The Sturmgeschütz III was the second most-produced German tracked Armored Fighting Vehicle (AFV) of the Second World War, with over 10,000 vehicles made. They were part of the Sturmartillerie (Assualt Artillery), a separate entity that was not part of the Panzer arm. The Sturmartillerie is often overlooked, despite its importance in the Wehrmacht’s tactics and its multiple roles as a ‘band-aid’ solution to fight the attrition problems that plagued the German military during the war.
The Sturmartillerie – Experience from the First World War
In order to overcome the deadlock created on the Western Front by trench warfare during World War I, two main approaches were chosen by the belligerents. In 1914, Jean-Baptiste Estienne, a French Colonel known as the Père des Chars (Eng: ‘Father of Tanks’), famously declared
“Messieurs, la victoire appartiendra dans cette guerre à celui des deux belligérants qui parviendra le premier à placer un canon de 75 sur une voiture capable de se mouvoir en tout terrain”
English translation: “Gentlemen, victory in this war will belong to that of the two belligerents which will be the first to place a 75 [mm] gun on a vehicle able to be driven on all-terrain”
His statement turned out to be true, as the French and British armies both started developing what would later be known as tanks in the following years of the war. These new weapons, all-terrain tracked armored vehicles carrying artillery pieces and machine guns, were supposed to progress at the pace of infantry while providing fire support.
The German Army, however, chose a completely different stance. They developed lightning infiltration tactics using specialized soldiers known as Sturmtruppen (Eng: ‘Stormtroopers’) operating independently from the high command in combination with intense artillery preparation and a creeping barrage. While these new tactics were certainly effective (similar theories were introduced by the Entente) and were of great influence on future infantry warfare, they were not sufficient to compensate for the major strategic disadvantages from which the German Empire suffered.
In 1916, the Infanterie-Geschütz-Batterien (Eng: Infantry Gun Batteries) were created to accompany the Sturmtruppen. They were armed with relatively light 75 mm mountain guns to allow direct fire support for the infantry. However, the arrival of the first tanks on the Western Front noticeably changed tactics. In response to this, the Oberste Heeresleitung (Eng: Supreme Army Command, or OHL) ordered the establishment of the Kahkampf Batterein (Eng: Close Support Batteries), which were tasked with anti-tank duties. Nonetheless, they were not able to effectively stop enemy armor.
Erich von Manstein’s Report and the Creation of the Sturmartillerie
The famous general (captain at the time) and decorated Great War veteran Erich von Manstein proposed, as early as 1935, the idea of an armored self-propelled gun to support the infantry. In 1936, he transmitted the following memorandum to the General der Artillerie (Eng: General of Artillery) and Chef des Generalstabes (Eng: Chief of General Staff) Ludwig Beck:
“To the Honourable Chef des Generalstabes (Chief of the General Staff).
Since the basic idea of creating the armored assault artillery has gained the approval of the Honourable Chef des Generalstabes, it is now necessary to establish the rules for tactical deployment along with the technical development of the Sturmartillerie. Otherwise, we will have a weapon at hand which no one will know how to use effectively.
Also, it should be noted that, at present, in many other countries there is the same confusion between the tasks of the Panzerwaffe (Army tanks) and of the Sturmartillerie (assault artillery infantry tanks)… On the one hand, tanks shall be used to break through the lines of the enemy infantry by making full use of their speed to destroy his artillery, reserve and command echelons. On the other hand, the tanks shall not lose touch with our infantry in order not to endanger the ground gained by their attack. Tank commanders tend to be of the opinion that the infantry has to keep pace with them, which is absolutely impossible. The infantry commanders want to keep at least one wave of tanks under their control. In doing so, the tanks would lose the advantage of speed and thus their main protection against the enemy artillery (anti-tank guns).
We wish to make it clear that the Panzerwaffe and the Sturmartillerie, although technically similar, are totally different weapons in regard to their tactical deployment.
I. Panzer units are mixed formations of several services, whose composition allows for autonomous combat and fulfillment of dedicated missions. Although a Panzer unit primarily relies on the tank, it does have motorized artillery to assist in the attack, motorized infantry to exploit any gained territory and other specialist troops under its command. Tank units detailed for independent combat missions will be committed for decisive attacks; where possible, these will be against the flank or rear of the enemy. Also, they can be assigned with the task of breaking through the enemy’s front-line defenses. In each case, they will have to attack independently. The tank unit’s ability to attack is significantly limited by the terrain… However, tank formations will not be successful in an attack against well-fortified enemy front-line positions. In contrast, their impact can be decisive if they hit the enemy at its weakest point, or if they surprise him before he can get ready for combat. Their commitment within the rapid forces (schnelle Division-Panzerdivision) appears to be most promising.
II. Panzer Brigades, pure tank formations, will be used at the points of main attack… In contrast to Panzerdivisions, they will not fight independently but will be joined to an infantry division attacking the main target.
III. The Sturmartillerie, equally whether it will be provided with tanks or self-propelled guns, is a support weapon of the standard infantry division. It will be used in the same manner as the escort batteries (the elite of the light artillery) in the last war. To enable the Sturmartillerie to conduct further duties, especially in defense, we demand that it has to be used to assist the divisional artillery. Thus, the option to conduct indirect fire, at a maximum range of seven kilometers, has to be permitted. Finally, the assault artillery will be an excellent weapon for defense against mobile anti-tank guns. The Sturmartillerie fights as escorting artillery within the framework of the infantry. It does not attack in the same way as the combat tank; it will not break through, but will push forward the infantry attack by rapidly eliminating the most dangerous targets. The Sturmartillerie will not fight in numbers as the tank unit will do, it will normally be deployed in platoon strength. The platoon or even a single assault gun will arrive suddenly, and then disappear just as quickly so as not to become a target for enemy artillery.
It follows from the above, that tactical training for the Sturmartillerie cannot be conducted by units of the Panzertruppe, but only by dedicated infantry units. A strict separation of these units is necessary, as their tactical principles are completely different.
To evaluate tactical methods, we request the establishment of an improved Sturmartillerie battery for trial purposes. To save time, this should happen promptly by bypassing all official channels. An allotment of six vehicles for this battery will be sufficient. Light tanks fitted with a dummy wooden superstructure would be suitable to achieve our purpose of developing tactical techniques.”
General der Infanterie Erich von Manstein memorandum addressed to Generalstab des Heeres Ludwig Beck dated 8th June, 1936. Translation from Anderson Thomas, Sturmartillerie: Spearhead of the Infantry, (London: Osprey Publishing, 2016), 11-16.
The key points of this report are that the Panzerwaffe (Eng: tank forces) had to be an independent arm, operating on its own in order to make use of its main advantages, speed and mobility, to break through the enemy line and exploit the rear. In consequence, the infantry lacked armored support and a new weapon thus had to be created. It had to be equipped with either tanks or self-propelled guns and would be tasked with accompanying the infantry while providing fire support, dealing with the toughest targets. It also had to be able to be used against anti-tank guns and to provide indirect fire along with the artillery. This new arm was called Sturmartillerie (Eng: assault artillery) by von Manstein. In a way, its role is close to a combination of those of tanks and of German escort artillery from World War I.
Despite a lack of support from a part of the high-ranking officers of the Heer (Eng: Army), including Guderian, who feared that the Sturmartillerie would overshadow the Panzerwaffe, Manstein gained the approval of Generaloberst (Eng: Colonel General) Werner von Fritsch, head of the Oberkommando des Heeres (Eng: High Command of the Army, or OHK). It was also decided that the Sturmartillerie would be placed under the control of the Heeresartillerie.
Development of the Sturmgeschütz
On 15th June, 1936, the Inspectorate IV (Eng: Ordnance Bureau) issued a document authorizing the Heereswaffenamt to design this new vehicle. It gave the specification for an armored artillery close-support weapon for infantry and anti-tank purposes.
1. The main armament of the vehicle must have a caliber of 7.5 cm.
2. The maximum vertical clearance of the gun must be of at least 30 degrees.
3. Optimal elevation of the gun must allow it to fire at a range of six kilometers.
4. The gun must have anti-tank capabilities and be able to penetrate every existing tank at a distance of 500 meters.
5. It must be fully armored with an open-top superstructure, and not have a turret. Frontal armor has to be impervious to a 2 cm shell at an angle of 60 degrees.
6. Total height must not exceed that of a standing man.
7. Other dimensions must take account of those of the biggest existing Panzer chassis.
8. Other imperatives will be established when new armaments and ammunition have been tested by the crews.
Source: Didier Laugier, Sturmartillerie Tome I, (Editions Heimdal, 2011), 8. Translated from French by the author
This text is the first detailed description of what would become the Sturmgeschütz, even though the open-top superstructure would be dropped in favor of a fully enclosed combat compartment in order to improve protection against ricochets, shrapnel and grenades in close combat situations.
Following this, in 1936, the Jüterbog Artillery Training Regiment started the development of standards of deployment and utilization of the new vehicle. The Heereswaffenamt awarded contracts for designing the machine. Daimler-Benz was tasked with the conception of the chassis and superstructure. Daimler-Benz was one of the most important tracked AFVs manufacturers and had developed the Panzer III, which would be the base of the Pak (Sfl.) (Panzerabwehrkanone for Anti-tank gun, and Selbstfahrlafette for Self-propelled gun), renamed Pz.Sfl.III (s.Pak) (Panzer Selbstfahrlafette III schwere Panzerabwehrkanone, or Armored Self-propelled carriage III heavy Anti-tank gun) during the year 1937, the prototype of the Sturmgeschütz. The specific model chosen was the Panzer III Ausf. B (Series 2.Z/W, chassis numbers 60201 to 60215) to assemble five 0-series s.Pak with soft-steel superstructures. Krupp, another major armament production company, was in charge of the gun. This was a low velocity, short-barreled, howitzer-like piece based on the 7,5 cm Kampfwagenkanone (Tank cannon, or KwK) 37 L/24. Its official name was 7,5 cm L/24 Sturmkanone (Assault cannon, or StuK), even though the actual barrel length was 23.5 calibers.
In September 1936, four Panzer III chassis were fitted with wooden superstructures. They were sent for trials in April and May 1937. By December 1937, three s.Pak were delivered by Daimler-Benz and successfully tested by the 7./Artillerie-Lehr-Regiment (7th battery of the artillery school regiment, motorized) in Jüterbog. The 7./Art.Lehr-Rgt. (mot.) (mot. for motorized) was therefore created and trials continued during the winter up to early 1938. Two others were probably completed and sent to the Panzer-Regiment I in Erfurt, but the surviving records are unclear. Due to delays, the operational guns were delivered in 1939, the five 0-series vehicles being listed on the Army inventory from September 1939, and completed Pz.Sfl.III (s.Pak) Versuchfahrzeuge (experimental vehicles) reported available by the Heereswaffenamt on 13 October 1939. They were never used in combat due to their soft-steel superstructure and hence used for training within the 7./Art.Lehr-Rgt. (mot.) up to 1941.
The base of the prototypes was the Panzer III Ausf. B chassis. The welded Panzerwanne (Eng: armor hull) was divided into three main parts: the rear engine compartment in the Heckraum (Eng: rear area), where the Motor (Eng: engine), along with 150 liters Kraftstoffbehälter (Eng: fuel tanks) and the Kühler (Eng: radiator) were located. In the Wannenmittelteil (Eng: middle hull section), the Zwischenwelle (Eng: drive shaft) went through a tunnel in the crew compartment, which was separated from the engine with a firewall. Finally, the Hauptkupplung (Eng: main clutch), Schaltgetriebe (Eng: transmission), Lenkgetriebe (Eng: steering unit), Bremsen (Eng: brakes) and Seitenvorgelege (Eng: final drive) ware in the foremost part of the hull, the Bugpanzer (Eng: forward armor compartment). Furthermore, a couple of 2-piece hatches for the crew were present on the glacis. On the lower hull, two hinged hatches allowed for access to the brakes and side drive shafts. The latter is a characteristic feature of the prototype and permits easy identification from the front.
The armor was made out of 153 kg/mm2 hardness (435 to 465 Brinell) RHA plates, effective against small arms fire from any angle.
Plate Thickness Angle to vertical Glacis 10 mm @ 87 degrees
Upper hull front 14.5 mm @ 50 degrees
Hull front 14.5 mm @ 20 degrees
Lower hull front 10 mm @ 68 degrees
Sides 14.,5 mm @ 0 degrees
Rear 14.5 mm @ 0 degrees
Belly 5 mm @ 90 degrees
Source: Thomas J. Lentz and Hillary Doyle, Panzer Tracts No.3-1, (Boyds MD, Panzer Tracts, 2006), 32.
Superstructure and Crew Duties
Bolted onto the hull was the superstructure, made of soft steel for the prototypes, making them unsuitable for actual combat. The vision ports and hatches visible on the few remaining photographs of the s.Pak are the following: a direct-vision visor made of a bulletproof glass block was on the left of the front plate, in front of the driver. On his left was another simpler slit. The gunner’s sight sat on the very top of the superstructure front, over the driver’s visor. Then, the roof of the crew compartment was made of thin steel, added in 1939 after an unspecified change in tactical requirements. At the request of the troops, a hatch was cut into the roof to permit the use of a panoramic sight for indirect fire.
The turretless arrangement of the armament allowed for a low profile (in comparison, the Panzer III Ausf. B was 43 cm taller), making the vehicle harder to hit. It also implied that the crew duties and positions were different from the Panzers: the Fahrer (Eng: driver), Richtkanonier (Eng: gunner), and Geschützführer (Eng: commander) sat in line on the left of the breech. In combat, the driver’s only role was to drive the vehicle and thus always had to be on the ready, waiting for the Commander’s orders. The Commander spotted potential targets and threats with his binoculars and ordered the Richtkanonier, who would then acquire the target and open fire when ordered to. Finally, the Ladekanonier-Funker reloaded the gun with the ammunition specified by the Commander’s order.
The main gun was a 7,5 cm StuK 37 L/24 (Sturmkanone, or Assault Gun), a very close variant of the early Panzer IV’s KwK 37 (Kampfwagenkanone, or Tank Gun), which was originally created for the Daimler-Benz Grosstraktor I. The barrel was actually 23.5 calibers long (176.25 cm), similar to a howitzer in regards to the caliber (fairly large for the time). It was conceived as a gun to support the infantry in its advance, hence the very low muzzle-velocity of around 300 to 450 m/s, depending on the ammunition. The only original shell was high-explosive, with a range of up to 6,000 meters in indirect fire. An anti-tank shell was developed in January 1936, the K.Gr.P (Kanonengranate Panzer). However, its performance was deemed unsatisfying and another project was started.
Engine and transmission
The vehicle was propelled by a Maybach HL108TR, V12, water-cooled 10.838-liter petrol/gasoline engine developing 250 hp at 2,800 rpm. It was the same as in the Panzer III Ausf. A through D and the Panzer IV Ausf. A. The power then went to the 5-speed SSG 75 transmission, and finally to the differential steering units in the front, connected to the final drives on both sides.
The somewhat complex running gear was made of two large leaf springs suspending four pairs of two Laufrollen (Eng: roadwheels) on each side. At the front, the Triebräder (Eng: drive sprockets) pulled the 360 mm wide Gleisketten (Eng: tracks), in contact with the ground for 3.224 m, over the three Stützrollen (Eng: return rollers). Track tension was taken care of by the Leitrad (Eng: idler wheel) at the back.
As they were not suitable for combat due to their mild steel construction, the 4 prototypes were used as training vehicles in the Sturmartillerie Schule Jüterborg (Eng : Assault Gun School Jüterborg) up until 1941. Their exact fate after that is unknown, but they were most probably scrapped. However, the Sturmgeschütz concept surely did not die. It underwent its baptism of fire in 1940 during the Battle of France, with only 30 StuG III Ausf. A. It only really started being used on a large scale, and to great effect, when Operation Barbarossa was launched on 22nd June, 1941. The StuG became a central element of the Army with over 10,000 vehicles produced in total. Its role evolved from infantry support to anti-tank tasks (every unit produced from March 1942 onward could act as a tank destroyer armed with a high-velocity gun) with excellent results.
5.38 m x 2.92 m x 1.95 m
(17ft 8in x 9ft 7in x 6ft 5in)
4 (driver, commander, gunner, loader)
7.5 cm Sturmkanone (StuK.) L/24 (37-44 shells)
Armor – Hull front
50 mm rolled homogeneous armor (RHA)
Armor – Hull sides
30 mm rolled homogeneous armor (RHA)
Armor – Superstruture
Maybach HL108TR V12, water-cooled 10.838-liter petrol/gasoline 250 hp engine
An understanding of what is a very complicated picture of German heavy tank development in WW2 is incomplete without consideration of the program by Krupp as a rival design to the Maus from Dr. Porsche. Although Porsche was the overall design lead for the Maus (Typ 205), he was not responsible for the turret or armor, which were Krupp projects. Krupp had some very different ideas to Porsche on how a heavy tank should look and be protected and, whilst they worked together on the Maus, they were also rivals over whose design would better suit the needs of the military and get into production. Dr. Porsche’s design would eventually weigh-in at around 200 tonnes, but Krupp’s was a smaller vehicle, with removable side armor and nearly 70 tonnes lighter. Whilst Dr. Porsche’s design would eventually win out over Krupp’s, the Krupp design is arguably a better design and far more practical for production, as it reused off-the-shelf components being used in the Tiger II and Panther.
The vehicle which would later form the foundation of the E100 started life in a conversation about the 150-tonne tank ‘Maeuschen’ project (another rival to the Maus from Dr. Porsche) which took place on 11th September 1942. Here, the representative from Krupp (Obering. Woelfert) expressed that Krupp was interested in making its own conceptual rival design for a 150-tonne vehicle. In order to do this though, they needed information on engines and transmissions.
