WW1 American prototypes

William H. Norfolk’s War Weapons

USA ww1 USA (1915-16)
None Built

When the United States entered World War 1 (1914-1919) on 2nd April 1917, it did so without any tanks or conventional armored vehicles outside of a few armored cars and trucks. Artillery was either horse-drawn or towed by unarmored lorries and infantry assaults would have to take place without armor protection. Whereas America’s allies, Great Britain, France, and Italy, had all quickly realized the butcher’s bill which followed unprotected infantry attacks meant a need for some armored vehicle, the US entered the war with none of that experience. That is not to say that there were no designs and suggestions in existence for such weapons though. One designer who submitted a variety of war weapons was William Norfolk of San Pedro, California.

Norfolk’s powered ‘dirigible’ float for deploying a net (left) and deployed from a building onshore (right). Source: US Patent US1181339

The Mine and Submarine Destroyer

In light of the raging conflict on mainland Europe, William Norfolk submitted a design for what was effectively a type of net. It was designed to counter enemy naval vessels and torpedoes. Filed on 25th August 1915, Norfolk submitted his idea for a cable-net deployed by means of a powered float driven electrically. This float could be steered from shore or even a ship and would tow out behind it a long cable-net designed to ensnare an enemy ship or torpedo. The net would be prevented from sinking by virtue of a series of buoyant floats and could even be fitted with magnets to make sure the net would attach to an enemy ship or torpedo. He must have been confident as to the utility of such a device, as he filed a patent for it in Canada on 6th November 1916 as well. However, what may have seemed like an innovative idea resulted in no further development.

Trench Artillery

The Mine and Submarine Destroyer net patent was granted to Norfolk on 2 May 1916 (US Patent). Sometime between then and September 1916, Norfolk turned his attention towards the war on land. Characterized by lines of trenches covered with belts of barbed wire and covered by machine-gun fire, no-man’s land was deadly for exposed men. Whilst the amount of information coming back from the Western Front was heavily censored in the media (primarily newspapers and newsreels), there was no concealing the scale of the losses and the primary reasons for them. The British had started their formal Landships program in February 1915, but this was still secret, including the development of the first characteristic quasi-rhomboid shaped ‘tanks’ at the end of that year. This secrecy continued through to September 1916 with the first tank deployment on the Western Front, but even then it was some time before a clear idea of what these machines really looked like became public knowledge.

Knowing this, it can be said with some certainty that Norfolk’s concept for breaking this stalemate and the static war was not inspired by the development of the British or anyone else. What he produced was, in fact, very similar to a plan by the British in 1940 for a trench digging assault machine. That machine, known under the codename of Cultivator Number 6, was very similar to Norfolk’s and perhaps indicates that Norfolk’s idea was perhaps not quite as ‘off-the-wall’ as it may have appeared at first glance.


Norfolk’s machine, like the future Cultivator Number 6 a quarter-century later, was a subterranean assault machine. It did not go underground but used the ground as its armor. The means of advance was simple in concept, mounted on wheels with traction from the front pair, the machine was driven by an engine and was faced with a full width cutting face consisting of what could be described as a very wide track with cutting teeth. Driven by a separate motor, this ‘cutting-track’ ran from the bottom upwards, progressively digging away the face of the soil and throwing it into a hopper (identified as point 46 on Canadian Patent CA174919) and from there onto an outwardly facing conveyor belt which threw the soil off to one side. In this manner, the machine not only dug a wide trench as it headed towards the enemy, but also created a berm along one side of the trench which would further conceal the vehicle from enemy fire. It is important to note that the height of the machine above the ground could be varied by adjusting the pitch of the cutting face so it could self-dig down up to a maximum depth of being level with the ground. No dimensions are given for this digging machine but based on an estimate of the wheel (item 74) as 1.5 to 2 m in diameter it would have an estimated height of around 3 m or so for the whole machine – certainly a very deep trench although it could, if needed, operate with a portion above ground in order to make use of its machine guns.

Norfolk’s Trench Artillery machine of 1916. Source: Canadian Patent CA174919


While the general layout may seem straightforward, the rest of the design, including the armament, was anything but straightforward or conventional.

Firstly, the primary armament was a ‘disappearing gun’ mounted on a central turntable on a triangular mounting. This unspecified caliber of gun was to be loaded under the cover offered by the machine and would then rise up and fire, destroying enemy strongpoints. The armored casemate was also meant to carry a series of machine guns mounted through circular loopholes along each side, although the type and number were not mentioned. Importantly, it should also be noted that the casemate had no protective roof – a significant flaw for a weapon below ground level and exposed to shrapnel and debris from above.

The final weapon system, for lack of a better description, consisted of a pair of catapults. Along the sides of the casemate, at the level of the bottom of the frame, were two ‘arms’ connected to a driven gear. Each arm was held down in the horizontal position during movement but, when required to be used, could be driven upwards-acting around the driven gear, propelling what appears on the patent diagram to be a large disc. Each ‘disc’ is described as an ‘Enfilading Machine’ and these machines were subject to a later patent application by Norfolk.

Each ‘Trench Artillery’ machine carried a pair of catapults with a single Enfilading Machine at the end of each one. When the machine closed on the enemy lines, it could activate these catapult arms either together or independently and these would quickly lift the Enfilading Machines up to the surface and onto the ground in front of the machine.

Norfolk’s Trench Artillery machine of 1916 from above showing the position of the main gun in its ‘disappeared’ position. The two large objects in the back corners are not wheels but the tops of the Enfilading Machines carried on the Trench Artillery machine. Source: Canadian Patent CA174919

The Enfilading Machines

This complicated facet of the design was so involved that Norfolk submitted a completely separate patent for the Enfilading Machine in its own right. The date for that patent application is February 1916, whilst the Trench Artillery Machine is September 1916 (Canada) and no trace of a filing in the USA. The Enfilading Machines, therefore, predate the Trench Artillery machine, which served as much as a launching platform for the enfilading machines as an armored war-machine in its own right.

Just as the Trench Artillery machine predated the Cultivator machine of World War 2, this Enfilading Machine predated another WW2 project known as the Great Panjandrum. Just like the Panjandrum, the Enfilading Machine was based on the principle of an unmanned wheel rolling towards the enemy. The Enfilading Machine though, was significantly more complex than the Panjandrum, which was little more than a barrel full of explosives on two rocket-propelled wheels. Norfolk’s idea was an entire weapon system in itself, consisting of a pair of traction wheels spaced slightly apart but on a common axle. Mounted between these two wheels was a frame to which was attached a trailing wheel for balance (fitted with ‘spurs’ for traction), but also an electric motor to drive the machine forwards, delivering power to the axle and wheels respectively. Around the periphery of each wheel was a pair of concentric circles, each made from 64 recessed tubular chambers. These 128 chambers were actually short barrels for what was a single shot charge firing a single cylindrical shell or bullet perpendicular to the direction of travel of the wheel. Across both sides of the machine, this meant 256 shots to be fired out to the sides. Ignition was electrical and triggered by means of a timer.

The outline of the Enfilading Machine (facing left to right) showing the pair of concentric shot-chambers around the periphery of the wheel. Source: US Patent 1227487 of 1916

Other weaponry for the Enfilading Machine was in the form of spherical exploding balls (shells) which were mounted into recess cavities in the outer face of each wheel, with 24 on each side for a total of 48. Each shell was detonated by a rather crude burning fuze ignited when it was launched by means of explosives. This was supposed to project the shell out to the sides, although the patent drawing shows them being launched in, at least, pairs at a time on each side. Just like the shot-chambers, to launch the spherical bombs chambers these were triggered electrically by means of a timer. The use of the timer suggests that it could be ‘programmed’ to travel a set distance before detonating some or all of its weaponry to the sides.

Cross-section of the Enfilading Machine showing the rectangular launching chambers for the pairs of spherical bombs to be launched from each side. Source: US Patent 1227487 of 1916


The Enfilading Machine was an interesting design in its own right and predates the Grand Panjandrum by a quarter of a century. The Grand Panjandrum proved impossible to control and was significantly wider and simpler than this Enfilading Machine, which was a serious flaw in its design. The concept was clearly not fundamentally bad, launching a remote demolition or assault weapon was, and still is, a viable tactic but the execution of the idea was completely unworkable. The machine was far too complex with too many weapons and working parts and mechanisms for a disposable weapon. It was far too narrow to avoid simply flopping over on its side on anything other than a perfectly flat surface and the single, heavy bearing surface from the two wheels would simply be hopeless in anything other than hard ground, as it would otherwise just sink and become stuck. The final criticism of the Enfilading Machine is the armament, which was too much and too weak. Considering the use of trenches rather than exposed troops, anything other than a direct landing of the wheel into a trench would produce nothing more than a lot of bullets fired into thin air and bombs landing harmlessly outside of a trench. The single, large high-explosive charge of the Panjandrum was simply a far better idea and a more effective weapon. One final note in favor of the Enfilading Machine though might be the trailing wheel. Acting as a counterbalance to help keep it on track, it has to be considered whether such an addition to the Grand Panjandrum might have helped rectify its flaw where it would lurch off to one side, becoming a potential hazard for the forces launching it.

Norfolk’s Enfilading Machine attacking a pair of flimsy barbed wire fences. In reality, barbed wire often formed very large and dense entanglements far removed from what appears to be a fence more suitable for restraining cattle than for warfare as depicted here. Source: US Patent 1227487 of 1916

For the Trench Artillery machine, a conclusion is equally nuanced. The concept of a giant digger approaching below the ground surface towards the enemy was clearly viable. The Cultivator No.6 proved this was possible, but where the Cultivator was tracked, the Trench Artillery was wheeled and used small wheels at that. Just like the Enfilading Machine, it would have become hopelessly stuck in anything other than very hard ground and the vulnerability of such a machine to shrapnel shells exploding above it is also patently obvious too. Once more, the idea was not completely unworkable but the solution offered was.

Neither the Enfilading Machine nor the Trench Artillery machine should be ignored or written off as a crazy idea though. Both have some merit and, in 1915-1916, they provide an interesting insight as to one of the possible solutions being considered to the problems of trench warfare. In some ways, the ideas are less crazy than some official projects which were attempted by the French or British and really present a picture of how the war was being viewed outside of the front where technical solutions to problems of machine guns and wire were being presented. Neither machine was ever built and far more sensible and better-considered ideas did prevail. However, a failure to consider even some of these flawed ideas does a disservice to men like Norfolk, his ideas, and to properly appreciate how difficult it really was to develop tanks as they first appeared on the battlefields of France in 1917.

Post-Script for Norfolk

William Norfolk had no luck with his military designs but he did submit one further patent, albeit not a military-related one. In 1930, he submitted an idea for a crack-filling and sealing device. It is not known what became of Norfolk, but perhaps with his crack-sealing invention, he found some success with his innovations.

Illustration of William Norfolk’s Trench Artillery Machine based on the design of 1916 produced by Yuvnashva Sharma, funded by our Patreon campaign.


US Patent US1181339 Mine and Submarine Destroyer, filed 25th August 1915, granted 2nd May 1916
Canadian Patent CA174919 Trench Artillery, filed 21st September 1916, granted 6th February 1917
Canadian Patent CA176438 Mine and Submarine Destroyer, filed 6th November 1916, granted 17th April 1917
US Patent US1227487 Enfilading Machine, filed 23rd February 1916, granted 22nd May 1917

Cold War Italian Fake Tanks Fake Tanks

Progetto M35 Mod. 46 (Fake Tanks)

Italy (1946)
Medium Tank – Fake

The popular online game World of Tanks (WoT) published and developed by Wargaming (WG) has many tens of thousands of players and a wide variety of historical and semi-historical armored vehicles to play. It also has a few ‘fake’ tanks as well, that is, tanks that never existed in either drawings or material. The Progetto M35 mod.46 Medium tank is one from the latter category. The tank is very handsomely represented with a 3D model, but it is a fake, as the tank never existed. However, the vehicle in-game is not wholly fabricated, as it has a minuscule basis in fact.

WoT Representation

In WoT, the Progetto M35 mod.46 is, as might be expected from its name, represented as a project dating from 1946 for a 35 tonne (hence the ‘M35’) medium tank. There is even a short ‘history’ provided:

“Conceptualization of a draft design developed at the request of General Francesco Rossi who believed that only light vehicles weighing up to 35 tons would be effective in a new war. Such an innovative design was not approved; development was discontinued when Italy joined the Standard Tank project.”

WoT Wiki extract.

This ‘history’ is a half-truth at best.

