points of armor or on the hatch of a tank, this mine, when detonated, could penetrate 20 mm of steel plate. With one mine on top of another, this could be increased to 30 mm, although, depending on the armor it was on, it could cause damage to a plate thicker than that.

The mine was not a shaped charge and 20 or even 30 mm of armor penetration was not much use against anything but the lightest of Allied tanks deployed against the Japanese, such as the M3 Stuart, unless they were placed in a vulnerable spot such as underneath, on the rear, or over a hatch. However, British testing and examination of these mines reported that, although the penetration was poor, just 20 mm, the shockwave from the blast could scab off the inner face of an armor plate up to 50 mm thick, although the penetration was still limited by it not being a shaped charge. The result also did not include vehicles designed with an inner ‘skin’ either, but the results were still substantial, as it meant that all of the Allied tanks used in the Pacific theatre were vulnerable to these mines depending on where they were placed.

A further development of it, known as the ‘Kyuchake Bakurai’, was rumored and capable of being thrown up to 10 yards (9.1 m), although as of October 1944, no examples were known to have been found.

The Japanese had, from about May 1942, obtained shaped charge technology from the Germans and the results were first recorded by the Americans following combat in New Guinea in August 1944. Here, they reported finding a Japanese shaped charge weapon shaped like a bottle and fitted with a magnetized base, very similar in description of the German Panzerhandmine. As of October 1944 though, the British, aware of this weapon, still had not encountered any:

“Although there are no details of Japanese hollow charge magnetic grenade it is highly probable that such weapons will be encountered soon”
D.T.D. Report M.6411A/4 No.1, October 1944

Scab blasted off from the inside of a 1 ½” (38 mm) thick armor plate by a Japanese Model 99 Hakobakurai ‘Turtle’ mine. Source: Department of Tank Design
Scarring on the outside (left) of a 2” (51 mm) thick armor plate and partially detached scab on the inside (right) caused by the detonation of at least 1 Model 99 mine. Note that the blast has dented the armor and the shape of the individual blocks can even be made out. The gaps between the blocks acted like miniature shaped charges causing these deep scars. Source: Department of Tank Design


The Kingdom of Italy, perhaps contrary to common ‘knowledge’, also made use of two devices of note. The first of these was a close copy of the British No.74 S.T. Mk.1 HE grenade reproduced from examples captured from the British in North Africa. The Italian version, known as the Model 42 grenade, was manufactured in limited numbers by the firms of Breda and OTO but, importantly, was not sticky. The Italians simply copied the large spherical explosive charge and omitted the not-so-reliable sticky stockinette and glass bulb part of the design. One important note on a heavy grenade like this is the range, just 10-15 meters at best.

The 1 kg Model 42 Grenade contained 574 grams of plastic explosive but was not sticky, it simply emulated the shape of the British No.74. Source:

Although the Model 42 was neither sticky nor magnetic, the Italians did develop probably the most advanced man-portable magnetic anti-tank weapon of all. Here though, there is very little to go off. Just a single photograph is known of the device consisting of a small battery pack and charge on a simple frame. The mine is relatively small, perhaps only 30 cm wide and appears to consist of a bell-shaped central charge, almost certainly a shaped charge with a rectangular battery and two large electromagnets on the ends of the steel frame. Certainly, this would have some advantages as it would not be magnetic all the time, unlike the German Hafthohlladung. It was simply placed on a tank and the switch was flicked to activate the battery and the powerful electro-magnets would hold the charge in place until it detonated. At least one prototype was made in 1943 but, with the collapse of Italy in September 1943, all development is believed to have ceased.

The experimental Italian electromagnetic anti-tank mine. Source: Cappellano and Pignato


Perhaps even more obscure than the Italian work on the subject of magnetic weapons is a single known Yugoslavian example. Known as the Mina Prilepka Probojna (Eng: Mine Sticking Puncturing), it was developed after the war and was intended for disabling non-combat and light combat vehicles rather than main battle tanks. It could also be deployed in the manner of the ‘Clam’ for sabotage purposes on infrastructure and consisted of a cylinder with a cone on top containing a 270-gram Hexotol shaped charge and was capable of piercing up to 100 mm of armor plate. Packed 20 to a crate, the MPP was a potent small mine but there is little information available on it in general outside of a small manual of arms. How many were made and whether it was ever used or not is not known.