Promised that a 1,000 to 1,200 hp version of the HL 230 P30 (this would be known as the HL 234) was possible by supercharging*, Krupp’s idea was delayed for four weeks to a meeting of the Panzerkommission in 17th November 1942. This gave Krupp 4 weeks to develop their own rival 150-tonne Panzer concept. At that meeting, Krupp presented a conceptual design for their 150-tonne vehicle, but it was short of a full proposal and a decision on whether to accept Krupp’s design or the one from Porsche for the 150-tonne class Panzer was delayed after the 17th November meeting until the end of the year. This would allow Krupp a little more time to submit a finished proposal for consideration. Just for added confusion, the tank in question (for which no design had been set or approved) was also being known as the Maus even though it is very different from the well-known Porsche-Maus. For clarity, in this article, the ‘Maus’ designation will only be used for the Porsche-Maus unless otherwise stated. (*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)
The First Design
The first design for this new 150-tonne vehicle submitted by Krupp had to meet a set of requirements and one of those was ground pressure. Originally, a maximum ground pressure of 0.8 kg/cm2 was permitted for the vehicle by the Panzerkommission (the body with overall responsibility for tank design and approval). This had, in turn, dictated to Krupp the layout of their design and had led to the adoption of a central turret (engine-rear) on the vehicle. When, shortly afterward, this ground pressure allowance was increased, Krupp changed their design to switch to a rear-mounted turret design (engine-forward). Although this had brought the ground pressure up to slightly exceed the new maximum, some additional minor changes managed to squeeze this design just within their criteria.
Original Krupp concepts November to December 1942
Engine Forward/Turret Rear*
Engine Rear/Turret Central
Engine Forward/Turret Rear
Engine Rear/Turret Central
est. 3,700 mm
Tiger I type (Henschel)
Tiger I type (Henschel)
Abandoned due to excessive ground pressure unable to meet 0.8 kg/cm2 maximum demanded.
Design meets ground pressure requirement.
Original idea readopted due to new ground pressure allowance of 1.1 to 1.2 kg/cm2.
* Arrangement based on the reading of the ground pressure figures.
Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.
Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.
** By the end of November 1942, this maximum possible figure was given as 800 hp instead, although 700 hp was the official rating for the HL 230. A modified version producing 900 to 1,100 hp was in development as the HL 234 using high-pressure fuel injection (Bosch) and superchargers.
It was the outline of a vehicle in drawing W1671 which met with approval, although the weight of the vehicle was already expected to grow from 150 tonnes to 155 tonnes, and by the end of November 1942 to 170 tonnes. Further, although it was to use the same drive-train as the Henschel Tiger (including the same engine), the HL 230, which had been promised as being able to deliver 1,000 hp, was now estimated to be able to provide just 800 hp. However, in his 1945 Allied intelligence debriefing interview, Von Heydekampf was clear that even supercharged this engine could only achieve 900 hp.
The next major step in this vehicle’s development was a meeting with Oberbaurat Kurt Kniepkamp on 1st December 1942. Here, the 150 tonne (now 170 tonne) vehicle being designed by Krupp and being referred to as ‘Maus’ was discussed. It is at this meeting that the two styles of tank Krupp was looking at were made clear. The first, with the turret at the back and the engine in the front, had a high ground pressure and was 3.7 m wide. This layout produced a much higher ground pressure than was achieved by putting the engine behind the turret and presumably offered a greater degree of protection to account for why it was otherwise larger and heavier. The alternative layout offered a much-reduced ground pressure and a narrower hull with the engine at the back and turret in the middle. The side armor though could be considered to be inferior to the other design as, apart from the thickness and shape of the armor, on this version, it had to be removable. This ‘removability’ was created by a series of hollow armored boxes (Raupenkaesten) which could be lifted on or off the hull by means of a small crane. Their removal allowed the vehicle width to be reduced to 3.07 m, meaning it would fit within the standard German rail gauge. It is not that the first design was unshippable by rail though, just that it would greatly impede other traffic on the railways as it would mean that no traffic could pass in the opposing direction. The advantages of using Raupenkaesten were obvious but it came at the price of using a technology that had not been produced before or tested.
This layout, albeit it a little unusual, met with approval from Wa Pruf 6 except that the drive-train was now going to be changed to share a commonality with Henschel’s Tiger II instead of the Tiger I. This would improve spares, support, and production, but meant that the lull and ground-contact length of track had to be lengthened slightly.
At the same time as forcing the tank to get longer and have a longer ground-contact length (to keep ground pressure constant on a bigger vehicle) by requiring a new drivetrain, the contrary was also proposed. Namely, it was proposed to actually shorten the ground contact length for the track, and instead to adopt a wider track, bringing the width of the vehicle to 3.27 m, the safe limit of width to stay within rail limits for opposing traffic on the rails. This option though also meant reducing some weight too and that meant reducing some of the armor being considered, and not by a little. Instead of the 150-tonne tank project which was currently weighing in at 170-tonnes before being made longer, the proposed vehicle was going to have to have nearly 50 tonnes taken off to get to 130 tonnes. A loss of some armor was considered an acceptable sacrifice to be made in order to avoid having to design and build a whole new heavy-weight steering system. Now, at 130-tonnes, it could use the same Lenkgetriebe L801 system from the Tiger II and still achieve 22 to 25 km/h, even with the Maybach HL 230 (HL 234) only being able to deliver 700 hp of the 1,000 hp originally promised.
Evolution of design W1674 1st December 1942
Krupp Engine Rear / Turret Central layout
Wa Pruf 6 suggestions (Longer 170-tonne version)
Wa Pruf 6 suggestions (Longer 130-tonne version)*
~1.1 kg / cm2
> 170 tonnes
Maybach HL 234
Maybach HL 234
Maybach HL 230
Power to Weight Ratio
22 to 25 km/h
New Krupp heavy-weight design (170-tonne)
New Krupp heavy-weight design (170-tonne)
Tiger I type (Henschel)
Tiger II type (Henschel)
Tiger II type (Henschel)
Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.
* Known thereafter as ‘Maeuschen 130’
** Same as used on the Tiger II
+Based on the E100 hull being 8.733 m long and that the E100 hull comes from this project, the 130-tonne ‘lengthened’ hull is approximately the same length overall.
++ Modified HL 230 motor using Bosch fuel injection and supercharging known as the HL 234
Wa Pruf 6’s suggestions appear to have saved Krupp from descending ever more rapidly into a vicious downward spiral of the weight going up and up. Not only did Wa Pruf 6 help to rationalize the design by removing the need for a new steering system and the elusive engine of 1,000 hp or higher, but they had also effectively dropped plans for a 150-tonne class Panzer in the process. Their new concept was to have this vehicle weigh-in at around 130 tonnes and Krupp was duly instructed to redraw W1674 to accommodate the changes needed to make this lighter tank with a lot of parts-commonality with the Tiger II. This was ready by the start of December 1942.
15 cm L/37 and 7.5 cm L/24
83.4 tonnes (52 tonnes bare hull)
Maybach HL 230 700 hp
Max. possible 22.5 km/h, limited by steering system to 21.5 km/h*
Tiger II (Henschel)
* Possible to increase this to 23 km/h but this would overstress the steering system by 12%
On top of the already significant weight reduction from 170 tonnes to ‘just’ 130 tonnes, the vehicle still needed to shed some weight. Here, the problem was the turret. As a percentage of the overall vehicle weight, it was simply out of proportion to the weight of the hull and a heavy turret produced additional problems with the means of traversing and balancing it. Wa Pruf 6 were therefore interested in a new design of turret with a further reduction in weight (and thereby armor protection). No figures were provided as no work appears to have been done in this regard but, assuming that a figure closer to the 20% of vehicle weight as represented by the Tiger, this would give a turret closer to 25 to 30 tonnes.
Hull and Turret Weight Percentage Comparisons
130-tonne Panzer with lightened turret per Wa Pruf 6
130-tonne Panzer with lightened turret per Wa Pruf 6
Hull as a % of overall weight
Turret as a % of overall weight**
* Estimates for the purposes of illustrative analysis ONLY
** For comparative purposes, the Serienturm on the Tiger II represented 21.9 % of the vehicle’s overall weight.
A couple more design changes that came out of this meeting between Krupp and Wa Pruf 6 showed that this new 130-tonne vehicle could not use everything from the Tiger II but was, on the whole, satisfactory for further development (especially if the turret could be further lightened).
There were two mutually supporting desires for getting this design into production as soon as possible. First, Wa Pruf 6 wanted this heavy tank available as soon as possible, and secondly, Krupp wanted to get the vehicle ready before Porsche’s Maus design (even though he was stating that it should be developed in parallel with Porsche’s design). Moving to ‘off-the-shelf’ components for the design, such as adopting elements from the Tiger II and Panther, would assist in this work, reducing the time taken for design and testing. When Krupp’s representatives met with a representative of the Munitions Ministry on 8th December, they were in agreement with this plan. The 130-tonne Maeuschen was therefore half-way to approval and was only waiting on final approval from Reichsminister Albert Speer to get the go-ahead, representing one of the fastest design processes for a heavy tank which can be identified, just 3 months from concept to design and approval.
Such a success though lasted just one week, with information coming on 15th December that Speer had not approved production. The 130-tonne Panzer design from Krupp was canceled. Only Dr. Porsche’s Maus design would continue as a decision on that vehicle had already been made by Hitler on 2nd December.
In a last effort to get production authorized, Krupp’s representatives met with Wa Pruf 6 on 17th December 1942 to seek answers as to why their design had been stopped. Wa Pruf 6 reiterated that they liked the design of this vehicle but that, as the Porsche-design had already been authorized, Krupp’s project had to stop. Bearing in mind their experience with two rival Tiger tank projects, they were anxious not to repeat the same situation a second time.
Krupp was not to be dissuaded so easily and went to meet directly with Speer, seeking this contract. At this time, the project was being known as the 130-tonne Tiger-Maus. It was exactly that, a hybrid from the Maeuschen program using Tiger components and weighing 130-tonnes, and at the same time confirming that the plans to reduce the turret weight below the 45.5-tonne design had not been progressed with (as the overall weight would be in the region of 110 tonnes). Production of the tank as a decision was reconsidered and the question of approval was put to Hitler on 5th January 1943. Then, Hitler again accepted the Porsche design and the Krupp plan was dead.
Right from day one in its life, this project required a powerful engine to propel its 150-tonne bulk. At that 11th September 1942 meeting where Krupp’s representative had outlined nothing more than the company’s desire to be allowed to develop their own concept in this class, they were informed that Maybach was promising to be able to deliver a 1,000 hp version of their HL 230 P30 engine*, the HL 234.
This engine, was, in fact, a variant of their HL 230 (HL 234) which was modified with the removal of the turbocharger, replacing it with a supercharger and modifications to the fuel system to deliver it at a higher pressure (Bosch fuel injection). It would also have to run on ‘special’ fuel.
Using even a modified HL 230 P30 (HL 234) would make this new tank much easier to maintain and sustain in the field and in production, as that engine was already in use. This was not the only area in which commonality of parts was considered. The next area was in the drive-train. Rather than adopting a bespoke system for this tank, it would, instead, opt for using components from the Henshel-Tiger, although, with a power to weight ratio of just 4.5 hp/ton, this tank would be able to achieve just 20 km/h. One thing which would differ from the Henschel-Tiger’s drivetrain though was the steering system (Lenkgetriebe). If the design had retained the steering unit from Henschel as used on the Tiger, it would be limited to just 13 km/h so a brand new system was needed allowing for speeds up to 25 km/h. This was undergoing development by Zahnradfabrik, Maybach, A.E.G., and Voith working together on a new heavy-weight hydromechanical transmission and steering system (hydro-mechanisches schalt und lenkgetreibe).
Unlike the Maus, which adopted an electrical transmission, this design from Krupp was to go for a more conventional transmission (Schaltgetriebe) although there were several to consider. Krupp’s preference was for a newly designed unit either mechanical or electro-mechanical from Zahnradfabrik which would have to be able to deal with up to 1,200 hp and a top speed of 30 km/h from a tank weighing 170 tonnes.
Transmissions and Gearboxes considered for
Krupp’s 150-tonne (170 tonnes) Panzer
Zahnradfabrik AK 7-200
7-speed transmission also suggested for the Tiger II, November 1942
Zahnradfabrik Elektromagnetisches Getriebe 12 EV 170
Installed in a Tiger 1 for testing, November 1942
Brand new design in development November 1942.
Zahnradfabrik Elektromagnetisches Getriebe
Brand new design in development November 1942.
Possibly the same 10-speed electro-magnetic transmission suggested for the Tiger II, October 1942
OG 40 20 16
B type box used in Tiger II
Brand new design in development November 1942.
Favoured by Wa Pruf 6
This is possibly the 8-speed OG 40 16 36 suggested for the Tiger II October 1942
On 1st December 1942, Wa Pruf 6 approved Krupp’s design with the proviso that the drivetrain elements were changed (apart from the improved steering system) to share commonality with those of the Tiger II instead of the Tiger I. This meant making the hull a little longer.
Following calculations in December on the new steering system, a 130-tonne basis for the tank was adopted instead of the 170-tonnes it had grown to, an Olvar Schaltgetriebe transmission was combined with the L801 steering system (Lenkgetriebe) (from the Tiger II), and Maybach HL 230 engine. The design work, which included the use of thirty-two 800 mm diameter road wheels (16 per side) produced a design superior to the Porsche-Maus:
Porsche-Maus vs Krupp 130-tonne Maeuschen December 1942
Krupp 130-tonne Maeuschen
Out of gauge*
170 – 180 tonnes**
Suspension protected by armor
* The out of gauge issue related to the width which as a result of manufacturing tolerances made the Maus too wide. This was later rectified and a dedicated spezialtransportwagen designed to move it around to stay within gauge.
** The Maus would get heavier
Green (Better), Red (Worse), Blue (Neutral)
Although, as of the start of December 1942, the 130-tonne Maeuschen would be hampered by the limits of the Maybach 700 hp engine, it had delivered the advantage of making the design much simpler than the alternative plan which required a whole new steering system. The reduction in weight from 170-tonnes to 130-tonnes had delivered the required improvements over the Maus, with the problem being a loss in armor protection, although the protection was still considered to be acceptable.
The improved-performance Maybach was promised to be ready and available from September 1943 onwards, meaning there would be 9 months or so in which to finish the rest of the design work. This is despite the promise of that 1,000 hp performance, and even 1,100 hp performance from the engine never being reached* and any such increase in power would also require a new steering system and final drive to cope with the stress.
One key element of the 130-tonne Tiger Maus design would be the design of the turret. It is commonly assumed online that the 130-tonne Tiger-Maus would use the Maus II/E100 style turret with the flat front, but this is not correct. The design for that turret started in March 1944, over a year after the Tiger-Maus had been canceled as an idea in favor of the Porsche-Maus. This is confirmed by the fact that when, in 1945, the Allies captured Adler’s works, they found many files had been burned. Under their supervision, drawing 021A38300 was redrawn from the burnt scraps of the original.
That drawing showed the original Maus-shaped turret from the Typ 205 dating back to the end of December 1942/January 1943 rather than the Maus II turm which was the turret intended. The reason for this is fairly clear, the Adler workers were simply working off the left-overs from the Tiger-Maus program and this was the Krupp turret shown on that hull. This accounts for why the turret retains so many early Maus features such as the side viewports, rear crew hatch, and the lack of coincidence rangefinder. That turret weighed in excess of 50 tonnes and was abandoned long before the E100 started. It was later found that the E100 hull (with its lighter suspension), in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work on that tank down to just 35 tonnes. The turret for the 130-tonne Tiger Maus, therefore, is essentially the same as the one depicted on the Typ 205 with the early-Maus features, such as the side view-ports and crew escape hatch in the turret rear.
The 130-tonne Tiger-Maus cannot, in fact, even be suggested to mount the Maus turret. The design of the Tiger-Maus ended on 3rd January and design work amending the turret design shown on the Typ 205 did not begin until 12th January. Certainly, had the Tiger-Maus been selected over the Porsche-Maus, the turret would have been modified, but the Tiger-Maus was not selected and therefore did not receive these considerations. The fact that, over a year later, the Adler workers were working from designs of the Tiger-Maus from Krupp (redrawn with new suspension), which still had this pre-January 1943 Maus-style turret, simply confirms this.
Although Krupp’s design had been better in some ways than the rival Maus design from Dr. Porsche, it had not met with favor from Hitler. Porsche’s design had been approved for production on 3rd January 1943 and the 130-tonne Krupp Tiger-Maus was not. At the time, the project was over, but the idea of another heavy tank in place of the Porsche-Maus was not. Ernst Kniekampf (Panzer Kommission) would, without informing Krupp, give their design over to the firm of Adler to complete a simple experimental version. That was part of his attempts to develop a newly rationalized program of German tank development with vehicles based on common components and delineated by weight class and roles. That work was conducted in secret and Krupp were not even aware of this until the following spring, over a year after being officially turned down. The 130-tonne Tiger-Maus was resurrected only as a 100-tonne experimental chassis, though there were changes made to the original design as well as to how it would look. The Tiger-Maus was already dead, but the E100 which was to follow it was actually built, proving that Krupp’s design did, after all, have substantial merit and that perhaps it was it, and not the Porsche-Maus, which should have been selected for production even if both tanks were a dead end for a country struggling with the problems of mass manufacturing and how to field increasingly heavy tanks.
