Categories
WW2 French Prototypes

Citroën P28 chenillette

Nation Flag IconFrance (1931)
Infantry tractor – 3 prototypes

The early 1930s were marked by the worldwide popularity of the tankette concept, which produced a variety of vehicles used in sometimes quite radically different manners across most major industrial powers of the world. The Citroën P28 original prototype was one of the more original derivatives of this design. Designed to serve as an infantry tractor, it used a half-track configuration with Kégresse suspension, which makes it a quite interesting and original design. While not adopted as an infantry tractor, with the more traditional fully-tracked Renault UE being picked, it became an interesting half-track cavalry armored car.

In the wake of the Carden-Loyd

In 1928, production of the British Carden-Loyd Mark VI tankette began. The result of several years of experimentation on one and two-man turretless armored vehicles, this British tankette was a 1.5 ton heavy vehicle with a two-men crew. A novelty on the international market, which was relatively stagnant and dominated by the WW1-era French Renault FT, the Carden-Loyd seemed to offer new possibilities as a lighter and cheaper armored vehicle.

The potential was not lost on France and, in June and July 1930, two Carden-Loyds were tested at the Centre des Essais de Véhicules (Vehicles Trials Center) of Vincennes. Those trials had been conducted at the initiative of engineer Edgar Brandt. Brandt was a prolific artillery designer, responsible notably for the Brandt 27/31 81 mm mortar, an evolution of the British Stokes that would, in turn, be adopted, modified, and/or copied by virtually every major and many minor military powers of the 1930s. It is reported two different Carden-Loyds were tested, one of a “light” and one of a “heavy” model. The light one could be outfitted with a machine-gun and used as a small combat vehicle, while the heavier one was tried as an armored tractor with a tracked trailer, with the purpose of carrying the Stokes-Brandt mortar and ammunition.

The Type N program

The trials of the two Carden-Loyd vehicles proved influential in the French Army’s infantry services. On October 7th, 1930, a set of specifications was issued for a new type of vehicle. These would be véhicules blindés de ravitaillement de l’infanterie, or armored infantry supply vehicles. This set of specifications was given the denomination of “Type N” a few weeks later. The Type N specifications requested vehicles with a maximum height of 1.10 m, able to carry a load of 950 kg, typically a mortar or heavy machine gun with ammunition, crewed by two men, able to reach 35 km/h, and with an autonomy of five hours.

Projects from three different companies were ordered to be built as prototypes. The orders covered six prototype vehicles, trailers to be used by these vehicles, as well as larger trailers on which the vehicles could be carried on, towed by a truck. The first company to receive orders was Latil, which produced a design created by Brandt and Vickers-Armstrong, the makers of the Carden-Loyd. The Latil design was very similar to the original British vehicle, and one of the six prototypes was actually imported from Great Britain. The second company was Renault, generally speaking, the giant of the French armored vehicles industry in the era, which produced the UE, a small entirely tracked tankette, obviously inspired by the British Carden-Loyd but still a new design. Finally, Citroën produced the P28, a vehicle far more different from the British tankette that inspired the Type N program

Citroën’s infantry tractor

Citroën’s military vehicles of the 1920s were almost systematically fitted with the Kégresse track system. This system consisted of tracks that, instead of separate metallic interlocked parts, were instead a unitary, flexible belt. It had been created by French engineer Adolphe Kégresse whilst he was based in Imperial Russia, from 1905 onward. In 1919, Kégresse returned to France and was hired by Citroën. From then on, his track systems were featured on a large number of military vehicles, often in a half-track configuration, including artillery tractors and armored cars such as the AMC P16 (designed by Citroën but produced by Schneider) and even some Renault FT light tanks.

The vehicle presented by Citroën to match the Type N specifications was no exception to the rule. It was a small half-track with two wheels at the front used for steering and powered Kégresse tracks at the rear. These had a large front sprocket and a single bogie holding two road wheels as well as a large rear trailing wheel. A notable feature of the Citroën vehicle was that it was crewed by only one man, who sat at the front-left of the vehicle, under an openable 6 mm-thick armored hood with vision hatches on the sides. The engine was to his right; the rear of the vehicle was unarmored and featured a storage bin where weapons or ammunition would typically have been carried. The front of the P28 featured two distinctive round headlights. No armament was fitted, as the vehicle was merely intended to transport arms and ammunition under minimal protection, not to actively fight.

The driver’s hood on prototype 35248. Source: char-français
Photo of prototype 4016-W1, showing the P28’s notable headlights. Source: char-français

The engine used was a Citroën C4 4-cylinder, 72×100 1,628 cm3 engine with an output of 30 hp. This gave it a maximum speed of 39.5 km/h on-road, without a trailer. It should be noted that, when the order for prototypes was placed by the French military, the production of three half-tracked vehicles and three fully tracked ones was requested. The tracked version never left the drawing board and even its design remains unknown as of today.

Unsatisfactory trials

Three prototypes were manufactured by Citroën, registered as 35248, 35249, and 4016-W1. The first prototype began its trials at Vincennes on 24th July 1931 and continued trials there until the 29th. The two other prototypes were delivered to the training grounds along with their trailers on July 31st of the same year. The trailer that had been designed by Citroën was wheeled, unlike the Renault UK trailer of the UE, which was tracked.

Prototype 4016-W1 shown towing the Citroën trailer, and with the side hatch open. Source: char-français
Prototype 35249 with a similar trailer on a platform. Source: char-français

The vehicles generally performed quite poorly during those trials, with complaints being addressed to Citroën. Notably, the vehicle’s cooling left a lot to be desired, with risks of overheating the engine. There was no system for the driver to detach the trailer without leaving the vehicle, which was both impractical and potentially dangerous under fire. The French Conseil Consultatif de l’Armement (Consultative Council of Armament) was pushed to make a choice between the different vehicles in October 1931. While its trials had not been without flaw either, the more conventional Renault UE was adopted by the French military, cutting short the P28’s life as an infantry tractor, though not as a military vehicle in general.

Conclusion – a future in the cavalry

Despite the rejection of the Citroën P28 infantry tractor, it did see further evolution thanks to interest from the cavalry, which considered the vehicle’s potential evolution into a light reconnaissance armored car, leading to at least one of three prototypes being converted to mount a turret instead of the storage bin, and the order of 50 armored car variants of the P28 featuring a centrally-mounted turret in October of 1931.

As for the infantry tractors prototypes, their fate beyond 1931 is unknown. It is quite likely they ended scrapped, if not by the French in the 1930s, then by the German occupiers during the Second World War.

Whilst Citröen’s proposals were not adopted, they remain the most original vehicles offered to the French Army as part of the Type N program. In comparison, the Latil-Brandt vehicle was little more than a copy of the original Carden-Loyd, and the Renault UE took a lot of inspiration from the British vehicle, particularly suspension-wise.

Illustration for the Citroën P28 tractor, created by Andrei ‘Octo10’ Kirushkin and funded by our Patreon campaign

Sources

Tout les blindés de l’armée Française 1914-1940, François Vauvillier, Histoire & Collections éditions,
char-français.net
Les matériels de l’armée Française: Les automitrailleuses de reconnaissance, Tome 1, l’AMR 33 Renault, François Vauvillier, Histoire & Collections, 2005

Categories
WW2 French Prototypes

AMX-40

Nation Flag IconFrance (1940)
Cavalry tank design – None built

The Char de Bataille AMX-40 modèle 1940, more famously known as simply the AMX 40, is one of the numerous French tank designs which were created in the 1930s and 1940s, but never went past the drawing board, either due to not garnering enough interest, or the unfortunate interruption caused by France’s military woes in 1940. AMX’s cavalry tank project is arguably one of the most famous of those designs, largely due to its appearance and distinct look in a popular video game.

Christie and Cruiser influences

One of the most important trends in worldwide 1930s tank design was the Christie suspension. This system made use of very large road wheels which moved vertically on bell cranks. One of its main advantages was that it enabled very high speeds in tanks and potentially allowed for convertible drive, which allowed the tracks to be removed. Christie-type suspensions were experimented on by a variety of designers in the 1930s, the British and Soviets being the most extensive users of the system with tanks such as the BT-2, BT-5, BT-7, Cruiser A13 Mark I and Mark II.

France was not one of the first countries to experiment with Christie designs, mostly due to French tank designers preferring suspensions which enabled greater cross-road capacities, even at the expense of speed. Nonetheless, Christie suspensions were considered to an extent. A Christie chassis is known to have been trialed in front of the Commission de Vincennes in March of 1938. Later, in April of 1939, there were some exchanges between the French and British technical services, including on the subjects of tanks. Some of the more modern British tanks of the time were the A13 Mark I and Mark II cruisers. Those designs, using Christie-type suspensions, offered faster maximum speeds than French cavalry tanks designs, with 48 km/h. The only French tracked vehicles that offered a better maximum speed at the time were the AMR 33 or AMR 35 reconnaissance light tanks/tracked armored cars, which could only bring to bear a 7.5 mm or 13.2 mm machine gun in a one-man turret, while the A13s featured the potent 2-Pounder 40 mm anti-tank gun in a 3-man turret. Those designs had some considerable influence on Joseph Molinié, chief engineer of the fairly young AMX design bureau, a state-owned tank manufacturer born out of the nationalization of Renault’s tank producing services in 1936.

The AMX 40 project

The influence of the Christie and Cruiser designs pushed the AMX design bureau to make plans for a vehicle that combined these features with some more commonly found in French, but not British designs, such as, notably, a cast construction. The result was the AMX 40, a design presented on 4th March 1940, which could be summed up as the meeting between the British Cruiser tank concept and French industrial techniques. AMX hoped the proposal could potentially become a replacement for the S35/S40 cavalry tanks manufactured by Somua & cie, a subsidiary of Schneider.

Basic characteristics

The AMX 40 proposal was a 16-ton cavalry tank, which featured a 3-man crew, a commander/gunner and a loader in a 2-man ovoid turret, and a driver in a centrally placed driving post. The vehicle would have had a length of 5.33 meters, a width of 2.45 m, and a height of 2.37 m (1.58 m without the turret). The hull, without the suspension, was 2.03 m wide. The vehicle made use of cast construction and featured, as main armament, the 47 mm SA 35 anti-tank gun, featured in a large variety of French tanks of the late 30s, such as the Somua S35 and S40, the B1 Bis, or the second production run of the Renault D2.

Hull design

The AMX 40’s hull used cast construction. In comparison to most other tanks of the era, it had a much rounder shape, which was interrupted by the central driving post. This post featured a large openable hatch, which could be opened to provide vision when outside of combat. In combat, three episcopes, one in the center and one on each side, would provide vision for the driver. To his right was the ammunition stowage for 7.5 mm drum magazines, and to his left batteries and storage.

A top view of the AMX 40’s hull arrangement; the driver sat in a central driving post, in front of the ovoid turret. Source: Archives de l’Armement, Châtellerault

The tank would have been steered via a steering wheel. One of the various unusual features of the AMX 40 would have been a Robin-Van Roggen continuously variable transmission, an automatic transmission system without individual gears. This transmission was installed on the rear left of the hull, behind the engine. The AMX 40 was, as designed, powered by a 4-cylinder Diesel Aster engine which produced 160 hp at 2,000 rounds per minute, though a larger and more powerful Aster Diesel which had 6-cylinders and would produce 220 hp was considered to replace this first engine. This engine was also installed on the hull’s left-side, with the air filter and radiator on its right; to the right of the transmission, was the tank for engine oil. The exhaust was on the transmission’s left.

A cutaway view of the AMX 40’s engine arrangement. Note the fuel tanks on the hull sides. Source: Archives de l’Armement, Châtellerault

The diesel fuel tanks of the vehicle were installed in the hull sides. As the diesel fuel used by the vehicle was less flammable than ordinary fuel, they were thought of as potentially increasing the tank’s protection to a small extent. The armor of the AMX 40’s hull was 60 mm thick at the front, 50 to 30 mm on the sides with additional 15 mm sponsons, and 40 mm at the rear. The use of cast and heavily sloped armor meant that, unless projectiles hit the driver’s post, they would strike the vehicle on sloped armor, heavily increasing the armor’s effectiveness.

The AMX 40’s fuel stowage arrangement, with diesel in the two front side fuel tanks, and engine oil in the rear one. Source: Archives de l’Armement, Châtellerault

In front of the engine compartment but behind the turret, the AMX 40 featured a radio, of which the exact model is unknown. Another very odd feature, the hull-mounted anti-aircraft machine-gun, was mounted in this area of the tank.

Suspension

The AMX 40 project featured a model of suspension based on the Christie design. At the rear of the suspension was the drive sprocket, and at the front, an idler wheel. The suspension featured four large road wheels per side, which had a diameter of 82 cm. Considering their size, there was no need for return rollers.