Progetto M35 mod.46 as represented by Wargaming in its World of Tanks game. Source: Wargaming

In-Game, the Design is as follows


The engine for the Progetto M35 mod.46 in the WoT game is given as a 652 hp ID36S 6V CA engine. Although the manufacturer’s name is not provided, the Italian firm of Isotta Fraschini did make a series of engines known as ID-36. These were 9.72 litre marine diesel engines with 6 cylinders arranged in a ‘V’ shape (hence the 6V in the name for a V6 engine) and producing 500 hp. Measuring just 92.5 cm high, 92 cm wide, and 137.2 cm long, this engine weighs just 890 kg. In WoT, the engine module weight is given as 1,200 kg, more than the actual engine. With an output of 652 hp, the engine in-game it is also much more powerful than the real engine, although static-engine versions of the ID-36 are available which produce in excess of 700 hp, like the Fire-pump version (725 hp)

Isotta Fraschini ID-36 series marine diesel engine. The particular model produced 500 hp. Source: mfc-ve on

The engines have only been around since the early 1980s, although the company itself dates back to the early years of the 20th century. Whilst the engine is neither for tanks and was not available in 1946, the engine is essentially genuine. They are still in use today for motorboats for example, as they are valued for their compact size and reliability. Their most notable use is in the Italian Lerici-class minesweeper ships of the Italian Navy. Other versions of this engine with 8 and even up to 16 cylinders are available producing up to 2200 bhp. The ‘CA’ added to the end of the WoT module in-game is simply to denote Carro Armato (tank use), although as already stated this engine was never used for tanks.

Suspension and Tracks

The suspension for the WoT Progetto M35 mod.46 is given in the game as ‘Progetto M35 mod.46’ suspension, although what sort of suspension this is open to question. With six evenly spaced road wheels on each side and a noticeable offset between the wheels on the left and right, it appears to be suggesting the adoption of torsion bar suspension for the tank. No such mention of this type of suspension or any other type of suspension is mentioned by General Rossi so this choice is entirely fictional/speculative on the part of WoT.

Secondly, the choice of tracks for the model is very odd too, as, with three rectangular rubber pads across each link, the tracks bear an uncanny resemblance to the British ‘hush puppy’ type of tracks as used on the British Centurion tank. There is no evidence that Italy ever operated a Centurion tank or the ‘hush puppy’ tracks for it either. Further, those types of tracks were not introduced on the Centurion until the 1960s in an effort to reduce the damage to paved roads. Therefore, even if Italy ever did get some of these tracks for some purpose, they would clearly be unsuitable to model on a tank from 1946.

Front view of the tracks on the Progetto (left) bear a striking resemblance to the British ‘hush-puppy’ (right) tracks. Source: WG WoT & Mark Nash


In WoT, the Progetto M35 mod.46 is shown using what is described as a 90/50 T119E1 main gun. This is a 50-caliber long 90 mm gun with a cylindrical muzzle brake/blast diffuser. The gun is a very interesting choice, as the history of the T119 gun makes it clear that it is entirely inappropriate as an option for this design.

For a start, the gun is American, not Italian. The T119 gun originated from the development of the US T42 Medium Tank which did not even reach the wooden mockup stage until March 1949. When it did, it was fitted with the M3A1 90 mm gun, but this was considered substandard and had to be improved with revised specifications for an improved pressure breech capable of withstanding 47,000 psi (324 MPa) instead of 38,000 psi (262 MPa). It was this revised 90 mm gun which became the T119.

T119 90 mm tank gun fitted with a single baffle muzzle brake. Source: Hunnicutt’s Patton

This T119 gun was able to fire the 90 mm ammunition of the M3A1 90 mm gun, but not the other way around, as it was a higher pressure (the cases were even modified to prevent an accident loading on the lower pressure gun with the higher pressure rounds).

The T119 gun fired the T33E7 AP-T shell (mounted in the T24 case) at 3,000 ft/s (914 m/s) as well as the M71 HE round (in the T24 case). At 177.15 inches (4,500 mm) in length, the T119 had a length of 50 calibers.

Manufacture of the T119 90 mm gun was not even authorized by the Ordnance Technical Committee for production at Watervliet Arsenal until 20th October 1948. This gun was still considered ‘new’ and experimental (hence the ‘T’ designation) in January 1950, when it was modified into the T119E1 and finally became the T125 gun (later standardized as M36) as part of the development of the M56 Scorpion (then the ‘Carriage, Motor, 90 mm Gun, T101). This T119 gun was originally fitted with a single baffle muzzle brake, but this was later replaced with a cylindrical blast deflector by the time it was mounted on the T42 Medium Tank. The gun on the Progetto M35 mod.46 is certainly a real gun, but it is neither an Italian gun nor in existence at the time of the vehicle. This is before even taking into account considerations of when a brand new and experimental American gun could even have got to Italy and certainly not an autoloader for that gun for Italy.

Other points of consideration for the Progetto M35 mod.46 include the armor. Data given by WoT states that the hull armor is supposed to be 60 mm thick frontally with 30 mm on the sides and rear for the hull, and 80 mm, 60 mm, and 25 mm on the turret front, sides and rear respectively. These figures are not based on any design but are purely a function of balance for the game.

Francesco Rossi

Having dissected the tank as claimed by WG, it is important to consider the man, General Franceso Rossi, claimed as the source and what he really wrote. General Rossi is certainly a real person. Born on 6th December 1885, Rossi was a professional soldier who was a Lieutenant Colonel by 1926. Through the 1930s, he rose through the senior ranks with appoints in Rome as Chief of Military Transport and then as the Commanding officer of various artillery regiments. By 1939, he was the Commanding Officer of an Artillery Corps and then Intendant of the Italian 1st Army. Through World War Two, he continued his rise going from the Commander of II Corps to Deputy Chief of the Army General Staff in March 1941. He was made a Lieutenant General in October 1942 and, in March 1943, Deputy Chief of Staff to the Chief of the Supreme General Staff of the Italian Royal Army (Regio Esercito – RE). It was in this capacity that Gen. Rossi was to play a crucial role during the Italian Armistice of September 1943 (the Armistice of Cassibile).

General Franceso Rossi. Source:

The Source of the Claim

The origin for the WoT claim is from a book written by Gen. Rossi, published in 1946, entitled “La Ricostruzione dell’ Esercito” – the reconstruction of the army. Written in 1946, this paper predates the Paris Peace Treaty of February 1947 and was outlining how a new Italian Army should be organized and the sort of equipment it needed. WW2 had been utterly devastating for Italy with a large but ill-prepared and usually rather poorly led army suffering severe defeats at the hands of the British and Americans. Germany, Italy’s ally in WW2, was not a particularly gracious ally at times either and, following the armistice with the Allies in September 1943, Italy basically collapsed into a civil war with some of the military remaining loyal to the Axis and the rest joining the Allies. This second half had suffered harsh reprisals from the Germans, who from then on had acted as an occupying power. Such a split in Italy required a lot of mending after the war. In this sense, Gen. Rossi’s short book was very well-timed. The Army was totally broken by the war and was still operating a few Italian vehicles left over from the war along with a mishmash of tanks and armored cars provided by the British and Americans. A total reorganization was certainly required. It is worth bearing in mind though, that Article 54 of the Paris Treaty of February 1947 strictly limited the Italian military to not more than 200 heavy and medium tanks and, through Article 61, a total of 250,000 personnel (Army and Carabinieri combined). The likelihood of authorizing the expensive and time-consuming development of a home-grown tank by Italy was simply neither likely nor realistic. It is hard to imagine that Gen. Rossi, from his senior position in the Italian military, would not have been aware of the parlous state of the Italian economy and military post-war.

Article 54 of the Paris Peace Treaty 1947 limiting Italy’s tank strength. Source: US Dept. of State

In his book, “La Ricostruzione dell’Esercito” Gen. Rossi wrote:

Italian Original:

“Accenno anche alle caratteristiche che dovrebbe avere un carro armato di produzione nazionale, unicamente per completare la visione dei mezzi meccanici, per il caso sia giudicato possibile ed opportuno, come io ritengo, procedere a studi ed anche all’approntamento del prototipo.”
“Carro armato veloce, ben corazzato, non mastodontico, perchè resti nei limiti consentiti dalle nostre ferrovie e dalle nostre opere d’arte, ma tale da tener testa ai più progrediti carri esteri: peso dalle 30 alle 35 tonn., cannone di calibro intorno ai 75 mm, motore di 5-600 H.P. di tipo appositamente ad iniezione per la minor facilità di incendio del gasolio rispetto alla benzina.
Dal carro armato potrà trarsi il cannone semovente, utilizzando lo stesso scafo per un cannone da 90, od un obice di calibro maggiore”

– La Ricostruzione dell’Esercito, 1946

English translation:

“I mention the characteristics a national production tank should have solely to complete the vision of the mechanic vehicles, if it is considered viable and appropriate, as I think, proceed to studies and the preparation of a prototype.
Fast tank, well armored, not too big and heavy [like an elephant], provided it stays within the limits allowed by our railway and artwork [bridges, tunnels, etc.], but able to stand up to the most advanced tank of foreign countries: weight between 30 to 35 tons, cannon of a calibre around 75 mm, 500/600 HP engine specifically of injection type due to lower risk of fire compared to a gasoline engine.
From the tank, a self-propelled gun might be derived using the same hull for a 90 mm cannon or a howitzer of a larger caliber”

General Rossi’s book and dust jacket cover binder, 1946. Source: Author

Despite the obviously weakened state of the Italian economy in 1946, Gen. Rossi was still hoping, perhaps vainly, for a new nationally produced tank at least to the level of the production of a prototype. To this end, he outlined the features it should have.

Firstly, powered by a fuel-injected diesel engine (due to the lower fire risk than a petrol engine) producing between 500 and 600 hp. The vehicle had to be quick, able to keep up with the most advanced foreign tanks. At the time of writing, the primary foreign tanks Rossi was likely familiar with would be the American Sherman, British Cromwell, Russian T-34-85, or even the German WW2 Panther with top speeds under ideal conditions of about 48 km/h, 64 km/h, 38 km/h, and 55 km/h respectively. Quite how much Gen. Rossi might have known about the most modern tanks from Britain, American, and Russian though is questionable, but he would certainly have been familiar with at least these WW2 tanks.

Weight-wise, Rossi was very clear, a tank of between 30 and 35 tonnes in weight and of sufficiently modest dimensions to be transported by rail. Armor-wise, the tank was supposed to be well armored yet not too large, hardly a thorough description but then that is because this was not a design – it was a concept of what tank Italy needed for a new army.

At 35 tonnes, this would still be heavier than the heaviest tank Italy produced during the war, the 26-tonne P.26/40 and around 10-tonnes lighter than the German Panther. The weight range given actually closely matches that of the American M4 Sherman. This is not the only similarity either. The gun called for by Gen. Rossi was one of a caliber of 75 mm or thereabouts. The British Cromwell was using the QF 75 mm gun, the American M4 used the M3 75 mm gun or the 76 mm M1A1 series. The British Comet had the 77 mm HV, whilst the German Panther had used the 75 mm KwK 42. Which, if any of these, Gen. Rossi might had been considering is unknown – perhaps he was considering an Italian gun in that caliber range, but he was clear on what he considered a suitable caliber – 75 mm or thereabouts. Bigger guns, like a 90 mm piece, were destined to be on a tank destroyer preferably based on the same chassis.

One of the more unusual elements of General Rossi’s book completely unrelated to its content is that the pages were actually printed and folded before being bound meaning that the majority of pages were still bound along at least one outer edge. Source: Author

That then, is literally ‘it’. There is no design, no model or plans and not a lot of specifics. This was 1946 too, so options were very limited for Italy. Gen. Rossi may have wished for a new tank to be produced in Italy- it would, afterall, be very good for Italian industrial rebuilding as well as for an independent army, but in 1946 this was wishful thinking. WoT’s “such an innovative design…” claim is simply false. There is no design and none of the features he mentioned were in any way innovative.

There was also no need at all for a new and expensive tank for Italy, especially a tank which, after all, would offer nothing that existing available and cheaper designs did not already offer. By the end of the 1940’s, the Italian Army had tanks and tank destroyers which matched what Gen. Rossi had been calling for in the form of Sherman tanks of various types armed with 75 mm, 76 mm and 105 mm guns, Sherman Fireflys armed with the British 17 pounder gun, and the American-supplied M36 Jacksons as tank destroyers armed with a 90 mm gun – a tank destroyer based on the chassis of a Sherman tank, just as Gen. Rossi had wanted back in 1946.