Specifications 130-tonne Tiger-Maus
estimated 11.073 m long, 3.27 m wide, est. 3.375 m high
Total weight, battle ready
estimated 128.9 tonnes (126.8 tons)
6 (Commander, Driver, Gunner, Loader x 2, Radio Operator)
15 cm L/37
7.5 cm L/24
7.92 mm M.G.34 or M.G.42 machine gun
Maybach HL 234 producing 1,000 to 1,100 hp (900 hp actually achieved)
The Maus is possibly one of the most recognizable tanks ever made, despite only two hulls ever being finished. The entire history of the development, design, testing, and construction of the heaviest tank ever built is a long and convoluted one stretching from early concepts in 1941 to a finished and operational vehicle in 1945. At nearly 200 tonnes, the Maus was an enormous machine, more than double the weight of any other tank and, as such, is often the butt of scorn for being too heavy or a waste of resources. Such criticism though is belied by the technical achievement in making this machine move under its own power and producing a vehicle with armor almost beyond the ability of any Allied tank-mounted weapon to penetrate. Of course, no tank can operate independently and wars are not fought and won by single tanks, so ideas of one-on-one tank comparisons between the Maus and something like a Sherman are not only fruitless and pointless but also completely disingenuous. Certainly, the Maus was not a military success, it saw no combat and was indeed the recipient of a lot of time and effort which could have been spent elsewhere in the German war effort. It may come as a surprise, therefore, that, despite just two hulls and one turret for the Maus being finished, it was proposed to use it as a base for another vehicle. Almost every German tank from the Panzer I onwards served as either a platform for an anti-tank gun or self-propelled gun. These vehicles were combat proven to be effective and were easier and cheaper to make than turreted tanks. It should be no surprise, therefore, that even the Maus project touched on this area at one point. The story of this improbable idea dates to May 1944.
An ever-popular topic with model and game companies are the ‘what-ifs’ of German tank evolution in WW2 and, with few exceptions, most tanks received a tank-destroyer version. That is that the hulls were repurposed for the mounting of a fixed superstructure on top with a forward-facing gun. The Maus too followed this direction in a very short-lived concept from May 1944.
The Maus project had actually already been canceled in November 1943 following severe production delays thanks to the Allied bombing of Krupp’s factory in August 1943. Despite this, the idea of restarting the Maus production program was being pushed by Dr. Porsche in March 1944 and he continued to press for this through the summer of 1944. Whilst the Maus program was finally re-killed in July 1944 with an order to scrap the remaining unfinished hulls (hulls 3 to 6), there had been a meeting held on 9th May 1944 which had offered some prospect of continuing Maus-related work. At that meeting, representatives from Porsche and Krupp met to discuss a new heavy type of self-propelled gun. This design was to revolve around the possible mounting of a 15 cm L/63 gun or the 17 cm L/53 gun on a heavily armored chassis to create a new heavy Sturmpanzer based on the Maus. Krupp, as before, would have responsibility for the production of the armor and fabrication of the hulls (obviously not the turrets as this would be a casemate-type vehicle), with Porsche being the design lead for the vehicle. Together, Porsche and Krupp had been two elements in the trio of firms that produced the Maus, the third being Alkett, which had responsibility for the assembly of the Maus. It is a fair assumption, therefore, that had this Maus-based vehicle ever gone ahead, Alkett would once more have been responsible for assembly. The entire vehicle-concept was intended as a competitor to the similar idea based upon the hull of the E100 being developed at that time by the rival firm of Adler.
Post 9th May 1944
The idea might, in hindsight, seem impractical or even absurd to the casual observer, but this was not the case for Porsche and Krupp. They had met on 9th May and clearly, from that meeting, it was felt that this idea of using Maus hulls for this type of vehicle was a viable prospect. So much so in fact, that a follow-up meeting was held on 17th May to discuss what the new superstructure (casemate) for this Maus-hulled Sturmgescheutz would look like. This vehicle would therefore be known as (depending on which gun was mounted) either the 15 or 17 cm Sturmgeschütz auf Mausfahrzeug.
It was during this meeting that Krupp was adamant that they only wanted to use the 15 cm L/63 gun, presumably because of the weight and size of the 17 cm L/53 and its ammunition. Krupp was obviously being very serious about the significant challenge to fit this enormous gun onto an admittedly enormous chassis, but one which was already absolutely crammed full of automotive components and where any available space inside the lower hull was used for ammunition stowage.
However, Dr. Porsche, it seems, was slightly less realistic and completely ignored the enormous size of the machine once more. Just as he had done with the original Maus turret development, he proposed a secondary turret mounting a 3 cm anti-aircraft gun (3 cm Flak-Turm) to provide air-defense for the vehicle. This idea was immediately discounted, as the vehicle would be escorted by air-defense vehicles, would be out-of-gauge for travel by rail, and would interfere with the breech of the main gun.
That idea was not accepted and nor was the Porsche/Krupp plan for using the Maus hull design either. The hull was too high and too heavy compared to the E100 hull. Instead, Krupp was contracted to produce a model for a 17 cm gun-carrying design based on the E100 chassis instead. With that contract, issued on 28th May 1944, there was literally no reason for Krupp to continue working on a Maus proposal and the idea was dead.
As it turned out, the E100-based idea did not fare much better either. If there were any lingering doubts on the matter, both concepts were over by the middle of the year after a meeting with General Guderian where he was shown the models. Guderian already disliked the Maus and had tried to kill that project by canceling all serial production, so the likelihood that he would agree to a new and heavier vehicle based upon one he already disliked was exceptionally unlikely. As could be expected, no further discussions or work on the project took place after this.
In total, therefore, this most unlikely of projects lasted from 9th May to no later than 28th May, 19 days in which to consider what a poor design choice it would be regardless of any consideration of what purpose this enormous vehicle was going to be put to. No drawings of the ideas from Krupp and Porsche survive for this project, if indeed anything more than a sketch was even prepared. What such a machine could have looked like is one of those essentially fruitless exercises in ‘what ifs’ so beloved by computer games and model makers but, aside from shamelessly exploiting an interest in ‘exotic’ German armor for commercial purposes, there are real questions to be asked of what any design could have looked like.
The primary consideration over what a 15/17 cm Sturmgeschütz auf Mausfahrzeug would have looked like starts with the hull. Obviously, the hull selected was that of the Maus and, given the incredibly tight space in which to operate the mechanisms of the hull, there appears to be no prospect for moving the engine, generators, or motor components around inside the hull. On top of this, any rearrangement of drive components etcetera would change the shape of the hull and the armor layout etcetera to such an extent that this vehicle’s hull would be very different from that of the Maus. Given that the name is ‘15/17 cm Sturmgeschütz auf Mausfahrzeug’ – an assault gun based on a Maus hull, any interpretation of the layout must begin with a look at the Maus hull.
The Maus hull should be considered as existing in four sections. Right at the front, in the center, is the driver’s compartment housing the driver and radio operator under a single ovaloid hatch. Behind this was a large section for the engine and air intakes for cooling the engine and electric motors. It was on this section that three large shell deflectors were fitted to protect the grills. Behind the engine section is the turret area defined by four plates cut and welded together to form the opening for the turret basket and ring. More automotive elements were below this area.
Finally, at the back, there was another section of grilles out of which warm, spent air was forced out having been drawn through the vehicle to cool the engine.
What this layout means is that there could only be one place to mount a casemate for the gun for the vehicle, the area previously occupied for the turret. Removal of the 60 mm hull roof armor and turret ring at this point would provide the space for the casemate, although this would mean that the gun was mounted behind the engine. This was not generally favored for a vehicle as it caused numerous problems, such as access to the engine area for maintenance. It would also mean a relatively small amount of depression would be available. Nonetheless, there was simply nowhere else it could go without a complete redesign of the hull. If the casemate was limited to just the space between the vents on the hull it would also not be long enough for the enormous gun breech. Although no drawings of this idea survive it is perhaps logical to consider that a realistic solution to expelling this air could have been found in a similar manner to that on the Elefant/Ferdinand tank destroyer – by venting air out of the rear of the hull plate under the fighting chamber but without the drawings or a description this is purely speculative.
The next question which would arise would be the armor on the vehicle and this is easier to resolve. The armor for the Maus hull is already well documented and knowing where the casemate would have to go would create a casemate behind the engine. The face of this casemate would have to match or exceed the armor value of the front of the hull which was 205 mm angled back at 55 deg. The Maus hull was designed as 200 mm but, due to manufacturing tolerances, was measured as 205 mm in a post-war British examination. Assuming the same basis was to match 200 mm at 55 degrees, this would mean an effective armor of 283 mm line-of-sight thickness.
Assuming the front of the Maus-casemate would match that of the Jagdtiger (probably the best analog of this general design concept – 250 mm at 15 degrees = 259 mm) it would require a front plate sloping back at about 15 degrees with about 273 mm of thickness, or, at 30 degrees a plate 245 mm thick. On the Jagdtiger, 250 mm at 15 degrees was already more than adequate for the task. It is perhaps more realistic to assume a rough equivalency to that layout but with a front sloped perhaps more like adopted and favored by Krupp for the Maus II and E100 turrets.
Regardless of whether or not the actual armor had ever even been fleshed out on paper or not, the front of the casemate would have to be substantially well protected, just as would the sides. The Maus hull sides, in order to meet rail gauge requirements, were 173 mm thick and vertical but the turret sides for the 15/17 cm Sturmgeschütz auf Mausfahrzeug could not be vertical as this would prevent it from fitting through rail tunnels. Indeed, the Maus had to have a special railcar designed for it to not only take the weight, but to also lower the height when being shipped by train so it could fit through a tunnel. As the Maus with a turret already was at the limits of the German rail gauge, there is no space for the casemate on top of a Maus hull to get either wider or taller, so therefore must have followed roughly the same dimensions and angles as the turret. That would mean sides sloping towards the roof at an angle of about 30 degrees, presumably at least the same thickness as the lower sides (173 mm) and possibly as thick as the Maus turret sides were (200 mm). The rear of the casemate is more complicated, as there is more room to create an overhang over those rear air exhausts. Armor could be reasonably assumed to be in line with the Maus, as would the roof. The shape and size of the casemate are simply dictated by the limitations of the hull already crammed with the drivetrain, and by the fixed restrictions imposed by the rail gauge. The biggest issue for the design was not the shape or position of the casemate, but the fitting of the gun.
There were only two guns in consideration for the 15/17 cm Sturmgeschütz auf Mausfahrzeug and, as the name makes clear, these were a 15 cm or 17 cm gun. Krupp was adamant that he would do anything to avoid having to use the 17 cm gun. That 17 cm Sturmkanone (Stuk – assault gun) was 53 calibers long (L/53), longer than the 17 cm Kanone 18, and is often referenced online as being the same gun as planned for the Grille 17 (Geschützwagen Tiger für 17 cm Kanone 17 (Sf.)), although that gun was an L/50 rather than the L/53 (3 calibers / 51 cm shorter) optioned for this design. The 17 cm Stuk. L/53 existed only on paper as of 22nd March 1944.
It is likely that the reason for Krupp’s desire to avoid the 17 cm gun was the sheer size of it as well as the weight, over 7 tonnes, the length (over 9 meters), enormous breech, and very large and heavy ammunition. Mounting and balancing such a heavy gun was no small task and that is before considerations over the speed of loading it in the tight confines inside the casemate, a task likely to require at least two loaders.
That 17 cm gun though, like the 15 cm L/63, had to meet a specific requirement set in April 1944 by General Guderian (Inspector General of Panzer troops) to be able to defeat up to 200 mm of armor at 4,000 meters, leaving no doubt as to a key intended purpose of this vehicle – the destruction of increasingly well-armored enemy tanks at long range. The focus was on this ‘smaller’ gun, as work had already been done on a 15 cm gun mount for the Maus when that gun was considered more suitable for the delivery of a heavy high explosive round to destroy concrete gun emplacements as well as for taking on enemy tanks with armor-piercing ammunition. The 15 cm Stuk L/63 would also be a very large gun but was at least manageable. Both the E100 and Maus were planned to be able to mount a 15 cm, although the longest 15 cm gun contemplated for the Maus turm was the 15 cm KwK. L/40. It is likely that neither of the planned guns, either the 17 cm L/53 or the 15 cm L/63, were actually made and so obtaining data on their performance and ammunition can only be inferred from scraps of available data.
The gun mounting for that 15 cm gun in the Maus turm was internal, that is the trunnions for the gun were behind the front armor of the turret. That turret had a serious potential flaw which was highlighted by Krupp, as the bottom half curved downwards and risked deflecting an incoming shell into the roof. This was highlighted in May 1943 by Porsche and the result was that, by the time of the Maus II turret in March 1944, it was to be replaced with a new, slope-fronted turret made from a single flat plate. That design change would obviate the problem of a deflected shot hitting the hull roof but it had also meant a larger turret ring and that the gun’s trunnions had to be moved onto the outer-face of the turret to cope with the new shape. That new gun mounting on the outside on the turret face would be repeated for the E100 turret and here, importantly, would have to be repeated for the face of the 15/17 cm Sturmgeschütz auf Mausfahrzeug.
Once it can be logically established that the casemate would follow a certain shape, and that, in order to mount the gun on that casemate, it had to follow the same design process, then other parts of what the 15/17 cm Sturmgeschütz auf Mausfahrzeug could have looked can be speculated. Firstly, the secondary weapon. The Maus, Maus II, and E100 all had a primary and a secondary gun, such as the 12.8 cm paired with a 7.5 cm, but for the 15/17 cm Sturmgeschütz auf Mausfahrzeug no such arrangement was either needed nor suggested. The Maus had its two guns mounted side by side, which caused enormous problems with space in the turret. One improvement on the Maus II was to stack these guns on top of each other, freeing up internal space albeit at the price of some gun depression.
With no secondary gun needed, the 15/17 cm Sturmgeschütz auf Mausfahrzeug could avoid both of those issues and would also have more space for ammunition which was significantly larger than the already large 12.8 cm shells on the Maus. Next, a machine gun. Both Maus and Maus II were to use a machine gun (MG.34 or MG.42) mounted on the left of the turret face and, although there is no mention of this weapon, it would appear extremely unlikely that one would not be considered for this vehicle too.
Finally, the range finder. The Maus was fitted with a rangefinder and this was improved with the Maus II by means of 2.1 m wide coincidence-type rangefinder across the roof of the turret. Later, this was to be further improved with a slightly narrower (1.9 to 2 m wide) rangefinder of the same type. There is no doubt that the 15/17 cm Sturmgeschütz auf Mausfahrzeug would have to have a rangefinder, especially given the 4,000 m ranges at which it was going to be expected to deliver accurate fire against enemy tanks and structures. Given the common positioning of the rangefinder on the Maus II and E100, it is reasonable to assume a similar arrangement of a similar size/type of rangefinder would also have to have been used on the 15/17 cm Sturmgeschütz auf Mausfahrzeug.
Obviously, it is not possible to determine exactly how many crew would have worked a vehicle that never even made it to the drawing board, but there is also scope here to consider the number of men needed to operate such a machine. The Maus, for example, required a crew of 6 men. A driver and radio operator in the front of the hull, followed by a commander, gunner, and two loaders.
Based upon the Maus hull, the 15/17 cm Sturmgeschütz auf Mausfahrzeug would be unlikely to have changed the front crew section, as this was fixed into the hull. That would mean the driver and front radio operator would likely be the same. In the casemate, where the turret would previously have sat, the rest of the crew would be situated. This would have to include a commander, and a gunner making for at least 4 crew at a minimum. The gun obviously also required loading and thus, at least one loader would be needed. On the Maus, a second loader was retained as it had two guns and the shells were heavy and hauling them around would tire a single loader. Whilst the 15/17 cm Sturmgeschütz auf Mausfahrzeug likely had no secondary gun to be served by a loader, the 15 or 17 cm shells were huge and heavy. A unitary (one piece) 15 cm shell, for example, weighed in excess of 34 kg and possibly over 40 kg depending on what ammunition might have been chosen. Moving those shells around would rapidly exhaust a single loader, so a second loader is almost essential just to make the machine viable. This would be aside from any loading assist systems which might have been considered, which theoretically could have reduced the crew to just a single loader.
Although the idea of the 15 cm or 17 cm gun using the Maus chassis had failed after a brief spark of interest in May 1944 with the E100 being selected in preference, it was not much of a loss. The E100 was to suffer the same fate by the middle of July, with Hitler stopping the development of such enormous and heavy weapons. The 15/17 Sturmgeschütz auf E100 fahrzeug, therefore, joined a long list of failed and abandoned Nazi projects.
Because it is not known what the 15/17 cm Sturmgeschütz auf Mausfahrzeug looked like, much of this article has been speculative about the shape and look of the vehicle. No firm drawing were ever even produced and no initial sketches are known to survive. Nonetheless, the speculation over its appearance is more than just idle chatter, but a serious effort to consider the problems the designers and builders would have faced and the solutions open to them. At times, such speculative contemplation has been taken to ludicrous extremes by game companies or model makers, but the 15/17 cm Sturmgeschütz auf Mausfahrzeug was still a very real idea. In hindsight, it may have been useless as a weapon and a waste of resources for the German war effort, but the idea was still made and seriously considered.
15/17 cm Sturmgeschütz auf Mausfahrzeug specifications
estimated 10.085 m long (9.034 m without gun), 3.7 m wide (series max.), estimated 3.649 m high
Total weight, battle-ready
estimated 188 to 200 tonnes
5-6 (commander, gunner, 1 or 2 loaders, driver, radio operator)
Front – estimated 250 mm at 30 degrees
Sides – estimated 205 mm at 30 deg.
Rear – estimated 205 mm at 10 deg.
Roof – estimated 60 mm at 90 deg.Hull
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.
Side – Upper – 173 mm at 0 deg.
Sides – Lower (skirt) – 105 mm at 0 deg.
Side 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.
Rof – Rear – 60 mm at 90 deg.