As with several Christie designs, the AMX 40 was meant to be able to continue operating in the event of a broken track. To this extent, the first two road wheels were driving wheels which could be rotated to an extent, while the two rear wheels were motor wheels.

Most of the suspension was protected by 15 mm-thick side skirts, which would only have left the bottom of the roadwheel, the front of the tender wheel and the rear of the drive sprocket visible.

A view of the AMX 40’s suspension design. Source: Archives de l’Armement, Châtellerault

As a cavalry/cruiser tank, the AMX 40 was planned to reach quite high speeds, with 45 to 50 km/h on-road being the goal. However, with a horsepower of just 10 hp/t with the first Aster diesel engine, whether or not such a maximum speed could be reached is quite questionable.

Turret design

A view of the AMX 40’s turret design. Source: Archives de l’Armement, Châtellerault

Like the hull, the turret of the AMX 40 had a cast construction. It had an egg-like shape, with the rounded gun mantlet sticking out at the front. This turret was meant to house two men. To the left of the gun, the gunner (who also assumed the role of commander), and to the right, the loader. They were sitting on a strap that rotated with the turret. Though a two-men turret was a quite commendable feature for French designs, which massively used ergonomically catastrophic one-man turrets in the 1930s, the small diameter of the turret ring, with just 90 cm, would likely have made this turret quite cramped.

The turret featured a hydraulic rotation system commanded by a handle in the turret. The tank for the liquid used for this system was located in the rounded top of the turret. There was a single vision source for the turret, a panoramic telescope installed on top of the turret. The two openings on the side of the turret were for the tank’s optical rangefinder. The right opening housed an optical sight which would have allowed for a field of view of 50°, whereas the left opening housed a telemetric sight which would have allowed for a field of view of 15°.

A top view of the AMX 40’s turret sight arrangement. Source: Archives de l’Armement, Châtellerault

The turret featured a 60 cm wide round hatch on the rear, which could serve to evacuate the vehicle. It may have also allowed the commander to sit on it when opened, and look out of the tank. The turret was protected by 60 mm of armor all around and, as with the hull, its cast construction made it heavily angled, which could have further increased its effective armor.

Armament and ammunition stowage

The main armament of the AMX 40 was a 47 mm SA 35 anti-tank tank installed centrally in the turret, which had a maximum depression of -14° and elevation of +18°.

The standard issue shells for the 47 mm SA 35 were the Obus de rupture modèle 1935, and the obus explosif modèle 1932, both 47×193 mmR.

The Obus de Rupture modèle 1935 was an armor-piercing capped (APC) shell. It weighed 1.62 kg, and had a muzzle velocity of 660 m/s. German testing of the shell showed an armor penetration of 40 mm at an incidence of 30° and a range of 400 m. This was far superior to the penetration capacities of the SA 34.

The Obus explosif modèle 1932 was a high-explosive (HE) shell. It weighed 1.41 kg, including 142 grams of explosives, and was fired at a muzzle velocity of 590 m/s.

A view of the 47 mm SA 35 gun used on the AMX 40 as well as B1 Bis, S35 and second-series D2. Source: http://www.dws-xip.pl/encyklopedia/brpoj47sa35-fr/

The AMX 40 also featured a coaxial machine gun, which, as with the vast majority of French tanks of the era, was a MAC 31E machine gun. It used the standard 7.5×54 mm French cartridge. The MAC31 Type E had a weight of 11.18 kg empty and 18.48 kg with a fully loaded magazine, those being 150-rounds drums. The machine gun was gas-fed and had a maximum cyclic rate of fire of 750 rounds per minute. It had a muzzle velocity of 775 m/s.

The AMX 40’s hull-mounted anti-aircraft machine gun, of very questionable practical use. Source: Archives de l’Armement, Châtellerault

One of the vehicle’s odder features, a retractable anti-aircraft 7.5 mm machine gun, most likely the MAC 31E, though the MAC 34 aircraft machine gun is sometimes mentioned instead, was also placed behind the turret. This machine gun would emerge behind the turret, and be used against aircraft to the rear of the vehicle. Though it did feature an anti-air sight, the usefulness of this machine gun in practice is very much questionable: its firing arc was to the rear only, and to operate it, one of the three crewmen would have to leave his post. Though an anti-aircraft mounted on the top of the turret would most likely have been far more effective, with no hatch on top of the turret, this would not have been practical either.

A top view of the AMX 40’s internal arrangement, showing the 47 mm ammunition stowage in the periphery of the turret. To its rear, the two 36-rounds racks, to its front in the center, the collapsing 30-rounds rack, and on the sides, the two 10-rounds racks. Source: Source: Archives de l’Armement, Châtellerault

The AMX 40 had two circular racks for 36 rounds each on each side of the hull, behind the turret and in front of the radio and anti-aircraft machine gun. Another ammunition rack for 30 rounds was located just behind the driver’s seat and could be collapsed for easier access from the turret. Two small racks of 10 shells each were located in the hull, in front of the turret, and to the sides of the collapsing rack. This gave the vehicle a total 47 mm ammunition stowage of 122 rounds, none of which were stored within the turret itself.

As for 7.5 mm ammunition stowage, 4 150-round drum magazines were present in the turret, on the side, and to the front of it. In the hull, to the right of the driver, was a rotating chain mechanism that could contain 30 drum magazines. This chain would be rotated as magazines were taken from it, in theory allowing for constant access to new magazines, though the need for such a system was questionable. With 34 150-rounds drum magazines carried, the AMX 40 had 5,100 7.5 mm cartridges at its disposal.

A project which did not go anywhere

The AMX 40 is often said to have been planned as the replacement to the Somua S35 and S40 tanks. This statement ought to be tempered to an extent. It is quite clear that, with the design of a cavalry tank such as the AMX 40, the state-owned tank manufacturer wanted to compete with the privately-owned Somua to provide a cavalry tank for the French Army. However, the AMX 40 was presented in March of 1940, mere months before the fall of France, and by June of 1940, it appears the project was still far from being considered for prototype production. The fall of France would result in a large number of projects being canceled, though the design of new French armored vehicles would continue both openly and covertly, with vehicles such as the Panhard 178 CDM, CDM Armored Car or SARL 42 on the covert side, or improvements of the Somua S40 on the more official side.

The plans of the AMX 40, the main source of information on the project. Source: Archives de l’Armement, Châtellerault.

Errors with the AMX 40 in World of Tanks

As it is, the AMX 40 was a short-lived cavalry tank project which, while it did include some unusual and interesting features, did not go anywhere near even prototype production, and as such would most likely have remained fairly ignored. This, however, changed drastically when Wargaming’s popular online game World of Tanks (WoT) added French tanks as part of its 7.1 update in January of 2012, with the selection of vehicles added including the obscure AMX cavalry tank project.

An old screenshot of the AMX 40 as the players unlocks it: armed with the ahistorical 47 mm SA 34 gun. Source: http://forum.worldoftanks.com/index.php?/topic/559188-lets-argue/page__st__20

The AMX 40, as it is featured in WoT, is in several ways inaccurate. When first unlocked, while the vehicle features its original turret, it is armed with the 47 mm SA 34, a much less potent predecessor to the SA 35, which was mounted in several tanks of the mid-1930s, such as the B1 or first series D2, but was long out of consideration for any new designs years before 1940. The historically accurate 47 mm SA 35 can then be researched. In-game, the armament of the AMX 40 can be upgraded even further though. The original ovoid turret design can be replaced by a new turret that the game calls the “Renault Balland”. This is, in fact, the turret design of the Renault G1R, a medium tank project which reached the mock-up stage, and of which a prototype was to be assembled in the summer of 1940. This turret, however, was a very particular design. The gun mount’s weight was laid on the hull itself, with the mount going to the bottom of the hull, its weight not laying on the turret itself. It is unlikely such an unusual turret design could have been fitted on the AMX 40 without extensive modifications. This is even more noticeable due to the fact that this turret is simply too large for the AMX 40 hull, with some considerable overhang on the side of the driver compartment. When first unlocked, this turret mounts the 47 mm SA 35, though it can later be armed with a 75 mm gun called the “SA 32”. While the turret does follow the historical path of the G1R turret, with evolved from a 47 mm to a 75 mm main armament (as well as from a two-machine gun to a one machine gun commander cupola), the use of the “SA 32” designation for a 75 mm gun is questionable.

The “Renault-Balland” turret with the 75 mm “SA 32” gun. This screenshot is from an older version, the gun having since been modified to look more similar to its appearance on the actual G1R turret mock-up. Source: https://www.youtube.com/watch?v=g-x6K-iIxUE
The new look of the 75mm-armed AMX 40 since update 9.22, with a gun more truthful to the actual G1R, though whether or not its turret could have been mounted on the AMX 40 is highly questionable at the very least. Source: https://thearmoredpatrol.com/2018/01/11/amx-40-coming-to-hd-in-patch-9-22/
The actual G1R design with the turret that Wargaming mounted on the AMX 40. Source: char-français

Among other inaccuracies present in WoT’s AMX 40 is the engine. The Aster engine the vehicle starts with produces 150 hp, instead of 160 hp. While a historical option for an engine upgrade, the only historically accurate potential upgrade for the AMX-40, exists in the form of the 220 hp Aster engine, Wargaming instead went with a 190 hp “Somua LM” engine. In-game, the AMX 40’s poor engine power translates to very poor mobility, with the tank struggling to reach 20 km/h on even ground. Though the 45/50 km/h maximum speed hoped by its designer was certainly optimistic, this remains a surprisingly low speed for a tank meant for cavalry duties.

Conclusion – an obscure project rendered famous by gaming

The AMX 40 is, as it was historically, a fairly obscure project, which only existed for three months, and as such never really went far at all in its development. It did feature a considerable number of odd and sometimes innovative features. Its cast construction took the general lack of hard angles and use of sloped surfaces on French vehicles to a new level, and its two-man turret was quite significant for a French cavalry tank below 20 tons, though by the time the tank would realistically have entered service if adopted, in 1941 or even 1942, its armament would most likely have been quite lackluster, and the hull’s ability to mount a larger turret was doubtful due to its design.

The vehicle entered a second life due to its introduction in the popular video game WoT, being generally laughed at, though at the same time viewed with affection by the community. This newly-found relevance of the vehicle may also make it confusing, as another project which went much further bears the name of AMX-40 – a major evolution of the AMX-30 MBT offered as an export tank in the 1980s, mounting a 120 mm gun and many system which are now featured in the Leclerc. Though a prototype of the modern AMX-40 remains in Saumur, all that has survived of the WW2 project are the plans.

Illustration of the AMX-40, created by Pavel ‘Carpaticus’ Alexe and funded by our Patreon campaign

AMX-40 specifications

Dimensions (l x w x h) 5.33 x 2.44 x 2.37 m
Hull width without suspension 2.03 m
Weight 16,000kg (estimated)
Engine Aster 4-cylinders diesel producing 160hp at 2,000 rpm; Aster 6-cylinders diesel producing 220 hp considered.
Maximum speed 45 to 50 km/h (estimated)
Power-to-weight ratio (in hp/ton) 10 (Aster 160hp)
Transmission Robin Van Roggen continuously variable transmission
Fuel Tanks 400 liters
Average hourly fuel consumption 17 liters per hour
Range < 500km
Suspension Christie
Crew 3 men (Commander/gunner, loader, driver )
Armament 47 mm SA 35 main gun (122 rounds), coaxial MAC 31E machine gun, hull-mounted MAC 31E or MAC 34 anti-aircraft machine gun (5,100 7.5 mm rounds)
Optics Panoramic telescope, telemetric & optical sight (turret); episcopes (hull)
Armor 60 mm on the turret & hull front, 50 to 30 + 15 mm on the hull sides, 40 mm on the hull rear

Sources

Tous les blindés de l’armée Française 1914-1940, Histoire & Collection editions, p 118
Char-français
Plans from the Archives de l’Armement via mémoire des hommes

Categories
WW2 French Prototypes

Char de Bataille SRB

Nation Flag IconFrance, 1921-1925, Experimental infantry tank – 1 prototype

One of, if not the most famous French tanks of the Second World War was the B1 heavy tank and its improved model, the B1 bis. These large infantry tanks were some of the most heavily armed and armored tanks that existed in the world during the late 1930s. While their production only started in the second half of this decade, they had roots going back as far as 1921, with the Char de Bataille program that started a search for a medium, well-armed tank to fill in the void between the small and numerous Renault FT and the gigantic and rare FCM 2C tanks. Within the proposals offered to this program was one designed by the tank and artillery manufacturer Schneider, in collaboration with the motorized vehicle giant Renault: the Schneider-Renault B, or SRB.