The Progetto M35 mod.46 is a fake. Not a completely made-up-from-nothing fake, but without doubt still a fake. The call from Gen. Rossi for a new tank made it clear that the 90 mm gun was not for this tank, but for a different vehicle. Not only that, but the 90 mm gun selected by WoT was simply not possible to be fitted to a tank in 1946, let alone one in Italy. The tracks, assuming they are ‘hush puppy’ tracks are neither Italian nor available in 1946. The engine certainly is a real thing, but it was not used in tanks and was not around in 1946. All this predated the attempts to develop a single tank as a ‘standard panzer’, sometimes known as the ‘Europanzer’ project.

Whatever Gen. Rossi might have been considering as a tank is unclear, but certainly what he wrote cannot be described as a design. The vehicle, as represented in the WoT game is simply not possible and purely invented.

Illustration of the Progetto M35 Mod. 46, produced by Ardhya Anargha, funded by our Patreon campaign.


Agarossi, E. (2000). A Nation Collapses: The Italian Surrender of September 1943. Cambridge University Press, UK
Data Sheet ‘Motore termico/ciclo Diesel/a quattro tempi/6 cilindri a V a 90: Isotta Fraschini Motori
Dunstan, S. (1980) Centurion. Ian Allen, England
Estes, K. (2016). M50 Ontos and M56 Scorpion 1956-1970. Osprey Publishing, England
Hunnicutt, R. (1971). Pershing: A History of the Medium Tank T20 Series. Feist Publications, California, USA
Hunnicutt, R. (1984). Patton: A History of the American Medium Tank . Presidio Press, California, USA
Isotta Fraschini. (1985). Industrial Diesel Power for Military Applications by Isotta Fraschini (advert)
Pettibone, C. (2010). The Organization and Order of Battles of Militaries in World War II, Volume VI – Italy and France. Trafford Publishing, USA
Rossi, F. (1946). La Ricostruzione dell’Esercito. Editrice Faro. Rome, Italy.
Symth, H. (1948). The Armistice of Cassibile. Military Review, 28(7). Command and General Staff College, Kansas, USA
US Bureau of Naval Personnel. (1990). Manual of Navy Enlisted Manpower and Personnel Classifications and Occupational Standards. US Dept, of the Navy
US Dept. of State. (1947). Treaties of Peace with Italy, Bulgaria, Hungary, Roumania and Finland. US Dept. of State, Washington D.C., USA
World of Tanks Wiki
Biography of Lt. General Rossi

WW1 British prototypes

Macfie Landship 1914-15

British Empire (1914-15)
Design Only

Overlooked by most histories of the era of early armor, Robert Macfie was a visionary who first pressed the use of tracks to the Landships Committee at a time when ‘big-wheel’ machines were seen as the solution to the problems on the Western Front, namely barbed wire and machine guns. Almost unknown today, Robert Macfie designed what was to be one of the first tracked Landships.

Born on 11th November 1881 in San Francisco, the American-born son of a sugar baron, Macfie took an early interest in military matters outside of the family sugar business. Aged just 17 or 18 years old, he enrolled in the Royal Naval Engineering College, at Davenport, England studying naval design. After this, he went back to help with the family’s sugar business before settling in Chicago in 1902.

Around this time, he began an interest in aviation and was back in Britain by 1909 building his own aircraft and testing them at Fambridge in Essex. It was during his endeavours in the then brand-new field of aviation that he met Thomas Hetherington, a man later connected with landships in his own right.

His attempts at getting into the aviation business, however, were not a success. He was back on the family sugar plantations in the years before the outbreak of war and it was there that he became acquainted with the Holt agricultural tractor.

When war was declared in August 1914, Macfie returned to Britain once more. He immediately sought out his contacts from his aviation days advocating for the use of Holt-based tracked vehicles, and was referred on to Commodore Murray Sueter, in charge of the Royal Naval Air Service (R.N.A.S.), which at the time was operating armored cars, the primary mobile armored force for the Army.

Macfie had a design for a tracked vehicle sketched out and, even without official sanction or support, was seeking a manufacturer. As such, he approached Mr. Arthur Lang, a well-known manufacturer of propellers, who gave Macfie an introduction to Captain Swann, Director of the Air Department. Armed with the previous referral and a recommendation from Mr. Swann, Macfie got to see Commodore Sueter and presented to him a design for an armored vehicle based upon the Holt agricultural tractor, identified as a ‘caterpillar’.

Despite his engineering training and education, he was still an outsider in military terms. Wanting his designs and ideas to be taken seriously, Macfie made what could easily be his greatest professional error. He enlisted in the Royal Naval Volunteer Reserve (R.N.V.R.) under a temporary commission as a Sub-Lieutenant in the belief that doing so would provide him with the contacts and credibility or ‘standing’ he might need. What it did though was to stymie his work and pigeon-hole him into armored car work and within a rigid military command hierarchy. On the plus side though, within this hierarchy, his immediate superior officer was his old friend Captain Thomas Hetherington, who he knew from his days with aircraft at Brooklands before the war.


The original sketch presented to Sueter in 1914 by Macfie was described as:

“triangular in side elevation, with a long base on the ground and a cocked-up nose to help it get a grip on banks or parapets. It even had a pair of trailing wheels aft, to keep it from swinging – just as our tanks had when they went into action two years later” and with a “comparatively long track and a comparatively short nose, and the nose is of such a nature as to give a climb…. There are three wheels, and the caterpillar goes round the third so that you get a flat base and a nose”

The vehicle was of a simple outline, being a rectangular box with a flat rear and sides and a wedge shape at the front. Hanging from the front was a large armored panel that descended at the same angle as the glacis until approximately two-thirds of the way down the height of the body. Below this, panel was a hinged flap allowing the tracks to be protected but flexible so as to not interfere with obstacle crossing.

At the back of the vehicle was a single fixed propellor intended to provide drive in the water and connected directly to a power take-off from the drive shaft.

Drive for the tracks was provided by a single-engine located centrally inside the hull, with the driving position directly behind. Steering for the driver was affected by means of a large steering wheel to his front but connected via a linkage to a pair of retractable trailing wheels at the back fitted with an Ackermann steering system.

The vehicle itself was fabricated from a framework to which panels of armor plate were fastened, presumably by means of bolts and rivets but creating a watertight body. This body was buoyant in water and the drawing identifies the metacentric height as very slightly below the centre-line of the vehicle’s body.

The most unusual element of the design though was the tracks. Despite being based on the Holt system, the track system designed by Macfie did not use wheels. Instead, it used a unique system whereby the tracklinks were a flattened ‘U’ shape with a square base. The base fitted onto a single smooth track guide running the full circumference of the track unit which was supported by spars, much in the same style of an aircraft. The track was driven though in a similar manner to the Holt system with a large 12-tooth drive sprocket at the back driven by a chain from the transmission located at the back of the vehicle.

No armament was specified for the Experimental Armoured Caterpillar, possibly because it was intended to be an experimental vehicle on which a future landship-of-war would be developed. As it stood though, with the driver at the back, it would have required a minimum of at least two men, a driver and a commander (who could see where to go, to operate the vehicle) and then more men for any weapons being carried.

Hauling Guns

Macfie had no success at persuading the authorities to accept his Holt-based caterpillar design, but on 2nd November 1914, whilst working as a Field Repair Officer at Wormwood Scrubs and then the nearby Clement Talbot Works, he saw a clipping from that day’s Daily Mail newspaper. The newspaper had an image showing a Holt Caterpillar in use headed ‘German Convoy entering Antwerp’ with the caterpillars hauling heavy naval guns. This article inspired a report from Macfie on 5th November 1914 to Sueter, once more pressing Macfie’s conviction over the use of tracked vehicles, albeit this time for hauling guns.

The plan was not armored though. Effectively, it was a train of 6 Holt tractors working together to haul a 85-ton (86.4 tonnes) load (the weight of a 12-inch naval gun and limber).

Further to the gun-hauling idea was that one of these Holt tractors could be gainfully employed in recovering the armored cars of the R.N.A.S., which had a habit of getting stuck when off-road or on what still passed as roads.

Sueter, however, had no interest in either option for the Holt tractor, but the die had been cast by Macfie and he had succeeded in convincing Hetherington of the validity of his ideas, although Hetherington too had his own ideas quite apart from those of Macfie.

Holt Redux to the Committee

Despite having discounted the idea of the Holt tractor for any use regarding an armored vehicle, a gun-hauler, or as a recovery vehicle, Sueter, in January 1915, asked for a report on Holt tractors. When he got the report back at the end of January 1915, Sueter must have been interested in the potential of the Holt track idea at least in principle, as he records in his own memoir that he saw Churchill several times bemoaning the problems of the tyres of his armored cars off-road and suggested that tracks might be more suitable.

It was then perhaps Macfie’s prior badgering about the merits of the Holt that proved most influential then, because when, in February 1915, a Landships Committee was being formed, Macfie was invited to attend at the behest of Hetherington. The 22nd February 1915 meeting was the first official meeting of the Landships Committee and it was to be the only time Macfie was in front of the committee.

The most significant person there other than Macfie with relevant experience to the problem of traction off-road and in mud was Colonel Rookes Crompton, a leading expert in wheeled traction. Crompton brought an idea for a giant wheeled machine and he would not be the last to suggest such a wheeled scheme, but Macfie was different. Macfie once more suggested the advantages of a tracked vehicle and was persuasive enough that Crompton acknowledged the advantages of tracks over wheels. Thus the die was cast, tracks were to be the primary solution to off-road traction for an armored vehicle and the man primarily responsible for this was Macfie.

The meeting was also a split between Hetherington and Macfie. Hetherington had his own wheeled battleship scheme he wanted to pursue and Macfie was wedded to tracks. Macfie then took his plans to Commander Boothby (R.N.A.S.).

Bootby was also won over by the idea of tracks and via Sueter arranged for Macfie to pursue a tracked vehicle as a test. Not a landship as originally planned, but the conversion of an old lorry into a tracked vehicle following a report from Macfie in April 1915.

April 1915

Macfie had no success with his traction schemes other than in persuading the Landships Committee of their virtue. He did have a task with the tracked truck but his mind was still on a tracked landship. To this end, on 13th April 1915, via Boothby, he made yet another submission, this time envisaging how the as yet non-existent landships could be used in combat suggesting:

“One form of attack I would suggest is as follows:
At dawn two columns of caterpillars would seize a zone of the enemy’s trenches – previously surveyed by Aeroplane – by getting astride them and killing everything in Zone A by enfilading fire. Immediately after this a horde of cavalry and horse artillery could pour through and seize the enemy’s base… I am aware that machines are proposed which will be armoured against rifle and Maxim fire which are to carry parties of soldiers to the trenches whereupon doors are to be opened and the men pour out. I would submit that this plan fails to deal effectively with the enemy’s artillery and that further only the front line of enemy’ can be dealt with in this way. Again caterpillar construction and operation like other branches of engineering is not as easy as it looks. Engineers without any experience of this work, no matter how distinguished in their own fields, are no more likely to succeed at it than a locomotive expert would be likely to succeed at hydroplane construction at the first attempt, or vice versa, without previous study or experience”

As well as this theory of attack, Macfie had also given serious consideration to the problems of steering saying:

“steering with wheels is easy, because a wheel touches the ground at one point, whereas a caterpillar presents a whole surface to the ground. Again, in a wheel the only rubbing surfaces are at the centre, well away from grit and dirt, which is also thrown away from the hub by centrifugal force”

Macfie was presenting his idea for a tracked and armored vehicle steered by wheels at the back and the truck conversion was as much a test of tracks as technology as they were to consider the issues of steering a tracked vehicle.

Original blueprint for Macfie’s Experimental Armoured Caterpillar, August 1915. Source: author


The work on the tracked truck took place at Messrs. Nesfield and Mackenzie along with the works director there, Mr. Albert Nesfield. The relationship between Nesfield and Macfie though was a thoroughly dysfunctional one and was the subject of acrimony during the post-war enquiry into the invention of the tank. The primary cause of the dysfunction seems to have a relatively straightforward clash of ideas. Macfie had to construct a tracked truck at the Nesfield and Mackenzie works and at the same time he was working on his landship idea. At the same time, Nesfield, with no previous involvement in matters, created his own ideas for a tracked vehicle borrowing extensively from Macfie.