The Maus is an easily recognisable vehicle, marking the largest and heaviest production tank of WW2. At nearly 200 tonnes, the Maus, fully loaded and ready for combat, was a feat of engineering which lacked a purpose by the time it was finished. Despite having been ordered into mass production, Allied bombing had slowed deliveries and then all but a few hulls and turrets were finished when the project was scrapped. Even though the Maus was effectively dead as a project by November 1943, the story for the vehicle and even for a possible follow-up ‘Maus II’ was far from over. Maus II would not be a new vehicle, but the improvement of the first design, most noticeably in the turret.
The first mention of a Maus II was in March 1943. At this time, production of the original Maus vehicle had already begun, with the project having been approved for mass production shortly beforehand. The rush to deliver the Maus meant that production began quickly by Krupp and was well underway by the summer of 1943. Following an Allied bombing raid of the Krupp plant on 4th August 1943, production of the Maus ground to a halt, with work on 30 hulls at various stages of completion. The result of this bombing was that there was an interruption in production which led to a scaling-down of production followed by the cancellation of the project in November 1943. This permitted just 2 hulls and a single turret to be finished.
At this time though, there were several Maus hulls in various stages of completion as well as armor plating in various stages of rolling, milling, and welding for dozens more Maus available at Krupp’s factory in Essen.
It is important to note, at this point in the understanding of the Maus II and what it would look like, that all of these Maus hulls were not the same. In May 1943, after production had started, it was realized that, due to manufacturing tolerances on the very substantial side armor plates, the first hulls were ‘out-of-gauge’, namely they were too wide for the standard rail width in Germany. Rather than scrap these vehicles, it was decided to modify them along with the ones moving through the production line to bring them back into gauge. What this meant was that, by the time of the August bombing attack on the Krupp works, there were several marginally different Maus in production at the same time.
By the time of the project cancellation, the partially completed plates, hulls and turrets were still at Krupp’s Essen plant and only one hull was actually operable. A second hull would follow later and would be paired up with a finished Maus-turm and be used for testing, but, for all intents and purposes, by the end of 1943, the Maus idea was dead in the water.
Having considered that several vehicles were already in various stages of completion, Krupp had a lot of time, money, and material invested in the Maus project, as did Dr. Porsche, the designer. However, it was not until March 1944 that Hitler would intervene. That month saw Hitler demand an update from Wa Pruef 6 as to the status of the Maus program and demanded that the Maus which had been completed to undergo testing and further development. At this time, the Maus was still mounting a test-weight ‘turret’ known as the Einsatzgewicht to load the hull as if a turret was mounted. The second hull arrived at Böblingen around this time too and mounted the newly produced turret.
Following Hitler’s demands, an assessment at Krupp was clear that production could, in fact, restart and that hulls 3 to 7 had been welded up and were sat in the armor workshop. Post-war evidence also suggests that all of these hulls also had Maus-turm turrets welded-up ready for them, as these four hulls and turrets were found by Allied forces after the capture of Krupp’s factory and testing ground in 1945.
Maus II, therefore, was not a recycling of one of the original Maus-turms, but a new turret and this was mentioned by Porsche when he requested a ‘Maus-II turm’ from Krupp. At this time, the Maus II-turm did not exist outside of some sketches of the initial design, as a contract for the production of a 1:5 scale Maus model with Maus-II turm was not issued until 8th April 1944. This contract is important, as it was exactly a week after the assessment of resuming production at Krupp was delivered. That assessment had shown that a resumption of Maus production at Krupp would need an additional 200 workers per month and could deliver vehicles at a rate of just 2 per month, just a fifth of the 10 per month which had originally been suggested. This production though would be starting from hull number 8 (for which armor had been cut) onwards.
Maus II Turm (turret)
On 8th April 1944, a contract had been issued for an improved Maus turret to be modeled in 1:5 scale. The model was to have the same armament as the original Maus, a 12.8 cm gun paired with a 7.5 cm gun, but rather than being side by side with each other like on the original Maus, these were to be stacked: the 7.5 cm gun was to be mounted above the 12.8 cm gun. No plans seemed to consider the possibility of a 15 cm gun.
Bearing in mind that, when Porsche first saw the Maus-turm on the full-sized mockup in May 1943, he disliked the curved front, concerned that it could deflect shells into the hull roof, it should be no surprise that the Maus II-turm would look quite different. Dr. Porsche had made a series of suggestions to modify the original turret, including wholly impractical ideas for sub-turrets and anti-aircraft guns, but his primary suggestion of note was to change the front profile of the turret by turning the curve in the bottom half the other way.
A second change was the gun mounting, although it is not clear whose idea this was. The mount would go from a side-by-side mounting with the 12.8cm Kw.K. 44 L/55 gun on the left and the 7.5 cm gun on the right to an ‘over-and-under’ mounting with the smaller gun mounted on top. This was not the same 7.5 cm gun as used on the Maus-turm. The mounting of that gun had caused problems because the position it occupied meant that fumes from the muzzle after firing could be drawn down into the engine bay, meaning that instead of a 7.5 cm L/24 gun the barrel had to be lengthened to avoid the problem. The result was a 7.5 cm L/36 as the secondary armament on the Maus turm. By mounting the 7.5 cm gun above the primary armament, much of that problem was removed as the gun was much higher up and this meant that the original 7.5 cm L/24 could be used instead.
The general shape of this new turret was ready by 15th March, as the changes needed to the hull to accommodate it had to be worked on by Porsche. A month or so later, on 16th/17th April 1943, Krupp met with Wa Prüf 6 to discuss the improvements to the Maus-turm.
These were to include an improved ventilation system in the turret with a fume extractor directly over the 12.8 cm ammunition bin and a new breech for the 7.5 cm gun which opened horizontally rather than vertically, as this would make loading possible. Mounting the 7.5 cm gun on top of the 12.8 cm and with a vertical breech would leave it almost impossible to reload otherwise.
Most importantly, though, was the incorporation of Porsche’s concerns over the front shape. Gone was the curved front and it was replaced with a single flat plate angled back. This design had the advantage of preventing the possibility of deflected shots striking the hull roof, but also reduced the space available for the gun trunnions (the mounts for the gun), which were originally behind the front plate. Keeping this arrangement would, in fact, have reduced the space so much that the 12.8 cm gun would not have been able to fit in the turret properly.
Where the front-curve design had ensured these trunnions were protected, the shape of the front of this new design got around this problem by simply putting the trunnions on the outside of the plate. This kept the gun-forwards in the turret, maximizing space inside, and simply required a large rounded casting on the front to protect them. On top of this casting was a second large steel casting forming the mantlet around the gun.
The new turret was a significant improvement over the original Maus-turm, providing a better ballistic shape, being easier to produce (no more bending a 240 mm thick steel plate to form the front) and having improved ventilation, but in order to fit it to the hull, certain changes were needed.
On 15th May 1944, the contract for the 1:5 scale model of the Maus-II turm was changed to include an additional model in 1:10 scale to incorporate a new range finder (EM – entfernungsmesser), which was slightly narrower than the original one (1.9 to 2 m long instead of 2.1 m). Krupp’s work on this new turret was underway by August 1944 in both options (the 1:5 and 1:10 scale models with and without the new rangefinder, respectively), but to make them he was forced to scavenge parts from the original 1:1 scale model for the first Maus turret which was at Kummersdorf.
The only practical difference between the Maus II turm and the turret selected for the E100 design by Adler was that the armor on the turret was changed to reduce the weight. In this way, the E100 turm can be seen as a ‘light’ version of the Maus II turm. Visually, they would have been very similar, with only the slightly narrower rangefinder distinguishing the two from the outside. Obviously, any upgunning of the E100 turm to a 15 cm or 17.4 cm gun would cement the visual differences between the two.
Maus II Wanne (hull)
The outline of the new Maus turm was ready on 15th March 1944 in order to allow for necessary changes to be made to the hull in order to mount it. Firstly, the turret ring was to be enlarged on the hull to accommodate this new and improved turret, which would also make it more stable and make the vehicle less cramped. The original Maus turm was sat on a turret-race attached within a 2,959 mm diameter opening in the hull, allowing for the 2,388 mm diameter basket to rotate within it. The Maus II turm required a larger turret ring. This would mean that the turrets would not be interchangeable between the Maus and Maus II.
Improved ventilation in the hull roof was also meant to be added, with improved or additional gratings which allowed for more air to be drawn in for cooling.
As of 4th August 1943, it is known that armor plates had been cut for Maus hulls 8 and 9, delivered from the armor works for hull 10, and another 20 Maus-worth of armor plate rolled ready for cutting. Bearing in mind the first 7 vehicles would in the event of a resumption of production clearly be finished as Maus with the Maus-turm, it is a fair assumption that plans for this second turret would be intended for hulls 8 onwards, with a potential to finish at 22 tanks in this manner using the armor already available (for the hulls). If that was the case, there would be 8 Maus I tanks and 22 Maus IIs potentially even before considering any new contracts for renewed mass production to the original Maus I levels.
One additional and rather speculative element to consider for a Maus II is the drive train. It is understood that the original Maus was, at one time or another, envisaged with a rather large variety of engines and options and that, whilst it eventually got a modified version of the Daimler-Benz MB 517 1,200 hp V-12 Diesel engine, it had suffered through using the less-powerful MB 509 1,080 hp V-12 Petrol due to shortages of engines. Given that the MB 517 was not available or installed prior to the end of 1944, it seems a fair assumption that either this engine or one of equivalent power would have been fitted to any Maus II or Maus tanks from vehicle 8 onwards. There were also numerous other ideas for even more powerful, lighter, smaller power plants for tanks, but so far as is known in the development of Maus II, the MB 517 is the most likely option.
Whether or not Maus II would have retained the electric transmission of the Maus or would have adopted a hydraulic or mechanical transmission is not clear, but given a demand to save weight and reduce the use of strategic materials (such as the copper in the electric transmission), a switch or at least consideration of a switch is also very likely. Evidence supporting this would come from a later plan envisaged for the E100 using the 8-speed Mekydro transmission – a mechanical/hydraulic type system.
One thing less considered is the suspension. It could be assumed that a new order for Maus production in the form of Maus II would have led to a replacement of the twin-bogie system. Dr. Porsche had always favored torsion bars and had adopted external horizontal torsion bars for his Tiger P/Elefant/Ferdinand. These had also been planned for the original Typ 205 from the end of 1942. As the weight of that design had steadily increased, Dr. Porsche had reluctantly gone to a spring suspension from his much favored torsion bar system. A new, larger and more resilient external torsion bar system could therefore easily be seen as a logical development in Maus II from Dr. Porsche if it had been ordered back into production. However, without drawings, plans, or documentary evidence, this remains speculative only.
Just like the original Maus, the idea for Maus II was to partner the high velocity 12.8 cm gun (12.8 cm KwK.44 L/55, known as the ‘12.8 cm Kw.K. 44 (Maus)’) with a 7.5 cm gun. For the Maus, it was a long-barrelled (to avoid gas from the propellant entering the hull-roof vents when it was fired) 7.5 cm gun (7.5 cm Kw.K. 44 L/36), but this was not required on the Maus II as a shorter 7.5 cm gun could be used. Also unlike the Maus, which mounted these two guns side by side, the Maus II design was to mount them in an ‘over-and-under’ style, with the 7.5 cm gun mounted on top. The only major change this required was the switch to a horizontal breech for the 7.5 cm gun so it could be loaded from the side. The unusual arrangement had several considerable advantages over the former arrangement. Firstly, mounting the 7.5 cm gun higher up ensured no gases could go into the hull roof-vents even with the shorter barrel. Secondly, it reduced the width of the gun mounting in the turret face, which meant a lighter mounting as well as a narrower hole being cut in the turret face. More importantly, though, was that by sharing the same vertical axis, these two guns were now much easier to range for the new rangefinders being considered.
The story of the Maus II, an improved version of the Maus, is a complicated one and one for which the entire story may never be known. Even after the original Maus hulls (3 to 6) were ordered scrapped in July 1944, work was continuing on models of the Maus II turret. This can be seen as confirmation that the Maus II was a viable new tank that needed a new hull – hence the non-reuse of the old hulls, or simply that the turret project had not been canceled or possibly was intended for the E100 or something else instead.
Likewise, the fact that hulls 3 to 6 for the Maus were not, in fact, scrapped has also been seen as evidence supporting the idea that Maus II was not much more than an improved turret for the original hull. Analysis of the information about this turret shows that this latter conclusion cannot be correct. The Maus II turret was too large for the original Maus hull and, at the very minimum, would have necessitated the removal of the original hull roof and replacing it with a ring large enough to take the new turret. Considering that hulls 3 to 6 had manufacturing tolerance issues and needed reworking just to fulfill the needs of the Maus, it is perhaps more likely that Maus II would simply have started from Maus hull 8 onwards, incorporating the manufacturing improvements needed to stay within gauge.
It is not even clear quite when Maus II was completely terminated, as work on the turrets was still going on in August 1944, a month after the spare Maus hulls were ordered scrapped. The relationship between the E100 turret and that for Maus II is almost equally as opaque. Whilst they are assumed to share a common turret-ring size (larger than that of the original Maus), and the same guns (12.8 and 7.5 cm over-and-under) and same general layout, they were not the same. The E100 turret offered much less protection than the Maus II turret and, at only 35 tonnes, significantly lighter than the 50+ tonne turret of Maus II. The E100 turret was announced as finished by 17th May 1944, yet work on Maus II turret was still continuing, suggesting further changes were still being considered, but after this date the project disappears. Likely, it was simply canceled by the end of the year as redundant. The Maus program had been canceled and those workers and resources were needed elsewhere. No Maus II was ever built and no turret finished.
Pz.Kpwg. Maus II specifications
est. 10.085 long (9.034 without gun), 3.7 wide (series max.), 3.649 m high
Total weight, battle ready
Est. 188 tonnes (50 to 55 tonne turret)
6 (commander, gunner, 2 x loaders, driver, radio operator)
12.8 cm Kw.K. 44 L/55
7.5 cm Kw.K. 44 L/24
7.92 mm M.G.34 machine gun
Front – 220 mm @ 30 deg.
Sides – 200 mm @ 30 deg.
Rear – 200 mm @ 15 deg.
Roof – 60 mm @ 0 deg.
Hull – as Maus
Est. Daimler Benz MB 517 V-12 Petrol 44.5 litre – 1,200 hp @ 2,500 rpm
After the Battle of Stalingrad ended in February 1943, a great effort was made by Germany to develop heavily armored vehicles armed to be more effective at assaulting fortified positions and buildings, particularly in urban environments. The realization that such a vehicle was required came soon after fighting in Stalingrad began, and the straightforward solution to this problem was presented at Hitler’s conference on the 20th of September 1942.
“Fighting in Stalingrad has clearly resulted in the necessity of having a heavy gun in a heavily armored vehicle to fire high explosive shells capable of destroying entire houses with only a few rounds…“
The initial result of this calling was the SturmInfanterieGeschütz 33B (Eng: Assault Infantry Gun 33B), a variant of the StuG III assault gun with a heavily modified box-like casemate armed with a 15cm (5.9 in) sIG/33/1 howitzer. With 80 mm (3.15 in) of frontal armor, the StuIG 33B was capable of directly attacking fortified positions while still being adequately protected against return fire.
Twenty-four of these vehicles were completed by October 1942, with 12 of them being put into service by the end of the month and the other 12 in November. Despite being optimized for demolition work, however, it would be far from the most powerful assault vehicle designs to come out of Germany during WWII.
As though the StuIG 33B was totally inadequate for its role as a demolition vehicle, 1943 would see the manufacturing firm Krupp propose a quintessential German wonder weapon. At a total combat weight of 120 tonnes (264,555 lbs.), the 30.5 cm L/16 auf Sfl. Bär was nothing short of a behemoth. As a Sturmmörser (assault mortar) intended to reduce enemy defensive positions to rubble anywhere from several kilometers away to direct fire at point-blank range, the Bär (appropriately translated to ‘Bear’ in English) was to be matched in firepower only by towed siege artillery, railways guns, and the famous and slightly heavier Karl-Gerät siege mortar, all while having comparable armor protection to the Tiger II.
Krupp Takes The Initiative
Historian and author Michael Frölich states that the proposal for 30.5 cm L/16 auf Sfl. Bär was done on Krupp’s own initiative without any requirements being issued to firms for such a vehicle. This is a good example of Germany’s procurement system gradually breaking down as the war dragged on, as firms started to more frequently propose their own vehicle designs with homegrown requirements in the quest for more government contracts.
Sources differ on when the 30.5 cm L/16 auf Sfl. Bär was proposed. Historian and author Thomas Jentz states that Krupp proposed the concept on the 4th of May 1943, and had completed a drawing of the vehicle on the 10th. However, Frölich states that the design was presented by Dr. Erich Müller, who was head of artillery development at Krupp, to WaPrüf 4/II (Bureau for testing artillery for fortifications and fighting vehicles, of Artillery Section of Army Ordnance Office) on the 11th of March 1943 under the designation SKA 758, and given the appropriate name Bär.
Loaded For Bear
Bär was to be armed with a 30.5 cm (12 in) L/16 siege mortar in a casemate located at the rear of the vehicle. The mortar itself weighed 8 tonnes and was mounted on a carriage weighing a further 6 tonnes which was bolted onto the floor of the fighting compartment. Around the gun was a large curved mantlet weighing 2.5 tonnes. The mortar could be elevated up to 70 degrees but could not be depressed further than 0 degrees. When horizontal at 0 degrees, the gun rested on a travel lock which featured a hinged cap that swung up to cover the muzzle of the mortar and lock it in place.
The mortar could only traverse 2 degrees left or right, so when aiming, the entire vehicle would need to be turned to effectively get the mortar onto target. This issue was also faced by the French Char B1 heavy tank, which featured a hull-mounted 75 mm (2.95 in) gun that was fixed in traverse, so horizontal aiming was done purely by steering the tank. This issue was largely overcome with the development of a very sophisticated steering system which allowed very precise control of the tank during steering. Since the Bär used a transmission not designed for that sort of precision, it is possible that accurate aiming at close range would have been difficult to achieve.