Estienne and the Char de Bataille

Arguably the most important figure of the first years of French tank development was general Jean Estienne. Nicknamed the “Father of Tanks” in France, Estienne, a major proponent of the use of armored vehicles from 1915 onward, was named the director of the AS (Artillerie Spéciale – Eng. Special Artillery), the French armored force, in September of 1916. It is largely thanks to his intervention to the Grand Quartier Général, France’s general headquarters, that the FT light tank reached mass production. Estienne was also a proponent of the Schneider CA1, the first French tank to see service.

Superstructure of Schneider CA1 tanks being manufactured in Le Creusot, December 2 1916. The first French tank to see service, the Schneider CA1 had a production run of 400. It used a 75 mm howitzer on the front-right of the hull and two 8 mm mle 1914 Hotchkiss machine guns in a side-mounted ball mount. The Schneider CA1 was a quite primitive tank design and performed quite poorly in its first combat operation in April of 1917 (though that was also due to a still primitive and untested use of the vehicle), but remains a key vehicle in the development of France’s tank forces. Source: Fonds Académie Bourbon

At the end of the war, Estienne continued in his role as the leading figure of French armored development. He was still at the head of the AS, which was attached to the French infantry and renamed the Subdivision des Chars de Combat (Eng: Combat tank subdivision), and he was also named Inspecteur des Chars de Combat (Eng: Combat Tank Inspector). In this position, Estienne had large amounts of power over the future development of French armored technology. With the French military having large quantities of largely effective light tanks thanks to the mass production of the Renault FT, and with the development of large tank already underway at FCM since 1916, with the FCM 1A and then FCM 2C super-heavy tanks, what the French military lacked in his view was an intermediate vehicle between the dwarves and the giants. A ‘Char de Bataille’ (Eng. battle tank) was desired, thought of as a vehicle of medium weight that would feature a fixed 75 mm gun able to engage enemy fortifications and positions and to move through the devastated terrain typical of trench warfare in an artillery-saturated battlefield. Estienne thought the type would offer the ideal compromise, mounting an armament capable of knocking out enemy fortifications and trenches, something the FT’s armament of either a machine gun or a 37 mm gun struggled with while being vastly more reasonable and easier to mass-produce than a monster the size and weight of the 69-tonne, 10-meter long 2C. If successful, the Char de Bataille would have eventually become the workhorse of France’s armored force.

The Char de Bataille program and the Estienne agreements

In 1921, Estienne gathered five of the largest French industrial companies: Schneider, Renault, FAMH/Saint-Chamond, FCM, and Delaunay-Belleville, and gave them the requirements of the Char de Bataille which he requested them to design. The vehicle was to have a weight of 13-tonnes, and feature a hull-mounted main gun: either a 75 mm howitzer with a muzzle velocity of 350 m/s or the higher velocity 47 mm mle 1902 naval gun, with 750 m/s muzzle velocity. The tank was to have a turret armed with either one or two machine guns. It was to have a power-to-weight ratio of at least 8 hp per ton and be able to run for 8 to 10 hours. The armor was to be 25 mm thick.

Most importantly, the program was not planned to result in the immediate adoption of the product that answered to the specifications the most. The plan was that, once the prototypes were produced, the most interesting features from each would be taken to then be featured in a new tank design that would not be the property of a company, but of the state. The objective of such a move was to reduce competition and encourage the manufacturers to innovate without the risk of a yet not entirely mastered concept leading to the refusal of a proposal. Once the vehicle that combined the best features of each proposal was adopted, each of the manufacturers involved would play a part in the production. This original policy was named the Estienne agreements.

Schneider-Renault Collaboration: Common features, separate designs

While FAMH and FCM went to design and build their own prototypes in complete independence from other firms, Schneider and Renault decided to collaborate to produce two different prototypes. This collaboration mostly consisted of some major elements of the prototypes being shared by both: notably the turret, designed by Schneider, and the powerplant, designed by Renault.

The design of the vehicles and their manufacturing outside of those two major elements, though, remained independent. The second prototype, the SRB, was designed and manufactured by Schneider in its facilities of Le Creusot, in Burgundy, while the SRA was produced by Renault in Billancourt, in the western suburbs of Paris (the SRA is even known to have had an internal designation code, Renault JZ). Still, the hulls of the vehicles in their design appear to be almost identical, though some significant differences exist in the suspension and armament that were fitted to those hulls.

The SRB: Bearer of advanced features

The overall shape of the SRB’s hull was remarkably similar to its SRA sibling, taking the shape of a mostly rectangular vehicle, with two front plates angled backward, the driver’s vision port being featured on the higher one. The first major difference between the two designs was the gun mounted to the right of the vehicle. While the gun mount was identical on both vehicles, the SRB, instead of a short 75 mm howitzer, mounted a 47 mm model 1902 naval gun, a weapon originally designed as an anti-torpedo boat weapon mounted on many French ships of the early 20th century.

A side view of the SRB prototype, showing the vehicle’s hull-mounted 47mm gun. Source: char-français

This weapon was present as an alternative to the 75 mm in the requirements formulated by Estienne, however, all other manufacturers opted for the 75 mm option, which may have appeared as a better option in the anti-fortification role the Char de Bataille was designed for. The 47 mm, however, offered a better velocity than the 75 mm. 750 m/s is generally quoted as the muzzle velocity of the SRB’s gun, which would suggest some modifications to the weapon, as the standard version is known to have had a muzzle velocity of 690 m/s. This was in any case superior to the 350 m/s of the 75mm howitzer. The gun had a semi-automatic action, giving a maximum rate of fire of 15 rounds per minute. While it is likely this would have been lower in the constraints of an armored vehicle, the 47 mm gun retained a better rate of fire than the 75 mm. It also had some decent anti-armor capacity. With the Obus de rupture acier mle 1911 G armor-piercing shell, it could reportedly penetrate, at an incidence of 30°, 40 mm of armor at 500 m, and 30 mm at one kilometer. Whether or not mounting the 47 mm on the SRB was intended to give the vehicle anti-armor capabilities is not known. A problem that has been suggested with the 47 mm’s quite long barrel is that it could possibly hinder the SRB’s crossing capacities, as the barrel extended beyond the hull.

As on the SRA, the mounting of the gun to the right of the hull on the SRB left a great deal of space for the driver. The SRB featured two large hatches on the side of the hull. In comparison to the SRA’s hatches, the SRB’s appeared to be taller, more rectangular, and less square-shaped. The suspension of the SRB is not known in as much detail as its SRA sibling, but it is known to have made use of leaf springs. 14 small wheels can be counted on the bottom of the vehicle. The SRB had a front-drive sprocket and rear idler wheel. The suspension was at its highest point in front of the side hatch of the vehicle. Unlike the three other prototypes, which used wooden pads track with a considerable pitch, the SRB used metallic tracks inspired from the Renault FT’s, which each pad directly linked to the other. The armor of the vehicle was 30 mm at its thickest, on the vehicle’s front. This was an impressive amount for 1925. The SRB was 6 m long, 2.50 m wide and 2.38 m high, making it the longest of the four Char de Bataille prototypes. The ground clearance was 0.41 m, and the tank had a weight of 19 tonnes.

A view of the SRB at a slightly different angle, with the side hatch open. Source: Tank archives

The engine, which was designed by Renault, was a six-cylinder one based on a bisected 12-cylinder aircraft engine. It produced 180 hp at 1500 rpm. This was 60 hp more than the Panhard 120 hp engine used on the FAMH and FCM. Despite being the heaviest tank in the competition, at 19 tonnes, the Schneider-Renault prototypes also had the highest power-to-weight ratio, with 9.5 hp/tonne. The SRB consumed 20 to 35 liters of fuel an hour, and its fuel tanks contained 370 liters, giving an average range of about 125 km. The tank had a maximum speed of 18 km/h on a road and could cross a 2.50 m gap. The transmission was at the rear. Arguably the most advanced feature of the SRB laid within its transmission. The vehicle had been fitted with a Naeder hydrostatic system. The purpose of this system was to allow for precise neutral steering of the hull in order to point the hull gun, which had no lateral traverse in its mount. It consisted of a system that received the movement of the engine and used it to move a fluid (a form of castor oil), sucking it in or out. This was used to operate slow and precise movements of the tracks in order to aim the hull. The hydrostatic system was used thanks to a steering wheel the driver/gunner of the vehicle could use. It allowed for very precise movement but also required the use of both castor oil and regular oil (as the engine was used & it was also necessary to heat up the castor oil at a proper temperature).

The turret featured on the SRB as well as the SRA was of Schneider design. This was a cast design, a particularly modern feature for the early 1920s, with an inclined roof, being at its highest at the rear. The turret had a turret ring diameter of 95 cm, weighed 700 kg, and was armed with two Hotchkiss mle 1914 8×50 mm Lebel machine guns. The crew of the SRB consisted of three, with the commander sat in the turret. The turret was mostly a command post, and the purpose of its armament was to defend the tank against enemy infantry, while the hull gun would engage static fortifications. The driver sat to the left of the hull, and also operated as the hull gunner, which made him quite overtasked. The loader sat behind the 47 mm gun, on the right side of the hull.

Trials: The best impressions

The SRB prototype was trialed along with the three other Char de Batailles starting in Rueil, from May of 1924 to March of 1925. It should be noted that it was tried with a supply trailer designed by Schneider, which had a weight of one tonne and could carry 800 liters of fuel and seat eight men. This was a forerunner to a Schneider trailer which was offered and used on the first B1s in the 1930s.

The SRB prototype towing the supply trailer during the trials, with the side hatch open. Source: Tank archives

The SRB is generally considered as the vehicle which performed the best during those trials. The internal configuration, which it shared with the SRA, with the hull gun pushed to the right of the hull, left the driver/gunner considerably less cramped and more comfortable than on the FCM and FAMH designs. The vehicle’s tracks were also praised. Their metallic and unitary nature left them a lot less worn out than the wooden pad tracks of all other prototypes. Most importantly, the Naedar system featured on the SRB was praised as by far the most effective way of accurately pointing the hull, far superior to the epicyclic transmission used on the SRA.

Conclusion – A deeply influential design on the future B1

Out of all the Char de Bataille prototypes manufactured, the SRB is arguably the one that had the most influence on the future Char B1.

While the SRA may at a first glance seem a little bit more similar to the final product, with its 75 mm hull gun, the SRB’s metallic tracks and Naeder systems were two major features of the B1 which were only featured on the Schneider design. The 47 mm naval gun may perhaps have had some influence as well. The second and third prototypes of the B1, in the early 1930s, were armed with 47 mm naval guns in a fully rotative turret, and the B1 and B1 Bis finally retained the 47 mm anti-tank gun as a feature of their design, albeit replacing the machine gun-armed turret of the Char de Bataille & first B1 prototype, and not the 75 mm hull gun.

The first prototype of the B1, n°101, showing a 47 mm naval gun similar to the SRB’s, but in a fully rotating turret. Source: char français
Illustration of the Char de Bataille SRB, created by Yuvnashva Sharma and funded by our Patreon campaign

Char de Bataille SRB specifications

Dimensions (L x w x h) 6.00 x 2.50 x 2.38 m
Ground clearance 0.41m
Weight 19,000kg
Engine Renault six-cylinder producing 180 hp at 1,500 rpm
Maximum speed 18 km/h
Power-to-weight ratio (in hp/ton) 9
Fuel tanks 370 litres
Average hourly fuel consumption 20 to 35 litres
Range 125km
Suspension Leaf springs
Trench crossing 2.50m
Crew 3 men (Commander/turret gunner, driver/gunner, loader)
Armament 2 turret-mounted Hotchkiss mle 1914 8 mm machine guns, 1 hull-mounted 47mm mle 1902 gun
Armor 30mm maximum

Sources

Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions, p 42-43
GBM N°107 (January-February-March 2014), Histoire & Collections editions, “Les voies difficultueuses du char de bataille”, p 45-46, Stéphane Ferrard
Trackstory N°3 : Les chars B, Editions du Barbotin, p 5-7
Tank Archives: http://www.tankarchives.ca/2016/12/char-b-difficult-beginning.html
Char-français: http://www.chars-francais.net/2015/index.php/engins-blindes/chars?task=view&id=684
Ateliers de Construction de Rueil – Services des Etudes – Char B1 Bis – Notice sur la description et l’entretien des matériels
Wikimaginot (47mm mle 1902 gun): https://wikimaginot.eu/V70_glossaire_detail.php?id=1000280&su=Canon_antichar_de_47_mm_mod%C3%A8le_1902_-_47_mle_1902

Categories
WW2 French Prototypes

Char de Bataille SRA / Renault JZ

Nation Flag IconFrance, 1921-1925, Experimental infantry tank – 1 prototype

One of, if not the most famous French tanks of the Second World War was the B1 heavy tank and its improved model, the B1 Bis. These large infantry tanks were some of the most heavily armed and armored tanks existing in the world during the late 1930s. While their production only started in the second half of this decade, they had roots going back as far as 1921, with the Char de Bataille program that started a search for a medium, well-armed tank to fill in the void between the small and numerous Renault FT and the gigantic and rare FCM 2C tanks. Within the proposals offered to this program was one designed by the industrial giant Renault, with collaboration from Schneider; the Schneider-Renault A or SRA, also known as Renault JZ.