When Macfie finished his model of his landship in June 1915, he took in to Sueter to show him. To his dismay, Macfie found that the very same model had already been brought to his offices on 30th June and shown to the Landships Committee (a fact disputed during the post-war commission). Two models were in fact made, a wooden one, and an aluminium one made on Macfie’s orders, and for security reasons, according to Macfie, these were later destroyed. Another model, powered by a pair of electric motors, was presented to the Royal Commission in 1919/1920. Macfie explained exactly why this model, even without trailing wheels was his:

“the model was never finished at Messrs. Nesfield and Mackenzie’s… but the state into which it had finally got when it disappeared was a body, open at the top, to represent the armoured body and two triangular tracks on either side made out of ordinary bicycle chain. Each track was driven by a small electric motor…I adopted that form of steering [one electric motor for each track] because it made a good demonstration form of steering. It would be very difficult to make a model which would be an effective demonstration model by using any other form of steering”

On or about 2nd or 3rd July, Macfie came to speak with senior officers at the Admiralty about his tracked vehicle ideas and asking for them to be taken over under the Defence of the Realm Act (D.O.R.A.). When he walked into the room to speak with them he found senior officers examining his model and sternly rebuked them saying:

“where on earth does this come from; this is mine, and I spent the last week looking for it”

Macfie was informed that the model brought there by some representative of Messrs. F.W. Berwick and Company, (colleagues of Mr. Nesfield) but Macfie’s anger was understandable. This unfinished model, still missing the trailing wheels, had been locked in a safe beforehand in Mr. Nesfield’s office and now had, after vanishing from there, mysteriously turned up at the Admiralty, delivered by colleagues of Nesfield. Macfie promptly seized the model back.

Macfie took this model back to the Clement-Talbot Works, the Headquarters for the Armoured Car Squadron and complained directly to Commander Boothby about what had happened. Boothby then sanctioned and approved for all work at Messrs. Nesfield and Mackenzie to cease immediately and Macfie set about finding a new site to finish his project. The working relationship between Macfie and Messrs. Nesfield and Mackenzie was to be dissolved. Boothby was thus in absolutely no doubt as to what was going on and acted decisively.

Macfie, with an armed guard to accompany him, then seized all of the remaining elements of the tracked work, and the as-yet unifinished tracked truck from Messrs. Nesfield and Mackenzie. For security reasons, all of the remaining drawings and models which were not handed in were burned, although in hindsight, this move, whilst efficient to maintain operational security, left Macfie with very little evidence in the post-war enquiry to refute the claims of Mr. Nesfield.


The important element of Macfie’s design and the one over which Mr. Nesfield was claiming invention was referred to as ‘angularization’. This term referred to the shape of the track at the front of the vehicle. On the Holt track system, the track was effectively flat with the leading section close to the ground, but Macfie’s design had a raised front end. This raised front end would permit the vehicle to climb a higher parapet or cross a trench which was wider than that which could be crossed by a low-fronted track.

This development was later summed up by Sueter during the enquiry into the invention of tanks saying:

“No one regretted it more than I did that Lieutenant Macfie failed me in producing an experimental landship, but the angularized track invention I am certain made the Tank the great success it became on active service. What an opportunity Lieutenant Macfie and Mr. Nesfield had. It was no fault of mine that they did not become as successful as my other Armoured Car Officer Lieutenant Wilson and Mr. Tritton of Messrs. Foster and Company were with their tank work”

Sueter refused to take any blame for the problems between Macfie and Nesfield, but Macfie was also undoubtedly an abrasive man in his own right and had rubbed Alfred Stern (the growing power within the Landships Committee) up the wrong way.

He would not see his unfinished tracked truck again, and in December 1915, his commission was ended. Macfie was to have nothing more to do with the official development of Landships or tracked vehicles of any kind during the war.

Macfie’s contested model which was demonstrated to the Royal Commission and now preserved at the Imperial War Museum, Duxford. Inside are two small electric motors but the drive arrangement of the sprocket and tracks (here modelled using bicycle chain) is readily obvious. The hole in the side was to model a possible machine gun position. Source: author


Despite the failure of Macfie to have the Landships Committee adopt his original design, he did have one significant success, namely convincing the authorities to pursue tracked vehicles instead of wheeled schemes for a landship albeit basing his ideas on the Holt chassis at the time. His design was not a success and the plans he burned for security purposes could have provided him with the evidence he needed to properly submit his claim in 1919 to the subsequent Royal Commission. As it was, he was awarded just a fraction of the money he may have been properly entitled to which Nesfield had also laid claim.

Despite being denied the chance to finish his tracked truck or to see his landship come to fruition, Macfie was not finished with tracked vehicles. In fact, he would go on to design more tracked vehicles, but sadly for him, these too were failures. Macfie returned to America after the war and died in New York on 9th February 1948.

Illustrtion of Macfie’s 1915 design, produced by Mr. R.Cargill


Crew 2 (driver and commander) and weapons crew as required
Armament At least 2 Machine guns
Armor Bulletproof


Hills, A. (2019). Robert Macfie, Pioneers of Armour Vol.1. FWD Publishing, USA (Available on Amazon)
Proceedings of the Royal Commission on Awards to Inventors: tank 1918-1920
Service Record Royal Naval Air Service 1914-1916: Robert Macfie

Cold War Soviet Fake Tanks Fake Tanks

Soviet “Turtle” Tank (Fake Tanks)

USSR (1951)
Self-Propelled Gun – Fake

There is no doubt that working in the field of espionage is a difficult occupation. Human intelligence sources are often unskilled or untrained and their information requires vetting and assessment. Even technical intelligence from eavesdropping or copying of documents is fraught with errors, counter-intelligence, mistakes, and, sometimes, complete fabrications. Experts in one field may not be experts in others and ‘fake’ information can be obtained even from an honest and reliable source who has been ‘fed’ fake information by the other side. This interplay of espionage and counter-espionage intelligence work can produce its fair share of false intelligence and the ‘Turtle’ tank of 1951 is certainly a contender in this category.

Side view of the Turtle tank. Source: Central Intelligence Agency


Before a substantive discussion on the technical elements of the Turtle tank, it is worth examining the one and only source for this information. It comes from the reading library of the Central Intelligence Agency (CIA) and, whilst still heavily redacted to protect the identity of the source, it provides some data on which to vet the information.

The source of the data is a group of unnamed ‘German experts’ examining a report from an informant. The German experts are not identified and it is not known in which field they have expertise. It is a reasonable assumption, however, that their expertise is in the arms industry, as not only do they provide a technical evaluation of the ‘Turtle’ but also relate some information that this relates to improvements of a design first identified in 1943, during the war. Further, the CIA would have no reason to hand a report from an informant to some experts if they were not specialised in armored warfare in some capacity.

The expert analysis states categorically that the design shown is impractical and not in keeping with either modern armored warfare or Soviet doctrine describing the original informant as “a rank amateur on the question of armored vehicles”. With that said, it is worth noting the characteristics relayed to these German experts on this new and secret Soviet tank.

Plan view of the Turtle tank showing crew positions. Source: CIA


The first and most obvious sign that something appears to be wrong with the informant’s data on this Soviet tank is that the primary armament is given as being an ‘8.8 cm L/56 type gun’. This was a German gun, most famously in the form of the Kw.K. 36, as mounted on the German Tiger I. Although the experts stated that it was possible that the tank described could be improved with an L/70 version of that gun (as fitted to the Tiger II), this was still a German gun. In 1951, there is simply no reason to suppose that the Soviet army would need to use, reuse or produce their own clones of this WW2-era German gun for their own purposes.

The secondary armament is also unusual as it is described and shown as consisting of two machine guns; one firing forwards and another to the rear. Each is mounted in a ball-joint capable of 90 degrees of movement left and right.

Front view of the Turtle tank showing a somewhat non-tanklike, but very curvy-looking front profile. Source: CIA


The layout and shape of this tank are unusual and quite unlike any Soviet tank known to have existed at this time. The dimensions of the vehicle given by the informant are 7 m long, about 3 m wide and about 2 m high, with a weight of just 30-35 tonnes. The entire body is made from a giant curved structure with a single entrance hatch on top and with the gun in the front and center of the hull. There is no turret but, with the gun mounted towards the mid-point of the tank and with a machine gun at both ends, there is little room inside in which to squeeze the gun recoil, crew, and ammunition. At least five crew positions; commander (top left), front gunner (front left), driver (front right), loader (rear center), rear gunner (rear right) are provided for within the design, although there is no mention of a gunner for the primary weapon. An arrow on the sketch with the report indicating either the position of the engine or gunner is redacted. Unless the commander is also doubling-up as the gunner, a sixth crew member would be needed to operate the primary weapon. All of them, apart from the rear gunner, are provided with a forward facing vision slit for observations and the top positions for the commander and possible gunner have sideways facing observation slits. If indeed there were only five crew, as indicated by the informant, then there would be no crew member in the top right and there would be no need for a vision slit. The predominant feature of the design is the heavily curved body extending about half-way down the suspension of the vehicle. Where the body goes over the tracks this is described as an “armored” or “chain” apron (chain as in the tracks).


The engine is described as lying between the driver and rear gunner, which would place it approximately underneath the center of the vehicle with the commander, loader and gunner sat over it. The engine itself is rather implausibly listed as being a 600 hp petrol engine of US manufacture rather than of Soviet origin, although the make and type are not specified. The informant gave the top speed as 25 km/h, although the German experts reviewing the data from the informant suggested that an 800 hp engine could be substituted instead to provide up to 50 km/h for the tank.


Despite the shape of the Turtle tank indicating a cast body, the informant provided data that the body was of welded steel. The data provided for the armor gave a value of 80 mm for the front, 50 mm for the sides, 30 mm for the rear, and 20 mm for the floor. In light of that, the informant’s claim that even 105 mm and 180 mm shells had no effect on the armor was justifiably considered to be ‘nonsense’ by the German experts.

One further suggestion of note regarding the analysis of the armor was that the German experts considered it possible that the vehicle could use a protective coating 12.7 mm to 25 mm (½” to 1”) thick over the surface which would remove all the seams and make it invulnerable to limpet-type mines. This reference to limpet-type mines and protective coatings is an interesting reference to anti-magnetic coatings, the most famous of which is the German Zimmerit of WW2.

The informant seems to have suggested some new type of steel alloy was used for armor but this was discounted by the German experts on the basis that there were so many German scientists ‘honeycombed’ within Soviet industry post-war that such a development would have become known.

Nonetheless, the assessment was that the tank with this shape would benefit from being able to deflect armor-piercing and delayed-action high explosive shells fired at close range but parts would remain vulnerable to shells fired from an 8.8 cm L/56 or those with a shaped charge.


The Turtle Tank is not even a tank, it is instead clearly an assault gun with a fixed, forward-facing gun in a casemate. The Soviets made some very competent assault guns based upon the hulls of existing tanks like the T-34 or IS-series with a roughly similar arrangement, but nothing like this Turtle Tank. The date is 1951, so there are not a lot of possible candidates for what real vehicle the informant might have been referring to and this presupposes that the informant actually saw a real vehicle. If it is something genuine then perhaps the best candidate is something related to the ASU-85 assault gun which was in the early design phase at around this time but even so, the resemblance is terrible.

Perhaps it was/is some kind of top-secret Soviet assault gun which has been hitherto undiscovered by Soviet and Western tank historians, perhaps the informant was simply mistaken, or lying, or perhaps the experts were subject to a counter-intelligence ruse by the Soviets.

The German experts were unconvinced by this informant’s information. It was not that the vehicle was not possible, but that it was not plausible, with the experts stating that it would “constitute a complete departure from known Soviet policies”. The idea that this vehicle, so totally different from the Soviet assault guns of the day such as the SU-100 or ISU-152, has subsequently gone undiscovered is somehow unimaginable.

That said though, the German experts assessing the information from this informant seem to have agreed on the most likely outcome being the latter of the possible options, a counter-intelligence ruse. Namely, Soviet intelligence deliberately supplying false intelligence to a suspected informant or double agent, and, to back this up, they compared it to “similar methods used by the Nazi regime”, probably referring to the ‘Panzer X’.
Nevertheless, regardless of how or why this information got to the West, it was given a proper examination, by experts, and assessed to be implausible.

The informant’s claim that a pilot model of this vehicle was actually built, and demonstrated to the East German paramilitary police is also unlikely. Whilst a design which may never have left the scribblings of an engineer’s notebook might have gone unnoticed for nearly three-quarters of a century, the existence of such an unusual vehicle, with such unusual features, and departing as it does from Soviet experience, means that the Turtle tank can be fairly assessed to be a fake tank.

What it does do though is provide an excellent case in point as to the difficulties of gaining intelligence of the latest weapons from an adversary (in this case the US spying on the USSR) and the caution which should be exercised post-script in reviewing these historic documents.

turtle tank
Illustration of the ‘Turtle’ Tank produced by Jarosław Janas, funded by our Patreon campaign.