However, it can be easily argued that, at close range with a 30.5 cm shell, aiming doesn’t need to be that precise.
At high elevation when firing at long range, accommodation had to be made for the massive breech of the mortar, which during recoil would travel 1 m (3.3 ft) rearward through a hole in the hull floor.
The mortar had a choice of two kinds of shell, a high explosive shell weighing 350 kg (772 lb), and an anti-concrete shell weighing 380 kg (838 lbs.). The high explosive shell had a propellant charge of 50 kg (110 lbs.) and was estimated to achieve a muzzle velocity of 355 m/s (1,165 fps) with a maximum range of 10.5 km (6.5 m). The anti-concrete shell had a 35 kg (77 lbs.) propellant charge and was estimated to achieve 345 m/s (1,132 fps) with a maximum range of 10 km (6.2 m).
Only 10 rounds were to be carried in the vehicle. However, this is not an unreasonably low number. As the shells each weighed hundreds of kilograms and a large winch mounted to the ceiling of the casemate was required to move and load them, the two loaders in the vehicle would have taken an exceptionally long time to load each shell, meaning the vehicle would not run out of ammo in any short amount of time. It also would not be unreasonable to expect very few targets to require more than one or two hits before they were no longer a threat.
According to historian and author Fritz Hahn, the 30.5 cm mortar was to be built by Škoda and would use ammunition that had already been manufactured as part of an old contract with Yugoslavia. No details about this contract are known, however.
To take advantage of parts commonality, the 30.5 cm L/16 auf Sfl. Bär was to be built on a chassis that made use of components from both the Panther II and Tiger II. It would be powered by the Maybach HL 230 found in the Panther, Tiger I, and Tiger II, providing 700 hp at 3000 rpm. It would also use the L 801 double differential steering system of the Tiger II, which was an upgraded version of the L 600 found in the Tiger I, and the ZF AK 7-200 7-speed gearbox of the Panther. This would have given the Bär an estimated top speed of only 20 km/h (12.4 mph).
The reason for choosing the Panther’s gearbox for the Bär is that, on 17th of February 1943, a proposal had been made recommending that Tiger II and Panther II should share a number of standardized components, including the engine (HL 230 P30), gearbox (ZF AK 7-200) and cooling system. During the time when Bär was being developed, this proposal was still in place, so considering Krupp’s involvement in the development of Tiger II, it is to be expected that they would have been well aware of the advantages of including these standardized components in the Bär. Like both Tigers and the Panther, the transmission of Bär was located at the front of the vehicle, and because the casemate and gun were located at the rear of the vehicle, the engine and cooling system were located in the center of the vehicle in front of the casemate in a layout similar to the Ferdinand tank destroyer.
As a very wide vehicle, the Bär’s tracks followed the same design process as those of Tiger I and Tiger II, in that a set of narrow transport tracks would be fitted to allow the vehicle to be transported by rail or trailer, and a set of full-width combat tracks would be fitted while the vehicle was traveling under its own power. The transport tracks were to be 500 mm (19.7 in) wide, and the combat tracks would double that at 1,000 mm (39.4 in) wide. In comparison, the Tiger II’s tracks were 660 mm (26 in) and 800 mm (31.5 in) respectively. With the transport tracks fitted, the vehicle had a width of 3.27 m (10.72 ft) and with the combat tracks this was increased to 4.1 m (13.45 ft). Despite the use of such wide tracks, at 120 tonnes, the Bär would have had very poor performance off-road, with a ground pressure estimated to be around 1.13 kg/cm2 (16.07 psi), compared to the Tiger II’s 0.76 kg/cm2 (10.8 psi).
The Bär featured overlapping 800 mm (31.5 in) road wheels but it is not confirmed if it was to use the same sprocket and wheels as on Tiger II. However, as the vehicle was intended to standardize on components with Tiger II, it is reasonable to expect that it would. Hilary Doyle, in his illustration of the Bär, presents it as having the sprocket, idler and steel-rimmed road wheels of Tiger II. This is supported by Thomas Jentz describing the road wheels as “rubber cushioned”, likely referring to the ring of rubber sandwiched under the wheel hub on either side of the wheel as a way to reduce wear without using rubber tires like those used on earlier Tiger I road wheels, which were prone to wear and contributed to rubber wastage.
While both Tigers and the Panther used torsion bar suspension which took up most of the space on their hull floors, Bär was instead, to use leaf springs. It is not known what these suspension units would have looked like but one of the main reasons for choosing leaf springs instead of torsion bars was to facilitate the inclusion of a baseplate built into the rear of the hull floor. This design feature would not be possible if the Bär used transverse torsion bars under a false floor like the Tiger and Panther. Prior to firing, possibly only for high elevation during low threat engagements, this base plate would be lowered onto the ground and locked in place. The purpose of this was to help absorb the massive amount of recoil generated by the gun during firing, which was estimated to reach around 160 tonnes of force. This design concept is present in some produced vehicles, such as the M55 and M110 Self-Propelled Howitzers, both of which feature a large dozer-like plate at the rear of the vehicles – known as a ‘recoil spade ‘ – which lower down onto the ground for the same purpose of absorbing recoil that could otherwise damage the vehicle, particularly the suspension.
The hull of Bär greatly resembled that of the Tiger II in both shape and protection. The reason for such a level of protection was that, as an assault mortar, the Bär had to be capable of resisting incoming fire from some of the most powerful AT weapons of the time. The floor armor was also intended to protect against mines, a sensible concern for an assault vehicle. To achieve this, it had the following armor values:
Upper Hull Front: 130 mm (5.12 in) at 55 degrees from vertical, 222 mm (8.74 in) LoS (Line of Sight) thickness.
Lower Hull Front: 100 mm (3.94 in) at 55 degrees from vertical, 173 mm (6.81 in) LoS thickness.
Upper Sides: 80 mm (3.15 in) flat transitioning into 80 mm at 25 degrees from vertical, 88 mm (3.46 in) LoS thickness.
Lower Sides: 80 mm flat.
Rear Hull : 80 mm at 30 degrees from vertical, 93 mm (3.66 in) LoS thickness.
Roof: 50 mm (1.96 in).
Front Floor: 60 mm (2.36 in).
Rear Floor: 30 mm (1.18 in).
Mantlet: 80-130 mm (3.15-5.12 in), 130-300 mm (5.12-11.8 in) LoS thickness.
Casemate Front: 130 mm, 130-170 mm (5.120-6.69 in) LoS thickness.
The driver was positioned in the front left of the vehicle and the radio operator was on the right. Each had a swing-out hatch like those found on the Panther and Tiger II and a single rotatable periscope. Despite the intended use of the vehicle, the radio operator did not have a ball-mounted machine gun for close protection against infantry. In fact, no other weapon is described as being present on the vehicle, although it can be reasonably assumed the crew’s personal weapons would be carried. Because of the placement of the engine, these two crewmen were physically separated from the rest of the crew who were in the rear fighting compartment. The commander and gunner were positioned on either side of the mortar and each had their own swing-out style cupola with 8 periscopes. It is notable that, because of the vehicle’s 3.55 m (11 ft) height, the cupola periscopes were angled downwards to reduce the massive blindspot that would otherwise be present all around the vehicle. The two loaders were positioned at the rear of the casemate, where they could operate the winch and load the mortar, and there was a hatch in the lower rear hull for them to enter or leave the vehicle.
It should also be noted that, in the drawing showing the interior layout of the Bär, what appears to be the elevation wheel for the mortar can be seen significantly below the positions of the gunner and commander on the gun carriage. This suggests two possible options. One option was that the gunner did not fight with his head up in his cupola, but he instead moved down next to the gun carriage and adjusted the mortar without actually seeing what he was aiming at himself, with the commander directing him using his own sight. A second possibility was that one or both or the loaders had a second duty in adjusting the mortar and it was the gunner who directed them using his own sight (no actual gunsight is shown in the drawings). With the placement of the elevation wheel, it was not possible to be up in the cupola while adjusting the mortar.
One other mysterious feature of the Bär shown in the drawing is the object protruding from the rear of the casemate. As it is shown with a shell inside it, it can be assumed to have been some kind of loading tray for loading shells into the vehicle and then stowed in their ready racks. What is not clear however is how it functioned. The rear of the object appears to be a wall the same thickness as the armor on the rear of the casemate, suggesting the object slid inwards into the vehicle much like a drawer, so that the rear was flush with the armor. If that was the case, it is not known if this drawer action was done specifically to move the shells into the vehicle where they were then moved by the internal winch, or if the tray stayed in place during loading and the shells were manually pushed in from the outside or were pulled in by some kind of mechanical rammer.
The loading process would have been time-consuming and undoubtedly would require the assistance of a Munitionsschlepper (ammunition tractor) with its own external crane, much like the Munitionsschleppers that accompanied the Karl-Gerät siege mortars. This is supported by Fritz Hahn who states the Bär would indeed be supported by specialist ammunition-carrying vehicles, however, no other descriptions of this vehicle are provided.
Hahn also states that a lighter version of the Bär had been designed, weighing significantly less at 95 tonnes. However, once again, no other details are provided. This is likely because Hahn wrote about the vehicle four decades after WWII ended while relying mostly on his recollections, and with his personal experience not being related to armored vehicles, without evidence, it is highly likely that this claim is not accurate.
As a unique and imposing vehicle, the Bär has proved popular amongst scale modelers, with modeling companies such as Amusing Hobby and Trumpeter producing their own model kits of the vehicle. However, a number of inexplicable inaccuracies are present in the models of both the aforementioned modeling companies.
The presence of a hull-mounted ball machine gun. While heavily inspired by the Tiger II, there is no evidence that the Bär possessed a hull machine gun.
A single cupola. While it is a sensible change to an impractical design, the Bär did not feature one cupola on the casemate roof, but a pair. As well as this, the cupolas on these models are not correctly designed in that the periscopes are not angled downwards to increase visibility, unlike the periscopes of the original design.
Fully sloped upper side armor. According to Doyle’s drawings for the Bär, the lower half of the sponson’s side armor was to be vertical, with the rest of the upper side armor all the way to the casemate roof being sloped at 25 degrees. There is no primary evidence that the Bär’s sponsons were fully sloped like that of Panther or Tiger II.
A complex cast casemate face. One of the most glaring changes to the Bär’s design in models is the presence of a large complex cast piece as the casemate’s frontal armor. There is no evidence to support such a design. While the Bär’s actual casemate face is highly curved in the vertical plane, it is completely straight in the horizontal plane. A comparable existing design would be that of the Maus, whose turret face very much resembles the shape of the Bar’s casemate face. This was produced by bending a straight armor plate using a huge metal press.
Fate and Conclusion
On the 27th of May 1943, in a meeting between the manufacturing firm Alkett and the Waffenkommission, Alkett revealed plans for a competing design in the form of a self-propelled 38 cm (14.96 in) mortar. Development for the vehicle was approved and by October the first prototype, a 38 cm rocket launcher mounted in a casemate built on a Tiger I chassis, was built and presented to Hitler. This vehicle would see further development and entered production as the 38 cm RW61 auf Sturmmörser Tiger. It is more commonly known as Sturmtiger.
30.5 cm L/16 auf Sfl. Bär seemingly ceased development sometime after Alkett revealed their competing design, and it is not hard to understand why. At 120 tonnes, it was significantly underpowered and, despite its enormous tracks, it would have had poor mobility and would have been vulnerable to sinking on anything but hard ground. While it could have been technically capable of fulfilling its intended role, the Sturmtiger demonstrated that the role could be more effectively filled by a vehicle half the size and weight without requiring vast resources to function.
With the existence of a later blueprint showing a significantly altered design, it is very possible that development of the Bär actually continued even after the introduction of the Sturmtiger, until at least December 1944.
Artists representation of the 30.5 cm L/16 auf Sfl. Bär in red-oxide primer with a 1.83 meter (6 ft) man for scale. Illustration produced by the author, Mr. C. Ryan, and funded by our Patreon Campaign.
8.2 x 3.27-4.1 x 3.55 meters (26.9 x 10.7-13.45 x 11.65 feet)
Total weight, battle-ready
120 tonnes (264,555 lbs.)
6 (Commander, Gunner, Driver, Radio Operator, 2 Loaders)
Nazi Germany (1942-45)
Super heavy tank prototype – 1 partially completed
The E100 was a project which is occasionally and somewhat erroneously referred to as a rival to Dr. Porsche’s Maus design. This is not strictly true, as the E100 came after the 130-tonne Tiger-Maus design from Krupp, which was the Maus-rival. When the Porsche-Maus was approved by Hitler on 3rd January 1943, the Krupp Tiger-Maus was abandoned. Shortly thereafter, Ernst Kniekampf (Panzer Kommission), without informing Krupp, gave work on the project over to the firm of Adler at Friedberg to build a simple prototype (E100 versuchs-farhgestell: Experimental 100-tonne test hull) for trials. This was done despite the lack of experience by the firm in the design or manufacture of tanks and turrets. According to Kniekampf, Krupp was already overburdened with other work, but it lay within Kniekampf’s general Entwicklungsreihe versuchs panzerkampfwagen (development series test armored vehicle) framework trying to rationalize tank development in different weight categories. It would be nearly a year later (after the failure of the Porsche-Maus production plans), that the failed Tiger-Maus, a vehicle which showed a large amount of promise in simplified production over the Maus, had shown any substantive progress.
Although Adler’s work on this 100-tonne hull project began at the end of June 1943, it would not be until spring 1944 that the program had progressed to the point of anything more than just an idea to produce a test hull (although some parts had started to be assembled at Paderborn). This means that the E100, strictly speaking, started after the Maus was approved and that it was not a rival to the Maus in any sense. It was not a copy of the Tiger-Maus, but a further development from it and was a promising step towards the rationalization of German tank production in WW2.
The Krupp 130-tonne Tiger-Maus had been a logical rival to the Porsche-Maus, using already available components from the Tiger II and Panther projects which had been designed and tested. From the engine to the suspension, the Tiger-Maus would be substantially heavier than both of those vehicles but would be much easier to produce, operate, and maintain than the Porsche-Maus because of those shared components. In contrast, the Porsche-Maus almost every element had to be designed from scratch. There was, by the end of 1942, when Krupp was seeking production orders, only 3 elements left to resolve for the Tiger-Maus. The first was the engine. A 700 hp Maybach HL 230 P30 had been selected for expediency, in the absence of the 1,000-1,100 hp* supercharged version promised to be ready in time for production by September 1943. The second was the transmission and steering. Although the L801 steering system from Tiger II could be used whilst the Tiger-Maus was still planned with the 700 hp HL 230 P30 engine, when the new engine (Maybach HL 234 delivering 1,000 – 1,100 hp*) was ready, the steering system and transmission needed to be strengthened to deal with the additional stresses. Work on that element was also underway and would be ready in time for the production of the vehicles. Finally, the least of the problems with the Tiger-Maus was the desire for a lighter turret. The original had weighed 45.5 tonnes and constituted an excessive proportion of the weight of the tank due to its heavy armor. Wa Pruf 6 had pressed for a much lighter turret, although by the end of 1942, this does not appear to have progressed, as the vehicle was still weighed just shy of 130-tonnes.
(*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)
If Krupp had started to play around with ideas for reducing the weight of the turret, this would have to have involved a significant reduction in the armor protection offered. This is due simply to the fact that the steel armor of the turret was the single largest contributor to its overall weight. Reducing the turret weight to between 25 – 30 tonnes would have meant that the vehicle would weigh around 110 tonnes. Coincidentally, when the 130-tonne Tiger-Maus was resurrected in 1943, it was in the class of a 100-tonne tank (Entwicklung 100 – Project tank 100 tonnes).
Projected Hull and Turret Weight Percentage Comparisons
130-tonne Panzer with lightened turret per Wa Pruf 6
Hull as a % of overall weight
Turret as a % of overall weight
For comparative purposes, the Serienturm on the Tiger II represented 21.9 % of the vehicle’s overall weight.
* Estimates for the purposes of illustrative analysis ONLY shown in italics.
The first mention of this new 100-tonne project was on 18 March 1944, when Krupp’s representative (Obering Woelfert) learned that a wooden model of this new tank was going to be inspected by the end of the month by representatives from Wa Pruf 6. This was after Director Jenschke from the firm of Adler in Frankfurt had handed over the drawings, presumably Krupp’s drawings from the previous January. At a meeting at the end of May 1944 between Krupp and Kniekampf, it was confirmed that the E100 was essentially just the 130-tonne Tiger Maus with a modified suspension.
Adler had been working on the E100 hull project since 30 June 1943 and had slowly been assembling parts at Paderborn, but little had really been done until the spring of 1944 when Krupp was to learn of the project. Krupp representatives, rather understandably, appear to have been annoyed by what they saw (quite correctly) as their hull design (for the 130-tonne Tiger-Maus), a design which was rejected in January 1943, given to another firm (with no experience in making such things) for development (in secret away from Krupp). It could be speculated that the reason for the involvement of Krupp was that someone had to assemble the hulls and they were the only firm able to take the armor plates and weld them together to produce a hull on which those parts could be assembled.
Regardless of being circumvented, Krupp appears to have fulfilled whatever obligation was being asked of them regarding the E100 Fahrgestell (test hull) and by 15th January 1945 assembly of the hull was well underway at Hauestenbeck (near to Paderborn).