The Post-War Yugoslavian Mina Prilepka Probojna magnetic mine. Source: Yugoslavian Arms Manual (unknown)


None of the attempts to produce a smaller anti-tank explosive weapon using either sticky or magnetic principles were shown to be effective. The magnetic charges required the soldier to be often suicidally close to the enemy tank. The sticky-option permitted the chance to be further away and possibly have the grenade hopefully strike the vehicle where the charge could perforate the armor. Many other ideas for hand-thrown anti-tank weapons were fielded by various armies in WW2 and thereafter, such as an attempt at a top attack hollow charge similar to that German Panzerhandmine S.S., but none were particularly successful. A short-range, inconsistent effect and a huge question over accuracy were not the reasons these devices do not appear in today’s army’s arsenals though. The answer is that far simpler, more reliable, and more effective systems became available. The German Panzerfaust had, by the end of the war, reached a level of performance where a soldier could be up to 250 meters from a target and perforate up to 200 mm of armor. The modern rocket-propelled grenade (RPG) really embodies this change in military thought for anti-armor weapons and appears in multiple forms for decades, providing an enormous punch for the average soldier against armor.

Examples of when the attack with a magnetic mine has failed. Here wedged into the screen over an air intake (left), and attached to the Schurzen (right) on a StuG III Ausf. G of 2nd Assault Gun Detachment, Bulgarian Army, after combat in Yugoslavia, October 1944. Source: Matev


Hills, A. (2020). British Zimmerit: Anti-Magnetic and Camouflage Coatings 1944-1947. FWD Publishing, USA
British Explosive Ordnance, US Department of the Army. June 1946
Federoff, B. & Sheffield, O. (1975). Encyclopedia of Explosives and Related Items Volume 7. US Army Research and Development Command, New Jersey, USA
Fedoseyev, S. Infantry against tanks. Arms and Armour Magazine retrieved from
Technical and Tactical Trends Bulletin No.59, 7th March 1944
TM9-1985-2. (1953). German Explosive Ordnance
Matev, K. (2014). The Armoured Forces of the Bulgarian Army 1936-45. Helion and Company.
Cappellano, F., & Pignato, N. (2008). Andare Contro I Carri Armati. Gaspari Editore
Department of Tank Design. (1944). The Protection of AFVs from Magnetic Grenades
Grenades, mines and boobytraps, retrieved from
Guardia Nazionale Repubblicana. (1944). Istruzione sulle Bombe a Mano E Loro Impiego
Armaments Design Department. (1946). Technical Report No.2/46 Part N.: German Ammunition – A Survey of Wartime Development – Grenades.

WW2 British Prototypes

TOG 300G

United Kingdom (1939)
Heavy tank – None built

The precipitous plunge into a new major European land war against Germany in 1939 found the British utterly unprepared for the type of intense combat fought a generation earlier on much of the same ground in Northern France and Belgium. As Britain and France raced desperately to design and deliver a new series of heavy tanks able to break the inevitable German defensive lines to beat them on this old battlefield, the mud of Flanders loomed large in British military thought.

The French Army and the British Expeditionary Force (B.E.F.) had tanks and a lot of modern equipment of a bewildering variety and utility, from the diminutive unarmed UE tracked resupply vehicle and obsolete WW1 Renault FT light tanks, to the giant Char B1 Heavy Tank for the French, and the ‘Universal Carrier’ and Mk.IV Light tank to the A.11 and A.12 Matildas of the British. These forces were meant, as succeeded by their parents’ generation, to blunt and stall the German advance through the Low Countries (Belgium and Holland). After that, the Allies would bring over new forces and push the Germans back. A fine plan maybe in the first months, September and October 1939, with the obvious problem that the Germans did not want to play that game and instead when in May 1940 the attack came, it was launched with greater speed and focus of intensity than the British and French could cope with.

Picturing a need in the first months of the war for a new and improved heavy tank for special purposes, there was no suitable vehicle at all, as the heaviest tank available was the A.12 Matilda. A new tank was to be rapidly considered and one of the first of these came from a team led by Sir Albert Stern – a team of men largely responsible for most of the British tanks of WW1. Stern was the chairman of the Special Vehicle Development committee – more commonly known by its adopted nickname; The Old Gang (TOG) and this was to be the first TOG tank of WW2, although it never left the drawing board.

The Theory

It has to be acknowledged that, in these first few months, the requirements for a new ‘Special’ or heavy tank were fluid. Despite the issuance at the end of September 1939 by the General Staff of a set of improbable and perhaps impossibly optimistic requirements for a tank, the team led by Stern took liberties with their task. It is clear from reading the letters of the time that, right from the start, the TOG team favored only a turreted tank. Adding heavy armor and a high front track to help climb an enemy parapet or wall, the vehicle design resembled almost a hybrid between the existing A.12 Matilda and a rival vehicle of sorts being built to a different set of demands, known as the A.20.