Estienne and the Char de Bataille

Arguably the most important figure of the first years of French tank development was general Jean Estienne. Nicknamed the “Father of Tanks” in France, Estienne, a major proponent of the use of armored vehicles from 1915 onward, was named the director of the AS (Artillerie Spéciale – Special Artillery), the French armored force, in September of 1916. It is largely thanks to his intervention to the Grand Quartier Général, France’s general headquarters, that the FT light tank reached mass production. Estienne was also a proponent of the Schneider CA1, the first French tank to see service.

The assembly sections of Renault’s Boulogne-Billancourt facilities, producing FT light tanks, 1918. The tremendous success of the FT light tank designed by Louis Renault with support from Estienne made the firm a leader of French military development. Source: Renault archives

At the end of the war, Estienne continued in his role as the leading figure of French armored development. He was still at the head of the AS, which was attached to the French infantry and renamed the Subdivision des chars de combat (Eng: Combat tank subdivision), and he was also named Inspecteur des Chars de Combat (Eng: Combat Tank Inspector). In this position, Estienne had large amounts of power over the future development of French armored technology. With the French military having large quantities of largely effective light tanks thanks to the mass production of the Renault FT, and with the development of large tank already underway at FCM since 1916 with the FCM 1A and then FCM 2C super-heavy tanks, what the French military lacked in his view was an intermediate vehicle between the dwarves and the giants. A ‘Char de Bataille’ (battle tank) was desired, thought of as a vehicle of medium weight that would feature a fixed 75 mm gun able to engage enemy fortifications and positions and to move through the devastated terrain typical of trench warfare in an artillery-saturated battlefield. Estienne thought the type would offer the ideal compromise, mounting an armament capable of knocking out enemy fortifications and trenches, something the FT’s armament of either a machine-gun or a 37 mm gun struggled with while being vastly more reasonable and easier to mass-produce than a monster the size and weight of the 69-tonne, 10-meter long 2C. If successful, the Char de Bataille would have eventually become the workhorse of France’s armored force.

The Char de Bataille program and the Estienne agreements

In 1921, Estienne gathered five of the largest French industrial companies: Schneider, Renault, FAMH/Saint-Chamond, FCM, and Delaunay-Belleville, and gave them the requirements of the Char de Bataille which he requested them to design. The vehicle was to have a weight of 13-tonnes, and feature a hull-mounted main gun: either a 75 mm howitzer with a muzzle velocity of 350 m/s, or the higher velocity 47 mm mle 1902 naval gun, with 750 m/s muzzle velocity. The tank was to have a turret armed with either one or two machine guns. It was to have a power-to-weight ratio of at least 8 hp per ton, and be able to run for 8 to 10 hours. The armor was to be 25 mm thick.

Most importantly, the program was not planned to result in the immediate adoption of the product that answered to the specifications the most. The plan was that, once the prototypes were produced, the most interesting features from each would be taken to then be featured in a new tank design that would not be the property of a company, but of the state. The objective of such a move was to reduce competition and encourage the manufacturers to innovate without the risk of a yet not entirely mastered concept leading to the refusal of a proposal. Once the vehicle that combined the best features of each proposal was adopted, each of the manufacturers involved would play a part in the production. This original policy was named the Estienne agreements.

Schneider-Renault Collaboration: Common features, separate designs

While FAMH and FCM went to design and build their own prototypes in complete independence from other firms, Schneider and Renault decided to collaborate to produce two different prototypes. This collaboration mostly consisted of some major elements of the prototypes being shared by both: notably the turret, designed by Schneider, and the powerplant, designed by Renault.

The design of the vehicles and their manufacturing outside of those two major elements, though, remained independent; the second prototype, the SRB, was designed and manufactured by Schneider, while the first, the SRA, was a product of Renault. It even had a two-letters internal designation code, JZ. The prototype was manufactured in Renault’s facilities of Boulogne-Billancourt, in the western suburbs of Paris.

Interestingly enough, two different photos of the SRA’s hull during manufacturing exist, while the production of other prototypes remains a lot more obscure to this day. This notably shows the vehicle’s suspension without the armored skirts that would otherwise hide it, and make the SRA’s suspension the most well-known of all the Char de Bataille prototypes.

The SRA/Renault JZ prototype being manufactured in Boulogne-Billancourt; the suspension still lacks its armored skirts, giving a good look onto its bogies and leaf springs. Source: Tank Archives

The SRA design: A mostly solid proposal

The tank designed by Renault took the shape of a mostly rectangular vehicle, with two front plates angled backward, the driver’s vision port being featured on the higher one. To the right of the hull front, a 75 mm howitzer was fitted but this solution offered no lateral traverse of the gun. It did, however, leave a great deal of space for the driver, who was now more comfortably accommodated than on FCM and FAMH designs. The vehicle featured two almost square-shaped hatches on each side of the vehicle, under the tracks and between the suspension bogies. The armor was 30 mm at its thickest, on the vehicle’s front. This was an impressive amount for 1925. The SRA was 5.95 m long, 2.49 m wide, and 2.26 m high; it had a ground clearance of 0.40 m; the vehicle’s weight was 19 tonnes.

The suspension and tracks were mounted to the side of this hull. Thanks to photos of the SRA during its production, they are a lot more well-known than on other prototypes. The vehicle had a rear-drive sprocket and a front idler wheel; interestingly enough, this rear wheel was mounted higher than the front one, meaning the highest point of the suspension was at the back of the tank. The suspension featured two bogies of six wheels per side, those being mounted on leaf springs. One bogie was in front and one behind the large escape hatch featured at the middle of the hull’s flank. The tracks used had wooden pads with a high track pitch; they were 53 cm wide. The vehicle could cross a 2.50 m-wide gap.

A side view of the SRA prototype during its trial, showing the suspension being higher towards the rear, and the square hatch in the middle of the tank’s hull. Source: char-français

The engine, which was designed by Renault, was a six-cylinder one based on a bisected 12-cylinder aircraft engine. It produced 180 hp at 1500 rpm. This was 60 hp more than the Panhard 120 hp engine used on the FAMH and FCM. Despite being the heaviest tank in the competition, at 19 tonnes, the Schneider-Renault prototypes also had the highest power-to-weight ratio, with 9.5 hp/ton. The SRA consumed 28 to 35 liters of fuel an hour, and its fuel tanks contained 420 liters, giving an average range of about 140 km. The tank had a maximum speed of 17.5 km/h on a road. The transmission was at the rear. It was an epicyclic transmission, which was intended to provide great accuracy in traversing the vehicle’s hull, adjusting for the complete lack of lateral traverse on the gun. The SRA also had hydraulically actuated brake disks.

The turret featured on the SRA as well as the SRB was of Schneider design. This was a cast design, a particularly modern feature for the early 1920s, with an inclined roof, being at its highest at the rear. The turret had a turret ring diameter of 95 cm, weighed 700 kg, and was armed with two Hotchkiss mle 1914 8×50 mm Lebel machine-guns. Out of the three crew members of the SRA, the commander sat in the turret; it was mostly a command post, and the purpose of its armament was to defend the tank against enemy infantry, while the hull gun would engage static fortifications. The driver sat to the left of the hull, and also operated as the hull gunner; the loader sat behind the 75 mm howitzer, on the right side of the hull.

Trials: A good base design with some lackluster features

The SRA prototype was trialed along with the three others Char de Batailles starting in Rueil, from May of 1924 to March of 1925.

Some considerable flaws of the design were made apparent during those trials. Notably, the epicyclic transmission was not effective in ensuring that the SRA’s hull movements were highly accurate, while the lack of traverse of the 75 mm hull gun demanded very precise traverse. The wooden pads tracks, which were a design element shared by all other vehicles except the SRB, ended up being disappointing and promptly worn out as well. In terms of both hull traverse and tracks, the SRA ended up bested by its Schneider sibling, the SRB, which featured the first model of the Naeder hydrostatic transmission/traverse system as well as metallic, FT-based tracks.

A frontal view of the SRA prototype during its trials, showing the opened driver’s hatch, as well as the worn-out wooden trackpads. Source: Tank Archives

The SRA design did have some notable advantages though. The configuration of the main gun being pushed to the right side of the hull made the vehicle far more comfortable for the driver, who was a lot more cramped on the FCM and FAMH designs, particularly the FAMH. While the wooden trackpads were a mediocre feature, the suspension in itself was judged as quite solid. In general, the SRA was one of the more appreciated designs, though the SRB and its advanced Naeder system and metallic tracks brought more novel features.

Conclusion – A forefather to the B1

Of all the four Char de Bataille prototypes trialed in 1924-1925, the SRA, along with its sibling the SRB, was one of the ones which ended up the most influential to the French army’s future infantry breakthrough tank, the B1.

The Char de Bataille during the 1924-1925 trials; from front to back the Schneider-Renault A, the FCM, the FAMH/Saint-Chamond, and an unrelated vehicle, the Renault NC-1 light tank prototype. Not shown on this cut of the photograph is the Schneider-Renault B, leading the column. Source: Tank archives

Most notably, the configuration of the hull, with the gun pushed to the right side, the loader at its rear, and the driver/gunner on the front left, would be the one adopted on the B1, and both vehicles most definitely look related, particularly from the front.

One could argue, though, that the SRA remained overshadowed by the Schneider side of the Schneider-Renault cooperation – the SRB. Indeed, while many of the influential features of the SRA were also present in the SRB – the configuration of the hull was quite similar, notably – the Schneider vehicle featured some advanced elements, particularly the Naeder system, that would be transmitted to the B1. The SRA nonetheless remains one of the most important forefathers of what would become one of the mightiest tanks of France’s army in 1940.

The SRA prototype on the move during its trials, featuring the large frontal headlight on the left of the gun. Source: Tank archives
Illustration of the Char de Bataille SRA/Renault JZ, created by Yuvnashva Sharma and funded by our Patreon campaign

Char de Bataille SRA/Renault JZ specifications

Dimensions (L x w x h) 5.95 x 2.49 x 2.26 m
Ground Clearance 0.40m
Weight 19,000kg
Engine Renault six-cylinder producing 180 hp at 1,500 rpm
Maximum speed 17.5 km/h
Power-to-weight ratio (in hp/ton) 9
Fuel tanks 420 litres
Average hourly fuel consumption 28 to 35 litres
Range 140km
Suspension Leaf springs
Trench crossing 2.50m
Crew 3 men (Commander/turret gunner, driver/gunner, loader)
Armament 2 turret-mounted Hotchkiss mle 1914 8 mm machine guns, 1 hull-mounted 75 mm howitzer
Armor 30mm maximum

Sources

Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions, p 42-43
GBM N°107 (January-February-March 2014), Histoire & Collections editions, “Les voies difficultueuses du char de bataille”, p 45-46, Stéphane Ferrard
Trackstory N°3 : Les chars B, Editions du Barbotin, p 5-7
Tank Archives: http://www.tankarchives.ca/2016/12/char-b-difficult-beginning.html
Char-français: http://www.chars-francais.net/2015/index.php/engins-blindes/chars?task=view&id=684

Categories
WW2 French Prototypes

ARL 37 ‘Char de Rupture’

France(1937)
Heavy tank – none built

The 1930s was a period of rapid re-armament and tank development. Many European nations were focusing on developing and improving their own tank forces, leading to more and more specialized and advanced fighting vehicles. France was not to be left behind, reorganizing part of its defense industry and starting new tank projects. The need for a new French heavy tank was amplified with the start of the construction of the German Siegfried Line, a defensive wall running across the German border with France, vis-a-vis the Maginot line.

This prompted the French Conseil Consultatif de l’Armement (Armaments Advisory Council) on 4th May, 1936, to start a new heavy tank program. The technical requirements for the new tank, named “Char de Rupture 1937” (roughly translating to breakthrough tank), were released on 12th November 1936. The Conseil Consultatif de l’Armement stated the following:

“Char lourd, très protégé et très armé, propre en particulier à être utilisé défensivement et offensivement dans la guerre en région fortifiée”.
(Eng: “A heavy tank, well armored and well-armed, suitable for both defensive and offensive purposes in fortified battlefields.”)

The main focus was the armor and armament. In Char B1 fashion, there were two main armaments, one in the hull and one in a fully rotating turret. The armor was to be able to resist anti-tank cannon fire from as close as 200 meters (220 yards). In addition, the top speed was requested at 30 km/h (18 mph) and a range of 200 km (125 miles) or 10 hours. The total weight was to not exceed 45 tonnes (49.6 short tons)

In the spring of 1937, three French companies presented their designs: AMX, FCM and ARL.