At this time (15 January 1945), the hull was awaiting its spring suspension to be fitted (the springs were made but were shipped to the wrong location by mistake) and the assembly of the fuel lines (which had not arrived). Other than those parts, the majority of the automotive elements had been installed and the track guard sections (all 6 of them) had been delivered. There was also a stock of the transport tracks (transportkette) on hand although the combat tracks (gefechtskette) had not arrived. The rest of the internal components in the fighting compartment were in the process of installation, after which the final drive-train components, such as the steering system, brakes, final drives, and driveshaft would be installed.
The report on the production status of this test hull also requested information about the turret (or similarly-shaped test weight) so that a means of mounting it onto the hull could be arranged. Further work on the assembly continued through these first months of 1945, but with the war situation collapsing, the vehicle remained unfinished when the site was captured by Allied troops in May 1945.
What the Allies found was a hull with the engine (700 hp Maybach HL 230 P30), transmission (Maybach OG 40 12 16 B) and steering system (Henschel L801) fitted. The combat tracks missing in January 1945 had arrived and the springs had been fitted, but the drive-sprocket toothed-rings were still missing.
The E100 followed the same path in automotive terms as the work on the 130-tonne Tiger-Maus which preceded it. It was initially to use a Maybach HL 230 P30 engine delivering 700 hp at 3,000 rpm, although on the 130-tonne vehicle this would have delivered an anaemic power to weight ratio of just 5.4 hp/t. What it did mean was that it could use an existing transmission and steering system and still manage a top speed of just over 20 km/h. This would overstress the Henschel L801 steering system, but was an expedient option to try and produce this test hull quickly. The transmission selected was the 8-speed Maybach Olvargetriebe OG 40 20 16 B which was limited to being able to handle 800 hp, but a new system would be required to handle more power from a new engine. The fact that Wa Pruf 6 and Krupp were both wanting a system capable of handling up to 1,200 hp for the Tiger-Maus as far back as November 1942 adds yet more credibility to this thought.
This led to the second scheme for the drive train for the E100. This scheme used a 1,200 hp Maybach engine (a supercharged version of the HL 230 known as the HL 234) connected to an 8-speed ‘Mekydro’ mechanical/hydraulic-type transmission and steering unit combined. Working together, this new engine and new transmission would have allowed this new E100 design to have an improved power to weight ratio and manage 40 km/h. Unlike the original E100 scheme which retained the common front-wheel-drive system on German tanks (engine at back, transmission at the front), this scheme would place the transmission at the rear, with the engine compartment becoming longer and further forwards. In turn, this would have brought the turret further forwards which would have resulted in a very different-looking E100. Sadly, no drawings remain of this layout as Adler destroyed many of their drawings at the end of the war. Indeed, the only reason the general layout of the E100 with the modified Maus II turm is known at all it because the Allies had draughtsmen from Adler redraw them after the war from partially burnt originals.
The only substantive differences between the 130-tonne Tiger-Maus and the E100 was the suspension. Gone on E100 was the Tiger II-style torsion bar suspension. Instead, the tank was to adopt an external Belleville-washer-type suspension system omitting the torsion bars under the hull floor. This would save weight, improve simplicity, and reduce space being wasted inside the hull, meaning the hull could be lower. Further, it allowed for an escape hatch to be fitted into the floor, which would have been difficult with a torsion bar design. The Belleville-washer system relied upon coiled springs, although delivery of them to the E100 prototype was delayed as they had been shipped by train to the wrong location in January 1945 and by the middle of the month had still not arrived. This system had been developed by Dr. Lehr of M.A.N. (the parent firm of the Panther) and was better than the torsion-bar system, as it reduced the pitch rate of the vehicle, making it more stable on the move.
The Belleville-Washer system used a pair of overlapping wheeled guide lugs which were suspended on the outside of the hull by a pair of double spiral coil springs. On the inside of the hull, there was very little space used up as only the shock absorbers for the system impinged on the crew space.
It is surprising for a very heavy vehicle like the Tiger-Maus that the turret was relatively poorly protected. The hull of the E100, just as the Tiger-Maus before it, was extremely well protected with 200 mm of armor angled at 60 degrees at the front on the glacis, sides 120mm thick (vertical) with additional, heavily armored demountable side sections and 150 mm at 30 degrees at the back. The turret, in contrast, provides less protection on all sides to the hull with a front 200 mm thick angled at 30 degrees, sides just 80 mm thick at 29/30 degrees and a rear 150 mm thick at 15 degrees. The turret sides, therefore, were only the same thickness as the sides of the Tiger I, albeit with some shallow angling. The same protection for the turret sides on this substantially larger turret was provided for on the Tiger II serienturm, but providing a much smaller target. It could be questioned why the rear armor was 150 mm thick on the turret but heavy armor on the turret rear obviated two problems. The first was reducing the chances of mistaken friendly fire from behind destroying the tank, and the second was that it added a lot of weight to the back to help counterbalance the enormous weight of the front of the turret (armor and guns).
NotesThe turret structures are essentially the same save for reduced thickness for the E100 turret, but the sides of the Maus II turm were 30 degrees yet are given as 29 degrees for the E100 turm. This is likely an error in production rather than a design difference.
* Ring diameter for Maus II lies between 2,388 and 2,959 mm
** Maximum possible diameter of ring
+ Consideration also given to a 15 cm and 17.4 cm gun
++ Drawing 021A38300 retained many early Maus turm-features such as the crew hatch on the rear)
Comparison between Maus II turm and E100 turm
Maus II turm
Maus II turm (mit neue entfernungsmesser)
<15th March 1944
15th May 1944
<17th May 1944++
220 mm @ 30 deg.
220 mm @ 30 deg.
200 mm @ 30 deg.
200 mm @ 30 deg.
200 mm @ 30 deg.
80 mm @ 29 deg
200 mm @ 15 deg.
200 mm @ 15 deg.
150 mm @ 15 deg
60 mm @ 0 deg.
60 mm @ 0 deg.
40 mm @ 0 deg.
Turret Ring Diameter (mm)
2,388 > ? < 2,959*
2,388 > ? < 2,959*
47 – 50 tonnes
47 – 50 tonnes
12.8cm Kw.K. 44 L/55 and 7.5 cm Kw.K. L/24
2.1 m wide
Improved 1.9 to 2 m wide
2.1 m wide
For all of the heavy armor protection on the E100, it is perhaps remarkable that the turret sides were left so poorly protected compared to the rest of the vehicle. The heavy armored side plates, for example, could have been scrapped from the design to save weight to make the sides of the turret thicker to match the protection levels of the hull sides, but instead, a vehicle whose armor everywhere else was all but immune to the majority of Allied tank guns was otherwise remarkably vulnerable on the turret sides, a flaw identified already on the Tiger II.
Obering Rabe of Porsche reported on 17 May 1944 that the turret for the planned E100 weighed just 35 tonnes (a loss of just over 10 tonnes from the original Tiger-Maus plans) and marks a reduction in armor from the Maus II turret. This can be confirmed as being the basic design of the Maus II turret by considering a timeline of the events of the Maus turm development
Maus / E100 turret key dates
Modifications to Maus turm (Type 205)
Full-sized mockup of original Maus shown – Porsche suggests reshaping front of turret to avoid shot-trap
Version with improved roof armor for bunkers considered – abandoned
Maus II turm
Drawings sent from Krupp to Porsche
Maus II turm
Slope-fronted with 7.5 cm gun over 12.8 cm gun
Maus II turm
Contract to Krupp for 1:5th model to be made
Maus II turm
Krupp and Wa Pruef 6 meet to discuss turret improvements for Maus II
Maus II turm
Contract amended for additional turret design incorporating new range finder
Slope fronted with 7.5cm gun mounted over 12.8 cm gun – this is a version of the Maus II turm with less armour.
35-tonne turret adopted for E100
Maus II turm
Work underway by Krupp of two Maus II turret models
When, in 1945, the Allies captured Adler’s works, they found many files had been burned. Under their supervision, drawing 021A38300 was redrawn from the burnt scraps of the original. That drawing showed the original Maus-shaped turret from the Typ 205 dating back to the end of December 1942/January 1943, rather than the Maus II turm which was the turret intended. The reason for this is fairly clear, the Adler workers were simply working off the left-overs from the Tiger-Maus program and this was the Krupp turret shown on that hull when they redrew it with their suspension changes. This accounts for why the turret retains so many early Maus features, such as the side viewports, rear crew hatch, and the lack of coincidence rangefinder. That turret weighed in excess of 50 tonnes and was abandoned long before E100 was even a glint in Heydekampf’s eye. E100, in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work down to just 35 tonnes. Depictions of the E100 therefore with this turret are incorrect even though they are shown in the recreated original drawing. Adlerwerke employees, after all, were not contending themselves with turret design, but with the completion of the hull for trials and awaiting a turret which was a separate development.
Typ 205 from December 1942/January 1943, showing the distinctive and very large rectangular Maus-stye turret. Drawing 021A38300, redrawn post war showed this turret on the E100 hull (see below) Source: Frohlich
Original Krupp Maus turm (number 1) as fitted to the Maus (top), and the improved Krupp Maus II turm dated 23rd March 1944 (not to scale). Source: Jentz and Doyle
Inverted-colour blueprint for the completed E-100 showing the Typ 205 (December 1942/January 1943 Maus-style turret per drawing 021A38300) on a hull with a new type of overlapping-wheel suspension.
The report from Rabe (Porsche) on 17 May 1944 confirms that the turret selected for the E100 was the Maus II turm Krupp was designing with the improved range finder. That turret was to have the sloped front with the armament mounted on trunnions on the outside rather than the inside and with the guns stacked – the 7.5 cm gun Kw.K. L/24 over the 12.8 cm Kw.K. L/55.
There was, at the end of May 1944, a discussion between Krupp and Kniekampf on a change in the planned armament for this experimental 100-tonne tank with the focus moving from the 12.8 cm/7.5 cm partnership carried over from the Maus and back to consideration of a 15 cm gun. The Porsche Maus had originally been intended for an option for a 15 cm gun as well, but this had been effectively dropped on the Maus II as the 12.8 cm gun was, after all, available, (unlike the 15 cm gun) and highly effective at what was required from it, namely penetrating enemy structures and armor.
Recovery and Fate
The partially completed E-100 hull was uncovered by the British and shipped back to the UK in 1945 for examination. The sheer bulk of the hull alone created problems and slowed the shipping, indicating perhaps just how impractical a 100+ tonne tank would have been for Germany in 1945.
Back in the UK, the vehicle was thoroughly examined and sadly was later disposed of, chopped up for scrap in the post-war austerity of a nation which had bankrupted itself to defeat Germany.
The development of the E-100 was a drawn-out and complex affair. Like other German heavy tank projects, the E-100 was heavier and more complicated than originally planned as the size, shape, and features of the tank had to be made to conform to the rail gauge. As the suspension, and in particular, the turrets were changed from one project to another.
The redrawn blueprint certainly has caused some confusion post-war but the idea of a 1944/45 tank project using a turret from 1942 remains a conundrum. Regardless of whether it had that Type 205 turm or the Maus II turm though, the project was a failure that did not address the fundamental weakness in German tank design or armor theory.
No single design or single vehicle was going to deliver a victory for Germany in WW2 and whilst we can, with the benefit of history admire some of the technical achievements for making such a large and heavy vehicle, we should also consider that Germany was abandoning vehicles half its weight when they broke down for lack of being able to recover them. With crippling fuel shortages adding a new, bigger, and thirstier, vehicle and one which surpassed any easy means to recover in combat if it was immobilized the E-100 was merely a distraction to the general German war effort.
Panzerkampfwagen E-100 Specifications
11.073 m long (8.733 m without gun) x 4.48 m x 3.375 m
6 (commander, gunner, 2 x loaders, driver, radio operator)
Maybach HL 230 P30 V-12 Petrol delivering 700 hp
Maybach HL 234 V-12 Petrol delivering up to 1,200 hp
23 km/h (HL 230), up to 40 km/h (HL 234)
12.8 cm Kw.K. 44 L/55 interchangeable with 15 cm
7.5 cm Kw.K. 44 L/24
7.92 mm M.G.34 or M.G. 42 machine gun
Front – 200 mm @ 30 deg.
Sides – 80 mm @ 29/30 deg.
Rear – 150 mm @ 15 deg.
Roof – 40 mm @ 90 deg.
Front Glacis – 200 mm @ 60 deg.
Lower front – 150 mm @ 50 deg.
Sponson floor – 30 mm @ 89 deg.
Side – 120 mm @ 0 deg.
Rear – 150 mm @ 30 deg.
Floor front – 80 mm @ 90 deg.
Floor middle and rear – 40 mm @ 90 deg.
Roof – 40 mm @ 90 deg.
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.
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.
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.
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.
Engines for Mäuschen up to October 1942
~June 1942 to October 1942
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
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
HL230 TRM P45
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 @ ?
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
(Min. 77 Octane)
1,080 hp @ 2,300 rpm**
1,200 hp @ 2,500 rpm
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
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.
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)
Original scheme for Maus hull # 1
Krupp’s suggestion (Reduced Milling)
Not possible as it interfered with the wheelbase
100 mm + 80 mm
Complex to machine plates to fit exactly and difficult to secure together
Spaced armor scheme
100 mm + 30 mm (air) + 80 mm
Would increase width beyond rail gauge limits and/or involve redesigning the interior
Spaced armor scheme
100 mm + 40 mm (air) + 80 mm
Would increase width beyond rail gauge limits and/or involve redesigning the interior
Spaced armor scheme
100 mm + 10 mm (air) + 80 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
Single piece of armor for the side with no milling – required new means of supporting the wheels
New suspension scheme
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).
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.
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.
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
Krupp Maus Turm
Krupp Maus Turm
Krupp Maus Turm for Typ 205
Turm Type 205 ‘Maus’ 12.8 cm
January – February 1943
49.5 / 51*
250 mm required
(232-241.5 mm actual)
250 mm + mantlet
200 mm required
(204.4 – 205.4 mm actual)
200 mm required
(205.5 – 205.8 mm actual)
90 mm required
(90.8 – 91.5 mm actual)
50 mm +
50 mm +
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
Type 205 with Maus Turm
220 / 205 mm***
Reshaping of the front to avoid the lower curve on the front
Addition of 3.7 cm AA turret
+ 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.
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.
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
Design and overall construction/development
Hull and turret fabrication
Suspension, tracks, and gearing
Alkett (Altmärkische Kettenfabrik)
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
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**
180 mm (upper), 100 mm (lower) plus 3% allowable manufacturing tolerance
(185 mm / 103 mm max. thickness respectively)
180 mm (upper), 100 mm (lower) milled down to 170 mm (upper) and 90 mm (lower)
180 mm (upper), 100 mm (lower) milled down to 170 mm (upper) and 90 mm (lower)
170 mm (upper), 90 mm (lower) plus 3% manufacturing tolerance
(175 mm / 93 mm max. thickness respectively)
* 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
Status as of 4th August 1943
1 – 4*
Hull welding finished 7th July 1943
Delivery delay for 4 weeks
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
At Panzerbau (construction shop) – awaiting crane repair before they can be delivered for welding
8 – 9
351458 – 351459
Armor panels cut and at Panzerbau
Most armor plates delivered by Panzerplatte Walzwerk (armor fabricators)
11 – 13
351461 – 351463
Most armor plates rolled but buried under rubble
14 – 30
351464 – 351481
Most armor plates rolled but buried under rubble
31 – 141
351181 – 351591
* 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.
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.
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.
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.
(M.G. 34 or M.G. 42)
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
Approximate Date Range
10.5 cm L/70
June 1942 to September 1942
Hitler’s choice June 1942
12.8 cm L/50
12.8 cm L/55
Using special ammunition can achieve 250 mm of penetration at 1000 m / 60 deg
12.8 cm L/60
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
12.8 cm L/?
October 1942 to
Type 205 concept drawing
12.7 cm Naval
12.8 cm Flak
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
Slow rate of fire, inadequate space for ammunition
Typ 205 concept drawing
15 cm Kw.K. L/38
Alternative mounting to 12.8 cm L/55 on the same carriage in Maus-Turm
15 cm Kw.K. L/40
7.5 cm Kw.K. L/24
July 1942 to
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
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
2 cm Flak
Built-in anti-aircraft gun
3.7 cm Flak
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)
Muzzle Velocity (m/s)
12.8 cm Pz.Gr. 43 (Medium charge)
12.8 cm Pz. Gr. 43 (Full charge)
12.8 cm Spr.Gr. Flak 40 (Medium Charge)
12.8 cm Spr.Gr. Flak 40 (Full Charge)
12. 8 cm Spr.Gr. L/5 (Medium Charge)
12.8 cm Spr.Gr. L/5 (Full Charge)
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
100- tonne Panzer contract to Krupp
100-tonne Panzer contract to Porsche
Initial drawings from Porsche
Pz.Kpfw. Mäuschen turret contract issued
Hitler orders 5 vehicles
Maus Turm contract issued to Krupp
Krupp Tiger-Maus terminated
Trio-production agreement between Porsche, Krupp, and Alkett
Full sized mockup shown
Turret and hull drawings ready (ahead of schedule which was March 1943)
Order to add heavy flame-projector system
120 vehicles ordered
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
Albert Speer inspects full-sized Maus model
Suggestion to adopt ZF electromagnetic gearbox instead of electric drive system is not adopted
Order increased to 135. First 2 to be ready by November 1943
End of May 1943
Manufacturing tolerances tightened to avoid oversize
Contract issued for 135 series production vehicles and 6 prototypes (141 total)
Gen. Guderian adjusts order to just 5 tanks (total)
Order amended to 5 Maus per month (a production speed cut of 50%)
Complete turret mockup ready
Armored hull welding complete
Serial numbers issued for production
Daimler-Benz MB509 engine arrives at test laboratory for testing. Modified to run inverted and on low octane fuel.