TOG 300G redrawn from blueprints. Source: Author

When the specifications for this new tank were finally revealed at the end of September 1939, the demands were extreme. The vehicle would have to be able to cross a 16’ (4.9 m) wide trench without the use of a bridge or fascine, be heavily armored, and capable of climbing a 7’ (2.1 m) high obstacle. The 300G was simply unable to cross such a huge gap. In an effort perhaps to assuage the General Staff and have them come around to a more conventional turreted option, the vehicle was even redrawn in a longer form capable of crossing a gap 10 to 12’ (3.0 to 3.7 m) wide. Although the goal was to produce this new special tank at just 32 tons (32.5 tonnes), this longer option would obviously mean more weight, perhaps around 40 tons (40.6 tonnes), and a reduced performance (assuming the same power plant was to be used).

Based on the drawing for the outline of the tank, it would measure around 20’ to 25’ (6.10 to 7.62 m) long for the ‘compact’ and ‘lengthened’ options respectively. The width is easier to gauge, as it is shown in a railway tunnel. Railway tunnels were the size-limiter for width. The 300G vehicle completely filled the tunnel allowable width, indicating a vehicle some 10’ (3.05 m) wide.


It is difficult to consider the automotive elements of 300G because the design simply never got that far. The requirements of TOG were to produce a diesel-engined vehicle and eventually that led to the adoption of the excellent Paxman-Ricardo series of diesel engines for the TOG 1 and TOG 2. In the early days of that part of the work of TOG, the lack of a suitable diesel motor prompted a look at various alternatives, including the use of petrol boat engines to provide sufficient power.

The designers involved in work on the S.V.D.C. project also considered alternatives to the ‘normal’ kind of mechanical transmissions, eventually considering alternatives including hydraulic and electric types. However, just like the engine, this was after the 300G idea had been replaced with work on a Mk.VIII-shaped machine for the General Staff. As a result, the engine and transmission choices or options for a TOG tank built to the outline of 300G remain unknown.

Surviving side outline of 300G in both compact and long’ forms crossing an 8’ (2.44 m) gap. The vertical obstacle shown is not given a size but is around 4’ (1.22 m) high. Source: Tanks of TOG by the author via UK National Archives.


Other than a single figure on the original drawing of a somewhat awkward-looking driver, no crew is shown, so it is hard to know how many crew were planned. The ‘special’ tank discussion originated with an idea for a tank with a crew of up to 7. Examining the design, it can be assumed this would be at least 5 or maybe 6 crew members, consisting probably of a driver in the front left of the hull, a hull gunner on the front right to operate the primary armament and BESA, and three more men, commander, gunner, and loader in the turret, just as they were on the A.12.

British A.12 Matilda. Source: Wikimedia Commons

Comparison between A.12 Matilda and TOG 300G Design

A.12 Matilda TOG 300G
Weight (ton / tonne) 25 tons (25.4 tonnes) 32 tons (32.5 tonnes) to est. 40 tons (40.6 tonnes)
Length (ft / m) 18’ 5” (5.61 m) 20’ to 25’ (6.10 to 7.62 m)
Width (ft / m) 8’ 6” (2.59 m) 10’ (3.05 m)
Height (ft / m) 8’ 3” (2.51 m) est. 8’ 9” (2.75 m)
Trench ~8’ (2.44 m) ~8’ (2.44 m) to
10 – 12’ (3.05 – 3.66 m)
Hull Armament None 7.92 mm BESA plus HV gun
Turret Armament 2 pdr. / 7.92 mm BESA 2 pdr. / 7.92 mm BESA
Hull Armor 3” (76 mm) basis 3 – 4” (76 – 102 mm)
Turret Armor 3” (76 mm) basis 3” (76 mm) basis


While the tank resembled an A.12, it certainly was not one. This tank was going to have to be able to take out heavily-fortified enemy positions and, as such, a variety of guns was being considered to find whichever was best suited to the task. Amongst these were the 2” (as used on the A.12), a 3” howitzer, a 3.7” howitzer, the Naval 6 pounder, and the French 75 mm gun. These last two were certainly too large in an A.12-style turret. Both the 3” and 3.7” options were abandoned quickly due to them being low-velocity weapons. No design studies are known to have been carried out for this turret. The solution would, therefore, be to mount the ‘big’ gun in the hull, much in the manner of the French Char B, and use the otherwise perfectly adequate 2 pounder in the turret on top. The requirements for a front-mounted Besa machine gun in the driver’s plate and another in the turret were to complete the complement of weapons.