Ateliers des constructions de Rueil

ARL was the only company that had not designed tanks before. In 1935, the Docks de Rueil, originally part of APX (Ateliers des constructions Puteaux) were renamed to Ateliers des constructions de Rueil (abv. A.R.L.) after nationalization. It was also then that the design bureau was created. Located in the suburbs of Paris, the workshop became more famous post-war, with the construction of the ARL 44, yet participated in the design of many other French tanks.

Triplets

Unlike its competitors, which presented the AMX 37 and FCM F4, ARL presented three designs simultaneously, the Variant C, Variant S and Variant V. Every version had different turrets, armaments and layout. It is important to note that blueprints of the rear of the hull do not exist. It is unknown if they were ever made or potentially lost, however, all the existing blueprints are on the armament layout, showing that they were supposed to use the same hull. Ultimately, the engine used and similar details are unknown. All three variants were, speculatively, based on the same hexagonal-shaped hull, with large tracks running over side skirts, similar to the Char B1. In addition, all versions had a flamethrower mounted in the hull, on the right side, to compensate for potential blind spots.

75 mm APX howitzer model 1929

The gun used inside the hull was the 75 mm APX howitzer mle 1929. Originally made for the Maginot Line as a static defense, it was developed from the infamous Model 1897 75 mm howitzer. It was later adapted for use in armored fighting vehicles and used in the later ARL V39 prototype. This gun was also used by the other competitors, FCM and AMX.

Side view plans of the gun mount in the ARL 37 (in this case, Variant C). The driver was also the gunner, as he had to traverse the entire tank to aim the gun, since it only had 5° of traverse. This arrangement was also present on the Char B1. Elevation and depression were better, at +18°/-15°.

Variant C

The most simple (from a mechanical and design perspective) out of the three, Variant C, was very similar to a Char B1 Bis. Besides the hull-mounted gun, a 1-man turret was mounted on the left side of the hull roof. The turret was very similar to the APX-1 turret on the Somua S35 and Char B1 Bis, however, the armor was greatly improved, at approximately 100 mm (4 inches) all around. Inside the turret, a 47 mm SA35 gun was mounted, the same gun as on the Char B1 Bis and Somua S35. The ammunition used would have most likely been the same Obus de Rupture Mle 1935 (AP model 1935) weighing 1.62 kg (3.6 pounds). The entire shell was 325 mm long (13 inches) while the projectile was 145 mm long (5.7 inches) and the case was 193 mm long (7.6 inches). On the Char B1 Bis, the muzzle velocity of the SA35 was 660 to 680 m/s (22 feet per second) with a penetration of 40 mm angled at 30° at 400 m. Variant C carried 106 rounds of ammunition for the 47 mm, 98 in the hull, and 8 in the turret.

It had a crew of four, a driver, responsible for driving the tank, but also aiming and firing the 75 mm gun. Behind him in the hull was the loader of the 75 mm gun. In the turret was the commander, responsible for commanding the tank, spotting targets, loading, and firing the 47 mm gun. This was a common feature of French tanks of the period. At the end of the crew compartment, a mechanic was seated. Quite common on WWI tanks, this position was archaic by 1937 standards. In practice, he would have been in charge of passing ammo up to the commander and fulfilling other, smaller tasks. He would have also been in charge of the radio, of unknown type, yet it is likely to have been the ER-53, used on Char B1s.

Side views of a SA35 gun from a B1 Bis tank. Source: Warspot
Side view of the crew compartment of the ARL 37 Variant C. The thick armor and crew layout can be seen.
Source: Chars Francais
Top view of the ARL 37 Variant C. The similarity to the Char B1 Bis is discernible.
Source: Chars Francais

Variant S

The second design proposed was more complex than the previous, and the plans available are even more scarce. The small turret was replaced with a larger, three-man turret. However, this increased the crew to six men. The turret was cast into a large octagon, still with 100 mm thick sides. In contrast to Variant C, it was equipped with a 47 mm mle 1934 gun, which was also designed for use on the Maginot Line. It fired APX mle 1936 Obus de Rupture (Armor-Piercing High-Explosive, APHE) shells, with a muzzle velocity of 880 m/s and could penetrate 77 mm (3 inch) of armor angled at 30° at 500 m (547 yards) and 56 mm (2.2 inch) of armor at 1,000 m (1,094 yards). The shell weighed 1.670 kg (mock warhead, translation from the French “fausse ogive”) and the charge weighed 610 g. It is hard to tell why two different guns were chosen for different designs.

The main turret had a smaller, rotating pseudo-turret or cupola for the commander. This was equipped with two machine guns, most likely 7.5 mm MAC 31, however it lost the machine gun mounted parallel to the main gun, like in the Variant C. The commander would now stand in this cupola and be able to more effectively scan the environments and engage infantry.

As the crew expanded to six men, the layout changed. The turret now had a designated commander, gunner, and loader. Meanwhile, inside the tank, the driver, loader, and mechanic were the same. The designated gunner and loader would have vastly increased the efficiency of the tank. However, these changes would have made Variant S vastly more expensive compared to Variant C.

Side cutout view of the Variant S turret. While the majority of the turret was still 100 mm thick, the cupola was thinner.
Source: Chars Francais
Top view of the Variant S turret. The much larger size of the turret is obvious, most likely taking much of the space on the hull roof.
Source: Chars Francais

Variant V

The most complex and interesting of the three designs was Variant V. The turret was now unmanned and was equipped with a 47 mm SA35 (same as on Variant C) and two 7.5 mm MAC machine guns mounted coaxially, on each side of the gun. As it was unmanned, it was made much smaller. To aim and fire it, a device was created by Lorfeuvre, that would allow the commander to aim and fire the guns in the turret, and even the 75 mm in the hull, from a dome-like casemate to the right of the 47 mm turret. To cover up the blindspot that was created by the casemate, an additional 7.5 machine gun was added, facing the rear.

The crew was now five men. There was a driver (it is unclear if the 75 mm howitzer could be aimed and fired by both the driver and the commander) and two loaders, one of which was also designated as a mechanic. They shared the task of loading the 47 mm and 75 mm. Despite being unmanned, the turret did not have an autoloader, the technology did not exist in 1937. Rather, the loader was underneath the turret and loaded from there. The commander was located in the dome-shaped casemate and the radio operator was on the right of the tank, “inside” the side skirt in between the tracks.

Cutout side view of Version V. The small unmanned turret and large, dome shaped casemate can be seen. Note the gas canister for the flamethrower in the bottom right.
Source: Chars Francais
Top view of Version V. The crew positions are clear, however how the two loaders (the two men sitting in line behind the driver) operated is hard to tell. Most likely, one passed on the ammunition, while the other loaded. Yet the interior seems roomy, so they could move around more in combat. The location of the radio operator, inside the track side skirts, gives information on the mysterious hull design. Since there was enough space to fit a man inside, it means the suspension most likely used leaf springs. Coil springs would be too large, like in the AMX 37, where the coils took up the whole height of the sideskrit.
Source: Chars Francais

Version V was a very unorthodox design, clearly being expensive and more complex than the other variants. The ARL 37 would have been extremely expensive no matter what, its undoubtedly large size, thick armor, and need for a massive engine would have made this program very expensive, let alone the complex devices needed on the Version V.

Hull

The largest mystery with the ARL designs remains the hull. Since no complete blueprints exist, it is hard to tell how it looked. From the existing blueprints above, we do get a clear image of how the front looked, and that it had small, leaf spring suspension, like many other French tanks of the time. The rear of the hull was never designed, as it included the engine, transmission, and other parts that did not exist and would be subject to change. Nonetheless, the ARL V39, a tank destroyer built by ARL in 1939, is clearly based on the ARL 37 and is a good clue to how the ARL 37 may have looked like.

Yet the ARL V39 was 25 tonnes lighter, had only 50 mm of armor, and used 190/240 hp engines, completely different from the heavy tank. The ARL designs, and the FCM and AMX proposals all “used” non-existent engines. The FCM and AMX designs weighed over 50 tonnes and required two V12 engines of unknown power.

The ARL V39 self-propelled gun prototype. Despite being a good 25 tonnes lighter than the AMX 37, it was inspired from the designs of the AMX 37 and would be a good indicator of how the ARL 37 looked like.
Source: Pinterest

Conclusion

Each variant of the ARL proposal tried to fix larger, underlying issues. Variant C was the “standard” French design, akin to the Char B1 Bis. However, the overworked commander and gunner/driver would have been a huge drawback, as proven on the B1. Variant S tried to fix this, by having a larger, three-man turret. Yet the larger turret proved to be very wide and it did not fix the overworked driver issue. Variant V eased out the work for the driver, however, now the commander had to aim two guns, and still relied on the driver to traverse the tank when aiming the 75 mm howitzer. All in all, it proved that multi-gunned tanks were not a good idea.

Just like the other competitor’s designs, the ARL variants failed. The entire project was deemed too expensive and the tanks could only be produced in small numbers. Logistical and reliability issues might have appeared when building such a large vehicle with engines made from scrap. The weight and size of the ARL variants are unknown, however, they most certainly went over the 45 tonnes mark. A final blow came when the Conseil Supérieur de la Guerre (Eng: Superior War Council) decided on 26th March, 1937 that a much smaller, cheaper yet heavily armored tank would be designed instead. This in turn went south as well, when the Section de l’Armement et des Études Techniques (Eng: Section for Technical and Armaments Studies) made a study which showed that a tank fulfilling those criterias was already under development, and there would not be a need of a new program. This tank was the Char G1.

The ARL 37 would continue to influence the ARL V39 Self-propelled assault gun, and in February of 1938. the requirements of a heavy breakthrough tank changed. Most importantly, the weight restriction was removed. This led to the development of the ARL 39 and ARL Tracteur C super heavy tanks.

ARL 37 Variant C. Note that the appearance of hull is mostly speculative.
ARL 37 Variant S. The significant difference between the SA35 and Model 1934 gun is clear. Observe the cupola with 7.5 mm MGs.
ARL 37 Variant V. The odd dome shaped casemate and the small unmanned turret are what made Variant V such an unusual design.

Sources:

Chars-francais.net
DGA Châtellerault
TNT number 11
Chars De France, Jean-Gabriel Jeudy
Memoiredeshommes.sga.defense.gouv.fr
Wikimaginot.eu
Modernfirearms.net

ARL 37 specifications

Variants C S V
Dimensions (L-H) 7.52 x 2.86 meters 7.52 x Unknown 7.52 x 3.12 meters
Total Weight, Battle Ready 45+ tonnes*

 

Crew 4 5 6
Propulsion Unknown; its competitors used 2x V12 engines
Speed 30 km/h*
Range 200 km*
Suspension Leaf Spring
Armament 1x 75mm model 1929 (11+ rounds)

1x 47mm CA-35 (106 rounds, 98 in hull and 8 in turret.

1x 7.5mm MAC

1x 75mm model 1929 (11+ rounds)

1x 47mm Mle 1934

2x 7.5mm MAC

1x 75mm model 1929 (136 rounds)

1x 47mm CA-35 (114 rounds)

3x 7.5mm MAC (5400 rounds)

Armor 100 mm (4 inch) all around
Total Production 0; partial blueprints only
Categories
WW2 French Prototypes

Char de Bataille FAMH

Nation Flag IconFrance, 1921-1925, Experimental infantry tank – 1 prototype

The B1 and B1 Bis heavy infantry tanks are some of the most famous and popular of all pre-war French tank designs. Those particularly well-armored vehicles, with their dual configuration featuring a turreted 47 mm anti-tank gun and a hull-mounted 75 mm infantry support gun, and sporting tracks going around all of the hull in a fashion reminiscent of WW1-era rhomboid British tanks with massive individual track links, are some of the most peculiar mass-produced tanks of the late 1930s. Despite their serial production only really starting in the second half of the 1930s, the B1 and its improved version, the B1 bis, have roots going back as far as 1921, with the Char de Bataille program. One of the prototypes of this program which had some influence on the final B1 was produced by the company FAMH (Compagnie des Forges et Aciéries de la Marine et d’Homécourt – Company of Marine Forges and Steelworks and of Homécourt), better known under the name of the city where their main facilities were located, Saint-Chamond.

Estienne and the Char de Bataille

Arguably, the most important figure of the first years of French tank development was general Jean Estienne. Nicknamed the “Father of Tanks” (père des chars) in France, Estienne, a major proponent of the use of armored vehicles from 1915 onward, was named the director of the AS (Artillerie Spéciale – Special Artillery), the French armored force, in September of 1916. It is largely thanks to his intervention to the Grand Quartier Général, France’s general headquarters, that the FT light tank reached mass production. Estienne had also been a proponent of the Schneider CA1, the first French tank to see service.

On the other hand, the Saint-Chamond tank, which entered in service soon after the Schneider, was not at all appreciated by Estienne, though 400 would still be manufactured as the père des chars’s control onto tank production was still incomplete by 1915-1916.