Second hull ordered – will be fitted with Daimler-Benz MB517 engine
Allied bombing of Krupp (Essen) slows production
Hull number 1 transferred from Krupp to Alkett for fitting of drivetrain – some machining still required
Development of Maus cancelled with order for 120 changed to a single vehicle
1 – 2
Trials programme set
Series production cancelled
Contract for 6 turrets reduced to complete just a single turret
1 – 2
Contract reduced from 6 to 2 hulls
Finished at Alkett
Test drive at Alkett
Shipped from Krupp to Alkett
Ordered to be shipped to Böblingen for tests
Shipped from Berlin to Böblingen via railway on a 14-axle Spezial Transportwagen
Unloaded at Böblingen and drove 5 km to the workshops without problems
First trials of hull number 1 (Typ 205/1) – very successful
Mid. January 1944
Assembly work at Alkett halted
Assembly and fitting of other interior components
1 – 2
Component parts (armored periscope housings and gratings for hulls 1 and 2 (Typ 205/1 and 205/2)) delivered to Alkett by Krupp
Off road trials – travels 14 km including 4.6 km off road. Failures found in rubber rings in the road wheels.
Further driving trials restarted. Wa Prüf 6 representative in attendance
Vehicle completed including addition of towing eyes
Off-road driving trials for Dr. Porsche for 6.4 km (64 km total).
Assembly work ordered transferred to Böblingen
Daimler-Benz MB509 engine installed
Shipped to Böblingen for completion
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
Assessment at Krupp that production could restart
3 – 7
Hulls 3 – 7 available at the armor workshops – welding complete
Improved road wheels fitted
Porsche requests second turret from Krupp
Production, if restarted, could deliver 2 vehicles per month
3 – 7
2 – 7
Can be completed due to bodies already finished
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
Assembly at Krupp finished
3rd May 1944
Shipped from Krupp to Böblingen for modification and mounting – turret arrives bare with guns and fittings separate
4th May 1944
Unloaded at Böblingen
Turret number 1 mounted on Hull Number 2 at Böblingen
Work on turret interior
Daimler-Benz MB517 engine arrives at Böblingen
Turret number 1 assembly finished
23/6/1944 to 2/7/1944
Under repair – improved ammunition stowage
Tests on electrical turret traverse
Driving trials – tears up cobblestones
3 – 7
2 – 7
Wa Prüf 6 gives permission to scrap leftover turrets and hulls
1 – 2
All work on Maus ordered to stop
Tests on MB517 show it is superior to MB509
1 – 2
1 – E
Both vehicles moved to Kummersdorf
February to March 1944
MB509 installed in vehicle number 2 started and breaks crankshaft due to bad alignment of engine when fitted
Mid March 1945
Replacement MB517 engine sent to Kummersdorf for vehicle number 2 to replace broken MB509 engine – technicians from Porsche attend Kummersdorf to fit engine
Blown up at Kummersdorf
After May 1945
Firing tests against Maus and E-turm at Kummersdorf
March to April 1946
Turret 1 mounted on hull 2 by Soviets and shipped to USSR
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
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)
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
6 (commander, gunner, 2 x loaders, driver, radio operator)
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
3.5 litres per km
2 m (without preparation), 7.9 m (submersible) with snorkel tube fitted
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
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.
The machine gun was, and still is, a devastating weapon of war. Able to deliver hundreds or thousands of bullets over a prolonged period of time, a single machine can tie down the advance of thousands of the enemy if it is positioned correctly. The main drawback with the machine gun though is that it is large, heavy, and requires a lot of ammunition. It is no surprise, therefore, that, over the years, there have been numerous attempts to create a vehicle which can carry the machine gun and its ammunition to get close enough to the enemy to deliver on its deadly potential.
Matthäus Höchammer of Fürth, Bayern, had exactly this line of thought in 1937 and submitted his concept for achieving this goal to the German patent office. He was to submit one of the most complex and interesting one-man tank concepts conceived, a vehicle that combined the ultra-low silhouette of a man laid prone with a trench digger and tank tracks combined.
The general layout for Höchammer’s design followed the same thought process of other one-man tank designs: a man lying down and controlling the tank with his feet while operating a forward-firing weapon.
Lying the operator prone in the tank created a low-profile for the vehicle. As the hands would be occupied by the weapon, the vehicle would be controlled almost completely by means of foot control for speed and direction and all of this would be clad in armor to protect it from enemy bullets. As such, there are several very similar designs, most notable of which is that of Ernst Mahlkuch, another German designer-submitted patent in 1938.
Lying face forward, the single-occupant was very low to the ground. This enabled him to make good use of cover, both from fire and visual cover, as a low vehicle like this could hide in just long grass. What was an advantage for protection though, was a significant handicap for operations, as it reduced the observation height for the operator, meaning he would find it hard to identify and target the enemy forces and make it difficult to see obstacles in front of the vehicle.
Construction of the design was relatively straightforward, with the lower half of the hull being made from a sheet of pressed steel. The upper half was angular with a pointed front and sharply sloping roofline, both of which would improve ballistic protection by encouraging the deflection of incoming enemy fire. The top half had the appearance of being welded together, made from flat panels of metal. Given its small size would likely be ‘bulletproof’ at best, this would mean around 10-12 mm thick with the lower half being much thinner, as it would be unlikely to have to be protected from enemy fire at all.
The single occupant of Höchammer’s design had to lay prone to keep the height of the vehicle down and had to face forwards in order to see where he was going. This meant that the controls were operated by his feet, keeping his hands free to operate the single machine gun pointing forwards.
As an effort to provide a modicum of comfort to the operator, Höchammer incorporated a mattress for him to lay on, a nice touch to improve the conditions inside an otherwise noisy, cramped, and rather crude weapon.
Behind the operator (commander, driver and gunner combined) was the engine, operated by means of pedals pushed by the operator’s legs. The engine was to be of a ‘particularly strong’ type, a high-speed 4 or 6-cylinder engine, although Höchammer made no comment as to whether it would be running on petrol or diesel.
Connected to this engine was the gearbox which delivered power to the final drives for the tank located at the back. Running on thin tracks for the full length of the tank, the suspension was provided for by means of 3 pairs of overlapping wheels with a large wheel at each end of the track run. Track support was provided by means of rollers above the road wheels.
Höchammer’s design had a very low ground clearance and this would make it very vulnerable to becoming stuck on a rock or tree stump, not a surprise in a tank just 25-30 cm high. Unlike Malkuch though, Höchammer had a viable solution to this problem, one which further increased the protection of the vehicle from enemy observation and fire – a bulldozer blade. This allowed the vehicle to carved a shallow trench for itself making it harder to see and hit.
As the vehicle moved forwards, the bulldozer blade would plough the earth in front of the vehicle, pushing the spoil out to each side. These earthen banks on each side provided additional cover for the vehicle and also meant it was even lower than it would be operating on the surface. If a stiff obstacle was encountered or the blade was not needed, it could simply be retracted upwards above the line-of-fire of the machine gun.
The blade had the additional advantage that it created a shallow trench in which following unarmored troops could crawl through as part of their advance.
Just like other one-man tanks, the one from Matthäus Höchammer was fundamentally flawed. It was so low that the occupant would have a terrible view of the battlefield, very thinly protected, and with all of the fightability, steering, and command of the tank in one man, hard to control too. There is simply too much in a tank as a combat system for one man to manage by himself and it is likely this reason, above all others, to explain why this one-man tank concept went nowhere.
The failure of the design though was not the end of Höchammer. He was a Master Carpenter by trade and survived WW2. His tank design might have been useless but Höchammer at least found some success in life as, between 1952 and 1956, he served as an elected member of the Fürth Block e. V. political movement on Fürth City Council.
German Patent DE665817 ‘Geländegängiger, gepanzerter Einmannkampfwagen’ filed 8th May 1937, granted 15th September 1938
Hrsg. Kreisverband SPD Fürth: 90 Jahre Fürther Sozialdemokratie 1872 – 1962. Eigenverlag Fürth, 1962 Via Fuerth Wiki
When Krupp’s Tiger-Maus was abandoned in January 1943, the design was surplus, as development effort went into the Porsche-Maus instead. However, Ernst Kniekampf (Panzer Kommission) did not throw out Krupp’s design. Instead, and regardless of whatever reservations he may have expressed later about heavy tanks, he handed off the plans to the firm of Adler by the end of June 1943. Adler then worked on the design, making changes to it but keeping the essential design. The only substantive change, in fact, was the switch from Tiger II-style torsion bar suspension to externally-mounted Belleville-Washer-type spring suspension. Very little, other than collecting parts, took place with the E100 until March 1944, when Krupp became aware of its existence.
Considering it was their original work, they were likely unhappy at having been sidelined on the matter, but they obligingly provided assistance to Adler in the construction of the E100 anyway. When, in May 1944, the opportunity to work on a new vehicle mounting a 15 cm or 17 cm gun came up, there were two hulls optioned for it: the Maus (designed by Porsche and built by Krupp), and the E100 (designed by Krupp, added to by Adler, and to be built by Krupp). Krupp, therefore, embarked on another task, how to fit the huge 15 cm or 17 cm gun onto their as yet unbuilt, and untested E100 chassis.
If the idea of a 15 cm or 17 cm gun in a fixed casemate on a Maus hull is not hard enough to visualize, then it is worth bearing in mind that mounting a gun of this size on an E100 chassis is even more so. Specifically, because the E100 chassis was so much lighter, under 90 tonnes fully laden for the chassis.
On 9th May 1944, representatives from Porsche and Krupp met to discuss a new heavy type of self-propelled gun. Drawings were presented at this meeting of ideas by Krupp for how to mount the 15 cm L/63 or 17 cm L/53 gun on the Maus chassis as a direct competitor to a similar idea from Adler (Adlerwerke) for mounting these guns on the E100. Both designs were to use a fixed casemate structure (Sturmgeschütz Aufbau) in which to mount the guns.
These ideas were considered at a meeting held at Porsche’s plant on 17th May 1944, and it was here that Krupp expressed their earnest desire to do anything to avoid having to try and use the 15 cm gun in preference to the 17 cm one, likely as a result of the size and weight of the gun and its shells. Obering Hendel, the officer dispatched to ensure production quotas were being met by tank factories, considered both Maus and E100 ideas. His conclusion was not in favor of the Maus. The Maus hull was too high for a new fixed casemate to still fit within the rail loading gauge (assuming a normal railcar), whereas the E100 hull, being significantly lower, was much more suitable.
The Maus-plan was over, it was not a suitable platform and was abandoned as an idea. Instead, the E100 was selected, and on 28th May 1944, Krupp was requested to produce a 1:5th scale wooden model of their design. The purpose of this model was to get a better insight into how the vehicle could be organized internally for crew and ammunition. Importantly, both the 15 cm and 17 cm guns were to be shown, and the design was known as 15/17 cm Kanone auf E100 Fahrgestell (15 or 17 cm gun on 100-tonne experimental chassis).
Development to Termination
Although the E100 chassis had shown more promise, primarily as a result of being lower and lighter than the alternative chassis (Maus), this success was short-lived. Just under two months after being told to produce this model, all work was stopped. Wa Prüf 6 (Waffen Prüfen 6 – the design office responsible for motorized equipment) forwarded to Krupp a copy of the letter from Reichsminister Albert Speer dated 10th July 1944. In the letter, Speer, on Hitler’s orders, required all work on heavy guns on tank chassis to cease. There was a model, however. Krupp must have finished or at least prepared a model by this date as the letter ended that they were to take the model of the Sturmgeschutz 15 cm L/68 to General Guderian.
Guderian was not a fan of these heavy tank projects and had scuppered plans for Maus production a year earlier. There was little-to-no likelihood that he would suddenly change his mind on this type of project seeing just a wooden model of it. Nothing more is heard of the project after this point as it met the same fate as the 15/17 cm Sturmgeschütz auf Mausfahrzeug before it.
Plans for the mounting of the 15 cm gun still survive, at least for mounting it on the front of the turret for E100, but there is no trace of the 1:5th scale wooden model. Nonetheless, it is worthwhile considering what this machine might have looked like, aside from the fantasy creations of model makers and computer game companies, which may be designed more for the ‘cool’ factor than from a basis in engineering.
The primary consideration over what a 15/17 cm Kanone auf E100 Fahrgestell would look like begins with a look at the E100 hull. As it was was, the E100 hull featured a conventional layout with the engine at the rear, transmission at the front, and a centrally-mounted turret. There were plans for a modified layout on the E100, but as of 1944, when these plans were being considered, these had not progressed, and the original E100 hull had still not been finished. It remains open to question as to whether or not the 15/17 cm Kanone auf E100 Fahrgestell being proposed was to use the first hull or this later modified hull, but as this was future planning it is possible it was to be based off the second, improved hull. Further, it remains open to question as to whether the layout would be fundamentally altered with a casemate placed at the rear with the engine in front of it, like the Elephant/Ferdinand, or if it would simply occupy the space previously filled by the turret and basket.
Regardless of which E100 hull was to be used, the turret, and therefore the casemate, could only be fitted centrally or just forward of centre. Mounting anything else on the already heavy front end, such as in the manner of a Jagdpanther, would simply overwhelm the suspension.
Assuming a central position for the casemate, in roughly the same manner as the Jagdtiger, would mean that no changes would be made to the engine and transmission layout in either hull and keep the front driving position (front left) able to access the main crew compartment. Moving to a rear casemate system would separate the driver from the fighting compartment. A rear casemate would also suffer from the additional problem of having the gun over the engine bay which would greatly complicate access to the engine compartment for maintenance, a serious consideration in the design of the Jadgtiger and a primary reason for adopting a central-casemate layout.
It is assumed that the basic armor of the E100 hull, including the removable side armor sections, would be maintained and also that the armor on the casemate would approximately match the same protection levels offered by the E100 turm. That turret weighed just 35 tonnes with 200 mm of armor on the front, 80 mm on the sides, and 150 mm on the rear. Being a fixed casemate would mean there would be little scope for manoeuvering to avoid being hit in the sides but, just like the Jagdtiger, which had over 200 mm on the casemate face and 80 mm on the sides, the casemate on a 15/17 cm Kanone auf E100 Fahrgestell would likely be done in a similar way, except that the rear turret armor planned (150 mm thick) would not be required. On the turret, it added a degree of protection to accidental friendly fire from behind but much more importantly, acted as a counterbalance to the enormously heavy front of the turret. No such counterweight was needed on a fixed casemate so the armor could, if so desired, be greatly reduced in that area. Although it makes sense to reduce weight, the rear of the lower rear hull would still be 150 mm thick.
The two guns in consideration for mounting on the E100 chassis were the 17 cm Stu.K. L/53 and the 15 cm Stu.K. L68. The 17 cm gun was, as of 22nd March 1944, still only a paper design and was unlikely to be available anytime soon given the demands of gun production already being very high. The second gun, and by far the preferred option of the two, was the 15 cm Stu.K. L/68 gun and the design for this piece was finished on 4th July 1944, just 6 days before Hitler killed the project.
Given the enormous size of the 17 cm gun, its huge breech, high weight, and the size of its ammunition and the date of the design for the 15 cm gun, it seems likely that Krupp did everything they could to avoid using the 17 cm gun. Both guns, however, had to meet the requirements set by General Guderian (Inspector-General of Panzer troops) in April 1944 to be able to defeat up to 200 mm of armor at 4,000 meters, leaving no doubt as to a key intended purpose of this vehicle, the destruction of increasingly well-armored enemy tanks at long range. Of note too is that there is no comment as to secondary weaponry. Not a machine gun, but a second, tank cannon, like was originally intended for the Maeuschen program with a 15 cm or 12.8 cm gun paired with a 7.5 cm gun. Only using this single large gun would free up significant space inside the casemate for this E100-based vehicle as well as providing additional stowage space for the 15 cm ammunition. Just as with Maus and E100, it could be expected that a machine gun (either M.G.34 or M.G. 42) would be mounted independently on the left-hand side of the main gun to be operated by the gunner.
One last note on the casemate is the use of a rangefinder. The two rangefinders considered for the Maus II and E100 turm rangefinders were coincidence type devices fitted across the width of the turret. Both types were around 2 m long (1.9 and 2.1 m wide) and there seems to be little doubt that the 15/17 cm Kanone auf E100 Fahrgestell would also have to have a rangefinder, especially given the 4,000 m ranges at which it was going to be expected to deliver accurate fire against enemy tanks and structures. Given the common positioning of the rangefinder on the Maus II and E100, it is reasonable to assume a similar arrangement of a similar size/type of rangefinder would also have to have been used on the 15/17 cm Kanone auf E100 Fahrgestell.
Regardless of which layout the 15/17 cm Kanone auf E100 Fahrgestell took, it would need a crew and it is hard to envisage this vehicle operating with a crew of fewer than 6. At a minimum, the vehicle would need a driver, a radio operator, a loader, a gunner, and a commander, which totals 5. The Maus required the sixth man in order to operate the secondary 7.5 cm gun, and whilst it was likely that no such gun was to be on the 15/17 cm Kanone auf E100 Fahrgestell, the use of a second loader was all but essential, unless some kind of loader-assist system was planned, considering the size and weight of the 15 cm ammunition. A unitary (one piece) 15 cm shell, for example, weighed in excess of 34 kg and possibly over 40 kg depending on what ammunition might have been chosen. Moving those shells around would rapidly exhaust a single loader, so a second loader is almost essential just to make the machine viable.
Although the idea of the 15 cm or 17 cm gun using the Maus chassis had failed after a brief spark of interest in May 1944, with the E100 being selected in preference, it was not much of a loss. The E100 was to suffer the same fate. On 10th July 1944, Hitler canceled all of the work on these heavy guns on heavy tanks and the 15/17 cm Kanone auf E100 Fahrgestell became yet another failed project in what was a very long list of such projects.