Dimensions (L-W-H) 7 x ~3 x ~2 meters
weight 30-35 tonnes
Crew 6 (Commander, Gunner, Loader, Driver, Front Hull Machine Gunner, Rear Hull Machine Gunner)
Propulsion 600 hp American petrol engine (possible to fit an engine up to 800 hp)
Suspension Independant torsion bar
Speed (road) 25 km/h (up to 50 km/h with 800 hp engine)
Armament .8cm L/56 gun (possible to substitute 8.8 cm L/70) and two machine guns (1 forwards facing and 1 rearwards facing)
Armor welded steel 80mm front, 50mm sides, 30mm rear, 20mm floor
Total production 7 prototypes


CIA Report ‘German Experts’ Analysis of the Alleged Soviet ‘Turtle Tank’ dated 4th April 1951.

Coldwar American Prototypes

M109 Maxi-PIP Howitzer Improvement Program

USA (1979-1984)
Self-Propelled Gun (SPG) – 1 Prototype

During the mid-1970s, the US Military determined that there was a need to update, replace or overhaul their existing and aging fleet of self-propelled guns (SPG). The focus was on the replacement of the M109 SPG and several options were available. The US Army could select a foreign vehicle such as the French GCT, or the Italian/UK/German SP-70 project, or a new project could be started. The military, unsurprisingly, selected a US-based program and had to consider whether to replace the whole fleet with a common chassis fulfilling roles of command, resupply, and repair or instead, just modernize/upgrade the existing fleet.

Amongst the replacement vehicles considered, the proposal made by Food Machinery Corporation (FMC) under the name DSWS New Start (DSWS – Division Support Weapon System) was rejected by 1983. The emphasis instead of replacement was going to be upgrade and modernization. FMC had invested a considerable amount of time and financial resources into their design and would try to reuse this development in an M109 rework. This was to be the M109 Maxi-PIP (Product Improvement Program)

Artist’s impression of the FMC M109 Maxi-PIP project. Source: Janes

The Flaws

The existing US SPG fleet was a mix of vehicles, calibers, and ages. There was no simple common Ammunition Resupply Vehicle (ARV) either, and a common vehicle platform for both an artillery system and its resupply vehicles would have obvious advantages for parts, supplies, logistics, and training. The work on FMC’s own platform for all of this had been discontinued already though.

The rate of fire for existing in-service SPG’s was also too slow, of the order of just 4 rounds per minute manually loaded. The US Army wanted to improve on this and an automatic loader would achieve this with up to 12 rounds per minute being possible. Another problem was that the crews of existing SPGs were too large, which lead to logistical problems such as training and maintaining these soldiers in the field. An automatic loader and automatic subsystems would help reduce this human burden.

In particular, the existing engine of the M109 was considered underpowered for its role. An improved power-to-weight ratio of 20 horsepower per ton was set for the upgrade project along with improved reliability. The M109 was a product of the 1950s and simply did not reflect the realities of modern warfare. It was vulnerable to counter-battery fire from Soviet artillery as it took too long to stop, fire, and then move on. Modernized fire control systems, gun elevation motors, and ground mapping would allow the improved vehicle to fire, move, and fire again to reduce successful enemy retaliation. Finally, the old M109 just did not have the range needed to counter fire the Soviets, which was a huge tactical weakness. These requirements formed the basic needs of the Howitzer Improvement Program (HIP).

Howitzer Improvement Program

The 155 mm gun caliber would remain, but the barrel had to be between 38 calibers (5.89m) and 50 calibers (7.75m) long. It had to be able to fire all current and future 155 mm rounds and have a range of 25 to 30 km when using High Explosive Rocket Assisted (HERA) ammunition. Either a fully or semi-automatic loading system was needed to increase the rate of fire and reduce the number of crewmen. New electronics were also needed to enable a 1-minute fire-move-and-fire-again cycle, along with a facility to fire a 3 round burst in 10 seconds. Increased ammunition capacity of at least 50 shells was also demanded.

Artist’s impression of the FMC M109 Maxi-PIP project. Source: Janes
The mock-up vehicle on display. Source: Ed Francis
Rearview of the same mockup showing the resupply doors open. Source: Ed Francis

FMC M109 Modification Proposal

When the original FMC DSWS project was canceled, FMC had luckily also submitted a proposal to update the existing M109 fleet. It was as an alternative to their own proposal for a completely new vehicle with the 155 mm L/45 gun. The upgrade/update idea though was to combine the old M109’s with some of the elements from the completely new vehicle proposal.

This would include the new suite of electronics which would improve accuracy from the same 155 mm L/45 gun but the most obvious and important change would be the switch to an automatic loading system. Fed from two large drums in the back of the turret, the 155 mm shells would be replenished by means of two circular hatches at the bottom of each door. Both doors could also be opened to allow for complete inspection or repair of the drums. The autoloader would also decrease the crew for the vehicle by eliminating the need for one of the loaders.

This upgraded M109 would be marketed under the name M109 Maxi-PIP (Product Improvement Program) and had the advantage of retaining the turret (albeit modified) of the M109. A wooden mockup was shown to the military and received sufficient interest to have a single test chassis produced based on an M109. This prototype weighed in at just over 29 tonnes.

M109 Maxi-PIP weighed mockup. Source: US Army

The M109 Maxi-PIP was still under development in 1982 with an existing M109 chassis modified to simulate the new 29-ton (26.3 tonnes) vehicle weight. The engine fitted was a 500 hp Detroit-Diesel 8V71TA and was subjected to the NATO 400 hour engine test. Tests were still scheduled to take place with this engine into 1983. Various other types of engines were considered but 500hp in a 29-ton (26.3 tonnes) vehicle would only produce 17 hp/t which was not the required 20hp/t wanted, therefore this new vehicle was not able to provide the required mobility improvements.


The M109 PIP from FMC faded away and was completely canceled 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. Pacific Car and Foundry (PCF) had also made its own proposal to fulfill the requirements for the future artillery system under the name ‘Self Propelled Artillery Weapon’ (SPAW). The PCF proposal was also a fully automatically loaded gun system but was capable of firing unassisted shells to a range of 30km and to 40km with a rocket-assisted projectile. The SPAW would have had a crew between 2 and 4 and with an engine providing a power to weight ratio of between 20 to 25 hp/t and could move at up to 40km/h off-road. Neither project could meet the Army’s needs and, as a result of the failure to develop or accept a replacement, the existing M109’s soldiered on.

Artist’s impression of the ammunition stowage and loading system on the Maxi-PIP. Source: Richard Eshleman

As with many of these multi-year huge contracts in the US, this one is an enormous project of overlapping requirements. The HIP program did not end with FMC or PCF concepts though and was still going on into 1991. This was the date by which the vehicles for the program were meant to have been entering service yet development hadn’t even finished and only 8 prototype improved vehicles for the entire program 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$28.5 million and nearly US$10.5 million the following year. It didn’t matter anyway for FMC. Their initial proposal had been rejected, as was their M109 improvement. The project was somewhat of a failure, no new vehicle was produced and a huge amount of financial resources was spent. The opportunity for a new and more capable platform producing a new family of vehicles was lost. The PIP had not managed to meet the needs for a future artillery system and the US finished out the 1980’s behind the Soviets in terms of self-propelled artillery, unable to select or develop a suitable M109 replacement.

Illustration of the M109 Maxi-PIP produced by Pavel Alexe, funded by our Patreon Campaign.


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

Tigerjäger Design B

Nazi Germany (1943)
Assault Gun – Design Only

The Jagdtiger (Hunting Tiger) is a highly recognizable vehicle consisting of a huge flat-sided casemate built on the hull of the Tiger II Heavy Tank. What is less well known is that the Jagdtiger as we know it (design started in early 1943), was not the vehicle originally requested and that, by tracking that design philosophy and evidence, it is possible to see a completely different Jagdtiger; one which was never built yet still offers a fuller picture of the evolution of German heavy armor in the Second World War.


In the spring of 1942, the Army General Staff was requesting a 12.8 cm gun mounted on a self-propelled chassis capable of supporting the infantry and of destroying unarmored as well as armored targets at distances up to 3,000 m. Armor and firepower were the priority, not speed and maneuverability.

By 2nd February 1943, this demand became an official request in the form of a letter sent from Wa Prüf 4 (the Army High Command design office for artillery) to Friedrich Krupp of Essen, setting out the requirement to mount a 12.8 cm Sturmkanone (Eng: Assault Gun abbreviated to ‘Stu.K’) on a modified Tiger H3. The ‘Tiger H3’ concerned was what we now know as the Tiger II, which was not named as such until March 1943 following the abandonment of the VK45.02(H), which was at the time known as Tiger II.

The requirements from Wa Prüf 4 for the modifications meant moving the engine forward on the chassis, with the gun being mounted in a casemate at the rear. This philosophy was felt to have the advantage of keeping the barrel overhang for the tank to a minimum and allowing for a better distribution of weight, although it was not without problems, as would soon become apparent.

The firm of Henschel und Sohn of Kassel would be responsible for the design of the hull modifications to fulfill this project and was contracted to produce designs. The gun desired was a 12.8 cm Stu.K, and the intention was to simply take the 12.8 cm Kw.K. L/55 gun unchanged, in its entirety, along with mounts, breech, brake, and recuperator from the Pz.Kpfw. Maus, although there was a strong emphasis placed by the High Command on the removal of the muzzle brake, as this allowed the use of Triebspiegel shells for heavy anti-armor work. The design, therefore, was not simply an assault gun, but also a tank-destroyer too, the difference between the two being blurred in this regard.

Further requirements set out in this letter were the use of as simple a design as possible with an elevation of -8 to +15 and 15 degrees of traverse. The sighting for the gun consisted of the Sfl.Z.F.5 and Rbl.F.36 telescopes to allow for both direct and also indirect fire.

Panzerjäger Panther design

By the start of 1943, the attempts to mount a 12.8 cm gun on a chassis were focused on using either the Panther or Tiger II as a basis. The Panther design to mount this 12.8 cm gun followed the design request closely. The engine, cooling, and ancillaries were moved to the front of the hull, behind the driver and radio operator, with the fighting compartment at the back.

Panzerjäger Panther mit 12.8 cm. Note: image has been cropped and cleaned. Source: Hoffschmidt and Tantum

The 12.8cm L/55 gun was mounted in the front of a well-sloped casemate with sloping sides, a flat roof, and a sloping rear, rather akin to the design of the back of the Ferdinand. Elevation limits for this gun were just +15 degrees to -6.5 degrees which did not meet the -8 degrees desired. Further, the rather small space of the casemate for the breech of this huge gun likely restricted the traverse to below the required 15 degrees each way.

The advantages of the design, such as the less complex and expensive Panther chassis compared to the Tiger II chassis, and the reduced length, just 8.5 m long from the muzzle to the rear, were offset by its deficiencies, such as the gun placement complicating maintenance of the engine and transmission. It is also possible that the armor which could be carried was not felt to be sufficient on the Panther chassis but, regardless of why the design was dropped, the attention was switched to the Tiger II chassis instead.

Enter the Tigerjäger

The Panzerjäger Panther design was dropped at some point, but Dr. Erwin Aders, the design lead at Henschel und Sohn, was working on two alternative designs for a Panzerjager based on the new Tiger II design. By March 1943, Aders was actively considering armor for the design up to 200 mm thick on the front and up to 100 mm on the sides, although this was subject to change in order to keep the weight to 70-tonnes (77.16 tons) or less. The goal was to provide a finished design by June 1943.

On 12th April 1943, Aders’ designs for Henschel were ready and the name being used at the time was Tigerjäger (Hunting Tiger). Designs plural, because Aders presented not one design but two: Tigerjäger Design A and Tigerjäger Design B.

Competing Designs

Design A had completely disregarded the requirement of the initial design brief to move the engine to the front of the hull. Instead, this design kept the engine at the back, with the transmission at the front as it was already arranged on the Tiger II. Despite this, the hull still had to be lengthened by 300 mm. Spielberger, Jentz, and Doyle (2007) describe the frontal armor of this design as being 150 mm at 40 degrees on the glacis and 200 mm thick on the 60-degree sloping part on the front of the casemate. However, the side armor had been reduced from the 100 mm desired in March to just 80 mm in order to keep the weight down. In other words, the frontal armor was now effectively double or more than the Tiger I but with the same side armor as the Tiger II.