A Saint-Chamond tank in its natural state: struggling due to the massive discrepancy between the length of the tracks and of the hull. On paper, the Saint-Chamond may have seemed like a better vehicle than the CA1 – featuring an axial-mounted 75 mm gun, which was not a mere howitzer but a true field gun, a Saint-Chamond model on the first series and the mighty “French 75”, the model 1897, on the late series. However, the vehicle’s tragic cross-country capacity made it mediocre on the battered terrains of WW1. Source: char-français

At the end of the war, Estienne continued in his role as the leading figure of French armored development. He was still at the head of the AS, which was attached to the French infantry and renamed the Subdivision des chars de combat (Combat tank subdivision), and was also named Inspecteur des chars de combat (Combat Tank Inspector). In this position, Estienne had large amounts of power over the future development of French armored technology. With the French military having large quantities of largely effective light tanks thanks to the mass production of the Renault FT, and with the development of large tank already underway at FCM since 1916 with the FCM 1A and then FCM 2C super-heavy tanks, what the French military lacked in his view was an intermediate vehicle between the dwarves and the giants: a “Char de Bataille” (battle tank), thought of as a vehicle of medium weight, that would feature a fixed 75 mm gun able to engage enemy fortifications and positions, and to move through the devastated terrain typical of trench warfare in an artillery-saturated battlefield. Estienne thought the type would offer the ideal compromise, mounting an armament sufficient to knock out enemy fortifications and trenches, something the FT’s armament of either a machine gun or a 37 mm gun struggled with, while being vastly more reasonable and easier to mass-produce than a monster the size and weight of the 69-tons, 10-meters long Char 2C. If successful, the Char de Bataille would have eventually become the workhorse of France’s armored force.

The Char de Bataille program and the Estienne agreements

In 1921, Estienne gathered five of the largest French industrial companies in France: Schneider, Renault, FAMH/Saint-Chamond, FCM and Delaunay-Belleville, and gave them the requirements of the Char de Bataille which he requested them to design. The vehicle was to have a weight of 13-tons, and feature a hull-mounted main gun – either a 75 mm howitzer with a muzzle velocity of 350 m/s, or the higher velocity 47 mm mle 1902 naval gun, with 750 m/s muzzle velocity. The tank was to sport a turret armed with either one or two machine guns. It was to have a power-to-weight ratio of at least 8 hp per ton, and be able to run for 8 to 10 hours. The armor was to be 25 mm thick.

Most importantly, the program was not planned to result in the immediate adoption of the product that answered to the specifications the most. The plan was that, once the prototypes were produced, the most interesting features from each would be taken to then be adapted to a new tank design that would not be the property of a company, but of the state. The objective of such a move was to reduce competition and encourage the manufacturers to innovate without the risk of a yet not entirely mastered concept leading to the refusal of a proposal. Once the vehicle that combined the best features of each proposal was adopted, each of the manufacturers involved would play a part in the production. This original policy was named the Estienne agreements.

The FAMH vehicle: Smooth drive

In the end, four manufacturers would produce new designs for the Char de Bataille program. Delaunay-Belleville offered a previous design of theirs, an enlarged FT with a 37 mm hull gun and a turret, that had little to do with the program’s requirements and was swiftly thrown out of the equation. Schneider and Renault cooperated to produce two joint prototypes of different designs, while Saint-Chamond and FCM produced their own prototypes individually.

The FAMH design was the one that looked the most different from the other three in terms of general shape. While the FCM and the two Schneider-Renault prototypes were generally long, quite narrow and low vehicles, the FAMH was shorter and a lot bulkier, though it technically was not the highest due to the FCM’s high cupola reaching higher than even the FAMH’s turret The Char de Bataille FAMH had a length of 5.20 m, making it the shortest of the four proposed designs, a width of 2.43 m (which did not make it the widest vehicle, though the two wider ones, the Schneider-Renault, were this way because of their tracks and suspension), and a height of 2.40 m. The ground clearance was 0.45 m.

A side view of the Char de Bataille FAMH prototype, showing the shorter suspension and higher hull when compared to the other Char de Bataille prototypes. Source: Tank Archives

Unlike the three other prototypes, which had tracks pretty much going all around the hull, the FAMH vehicle had a much lower suspension, with the hull reaching out on top of it, unlike the other designs in which the hull was as wide at the top as at the bottom. This hull used riveted construction. The armament of the prototype consisted of a centrally mounted 75 mm howitzer, designed by Saint-Chamond (the industrial also being a prolific artillery manufacturer) and featured in a casemate, the only vehicle using such a configuration. The FAMH Char de Bataille also featured a turret designed by FAMH, which used riveted construction as the hull, and was armed with two Hotchkiss modèle 1914 8 mm Lebel machine guns. This turret’s functions were mostly to serve as a command post, and for close defense of the vehicle, with the commander serving in the turret, while the two other crewmen took place in the hull, which featured the vehicle’s main armament, the 75 mm howitzer. The FAMH is also reported to have been able to be armed with a hull machine gun, but this is not apparent on the prototype, and it is unknown from where this weapon would have been firing from.

A front view of the Char de Bataille FAMH, showing the centrally mounted 75 mm gun fitted in a casemate, the driver’s driving post, the riveted construction and the turret of the vehicle. Source: Tank Archives

As with the other Char de Bataille, the FAMH featured armor skirts protecting the suspension. The exact design which was used for the suspension remains unknown. What is known about it, is that it used six pneumatic systems, each weighing 55 kg, and damping springs. The pneumatic controls are known to have made the vehicle require a lot less physical effort from the driver, unlike other vehicles of the program. The track used wooden pads, as on the FCM and Schneider-Renault A prototype. The pitch was also considerable.

Trials – Estienne’s horse

FAMH’s Char de Bataille was trialed along with the three other vehicles in Rueil, starting with their presentation on 13th May 1924.

The Char de Bataille FAMH was powered by a Panhard engine producing 120 hp at 1500 rpm. This was the same engine as on the FCM, however, the FAMH weighed in at 17,000 kg, whereas the FCM had a weight of just 15,640 kg. This made the FAMH the vehicle with the lowest power-to-weight ratio of the four, with 7 hp/ton – 1 hp/ton under the requirements of 8. The vehicle could reach a maximum speed of 18.2 km/h, which actually appears to have made it the fastest of the Char de Bataille, by 0.2 km/h in comparison to the Schneider-Renault B. However, a domain in which the difference between the FAMH and the other vehicles was notable, and not in a good way for Saint-Chamond’s vehicle, was range. With the smallest fuel tank of all designs, at only 230 l, and a medium hourly consumption of 30 liters, the FAMH had a range of only about 75 km, the second-worst. The Schneider-Renault B had a whole 50 km more, with 125 km. Out of the three vehicles of which we know the trench-crossing capacity, the FAMH also had the shortest one, being able to cross a 2-meters wide gap, a consequence of the shorter suspension which did not fully go around the vehicle’s hull. At the same time though, the pneumatic drive of the FAMH considerably reduced the physical efforts of the driver and was quite appreciated.

A rear view of the Char de Bataille FAMH, showing the rear and side ventilation for the Panhard 120 hp engine. Source: char-français

The vehicle’s armament had both issues and advantages. The central mounting of the 75 mm gun proved mediocre for the driver, as it took a considerable amount of space, and made his position quite cramped. At the same time, the central casemate mounting was praised by Estienne. It was judged as perfectly placed, both in axis and height, to fire through the embrasures of enemy fortifications, where a successful shot would inflict the most damage. In general, out of all the Char de Bataille proposals, the FAMH appeared to be Estienne’s favorite.

Conclusion – The rejected favorite

The FAMH prototype was trialed along with the three others Char de Batailles from May 1924 to March of 1925. Its trials underlined some interesting features, mostly regarding the pneumatic controls.

The Char de Bataille during the 1924-1925 trials. From front to back the Schneider-Renault A, the FCM, the FAMH/Saint-Chamond, and an unrelated vehicle, the Renault NC-1 light tank prototype. Not shown on this cut of the photograph is the Schneider-Renault B, leading the column. Source: Tank archives

The FAMH prototype was not the least influential when it came to the development of what would become the B1. Its pneumatic controls and damping springs ended up being featured on the much less obscure heavy tank, giving it some quite light controls for such a heavy machine. The Saint-Chamond 75 mm gun was also retained for the first two prototypes of the B1, though the third vehicle as well as the serial-produced B1 and B1 Bis would not end up using a FAMH 75 mm howitzer.

The final suspension design of the B1/B1 Bis, featuring a large damping spring. Source: Ateliers de Construction de Rueil – Services des Etudes – Char B1 Bis – Notice sur la description et l’entretien des matériels

Nonetheless, the influence of Saint-Chamond’s designs remains fairly limited. For a vehicle that was dubbed Estienne’s favorite, the FAMH Char de Bataille is indeed overshadowed by the two Schneider-Renault prototypes, which laid the basis for the final architecture of the heavy infantry tank, as well as its complex Naeder hydraulic direction system. The fate of the FAMH prototype, arguably the most unique looking of the four Char de Bataille, is unknown, though ending up scrapped appears to be, by far, the most probable theory.

Char de Bataille FAMH specifications

Dimensions (L x w x h) 5.20×2.43x.2.40 m
Ground Clearance 0.45m
Weight 17,000kg
Engine Panhard producing 120 hp at 1500 rpm
Maximum speed 18.2 km/h
power-to-weight ratio in hp/ton 7
Fuel tanks 230 litres
Average hourly fuel consumption 30 litres
Range 75km
Trench crossing 2m
Crew 3 men (Commander/turret gunner, driver/gunner, loader)
Armament 2 turret-mounted Hotchkiss mle 1914 8 mm machine gun, 1 hull-mounted 75 mm howitzer, perhaps 1 hull-mounted Hotchkiss mle 1914 8 mm machine gun
Armor 25 mm maximum

Sources

Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions, p 42-43
GBM N°107 (January-February-March 2014), Histoire & Collections editions, “Les voies difficultueuses du char de bataille”, p 45-46, Stéphane Ferrard
Trackstory N°3 : Les chars B, Editions du Barbotin, p 5-7
Tank Archives: http://www.tankarchives.ca/2016/12/char-b-difficult-beginning.html
Char-français: http://www.chars-francais.net/2015/index.php/engins-blindes/chars?task=view&id=684
Ateliers de Construction de Rueil – Services des Etudes – Char B1 Bis – Notice sur la description et l’entretien des matériels

Categories
WW2 French Prototypes

Char de Bataille FCM

Nation Flag IconFrance, 1921-1925, Experimental infantry tank – 1 prototype

One of, if not the most famous French tanks of the Second World War was the B1 heavy tank and its improved model, the B1 Bis. These large infantry heavy tanks were some of the most heavily armed and armored tanks existing in the world during the late 1930s. While their production only started in the second half of this decade, they had roots going back as far as 1921, with the Char de Bataille program that started a search for a medium, well-armed tank to fill in the void between the small and numerous Renault FT and the gigantic and rare FCM 2C tanks. One of the proposals to this program was created by the manufacturer of the FCM 2C, Forges et Chantiers de la Méditerranée.

Estienne and the Char de Bataille

Arguably the most important figure of the first years of French tank development was general Jean Estienne. Nicknamed the “Father of Tanks” in France, Estienne, a major proponent of the use of armored vehicles from 1915 onward, was named the director of the AS (Artillerie Spéciale – Special Artillery), the French armored force, in September of 1916. It is largely thanks to his intervention to the Grand Quartier Général, France’s general headquarters, that the FT light tank reached mass production. Estienne was also a proponent of the Schneider CA1, the first French tank to see service.

The Renault FT light tank, armed with a 37 mm gun. A very successful industrial venture by Louis Renault, the light tank received extensive support from Estienne and would become the most successful tank of France, and arguably all belligerents, during the First World War. Source: char-français

At the end of the war, Estienne continued in his role as the leading figure of French armored development. He was still at the head of the AS, which was attached to the French infantry and renamed the Subdivision des chars de combat (Combat tank subdivision), and was also named Inspecteur des Chars de Combat (Combat Tank Inspector). In this position, Estienne had large amounts of power over the future development of French armored technology. With the French military having large quantities of largely effective light tanks thanks to the mass production of the Renault FT, and with the development of large tank already underway at FCM since 1916 with the FCM 1A and then FCM 2C super-heavy tanks, what the French military lacked in his view was an intermediate vehicle between the dwarves and the giants. A “Char de Bataille” (battle tank) thought of as a vehicle of medium weight, that would feature a fixed 75 mm gun able to engage enemy fortifications and positions, and to move through the devastated terrain typical of trench warfare in an artillery-saturated battlefield. Estienne thought the type would offer the ideal compromise, mounting an armament capable of knocking out enemy fortifications and trenches, something the FT’s armament of either a machine-gun or a 37 mm gun could struggle with, while being vastly more reasonable and easier to mass-produce than a monster the size and weight of the 69-tons, 10-meters long 2C. If successful, the Char de Bataille would have eventually become the workhorse of France’s armored force.