Although it is not known what the 15/17 cm Kanone auf E100 Fahrgestell would have looked like and much of this article has been speculative about the shape and look of the vehicle, it is important to consider the design in order to gain an understanding of the challenges involved in mounting very large guns on very large chassis.
For Germany in mid-1944 to be considering these weapons though was pure folly. It would take months to get such a machine into production and longer still to get crew trained and units issued and deployed to combat. At a time when Germany was on the retreat and the war was a foregone conclusion, to focus precious and ever-dwindling resources on these machines was wasteful. It did nothing more than hasten the end of Germany.
What-if illustration of a Sturmgeschütz auf E100 with a centrally-mounted fighting compartment sporting the 15 cm Stu.K. L/68 gun in a Dunkelgelb finish.
What-if illustration of a Sturmgeschütz auf E100 with a centrally-mounted fighting compartment sporting the 17 cm Stu.K. L/53, lacking the E100 side skirts and with only a layer of Rotbraun primer paint.
Both illustrations by Mr. C.Ryan, paid for through our Patreon campaign.
est.39.3 feet x 14.6 feet x 11 feet (12 x 4.48 x 3.37 meters)
est. 127 long tons (130 tonnes)
est. 6 (commander, gunner, 2 x loaders, driver, radio operator)
Maybach HL 230 P30 V-12 Petrol delivering 700 hp
Maybach HL 234 V-12 Petrol delivering up to 1,200 hp
<23 km/h (road) (HL 230), up to <40 km/h (road) (HL 234)
17 cm Stu.K. L/53 alternatively 15 cm Stu.K. L68
7.92 mm M.G.34 or M.G. 42 machine gun
Front – est. 200 mm
Sides – 80 mm @ 29/30 deg.
Rear – est. 80 mm
Roof – 40 mm @ 90 deg.
Front – Glacis – 200 mm @ 60 deg.
– Lower front – 150 mm @ 50 deg.
Track guards –
Sponson floor – 30 mm @ 89 deg.
Side – 120 mm @ 0 deg.
Rear – 150 mm @ 30 deg.
Floor – front – 80 mm @ 90 deg.
Floor – middle and rear – 40 mm @ 90 deg.
Roof – 40 mm @ 90 deg.
Nazi Germany (1935-39)
Heavy Tank – 3 Hulls & 1 Turret Built
The Tiger I and the Tiger II are some of the most famous tanks in the whole history of armored warfare. These behemoths of World War Two have captured the imagination and attention of many generations of tank lovers and armor researchers. However, while the Tiger was the product of a rushed development following the lessons of Operation Barbarossa, the German quest for a heavy breakthrough tank stretches back to 1935, with the design process of a 30 ton Panzer that would become the Durchbruchswagen.
A Long Incubation
The first mention of what would eventually become the Tiger series appears in a report from October 1935, at a time when Germany had barely started building the Panzer I. General Liese, the head of the Heeres Waffenamt, the German Army Weapons Agency, stated that:
“The initial velocity of the 7.5 cm gun must be increased to about 650 meters/second to be effective against the Char 2 C, 3 C, and D. This type of increase requires the design of a completely new Panzer. Based on rough calculations, armor protection up to 20 mm thick (still not fully protected against 2 cm guns) would result in a weight of at least 30 tonnes. The head of the army recently spoke out against this type of tank. As a follow-up action, confirm that the development of a medium Panzer weighing about 30 tonnes with a 7.5 cm gun with increased capability can be dropped.”
It is notable that a 30 tonne tank was seen as a medium tank at the time, given that the newly built Panzer I weighed just 5 tonnes, while the first versions of the Panzer IV would go on to weigh 18 tonnes. Nonetheless, it is important to note that this tank, armed with a 7.5 cm gun, was intended as a counter to enemy heavy tanks, most notably the French Char 2C and the Char 2C bis, incorrectly called the 3C in the document.
The weight of 30 tonnes was chosen because, as was brought up during a 1936 meeting on the development of an engine for this tank:
“a higher weight would hardly be allowable when considering the Pionier bridging equipment”
The 30 tonne Panzer development project was not dropped by the Army and reappeared in the documentation in December 1935, with the problem of the engine:
“Dipl.Ing. Augustin turned the discussion to the development of a 600 hp engine for the heavy Panzers and noted that his opinion was that 600 horsepower will not be sufficient and that indeed it would be more correct to immediately develop a motor capable of 700 hp.”
This was just wishful thinking. At this point, Maybach was barely testing a 300 hp engine. The planned 600 hp 32 liter Maybach HL 320 V-12 petrol engine never got built. One year later, in October 1936, Wa Pruef 6, the German design office for armored vehicles, sent a request to Krupp for a conceptual design of a turret for this 30 tonne Panzer sporting the 7.5 cm L/24 gun.
A Tank With Many Names
At this point, the 30 tonne Panzer was known as the Begleitwagen (verstaerkt), meaning ‘Escort Vehicle, Strengthened’. This indicates that the new 30 tonne Panzer was meant to cover the same role as the Panzer IV, which was also known as the Begleitwagen in its development. This would have meant that small units of 30 tonne Panzers would have been used to accompany lighter tanks during operations, being responsible for taking out enemy strongpoints which could be destroyed using their high explosive shells.
In March 1937, this designation was changed into Infanteriwagen, or ‘Infantry vehicle’. This also indicates a change in the role it was meant to carry out, presumably to having to work alongside friendly infantry to overcome enemy defenses, probably closer to the British and French concepts of an Infantry tank. This would not last long and, in April 1937, the vehicle would receive its most known designation, Durchbruchswagen, or ‘Breakthrough vehicle’. Again, this probably came with a role change, a role that would stick with the German heavy tanks up to the E100. This breakthrough role, which also appears in both Soviet and French armored doctrines before the war, proposed the use of heavy tank units to punch through the enemy defensive line, thus creating a breach which could then be exploited by other armored and motorized divisions.
The construction of the first Durchbruchswagen began with a January 1937 order from Wa Pruef 6 to the Henschel company for the design of a chassis for the 30 tonne Panzer. This would cement a practice that would hold on for most of the German heavy tank development of having two companies designing the vehicle, Krupp doing the turret and gun and another company doing the chassis. Two versions were built, the D.W.1 and the D.W.2, meant to be delivered in the second half of 1938, mostly with automotive differences.
The Durchbruchswagen I was protected by flat 5 cm thick armor on the front, sides and rear, which was meant to be proof against the armor-piercing shells of the German 3.7 cm PaK, although it is unclear at which range this was supposed to be at. The Armor Piercing (A.P.) shell of the 3.7 cm could penetrate more than 5 cm of armor at point blank range. To give a comparison, the Panzer IV Ausf.F, which had the same gun, same engine, a very similar turret and the same 5 cm frontal armor, weighed just over 7 tonnes less than the Durchbruchswagen’s intended weight. A significant part of this difference can be accounted for by the thinner side, rear, top and bottom armor, although other differences between the two tanks make this comparison just indicative.
The roof and bottom of the hull were 2 cm thick. The armor at the front was stepped. However, both of the constructed vehicles were made out of ‘soft’ (not armor) steel, as they were meant mostly for automotive tests. Also, due to the inability of existing milling machines to fabricate such long 5 cm armored plates, the side armor was made from two parts, with a split at the front of the engine compartment. At the joining, they were riveted to an internal frame. This increased the weight of the vehicle and affected the structural integrity of the side armor.
For that time, this was quite thick armor. Only the Char B1 bis had thicker armor (60 mm front and 55 mm sides), with the SOMUA S35 also having similar armor (47 mm front, 40 mm sides). Furthermore, just like on the Tiger I prototype, there was a foldable armor plate that could be lowered using hand cranks to protect the drive sprockets at the front. This foldable armor plate was allegedly put through a protection test which it failed. There were two escape hatches in the bottom of the tank, one on the right front, close to the radio operator, and one at the rear left of the hull, in the engine compartment. This could be accessed through a door in the firewall that separated the engine from the crew compartment. While not specifically mentioned in any source, the Durchbruchswagen I hull probably had a driver’s visor in the front of the upper glacis and a hatch in the roof. The radio operator on the right side of the front hull also probably had a hatch in the roof and a ball-mount machine gun.
The engine was a 12-liter water-cooled gasoline Maybach HL 120 TR giving out 280 hp, placed at the rear of the tank. The TRM version of this engine also propelled the Panzer III, Panzer IV and their derivatives. The engine was coupled to a Maybach-Motorenwerk Variorex semi-automatic transmission, also used on the Panzer III, placed at the front of the tank. These could allegedly propel the vehicle to a maximum speed of 35 km/h. The steering system consisted of three Cletrac stages in series. A Cletrac system allows the transfer of power from one track to the other when steering, without the usual loss of power due to braking. The three stages allowed the use of three different turning radiuses, so the tank could make a shallower or tighter turn without losing power. However, problems appeared with the steering system, with the cast iron housing being broken twice. The exhaust was at the rear of the tank, coming down from the upper part of the rear of the vehicle. There were also problems with the brakes, as the first version, done by Henschel, gave out a lot of smoke when breaking, so the coating had to be replaced.
The running gear consisted of a drive sprocket at the front, an idler at the rear, three return rollers and five medium-size double road wheels on each side. They had rubber rims in order to decrease the noise made by the tracks. Due to the use of a torsion bar suspension, the road wheels were not symmetrically placed. The ones on the right side of the tank were slightly forward compared to the ones on the left. The torsion bars were square and hollow on the inside. They were very soft-springed, meaning that they could give a smoother ride in certain conditions, but could not handle rough terrain and would lead to a lot of pitching during driving and when stopping or starting. Two shock absorbers were mounted on each side, one on the first roadwheel and one on the last roadwheel. These were meant to assist these torsion bars, as they were subjected to stronger shocks, especially when stopping or accelerating. Also, bump stops were added to the suspension in order to stop the road wheels from being deviated too much and thus protecting the tank from bellying out. The tracks had a pitch of 300 mm. The pitch of a track is the distance between the centers of two subsequent track links. In general, decreasing the pitch could lead to better speed and ride, but also means more track links were needed, with more connections and more parts. The tracks were lubricated and could be fitted with rubber pads. The rubber pads would have made the tank quieter and less prone to damaging or destroying the pavement on roads, while the lubrication decreased friction and thus increased the speed of the vehicle. These were both characteristics that seem to have been carried over from half-track designs.
The crew probably consisted of five people as on other German tanks being developed at that time. This would have included the driver and radio operator in the front part of the hull of the tank, and a gunner, a loader and a commander in the turret. This would have been a very important feature of this vehicle, as it would have allowed the commander to focus on his duties of observation and tactical leadership instead of having to aim and load the gun.
The dimensions of the Durchbruchswagen are not available in any of the sources, but it can be reasonably assumed that they would have been similar to those of the VK30.01(H). This later vehicle had a length of 5.7 and a height of 2.6 meters. The width of the VK30.01(H), of 3.1 meters, was probably larger than that of the D.W. due to the different suspension system. Nonetheless, these values are also very close to those of the Panzer IV.
Work on the Durchbruchswagen 2 was started halfway through 1937 and it mostly had automotive improvements. In the book ‘Tiger and its variants’, Doyle’s drawing of the D.W.2 shows it with the one-piece side armor. However, in the book ‘Germany’s Tiger tanks’, Jentz specifically mentions that the one-piece side armor was introduced with the VK30.01(H) neue Konstruktion, and thus the D.W.2 should have the two piece side armor. Similarly, ‘Tiger and its variants’ shows the addition of a hull side-escape hatch to the D.W.2 while ‘Germany’s Tiger tanks’ makes no mention of such a thing.
Automotive-wise, the larger stages of the previous Cletrac system were replaced with a three-stage differential with magnetic clutches. Not only did these allow for power to be transferred from one track to the other while turning, but a triple stage differential also allowed to reverse one track with respect to the other, thus allowing the tank to neutral steer. The Cletrac stage with the smallest turning radius was kept though.
Also, the track pitch was decreased to 260 mm, which is claimed to have significantly improved the ride of the vehicle. The torsion bars were also changed to a more rigid type, with a three-times larger springing constant.
Due to these changes, the drive sprocket, final drives and parking brakes also needed to be modified.
These two hulls were supposedly trialed to test all the components and identify what improvements could be made for future projects. However, almost no details remain about these tests. What is certain is that the Durchbruchswagen was not accepted as built.
Work on the Durchbruchswagen turret was done in parallel to that on the hulls. Krupp sent the requested conceptual drawings for the turret in February 1937, and was quickly informed by Wa Pruef 6 to use it as a basis for subsequent development. In the March 1937 answer, Wa Pruef details the desired characteristics of the D.W. turret.
The turret was to have a turret ring diameter of 1,500 mm, smaller than that of the Panzer IV. Also, the turret would be rotated manually, as
“No plans are made for an electric drive for traversing the turret. Auxiliary traversing gear for the loader is to be included.”
The armor of the turret would be 50 mm all around, with a 20 mm external mantlet and a 15 mm turret roof, affording similar protection as the hull. There is no other information on the shape of the turret of the Durchbruchswagen, although H.L.Doyle’s line-drawing in ‘Tiger and its variants’ shows a Panzer IV-like turret with a large commander cupola at the rear, a crew access hatch and a vision port on each side.
The gun to be used in this turret was the same 7.5 cm Kampfwagenkanone L/24 that would be mounted on the early versions of the Panzer IV. In a meeting in January 1939 on the topic of the heavy 30 tonne Panzers, it was expressly specified that no gun larger than the short 7.5 cm should be pursued because the increased weight would have to be compensated by a decrease in armor, which was deemed unacceptable.
The main shell for this gun was the Sprenggranate 34 high-explosive shell. This shell weighed around 4.5 kg and had an explosive filler of almost half a kilogram. This was meant to be used against enemy infantry, machine-gun posts, anti-tank guns, bunkers and soft-skinned vehicles. For anti-tank purposes, a series of High Explosive Anti Tank (H.E.A.T) shells were introduced during the lifetime of this gun, with penetrations ranging from around 45 mm to over 100 mm, although they were introduced into service later. Two types of Armor Piercing Capped Ballistic Capped (A.P.C.B.C.) shells were also available, with a penetration of 54 mm to 60 mm at 100 m distance. An APCBC shell works basically as a normal Armor Piercing (A.P.) shell, but has two additional caps added to the tip of the shell. The first cap is made of soft metal and is meant to absorb a part of the shock on impacting the armor and thus preventing the armor piercing tip from shattering. The ballistic cap was a hollow light cone added on the top of the shell with the sole purpose of improving the aerodynamics of the shell. This improved both accuracy and the penetrating power, as the shell kept more of its kinetic energy at longer ranges.
Another machine gun (most probably an MG 34) would have probably been mounted coaxially with the gun. The instruction letter from March 1937 specifies that the radio should be mounted in the turret, behind the gun. However, this seems impossible to do in a Panzer IV-like turret. If the turret was as the one drawn by Doyle, then the radio would have almost certainly been mounted in the hull.
Krupp finished the D.W. turret in May 1939, building it from soft steel. It was then shipped to Magdeburg, where it was put on display along with other developments, such as the Panzer IV turret. Nothing is known about what happened after this with the turret.
The End of the Line
The Durchbruchswagen project melts into the subsequent VK 30.01 (H), which inherited many of the characteristics of the D.W. designs. The Durchbruchswagen design also underwent its last designation evolution in November 1939, also receiving the designation Vollketten 30.01 (H) alte Konstruktion.
Nonetheless, a final D.W. hull was constructed from armor plate for ballistic tests. This hull had some changes compared to the previous two hulls, having slightly different armor values that were closer to those on the VK30.01(H). This was completed after September 1940 and shipped to Kummersdorf for firing tests. No information about the results are currently available.
A Note on Sources
There is almost no photographic evidence for the Durchbruchswagen. The only known photographs of the project were published in ‘Tiger and its variants’ and consist of a photograph of the tracks and one of the final drives at the front of the vehicle, along with a roadwheel and a shock absorber. This paucity of photographic evidence is disturbing. Other visual references include a 1940 armor scheme of the ballistic test hull and a 1945 British reconstruction of the D.W. hull based on the interrogation of Dr. Aders, the head of the design department of Henschel. Finally, two beautiful line drawings from Hillary Louis Doyle are available in the book ‘Tiger and its variants’, but how many of the details on it are based on historical references and how many are conjectural is unknown.
It is also important to note that there is annoyingly little information available on the Durchbruchswagen, with only three books treating it in any detail. Even so, most of the technical details and specifications come from the 1945 interrogation of Dr. Aders by the British and not from contemporary German documents, so they should be treated with a degree of skepticism.
Nowadays, the Durchbruchswagen are mostly forgotten except for some mentions in a couple of books and their appearance in a popular video game. However, they played an important role in the development of German heavy tanks that would culminate in the Tiger tanks. They were the main designs worked on at a time when the German heavy tank doctrine was being crystallized. Also, they were very important in testing the capabilities of the German armaments industry and helping identify where research and development were needed, such as designing better armor milling, better suspension and better engines.
Nevertheless, the Germans would not adopt a heavy tank for the Wehrmacht until 1942, meaning that the German tank divisions went into the Second World War without such a vehicle. During the peak of the German offensive successes, when such a tank would have been most useful in breaking down Polish, French, or Soviet defensive lines, none was available. The Germans nonetheless achieved great success despite the thin armor of their tanks due to excellent communications, training, leadership, and tactics.
Illustration of the Durchbruchswagen 2 based on H.L.Doyle’s drawing produced by Tank Encyclopedia’s own David Bocquelet. The hull side is in one piece
Around 5.7 x 3.1 x 2.7 m
7.5 cm Kampfwagenkanone L/24
2 x MG 34
50 mm hull front, rear and sides
20 mm hull roof and floor
50 mm turret front, rear and sides
15 mm turret roof
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