Construction of a casemate with the armor desired and enough room for the breech of the huge 12.8 cm gun created a major problem and the height of Design A had to be reduced by 40 mm to allow it to fit inside the German rail gauge height limits for transportation. This had the effect of reducing gun depression from the -8 desired to -7 but, other than that, the design had met almost all of the requirements desired in the original letter from Wa Prüf 4 in February.

Design B, on the other hand, was significantly more problematic. In order to meet the requirements of Wa Prüf 4’s request to move the engine to the front, the hull roof had to be raised. Further, the cooling system of fans and radiators would not fit and would require a total redesign but even so, the engine was put in the middle of the hull. This, in turn, created additional problems with the transmission of power from the engine to the transmission at the front and to resolve that dilemma would mean designing new intermediate gearing. If that was not bad enough, Dr. Aders had not managed to design an effective system for exhaust from the engine and ventilation as the new arrangement had created so many difficulties for the design, and that was just the automotive problems.

Along with this total redesign of the Tiger II to accommodate this new automotive arrangement and the casemate at the back, the vehicle was too large for the rail gauge. Altering the design in order to meet this limitation would further reduce the movement of the gun which was already reduced by the height of the hull in front of the casemate. Assuming for a moment that the height could be amended in the same manner as Design A, reducing the -8 depression to just -7, then we can only surmise that the figure of -7 would be yet further reduced by this engine deck-height issue to -6 or less. Significant benefits of this gun mounting which should not be forgotten, however, were that it kept the center-of-gravity of the vehicle further back and meant there was very little overhang of the gun over the front of the hull.

One more problem to add to this litany of issues was maintenance. Not only would Design B require parts unique to it which were not compatible with the Tiger II, such as the gearing and cooling systems, but access to these parts was hard too. The 12.8 cm gun and mantlet would overhang the engine deck and, with limited traverse and elevation, there was no means to remove the engine or transmission without first removing the gun. This would also have to be done anyway for the Design A option but only for a change of the transmission and not for the engine. A short note here is that, at this time, the only engine being considered for the Tigerjäger was the same as that of the Tiger II, the Maybach HL 230 TRM producing 700 hp.

When Design A was amended with the casemate 200 mm further back due to a design change over the gun mounting, it resolved the centre-of-gravity issues and also reduced the gun overhang at the front. Design B, therefore, offered little in the way of advantages over Design A and a whole slew of major and unresolved problems. With an urgency to get this heavy 12.8 cm assault gun platform into service, there was only one logical choice and Design A, despite not being the engine-forward design requested, was selected instead. Design A went on to be the Jagdtiger and Design B was dropped.

The Duplicate

The first ‘Tigerjäger Design B’, as previously described, dates to the first half of April 1944 and the creative mind of Dr. Aders at Henschel und Sohn. Just to be confusing for historians, there is another Tigerjäger Design B. In fact, it is actually written as ‘Tiger-Jäger B’ and also emerges from Henschel just a month after the first Tigerjäger Design B. This means it is almost certainly from Dr. Aders as well, as he was the chief designer at Henschel.

Given the fact it was almost certainly proposed by the same designer responsible for Tigerjäger Design A and Tigerjäger Design B, from the same firm and only separated by a month, it would be easy to assume that there may be an error and that there was, in fact, only 1 Tigerjäger Design B. Here though there is a lucky break for the curious, as the plans for the May 1944 Tigerjäger Design B, unlike the April 1944 Tigerjäger Design B, actually survive.

Tiger-Jäger B with 12.8cm L/55. This is a different Tigerjäger Design dated 15th May 1943. Source: Hoffschmidt

Looking at the plans for the May Tigerjäger Design B and comparing it to the description known for the April design, it becomes very apparent that they are not the same vehicle which have been confused. The April vehicle was an engine-forward, rear casemate design with the 12.8cm gun over the engine with a small projection, whereas the May vehicle is the engine-rearward center-casemate design just like that known for Tigerjäger Design A from April, mounting the same gun but only over the front of the hull and projecting forwards.

The May Tigerjäger Design B initially looks like Design A, but there is one key visual difference that is easy to overlook; a cut-away portion on the top edge of the glacis. This cut-away reduced the point at which the gun would foul on the hull during depression.

The armor listed on the plan for the May Tigerjäger Design B also matches the armor described for the April Tigerjäger Design A, namely 200 mm on the front of the casemate, 150 mm on the glacis, and 80 mm on the sides. As these armor figures both pre- and post-date the April Tigerjäger Design B, it can be reasonably assumed even without the plans that the armor would be the same.

Resurrection: September 1943

Design B might have failed but the idea of sticking the 12.8 cm gun is a rear-casemate engine-forward design certainly had one last surprise. This time it was not from Henschel but from Krupp.

On 24th September 1943, Colonel Crohn (Wa Prüf 6) wrote to Krupp about improving the armament for the Tigerjäger, which was now the Henschel Design A type vehicle. There had been problems with the 12.8cm L/55 from Krupp which was, as yet, still unfinished. The gun suggested by Colonel Crohn was the 12.8cm L/70 version of the gun which used the same two-piece ammunition as the shorter gun but would deliver a higher muzzle velocity for armor-piercing rounds.

Krupp set to work and on 21st October replied that they had altered the design (the current Design-A type vehicle) to take the L/70 instead of the L/55. The gun could still fit in the same mounts as the L/55 gun but caused serious problems. The extremely long barrel now projected nearly 5 m beyond the front of the tank, bringing the center of gravity much further forwards, leaving a great strain on the front suspension.

The solution, in one way, was obvious – put the gun further back. In fact, mount the gun in a casemate at the back of the hull and, in doing so, move the engine forwards. This was then unsurprisingly exactly what Krupp suggested. At the same time, they outlined what effect the use of an L/70 would have on the primary design they suggested, and outlined this exact alternative, namely moving the engine forwards and the gun backward. This would reduce the overhang at the front to just 2 m or so and bring the center-of-gravity further back too. The drawbacks though, would be the same as before on the Design B and, on top of this, Krupp foresaw an increase in weight too on top of the weight of the heavier gun. Krupp said that it would consult with Henschel on the matter but, as Henschel had already considered this problem, it is no surprise that this idea died as quickly as it started.

By the end of October 1943 then it can be said that the rear-casemate engine-forward Tigerjäger was well and truly dead as an idea.


Because the designs were both rejected,k as both had so many faults and neither drawing has survived, it is perhaps no surprise that the descriptions provided, along with a knowledge of the development of the 12.8 cm Panzerjager and Tiger II programs, only allow for an approximation or surmised layout to be offered.

Looking at all of the other Panzerjägers following this engine-forward principle, such as the Panzerjäger IV mit 8.8 cm L/71, the Elefant/Ferdinand with the 8.8 cm L/71, and the Panzerjäger Panther with the 12.8 cm L/55, they all share the same core elements of sloping casemate sides, flat roof, and a rear which slopes both out from the floor to about the midpoint before sloping back to meet the casemate roof.

It is also worth considering that rear-mounted guns were actually installed on the Tiger II chassis, such as the 17 cm Selsfahrlafette 17/21, better known as the ‘Grille’ (Cricket). For that design, the engine was brought forward and the gun taken to the rear. A look at the engine position in the Grille, therefore, provides a view of what the front section of Design B might have looked like with the engine brought forwards. Why was it not a problem for the Grille when this layout was such a problem for the Tigerjäger? Simple: the Grille’s 17cm gun could be elevated far enough that access to the engine and transmission was relatively easy, as the gun did not need to be removed first.

Plan view of the 17cm Grille using the Tiger II chassis with the engine brought forwards. The vehicle is facing to the left and the front of the casemate for the gun on the Grille is outlined. This illustrates yet another problem with the engine-forward design – the isolation of the two crew at the front from the crew in the back. Source: Frohlich
Artist’s impression of the Tigerjäger Design B. Source: Author

Without seeing the original design, it is not possible to know for sure what Tigerjäger Design B looked like and the ‘invention’ of a tank, however reasonable it may look, is avoided by serious historians, which is why the artist’s impression shown here by the author is offered with the warning that it is exactly that, a rough impression of what it might have looked like based only on the little information available and from contemporary designs. Only if, and when, the original drawings are found can it be known for sure how close this impression is to reality.


The Tigerjäger Design B was literally a ‘paper panzer’ – it never left the drawing board. Designed by Henschel exactly as was actually demanded, it was simply surpassed by the alternative design (Design A), the design which went on to be the Jagdtiger. Using a rear casemate design with the engine forward would have allowed the use of the 12.8cm L/55 (April/May 1943) or even L/70 (September/October 1943) without the otherwise enormous overhang and without the excessive weight on the front suspension. Nonetheless, the design caused other problems relating to maintenance, the need for new component parts and really was not needed. There had been serious delays already in the Jagdtiger program at the time and 12.8cm L/55 production was behind schedule; switching to a longer gun would simply have slowed things down even more and the L/70 was simply not necessary to deal with its intended targets.

Krupp’s ideas for mounting the L/70 in the Design A never came about either and its ideas about moving the casemate to the rear were equally impractical given the problems of engine access. As it was, the Jagdtiger would follow a more conventional layout and the Design B of April 1943 was dropped. Together, the discussions over the Tigerjäger come together to provide a fuller picture of the small, but important steps in the evolutionary process for the Germans’ heavy Jagdtiger program.

Illustration of the Tigerjäger Design B produced by Mr. C. Ryan, funded by our Patreon Campaign

Tigerjäger Design B (April – March 1943)

Total weight, battle-ready est. 75 tonnes
Crew 6
Propulsion Maybach HL 230 TRM petrol producing 700hp
Armament 12.8cm Kw.K. L/55 plus hull mounted machine gun
Armor Up to 200 mm frontal, 80 mm sides and rear. 40-50 mm roof

Tigerjäger Design B (September-October 1943)

Total weight, battle-ready est. 70 – 75 tonnes
Crew 6
Propulsion Maybach HL 230 TRM petrol producing 700hp
Armament 12.8cm Kw.K. L/70 plus hull mounted machine gun
Armor Up to 200 mm frontal, 80 mm sides and rear. 40-50 mm roof


Spielberger, W., Doyle, H., Jentz, T. (2007). Heavy Jagdpanzer: Development, Production, Operations. Schiffer Military History, PA, USA
Hoffschmidt, E., Tantum, W. (1988). German Tank and Antitank. WE Inc., CT, USA

Cold War Canadian prototypes

Modified Tracked Jeep

Canada (1950s) – None Built

Every army, at some point, has to get around to tackling the design of a utility vehicle. These are small, mobile vehicles for a variety of roles, from hauling troops and supplies, to towing field guns, and even for combat. The small 4-wheeled utility vehicle known as the Jeep fulfilled many of these lighter roles during World War 2 as did the not-less-famous Universal or ‘Bren Gun’ Carrier. Both saw extensive use and modification to the extent that Universal Carrier and Bren Gun carrier are used as interchangeable terms and ‘Jeep’ became synonymous with an off-road vehicle.
What is less well known is that the Canadians did an extensive amount of work of their own for a tracked utility vehicle during the War. This was known as the ‘Tracked Jeep’; effectively a go-anywhere multipurpose tracked vehicle made with a lot of components from Jeeps. This small vehicle would be able to be borne by gliders for use by airborne troops and fulfill various support, logistic, and scout functions and had entered prototype testing by 1944. Orders placed in 1945 though were delayed in production and by the end of the War, the Tracked Jeep project was effectively dead, although some testing in the very marshy conditions of northern Canada’s Manitoba province provided useful information for later tracked developments. The primary author of this work was Major M.G. Bekker of the Canadian Army who worked for the Canadian Directorate of Vehicle Development.
Major Miecyslaw Gregory Bekker was a Polish emigree who had worked for the Polish Ministry of Defence from 1931 until 1939. In 1940 he was working for the French Ministry of Armaments, but with the Fall of France, that position did not last long, and by 1943, was living in Canada and working for the Canadian Military until 1946. His speciality was off-road traction and all-terrain vehicles and by 1950 was working on secondment for the Canadian military at the Stevens Institute of Technology in Michigan. He would later go on to become head of general mobility with General Motors Corporation, meaning that this highly experienced and well-travelled engineer could even have had a hand in the early stages of what became the US HMMWV program.

Canadian Tracked Jeep Pilot No.1, May 1944. Photo: MilArt blog
The lessons learned from the design were not forgotten though, and in 1950, with the Korean War (June 1950 – July 1953) starting, the US and Canadian authorities worked together on a new series of highly mobile tracked vehicles, and in doing so, looked back on developments including the experience from Canada with the Tracked Jeep. By 1950 though, the Tracked Jeep of WW2 had substantially evolved and was now more of a tank destroyer than a utility tractor.