Although a thickness of armor is actually shown on the blueprint, this was not a ‘to-scale’ drawing, just an illustrative one. The armor is shown, quite rightly, as being focussed on the front with a thick and slightly angled glacis, a cut-back lower front and a vertical and slightly thicker driver’s plate. No armor is shown on the turret, which is assumed to be identical to that of the A.12, which makes it cast armor 3” (76 mm) thick all around.

If 76 mm is to be assumed as the basis, this would give the 300G a 3” thick glacis and a driver’s plate perhaps as thick as 4” (102 mm). It is certainly not possible to consider the armor to be 60 mm or so, as the ‘rival’ A.20 design was already known to be woefully under-protected with armor of that thickness, unable to keep out German 37 and 47 mm anti-tank guns even at generous combat ranges. The other reason to discount the idea that the armor was less than around 3” is that the armor designer on the TOG team was Kenneth Symes. Symes was an expert in armor protection and a strong proponent of face-hardened armor plates made in flat slabs. The slabs meant ease of production not available to castings, which needed machining, but also the ability to produce a uniform hardening on the surface. Against uncapped anti-tank shot, this face-hardened armor provided improved protection over the ‘softer’ homogenous or cast armor plate. The side armor, being vertical, would have to at least match the nearly vertical turret sides, so once more 3” (76 mm) is the most reasonable estimate for this.

If the relationships between thicknesses on the only surviving drawing (drawing 477G) are reliable, then the rear armor was about half the thickness of the front, probably around 1.5” (38 mm) thick.

A lengthened version of ‘TOG 300G’ shown crossing an 8’ (2.4 m) gap. Source: Author

Death of the Project

The death knell for what would basically have been a heavier Matilda-type tank came almost as soon as the idea was born. The General Staff were insistent that they wanted an all-round track machine with heavy unditching gear on top, which meant no turret. Lengthening the 300G would not suffice and the attention of The Old Gang would be diverted into producing a tank they very much did not want to make to meet the exacting criteria issued by the General Staff in September 1939 as ‘RMB-17’.


The opportunity of TOG 300G, however, was small. The Army did not need a bigger, heavier, and wider Matilda-type tank even with the benefit of a little more armor, a little more obstacle-crossing capability, and the benefit of a large front-mounted gun. They wanted something much larger, inevitably much heavier, better protected, and even more capable of crossing obstacles. That was the direction TOG was to take, against their better judgment, and it is perhaps with some irony that the 300G-style option was eventually the one adopted after years of messing around, as the A.22 Churchill. That tank was to start life as much the same layout, a small cast turret with a 2 pounder gun and a 3” howitzer in the front and got off to a rough start with serious design flaws, reliability issues, mobility problems, and inadequate armor and firepower. A similar fate might have been expected from 300G but, given that the A.22 went on to be a very successful design by the end of the war, after years of upgrades to every feature, it is hard not to project that the 300G had the same sort of potential.

Concept art of the shorter variant of the TOG 300G taken from the drawings. The hull’s similarity to that of the later Churchill is striking, while the turret is very similar to that of the Matilda 2. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.


Hills, A. (2017). The Tanks of TOG. FWD Publishing, USA

TOG 300G Specifications

Dimensions (L/w/h) 6.10 to 7.62 x 3.05 x est. 2.24 (short version), 2.75 m (longer version)
20’ to 25” x 10’ x 8’ (short version), 8’ 9” (longer version)
Total weight, battle ready 32 tons (32.5 tonnes) (compact) – longer version ~40 tons (40.6 tonnes)
Crew 5 – 6
Propulsion Diesel
Range (road) 50 miles
Trench Crossing 8’ (7.3 m) to est. 10 – 12’ (3.0 -3.7 m) wide
Step Up to 7’ (2.1 m) high
Armament Naval 6 pounder or French 75 mm in the front hull
7.92 mm Besa machine gun.
2 pounder and 7.92 mm BESA MG in the turret.
Armor Turret: 3” (76 mm)
Glacis: est. 3” (76 mm)
Driver’s plate: est. 4” (102 mm)
Sides: est. 3” (76 mm)
Rear: est. 1.5” (38 mm)