The Char de Bataille program and the Estienne agreements

In 1921, Estienne gathered five of the largest French industrial companies: Schneider, Renault, FAMH/Saint-Chamond, FCM and Delaunay-Belleville, and gave them the requirements of the Char de Bataille which he requested them to design. The vehicle was to have a weight of 13-tons, and feature a hull-mounted main gun: either a 75 mm howitzer with a muzzle velocity of 350 m/s, or the higher velocity 47 mm mle 1902 naval gun, with 750 m/s muzzle velocity. The tank was to have a turret armed with either one or two machine guns. It was to have a power-to-weight ratio of at least 8 hp per ton, and be able to run for 8 to 10 hours. The armor was to be 25 mm thick.

Most importantly, the program was not planned to result in the immediate adoption of the product that answered to the specifications the most. The plan was that, once the prototypes were produced, the most interesting features from each would be taken to then be featured in a new tank design that would not be the property of a company, but of the state. The objective of such a move was to reduce competition and encourage the manufacturers to innovate without the risk of a yet not entirely mastered concept leading to the refusal of a proposal. Once the vehicle that combined the best features of each proposal was adopted, each of the manufacturers involved would play a part in the production. This original policy was named the Estienne agreements.

The FCM vehicle: Miniature Char 2C

In the end, four manufacturers would produce new designs for the Char de Bataille program. Delaunay-Belleville offered a previous design of theirs, an enlarged FT with a 37 mm hull gun and a turret, that had little to do with the program’s requirements and was swiftly thrown out of the equation. Schneider and Renault cooperated and produced two joint prototypes of different designs, while Saint-Chamond and FCM produced their own prototypes individually.

FCM (Forges et Chantiers de la Méditerranée – Forges and Shipyards of the Mediterranean) was originally a naval shipyard, which became involved in tank production with the FCM 1 heavy tank design that started development in 1916. While it would remain at the prototype stage, the FCM 1 would serve as the basis for the development of the FCM 2C, a 69-tons behemoth. Ordered at first in January of 1918, canceled with the end of the First World War but ordered again by the request of Estienne in April of 1919, albeit only for 10 vehicles, instead of hundreds as originally planned, the FCM 2C took much of FCM’s industrial capacities in the early 20s. The vehicles were completed in 1921, but still received modifications until 1923.

Production of FCM 2Cs at FCM’s factory of La Seyne sur Mer, showing the two turret rings for the forward-firing 75 mm-armed and the rear-mounted 8 mm machine gun-armed turret, the later which would be fitted on the FCM Char de Bataille prototype. Source: Char-français

Therefore, it comes as no surprise that FCM’s Char de Bataille design takes much inspiration and many features from the company’s super-heavy tank design. The turret of the new tank was straight-up the rear machine gun-armed turret of the FCM 2C, which would be armed with a Hotchkiss mle 1914 8×50 mm Lebel machine gun (though the prototype was not outfitted with one). Just like the FCM 2C, the FCM Char de Bataille featured a large engine block protruding from the hull, meaning the turret would only cover the forward firing arc.

Features and trials of the prototype

FCM’s Char de Bataille was trialed along with the three other vehicles in Rueil, starting with their presentation on the 13th of May 1924.

The FCM Char de Bataille prototype, often referred to as “FCM 21” on the Internet, though this designation does not appear to have a historical basis. Source: Tank Archives

The FCM Char de Bataille prototype was a 6.50 meters-long, 2.52 m high, 2.05 m wide tank. It was the longest and highest, but also the narrowest and lightest of the four Char de Bataille designs, though, with a weight of 15,640 kg, it still exceeded the requirements of the program by over two and a half tons. The ground clearance was also the highest, at 0.50 m.

The vehicle was powered by a Panhard engine with an output of 120 hp at 1500 rpm. This was the same engine as the Saint-Chamond prototype, though the FCM’s lower weight meant it had a horsepower per ton ratio of 7.7 hp/ton, almost reaching the requirements of the program. The Saint-Chamond had merely 7 hp/ton, while the two Schneider-Renault featured a more powerful 180 hp engine that gave them both 9.5 hp/ton. This engine allowed the tank to reach a maximum speed of 17.4 km/h, which was quite respectable for early 1920s standards. The FCM had the largest fuel tank of any of the Char de Bataille, 500 liters, though it also had the highest hourly consumption of 35 liters. It had the greatest range of all vehicles, with 175 km. The tank had a suspension of which the exact workings are unclear. It consisted of fifteen small road wheels, with a large front idler and a smaller rear drive sprocket. The suspension was apparently moved by a “Chaîne galle”, a type of mechanical piece usually used in barrages, great at transmitting high efforts at low speeds, which was kept tense by a pneumatic system. The tracks used were inspired by Holt tractor tracks which used wooden pads, with a quite long track pitch. These tracks went all around the hull, as with British rhomboid tanks such as the Mark I and IV. French experience with the CA 1 and particularly Saint-Chamond tanks had shown that tanks with too small of a track run performed far worse in terrain battered by artillery craters.

A side view of the FCM Char de Bataille prototype, showing the 15 road wheels under an armored skirt. Source: CAAPC

The FCM Char de Bataille featured 25 mm of armor. Its main armament was a 75 mm gun located on the right of the hull. Unlike other vehicles, which had the gun in some sort of casemate or mount, the FCM’s gun went straight through the armor plate. Most sources mention a hull machine gun was also featured, though the lack of clear photos of the vehicle’s front makes it hard to confirm that claim. The turret is often claimed to feature two machine guns, but this appears not to be the case as it was taken straight from the FCM 2C, and was of a cylindrical design which would be hard to arm with two forward-firing machine guns. As with other tanks of the Char de Bataille program, this turret was the place from which the commander gave orders to the two other crew members. In combat, the machine gun was to be used mostly to defend the vehicle from enemy infantry. The driver sat to the left of the hull, with the third crewman, tasked with loading the 75 mm gun, sitting to the right; considering the vehicle was the narrowest, it appears the two crewmen sitting in the hull were quite cramped.

Conclusion – A mostly inconsequential design

The trials of the Char de Bataille lasted from May of 1924 to March of 1925. The FCM appeared to have had an unreliable gearbox, and the tracks using wooden pads, used by all prototypes but the Schneider-Renault B, proved to wear down a lot quicker than metallic tracks. Little else is known about the results of the trials.

The Char de Bataille during the 1924-1925 trials. From front to back: the Schneider-Renault A, the FCM, the FAMH/Saint-Chamond, and an unrelated vehicle, the Renault NC-1 light tank prototype. Not shown on this cut of the photograph is the Schneider-Renault B, leading the column. Source: Tank archives

Out of the four Char de Bataille prototypes, the FCM is arguably the one which had the least inspiration taken from for the definitive design, which would become the B1. While the suspension of the final product was mostly inspired by the Saint-Chamond/FAMH, and most of the hull design as well as features, such as the Naeder hydrostatic system allowing for accurate hull movements, were taken from the Schenider-Renault prototypes, the influence of the FCM appears limited to the track-tensioning and clutch systems.

The fate of the FCM prototype beyond the trials is unknown, though the most likely way it ended its life was in a scrapyard.

Char de Bataille FCM illustration, created by Yuvnashva Sharma and funded by our Patreon campaign

Char de Bataille FCM specifications

Dimensions (L x w x h) 6.50 x 2.05 x 2.52 m
Ground Clearance 0.50 m
Weight 15,640 kg
Engine Panhard producing 120 hp at 1500 rpm
Maximum speed 17.4 km/h
power-to-weight ratio (in hp/ton) 7.7
Fuel tanks 500 liters
Average hourly fuel consumption 35 liters
Range 175 km
Crew 3 men (Commander/turret gunner, driver/gunner, loader)
Armament 1 turret-mounted Hotchkiss mle 1914 8 mm machine gun
1 hull-mounted 75 mm howitzer
Possibly 1 hull-mounted Hotchkiss mle 1914 8 mm machine gun
Armor 25 mm maximum

Sources

Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions, p 42-43
GBM N°107 (January-February-March 2014), Histoire & Collections editions, “Les voies difficultueuses du char de bataille”, p 45-46, Stéphane Ferrard
Trackstory N°3 : Les chars B, Editions du Barbotin, p 5-7
Tank Archives
Char-français

Categories
WW2 French Prototypes

CDM Armored Car

France (Vichy Regime) – 1941-1942
Armored Car – 1 prototype completed, 224 other vehicles ordered at various stages of completion by the end of production

A little known armored car design, the Automitrailleuse CDM, or CDM armored car, is one of the most extensive armored vehicle projects undertaken in secrecy, not only from the general public but also from the higher-ups of the manufacturer’s own military. This was a project undertaken by a rogue element of the Vichy Regime’s military that refused to accept the Armistice and prepared to resist a German invasion of the unoccupied southern half of France. The CDM armored car’s production was in full swing by the point the invasion of the Vichy “Free Zone” in November of 1942 put a definitive halt to the secret armament project.

The CDM’s armored vehicles design bureau and its previous works

France’s swift defeat at the hands of the Wehrmacht in May-June 1940 brought down upon the country a harsh armistice, not entirely uncomparable to the one Germany was subjected to at the conclusion of the First World War. The French Army’s size was reduced to a mere 100,000 men, at least in mainland France, with its armored component reduced to 64 Panhard 178 cars vastly weakened by the removal of their 25 mm SA 35 anti-tank gun, and -further studies of armored vehicles design prohibited.

Many within the reduced army of the new “Vichy Regime”, as it came to be called, were far from pleased with the conditions of this armistice. Overwhelmingly composed of personnel already in service in 1940, the Army did not see with a good eye the occupation of France’s northern half and the vast reduction of its capacities. As early as July of 1940, a French colonel, Emile Mollard, created a secret service within the army of the new regime, the CDM (Camouflage du Matériel – Equipment Camouflage). The CDM was originally intended to stockpile as much armament as possible, often instead of surrendering it to the German armistice commission. Its goal was to be able to raise the French Army from 100,000 to 300,000 men in just a few days, which was hoped to be enough to delay German forces long enough for reinforcements from the Western Allies and the colonies to arrive in France. Through late 1940 and 1941, the service stockpiled tens of thousands of rifles and machine guns, and dozens of field artillery, anti-tank and anti-aircraft guns. In the spring of 1941, Mollard sought to expand the CDM’s missions, and entered in contact with engineer Joseph Restany, with the goal of producing 45 turrets for turretless Panhard 178 hulls that the CDM was in possession of. This prospect was successful, leading to the Panhard 178 CDM armored car. In early June of 1941, while the production of those turrets was still in its early phases, Mollard made another request for an armored vehicle to Restany and the armored vehicle production service he was setting up.

An armored car on a GMC truck chassis

In early June of 1941, Emile Mollard and Joseph Restany, along with a number of officers involved in the CDM, met in a conference in the town of Saint-Cyprien, in Dordogne, where Restany was setting up a new workshop for the production of the CDM Panhard 178 turrets. Mollard informed Restany that the CDM had, within its reserve, 225 chassis of 4-wheel drive GMC trucks (the exact model of which sadly is not specified or known) and, upon presenting one to Restany, asked if the production of an armored car based on this chassis could be possible. Upon Restany’s affirmation that it could, Mollard placed some additional but still fairly vague requirements, requesting an armament that could be as heavy as possible, a fully rotating turret, and a rear driving post which would improve the vehicle’s mobility. He then requested Restany and his workshops to get to work on this new project as soon as possible.

In July and August of 1941, while the CDM turrets for the Panhard 178 were yet to be assembled (the first would be completed in October), Restany set up a designing bureau as well as a workshop working on the chassis in Saint-Cyprien. At the same time as the overall vehicle’s design was being created, modifications were done to the chassis in order to make them more suitable to base armored cars on. Those were quite extensive: the rear was shortened by 1.10 m, and the front by 20 centimeters; the rear wheels were brought forward by about 1.10 m to reduce the wheelbase; the frontal radiator was lowered, as well as the ventilator; modifications were made on the direction, brake controls, the original carburetor was replaced by a smaller one; and the traction hook was moved, among others.