Front and side views of the Tracked Jeep circa 1950. Source: Army Service Technical Information Agency 1951


The Tracked Jeep name had been kept, but the old suspension of 5 small 12 inch (300mm) diameter wheels had been abandoned in favour of a much simpler big-wheel design. The new design featured four much larger diameter wheels about 24 inches in diameter (600mm) with three of them in contact with the ground via the tracks, and the fourth at the front providing the drive. The rear-most wheel was on a trailing arm and was also provided with a large spring for suspension. The other wheels were sprung individually, horizontally.

Original suspension on the Canadian Tracked Jeep Pilot No.1, May 1944. Photo: MilArt blog

Improved suspension arrangement for Canadian Tracked Jeep showing the three ground contact wheels and rear trailing arm spring. Source: Army Service Technical Information Agency 1951
This tracked Jeep bore little or no resemblance to the older one. The hull one was different too. In place of the clean lines of the 1944 vehicle, this new 1950 vehicle was much more angular and now sported a turret. Not a full turret, but an unusual offset turret mounted on the rear right-hand side of the vehicle with limited 30 degrees traverse to the left and right. One similarity with the original tracked jeep though, was the retention of the original Willys Jeep engine, although as the original design had switched to the more efficient Carmazin radiator, it is likely this 1950 version retained that improvement too.


This diminutive vehicle was to have a crew of just two. A driver, located in the front left, and the overworked commander/gunner/loader in the rear centre sat facing outwards towards the breech of the rifle with the ammunition for the gun stowed behind him.

Illustration of the ‘Modified Tracked Jeep’ produced by Yuvnashva Sharma, funded by our Patreon Campaign.


The hull of the Tracked Jeep was just 112” inches long (2.84m) extending to 134” (3.4m) to the end of the gun barrel which overhung the front of the vehicle. The vehicle was light too, just 6,400 lbs gross weight (2.9 tonnes), but this was at the expense of protection. The armor was seriously thin with just 5/16” inch (8mm) at the front and ¼” (6.4mm) on the sides, making the vehicle barely bulletproof to normal small arms and not able to withstand machine-gun fire.
The small size of the vehicle (just 2.84m without the gun and 3.4m with it pointing forwards) was a very important factor. and could be reduced by stowing the gun at an angle across the hull to the front left corner). The vehicle was just 73” inches (1.85m) wide and 64” inches (1.63m) high and under 3 tons, meaning it was small enough and light enough to fit in every transport aircraft and glider in service at the time.


The advantage of this small vehicle was the armament. This design would provide a highly mobile platform, ideal for airborne troops with firepower to match. This firepower was in the form of a single 105 mm recoilless rifle. Assuming this to be the American M27 rifle, this would be able to fire the T-43 High Explosive Anti-Tank (HEAT-T) round at 1,250fps (381m/s), as well as the T268 High Explosive (HE)(standardised as the M323), T-269 White Phosphorus (WP)(standardised as the M325), T139 High Explosive Plastic (HEP-T)(standardised as the M345B1) and M326 High Explosive Plastic (HEP)(standardised as the M326) rounds. Only eight rounds could be carried in the vehicle though, limiting its usefulness for infantry support. If American practice was followed, this would be increased to 9 as the weapon was expected to be carried loaded into a combat zone.
There were three types of ranging available for the main gun from plain visual ranging, to stadiametric ranging, and finally, a rangefinder. With just a single shot, the estimated accuracy for a first shot hit with this weapon assessing those three types of range-finding was assessed in 1951 as 8%, 18%, and 49% respectively at 1000 yards (914 m). It should be noted too that the High Explosive Anti-Tank (HEAT or HEAT-T) round was capable of defeating 13” (330 mm) of armor plate which meant it was able to defeat any tank then in service.
The small turret in which the main gun was housed is shown in data tables as having 60 degrees of traverse with 30 degrees each side, however, a measurement of the blueprints shows, only 30 degrees to the right and just 21 degrees to the left for a total of 51 degrees. Elevation and depression are not stated but are measured from the blueprints as -10.5 degrees to +30 degrees.

Plans of the Tracked Jeep circa 1950. Source: Army Service Technical Information Agency 1951


The tracked jeep was not a bad concept in 1944 and it was still a viable concept in 1950, but it had very little growth potential. The vehicle was not really much more than a universal carrier with a very lightly protected superstructure and a recoilless rifle. That rifle could and was already easily fittable on a normal wheeled jeep or onto almost any other tracked vehicle. The small size, two-man crew and lack of ammunition with just 8 rounds meant that the tracked jeep of 1950 was not heavily armored enough to withstand enemy counterfire and not well-armed enough to provide sustained fire support in battle. As such the project was discontinued, the merits simply did not outweigh the problems and other solutions were available.


Dimensions (L-W-H) 112” x 72” x 52”(2.84m x 1.8m x 1.32m)
Total weight, battle-ready 6,400 lbs (2,900kg)
Crew 2 (Driver, Commander/Gunner/Loader)
Propulsion Willy’s 4×4
Suspension Torsion Bar
Speed (road) 36mph (road), 6mph (cross country)
Range 140 miles (road), 50 miles (off-road)
Armament 1 x 105mm recoilless rifle – 60 degree traverse, 8 rounds
Armor ¼” armor basis (5/16” inch (8mm) at the front and ¼” (6.4mm) on the sides


Army Service Technical Information Agency. (1951). Working Paper ATI 149375: Analysis of a Light Cross Country Combat Vehicle ‘The Cobra’.
Hall. C. (2008). A Biographical Dictionary of People in Engineering. Perdue University
Lucy, R. (2014). Canadian Tracked Jeep (Willy’s). MilArt blog.

WW2 Italian Prototypes

‘Rossini’ CV.3 Light Tank Prototype

Italy Kingdom Of Italy (~1935)
Light tank – 1 built

Giuseppe Rossini was the engineering brains behind the Ansaldo Carro Veloce (Ansaldo Fast Tank) projects. In 1930 and 1931, he had created a prototype based loosely on the general arrangement of the CV.29, which, in turn, was copied from the Carden Loyd Mark VI Light Tanks purchased from Great Britain in 1929. Throughout 1930 and 1931, that design had been refined and tested, which resulted in the 2-1-1-2 bogie suspension system seen on production CV.3 series vehicles from the model of 1933 to the model of 1935.

Whilst it was a robust suspension system, it was not perfect, and various minor changes were made, mostly to the rear idler, but also to the bogies themselves. On top of this, the armament was weak. A single machine-gun had been mounted inside the Prototypes of 1930 and 1931 in a limited-traverse mount. It would not be until 1934 when this was this switched to a double machine-gun but, again, this was in a hull mounting with a limited field of fire. The obvious solution to the underwhelming firepower was the addition of a turret. Rossini clearly saw an opportunity to address both the suspension and firepower limitations and, sometime between 1932 and 1935, created a new vehicle with improvements to both suspension and firepower.


This new vehicle was using the same welded steel hull, with armor ranging from 8mm to 14mm, as in the CV.3/33 Series I Light Tank (the Series I being distinguished by the air intake for the engine being located centrally at the back of the casemate, flanked by two rectangular hatches which could be opened from inside). Based on the use of this hull (which was discontinued in 1934 when production switched to the Series II vehicles), this would appear to date the design between 1932 and 1934. It is possible, however, that Rossini was simply experimenting with an older body that had been discontinued after this date. By 1935, production had switched from welding the casemate to a bolted structure, so the estimated likely date range is kept at 1932 to 1935 for this reason. The rest of the casemate retained the features of the CV.3/33 Series I production tank, with the same flush-fitting mudguards and casemate mounted headlamps.

The machine gun position cut into the front left was replaced with a new glacis plate which covered the hole all the way up to the nearly vertical driver’s plate. This too was now a single piece without the machine gun opening, and other than the driver’s hatch which had been retained on the right, this was now a clean single plate. The driver’s position remained unchanged. Sat on the right and steering by levers, the driver still had a single large rectangular hatch over his head to get in and out, plus the same small square vision port to his right to see out of. The vision port on the left of the casemate was kept, but instead of a seated weapons position for the commander/gunner, he would now have a turret. He would have to stand up to use this small turret, though he could presumably sit back down in the hull if he wished to when he did not need to maintain observation or man the machine gun in the turret.


Other than the obvious addition of a turret, the most significant change to the vehicle was the new suspension system. The normal CV.3/33 used the standard 2-1-1-2 suspension consisting of bogies connected and held together by a stiff outer steel bar. The movement of the wheels was thus limited, which reduced off-road performance. A new type of coiled spring suspension was tested at around this time on a Series I Production CV.3/33 and showed that the wheels had a wider range of movement than the bogies which were held rigidly in place by a horizontal bar.

For this turreted tank, Rossini used a new system. Four large wheels connected by a horizontal flat steel bar sandwiching the wheels. This steel bar was connected to a pivot point on the lower edge of the hull. A leaf spring was at the back of each side of the tank on the horizontal bar, although this was reversed on the rear pair of wheels on each side. This system meant that when the wheels encountered an obstacle or change in ground-height, the wheels could pivot together around this central pivot point and the leaf spring attached to the horizontal bar provided both shock absorbency but also returned the bogey back to its starting position.

‘Rossini’s’ CV.3 prototype showing the effectiveness of the new suspension system. Source: Ansaldo

Turret and Armament

The armament of the Series I vehicle had been weak, consisting of just a single Fiat Model 1914 6.5 mm machine gun (tipo aviazione). This was a much more suitable weapon for a vehicle than the previous water-cooled machine gun used in the prototypes of 1930 and 1931, but was still inadequate for providing sufficient weight-of-fire to support infantry attacks and had insufficient power to penetrate enemy revetments or even light armor. This deficiency was addressed in the production of the Series II vehicles from 1934 when a new mounting was fitted, this time coupling a pair of Fiat 1914/1934 8 mm machine guns together. This firepower increase came at a price.

The single machine gun of the Series I was able to move 20 degrees in each direction horizontally and could be elevated between -12 and +18 degrees with space inside for 3,800 rounds of ammunition. The two 8 mm machine guns though, had a reduced traverse, with just 12 degrees to each side, and the elevation was limited too, down from +18 on the Series I to 15 degrees on the Series II. A bigger bullet also meant that fewer rounds could be carried, with just 2,320 8 mm rounds on the Series II compared to the 3,800 6.5 mm rounds carried on the Series I tanks.

Side view of the modified CV.3 showing the turret and new 4-wheel suspension system. Source: Ansaldo

Along with this decrease in ammunition stowage came the further downside of weight. The new machine gun mounting was also significantly heavier. The solution was clearly met with the addition of a turret. A machine gun mounted in a turret atop the machine would be able to provide not 24 total degrees of traverse, but 360. Thus, a small circular turret was added over the commander/gunner’s position. Around the circumference of the turret sides and rear was a series of 4 horizontal vision slits which served to significantly improve visibility from the vehicle too. The front of the turret had a similar style of mounting as was fitted previously in the hull, projecting out of the front of the turret in a box structure, into which a second fitting was installed which could move up and down. Through this second piece, the single machine gun armament was mounted to the right-hand side. Unlike the former hull mount, there does not appear to have been any ability to move the machine gun side to side within this mounting, which would be no surprise as lateral movement was now provided by the turret.

The roof of the turret was formed from a single steel hatch opening backward, but when closed, actually sloped forwards slightly. The exact armament is not clear. Rossini demonstrated his vehicle fitted with just a single machine gun of an unknown type, possibly the Fiat M.26 or M.28 (experimental) 6.5 mm machine guns, although whether a different machine gun was planned is unknown as the 6.5 mm Fiat Model 1914 (tipo aviazione) was already known to be insufficient. With added space inside the tank, it is also likely that there was sufficient room in which to store more ammunition in addition to the 2,320 rounds carried in the Series II vehicle. Photographic evidence shows one extremely useful feature of the design, which was that the machine gun could actually be withdrawn by the commander/gunner and, with the turret roof open, mounted pointing upwards as a defence against low flying aircraft. None of the CV.3 vehicles had, to this point, any capacity for protection against aircraft whatsoever, and a single 8 mm anti-aircraft machine gun was as much as most Italian tanks in WW2 had a few years later, so the flexibility of the firepower on offer was excellent.

Questions arise as to why the fitting of a 20 mm cannon, such as the 20 mm Breda (20/65 Breda M.35), was not attempted, although it is possible that it was considered. Without the original paperwork for the development, designer’s notes, or blueprints though, it can only be speculated. Should such a weapon have been considered however, it would have been a significant increase in firepower, providing just what the Italian troops fighting with Franco’s Nationalists had really needed in the Spanish Civil War (1936-1939). During that war, the Italian machine gun armed tanks were mostly ineffective against the Soviet-supplied T-26 tanks of the Spanish Republic. Ironically, the Italian Breda 20 mm cannon, being the ideal weapon against the T-26, was mounted on another light tank during that war, the German Panzer I, and on an Italian CV.3 Series vehicle for exactly this purpose.

Illustration of the Rossini CV.3 light tank prototype. Illustrated by Yuvnashva Sharma, funded by our Patreon campaign.


Very little is known about this development. At a time when the CV.3/33 Series II was either starting production or in production, this design was a significant improvement over that tank in all areas from enhanced mobility on and off-road, better visibility, to improved firepower. Even retaining the same CV.3-005 43 hp petrol engine of the Series I and II vehicles, this tank would have had comparable performance in terms of speed, combined with beneficial features, such as greater cross-country ability, better visibility and more flexibility in terms of firepower.

Modified CV.3 showing the elevated position of the main armament for use as an anti-aircraft gun. Source: Ansaldo
It was to come to nothing, however. The potential of this vehicle was never realized, as the development of the CV.3 continued into 1935 and other schemes for a light, turreted tank began. Those plans would improve on the Series I’s suspension as well, but never again was the CV.3 series vehicle to have this big-wheel suspension system fitted.


Pignato, N, Cappellano, F. (2002). Gli Autoveicoli da Combattimento Dell’Esercito Italiano V.2. Stato Maggiore dell’Esercito
Curami, L., Ceva, A. (1994). La Meccanizzazione dell’Esercito Italiano. Arte Della Stampa

‘Rossini’ CV.3 Light Tank Prototype specifications

Dimensions 3.167 x 1.4 x ~1.7 m
Total weight, battle ready ~3.4 tonnes
Crew 2 (Commander/Machine Gunner, Driver)
Propulsion 2.745 litre 43hp Fiat CV.3-005 4-cylinder petrol
Speed est. 40 km/h road, 14 km/h off-road
Armament Single machine gun (Fiat M.26 or M28) 6.5 mm
Armor 8-14 mm
Total production 1 built
For information about abbreviations check the Lexical Index
WW2 German prototypes


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

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

Maus Typ 205/2 hull mounting the number 1 turret during tests. Note the Polish TKS tankette next to it, giving a sense of the size of this super heavy tank. Illustration by David Bocquelet


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.

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


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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
El Salvador Armor

‘Mazzinger-Z’ and ‘Astroboy’


El Salvador (1979 to ~1992)
Armored trucks – 20+


Following the 1969 invasion of Honduras, arms sanctions were placed on El Salvador, significantly limiting its access to arms and armored vehicles. The result was that, throughout the 1970s, a series of improvised armored vehicles were manufactured, most notably by the Maestranza de la Fuerza Armada de El Salvador (FAES) – the central command for ordnance for the military. Some arms deliveries did make it to El Salvador, usually via third parties, such as 27 tracked log haulers (based on the US-built M114 APC) from the USA which arrived via Guatemala and would eventually be converted into the ‘Marenco’ armored vehicles. A delivery of West German UR-416 armored cars arrived by the end of 1975 and, although these had been delivered unarmed, they were soon armed and used in the civil war (1979-1992). The attacks on roads, bridges, government buildings, and other infrastructure by six to seven thousand guerillas of the Marxist Farabundo Marti National Liberation Front (FMLN) meant that the government junta, made up of the military and Christian Democratic Party, struggled to maintain effective control over the country and supply routes. Despite financial backing and military advisors from the USA, the harsh crackdowns and human rights abuses by the government were not giving them victory in the civil war, and the need for the army to have armored vehicles was acute.
Back in 1969, a series of trucks known as ‘Rayos’ had been fitted with armor for the invasion of Honduras, and this highly successful strategy was repeated post-1979 for the deteriorating security situation. Wheeled vehicles offered significant advantages over tracked vehicles, not least of which was their availability. With the majority of the fighting being short and of low intensity, wheeled vehicles were able to move much more quickly to where they were needed and had a much lower maintenance footprint than a tracked vehicle. The speed and availability of wheeled vehicles meant that they were a simple solution to the patrolling and protection of roads and infrastructure. Including the 27 M114 conversions, El Salvador produced about 150 armored vehicles in the years between 1978 and 1985, a remarkable achievement for a small and relatively poor country and especially so considering the arms sanctions and security climate.


Trucks converted into armored vehicles included those made by MAN, Magirus, International Harvester, as well as more REO M34/M35A1 2.5 ton utility trucks. Together, these vehicles were no longer ‘Rayos’ but were named after a giant Japanese robot cartoon character and known instead as ‘Mazzinger-Z’s’.

Mazzinger-Z based off an International Harvester-built truck – ‘FAES 12001’. Source: Spencer
One Mazzinger-Z was based on an International Harvester (IH) truck, although initially, it was unarmed. Later, it was fitted with the same type of turret and M55A2 triple 20 mm anti-aircraft cannon as used on the Anti-Aircraft/Armored Personnel Carrier vehicle built by Captain Oswaldo Marenco on the M114 chassis. The truck used large flat steel panels to form the armor, which was slightly tapered upwards from the sides with a very short tapered portion along the bottom of each panel. Four vision blocks were made in each side with three more in the back, including one in the main access door. The vehicle was not open-topped as was the norm with other APCs produced in El Salvador. The cab also featured sloping armor over the engine bay, a steel armored grille over the radiator at the front and bulletproof glass windows in the door and windscreen.

Front view of the turret on the International Harvester-based Mazzinger-Z with 20 mm turret fitted. The triple-barreled M55A2 cannon imported from Yugoslavia was a potent weapon for suppressing ground and air targets alike. Source: Spencer
The MAN truck-based Mazzinger-Z was overall very similar to the shape of the International Harvester (IH)-based vehicle, with a large angular body at the back made from sloping plates tapering towards the top and with a fully enclosed roof. The bottom half of the side plates tapered in sharply under the vehicle. Unlike the IH-based vehicle though, the wheels at the back were covered by angled steel plating and the engine area was much more steeply sloped. The front wheels on both remained unprotected though.

MAN-based Mazzinger-Z with triple 20 mm cannons, a pair of 90 mm recoilless rifles and light machine gun mounts. Source: Spencer
Armament for this MAN-based Mazzinger-Z consisted of the same M55A2 triple 20 mm anti-aircraft cannons fitted in a small turret right at the front of the cargo body and projecting over the cab. The rest of the cargo body portion of the vehicle, which was the troop compartment, raised up sharply behind this turret forming, a high roof on the back of the truck which would have seriously hampered any attempts to fire directly backward. To the sides of this cargo body, though, were two firing ports, one on each side at the height of the cab for soldiers’ weapons, and near the top of the body were two more loopholes (one on each side), each of which was designed to take an HK21 light machine gun. These were not all of the weapons fitted to this vehicle, for attached to the top of the turret on either side were also two 90 mm recoilless rifles which had been cut down to make them shorter and lighter. These would fire with the 20 mm cannons, providing a significant weight of fire against a target, although they could not be reloaded from inside. A crew-member would have to expose himself to enemy fire in order to reload these from the rear.
The Magirus-based vehicles were longer, with an additional axle on the truck, meaning they could also carry more troops as the cargo area was longer. Just like the MAN and IH vehicles, these were armored, although the sides were no longer tapered and were simple vertical plates for the most part until near the top where they would taper in at about 45 degrees to the roof. These angled plates though could be folded down by troops inside for ventilation, visibility, or even to fire from. Visibility for the occupants was mainly provided by four rectangular vision blocks on each side.

‘FAES 1305’ – a Magirus-based Mazzinger-Z rebuilt for the third time after damage from guerillas. Source: Spencer
The cab on the Magirus truck was clad in simple flat steel panels and bulletproof glass replacing the windows. Normally, no armament was carried other than the weapons of the troops in the back, although at least one vehicle was fitted with an M60 machine gun and gun shield over the cab. In an attempt to improve protection for the troops in the back, Kevlar sheeting was used to line the bed, providing protection from fragments being blown up from underneath the vehicle.

Magirus-based Mazzinger-Z at the head of a column with an M60 machine gun fitted over the cab. The driver stands outside the vehicle and can be seen to be wearing body armor. Source: Spencer
In combat against the guerilla forces, it was common to shoot out the tires of the trucks to immobilize them before attacking them with rocket-propelled grenades (RPGs). Just like the rebuilt M114s, an attempt to counter the RPG threat came from the use of mesh screens placed over the sides and cab of the vehicles, although not all had this feature and the success of it was questionable.

‘FAES 1496’, a Magirus truck-based Mazzinger-Z with additional side mesh armor in an attempt to counter RPG use. Source: Spencer
At least one Mazzinger-Z vehicle used this same style of cargo body, but with the addition of what appears to be a raised curved section at the top. The cab is crudely armored with a small bulletproof glass window on each side and no protection for the tires. One method which was tried to protect the tires from enemy fire and mine damage was to clad them with tracks taken from M114s, effectively wrapping them in the track links to armor them. It is not known how successful this idea was.

Unidentified Mazzinger-Z with track platted tires carried on the raised roof. This vehicle also appears to have kevlar sheet-reinforced fold-down panels near to the top of the cargo body too. Source: Spencer
Mazzinger-Z’s were mainly used for convoy escorts, protecting against guerilla attacks and for carrying a dozen or more soldiers in the back. Due to the lack of air conditioning in the vehicle, it was normal for those angled side panels to be folded down, leaving the men exposed to enemy fire, although it was standard practice for the driver to wear body armor.

International Harvester-based Mazzinger-Z armored truck, fitted with a turret mounting an M55A2 triple 20 mm anti-aircraft cannon. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.

Dump-Truck Mazzinger

One odd Mazzinger, which stands out from all the others, was not based on a standard truck at all. Instead, this oddity was built off the body of a repurposed 5-ton dump truck. This vehicle was locally created rather than FAES-constructed and was built at a motor pool near Zacatecoluca.

Pictured outside the Engineer’s barracks at Zacatecoluca in July 1991, this vehicle has the words ‘Mazzinger-Z’ written in red over the central light at the front and is painted bright green with black and brown. Source: Spencer
The armor protection for this vehicle was cruder than for the other Mazzingers and had a large armored covering over the cab area and in front of the engine, although it is not known if the sides of the engine bay were armored or not. At the back of the vehicle, the dumper body was already well protected, being built out of steel, and was added to by means of rectangular panels welded over the sides and a large square panel at the back into which a door was made. Three small rectangular loopholes were cut into each side with no flap or bulletproof glass, and at least one more in the back. Armament consisted of the soldiers’ personal weapons and a pair of M60 machine guns, one mounted on each side in the back and protected by a shield.

5-ton dump-truck based Mazzinger-Z pictured in 1991. Source: Spencer


Following a series of engagement with the guerillas with these Mazzinger-Z’s, a second series of vehicles was ordered by 1982. These were smaller than the Mazzinger-Z’s, which had been based on full-size trucks. These new vehicles, named after ‘Astroboy’, another Japanese cartoon character, were instead based off Ford F250 trucks, fulfilling the role of a light armored personnel carrier

Astroboy Ford F250 based APC pictured May 1987 showing a complete coat of armor over the truck save for the tyres. Source: Spencer

Astroboy Ford F250 based APC. Source: Montes
Approximately 20 such vehicles were produced and there was significant variation amongst them. Astroboy ‘828A’, for example, had a fully armored body made from sloping sides front and rear and a covered roof. The sides had multiple bulletproof glass portholes and four large rectangular doors and the vehicle was used as a mobile command post.

Astroboy used by the Atlacatl Battalion. Note the addition of double tires at the back to take the weight of the troops and armor being carried. Source Spencer
Another known ‘Astroboy’, though, had no armor at all on the truck cab, with only the body at the back protected by a large angular welded body. Inside here, the soldiers could use four bulletproof glass windows in each side, below which was a firing portal, and two more in the back. The soldiers here would be able to fight from behind the protection of the armor, although the driver would be exposed with no protection. An odd choice considering the complete protection provided for ‘828A’ which was only for use as a command post rather than direct combat.


The Mazzinger and Astroboy vehicles came about at a time of great wheeled military vehicle shortage in El Salvador. On the whole, they were quite well designed, showing that a lot of thought had gone into the construction of the various armored bodies, especially considering the scarce resources available at the time and limited production facilities. These vehicles saw much service, conducting patrols and convoy escorts, although finding accurate accounts of their use is limited. None of these vehicles are currently known to have survived.


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