Design of the CDM armored car

Most of the designing work done by Restany and his team was performed in the summer of 1941. The vehicle they came up with had a mostly rectangular armored body, with a visible radiator and two headlights at the front, typical of armored cars manufactured on truck chassis. The hull had a door on each side and two frontal hatches that could be opened for better vision, or closed in combat. The two front wheels had no cover, while the upper half of the rear wheels was covered. The vehicle had a rear driving post which made it easier for the armored car to leave a position if located by enemy forces, though the speed of the vehicle in reserve or going forward was unknown. Details on the engine are scarce, but it appears to have had 75 hp one. The vehicle had a fully rotating hexagonal turret quite similar in shape to the pre-armistice APX 3 mounted on Panhard 178s. This turret had a top hatch and a rear door, and two viewports on the side. A number of different armaments were to be mounted in this turret, with three different configurations being planned. The production process of such a vehicle, especially in the context of high secrecy, required a number of different workshops which were all overseen by Restany.

Profile plans of the CDM armored car. Source: Une entreprise clandestine sous l’occupation allemande

The modified chassis: the Saint-Geniès workshop

In July of 1941, Restany ordered a workshop set-up in Saint-Geniès, in Dordogne. This workshop was located on the road to Sarlat, a town where he was setting up the most extensive part of his production efforts. The objective of this workshop was to receive the original GMC truck chassis and apply the modifications Restany and his team devised to those. The workshop was set up from the 15th August to the 15th October 1941. It immediately began modifying the chassis it received. By May 1942, all 225 had been transformed. Restany lauded the production rates of the workshop, which produced 1.1 modified chassis a day during most of its operation and up to 1.8 towards the end. However, he found the workshop to be a considerable risk. While some CDM commanders delivered the chassis stripped bare of anything unnecessary, as Restany preferred, some delivered trucks which still had driver’s cabins and bodies. This not only made the production a little more complicated, but, most importantly, created a significant quantity of waste which took a considerable amount of storage space, and which Restany feared could be discovered and compromise the whole operation, especially as the Saint-Geniès workshop was located near a road. As soon as the last chassis was finished, the workshop was dismantled. Two of the three buildings used, which already existed prior to the CDM’s installation, were kept, the third one, which had been constructed for the operation, was entirely dismantled, with the materials all being transported to Sarlat, where they were used to build a garage for the operations there. As for the chassis, they were kept in a number of farms around Sarlat.

Mechanical pieces: the Sarlat factory

Sarlat (officially Sarlat-la-Canéda) was the town that became the center of Restany’s operations. The mayor of Sarlat, which Restany noted was sympathetic to his work, lended to the CDM a former tramway depot at basically nominal fee. In this depot, Restany organized a workshop dedicated to the production of mechanical pieces necessary for the CDM armored car, most notably pieces needed for the turret race. Finding adequate industrial machines was the hardest part of setting up this workshop. While, on the orders of Mollard, local branches of the CDM were to provide machines to Restany’s operations, some did not follow the orders, while others did it very reluctantly. The Roanne workshop, also known as ARL, provided very old machinery which had not been put to use in a long time. Restany reported that within what they provided was a shaper dated from 1867. Not all workshops provided such a lackluster aid though. Restany praised the Manufacture Arme de Tulles (MAT/ Tulle Arms Factory), a major pre-war firearms producer which produced some of the most complicated pieces for Restany’s operation, and also provided some raw materials, allegedly taken from stocks used to produce 25 mm SA 34 anti-tank guns for Romania, an order imposed by Germany to the factory. To complete those very deliveries of machines and pieces, Restany also purchased machinery from private industry. The Sarlat workshop began operations on 15th January 1942. Orders for mechanical pieces that could not be identified as of military use were also placed with civilian manufacturers, which were in no way informed of the actual use of the pieces they were producing. A bureau was also installed in La Canéda, a rural suburb of Sarlat.

Armor: 670 tonnes of improvisation

A key part of Restany’s operation was finding the armor plates necessary for the production of the hulls and turrets. The CDM armored car used plates of four different thicknesses: 5, 10, 15, and 20 mm. Restany wanted this armor to be military-standard steel, made under the same conditions, and with the same quality as the armor of French military vehicles produced before the armistice. Finding enough armor for 225 armored cars while avoiding discovery was a complicated process, in which Restany and the CDM had to acquire steel from a variety of different providers.

Three different steelworks provided steel for the CDM: Saint-Etienne, Saint-Chamond (also known as FAMH, an important artillery and tank manufacturer prior to the armistice), and Ugine. Getting those facilities back to work was a complicated affair, as the production of military-grade steel had been stopped since the armistice. The CDM had to deliver 856 tonnes of coal to the steelworks through the months of March, April, and May of 1942 in order to get them to get steel production back on track. Molded steel was provided from the steelworks of Saut-Du-Tarn. In order to get those back in operation, the CDM had to provide them with particularly hard to find chromium and nickel, an operation that was executed under the management of Mollard.

An additional quantity of steel came from an unexpected source, the French SNCF (Société National des Chemins de Fer – National Railways Company). In possession of an armored train, the company removed its armor plates and delivered those to the CDM.

By June of 1942, 670 tonnes of military-grade steel had been moved to the storage facilities of the CDM, in the steelworks of the large city of Toulouse. More details are available on the composition of those 670 tons. There were 155 tons of 5 mm-thick plates, 297 tons of 10 mm-thick plates, 98 tons of 15 mm-thick plates, and 120 tons of 20 mm-thick plates.

Top view of the CDM armored cars plans
Top view of the CDM armored cars plans. Source: Une entreprise clandestine sous l’occupation Allemande

Body assembly, and the armored car’s armor scheme: Vitrac and Sousceyrac workshops

The assembly of the armored car’s body was carried out at the workshop of Vitrac which was installed in a well-camouflaged cave. Another workshop was installed in the town of Sousceyrac, in Lot, where a large, unused industrial building was located. The Sousceyrac workshop was tasked with the final assembly of the armored cars, mating the hulls, chassis, and turrets together. In case this workshop would prove insufficient, another assembly workshop was created in Calviac, Dordogne, but it was to only operate as a depot unless needed. Sousceyrac’s workshop first’s work was producing external elements that were to be placed on the hull of the vehicle: wheel casings, skirts, hatches, etcetera.

The body of the vehicle had an armor scheme using 5, 10, 15, and 20 mm plates. The front of the superstructure, and driving post, used 20 mm plates. The rear used 15 and 20 mm plates. The sides of the vehicle, from the engine to the rear, used 10 mm plates. The front of the engine used 15 mm plates. The bottom of the vehicle and the mudguards used 5 mm plates. The vehicle had a crew of three, with a driver and rear driver/machine gun operator in the hull, and the commander/gunner/loader in the turret. The vehicle had three fuel tanks. While the range it had is unknown, the vehicle could move for 8 hours with the fuel it had. The vehicle’s mobility is pretty much entirely unknown. It had a width of 2.230 meters (with the rear wheels being the widest point), a height of 2.545 meters, and a length of 4.600 meters.

Front view of the plans of the CDM armored car.
Front view of the plans of the CDM armored car. The hatch on the left of the superstructure was advanced by a few centimeters in comparison to the one on the right. Source: Une entreprise clandestine sous l’occupation Allemande

Turrets: Saint-Cyprien and Griffoul

Assembly of the turrets was organized in the workshop of Saint-Cyprien, where the production of Panhard 178 CDM turrets began in the autumn of 1941. Griffoul, a quarry that had been modified into a workshop and depot for the production of those Panhard 178 turrets, retained this role for the turrets of the CDM armored car.

The CDM armored car had a turret of hexagonal shape. The front of the turret was given 20 mm of armor, its sides and rear 15 mm, and its roof and turret ring 10 mm. A variety of different armaments were to be mounted on the turrets. 60 vehicles were to be armed with the 25 mm R.F (Région Fortifié), a shortened, fortification model of the 25 mm SA 34 anti-tank gun, and two 7.5 mm MAC 31 machine guns, mounted under the main gun. This configuration was inherited from the original fortification mount of the 25 mm R.F which was coupled with those two machine guns. 150 armored cars were to be armed with a heavy machine gun, which Restany refers to as a “13,6”, but most likely a Hotchkiss 13.2 mm, as well as a coaxial 7.5 mm MAC 31 machine gun. Finally, 15 vehicles were to be armed with a “25 mm gun”, presumably a 25 mm SA 35 or SA 34, as well as a coaxial 7.5 mm machine gun. In all cases, an additional 7.5 mm machine gun would be carried within the hull, which could be fired from the hull either at the front or at the rear. Ammunition for vehicles using the first armament type was of 20 7.5 mm magazines (the MAC 31 used 150 rounds drum magazines, so 3,000 rounds) and 100 25 mm shells. The exact ammunition count of the two other types of armament is not specified in detail, but Restany notes that it is the same weight of ammunition. 7.5 mm magazines were located in axles welded in the turret, while the 25 mm shells were located within “ad hoc ammunition lockers”.

Plans of the turret armed with a 13.2 mm and a 7.5 mm machine gun
Plans of the turret armed with a 13.2 mm and a 7.5 mm machine gun. Source: Une entreprise clandestine sous l’occupation Allemande
Plans of the turret armed with a 25 mm R.F and two 7.5 mm machine guns.
Plans of the turret armed with a 25 mm R.F and two 7.5 mm machine guns. Source: Une entreprise clandestine sous l’occupation Allemande

Prototype and trials

A first completed vehicle was ready by October of 1942, the assembly having been done in the workshop of Saint-Cyprien (though it was to be conducted at Sousceyrac for future vehicles). This prototype was identical to the serial standard expected with the CDM armored car and had a full weapon complement (it used the 25 mm R.F & double 7.5 mm MAC 31 configuration). The vehicle moved on its own power from Saint-Cyprien to the park of the Marquay Castle, 20 km from the workshop, where the trials were to be conducted. The convoy from the workshop to the park, which included not only the armored car but several other vehicles transporting personnel and prepared to potentially repair or tow the armored car if it broke down, moved in the night of 16th to 17th October. The local gendarmerie based in Sarlat, which collaborated with Restany, assured the path taken by the convoy was barred from other vehicles and safe.

A front view of the CDM armored car
A front view of the CDM armored car during the trials in the park of the Marquay Castle, showing the radiator, headlight, with one of the front hatches open and another closed. Source: Une entreprise clandestine sous l’occupation Allemande via char-français.net

Trials were performed in the park on 17th October. Restany reported that the vehicle drove well in mediocre pathways and cross-country, and was “infinitely more flexible and maneuverable than the original GMC truck”. The crew was satisfied with the vehicle’s handling, with the driver having very satisfactory vision, and decent internal comfort and space. While some minor issues that could be fixed were found, Restany was very satisfied with the trials and decided the vehicle was ready to be presented to Mollard. The prototype returned from Marquay to Saint-Cyprien on the night of 17th to 18th October. At an unspecified date later in October, it was presented to Mollard in Marquay. The Colonel had no objection to the design, and the vehicle was then moved again to Saint-Cyprien. It was then supposed to be moved to Sousceyrac, to serve as a model for the assembly of the following 224 vehicles.

A side view of the prototype
A side view of the prototype during the trials at the Marquay Castle, showing the side doors and opened front view hatches. Source: Une entreprise clandestine sous l’occupation allemande via char-français
A rear view of the prototype
A rear view of the prototype during the trials at Marquay Castle, showing the rear view hatch. Source: Une entreprise clandestine sous l’occupation Allemande via char-français

State of Production by the end of October 1942

At the end of October of 1942, with the trials producing satisfactory results, the production of the CDM armored car was about to enter full swing. A considerable number of parts had already been completed. By that point, all the chassis had long been converted to the required length and been subjected to the required modifications. 15 entire armored bodies were ready. Internal structures for 150 armored vehicles, 100 armored shutters for the radiator, 200 turret races, and 250 doors were complete. As for turrets, 65 had been completed and armed. 15 more were assembled and in the process of being armed. Restany’s operation was going smoothly, with the assembly of completed vehicles in the near future starting to be a realistic consideration. Restany, his team and Mollard had successfully set up an extensive, secretive armored vehicle manufacturing structure, away from the eyes of both the collaborative higher authorities of the Vichy Regime and the German armistice commission. Sadly for them, though, their project would not bear its fruit, due to geopolitical events far beyond their reach.

November of 1942: Self-sabotage

A first worrying event came on 29th October, when the German armistice commission from Toulouse made a visit to Sarlat. Thankfully for Restany, he had been informed of this visit about a week prior. All the machinery of the Sarlat workshop was urgently evacuated to two newly created workshops, about 30 km from there. The Saint-Cyprien workshop was displaced from a building to the nearby woods. A warehouse in Sarlat, the bureau in La Canéda and the Vitrac and Griffoul workshops were closed. The local commander of the gendarmerie, Captain Rouchaud, who had organized the escort of the prototype a few days earlier, led the commission into a tobacco warehouse that had been recently constructed, opposite to the CDM workshop. Restany’s operation remained undiscovered by the Germans, but he feared they may have a lead.

In the following days, while the transport of all the equipment and machinery that had been evacuated back into the workshops was taking place, extremely worrying rumors of a German invasion of the Free Zone, the unoccupied part of France Restany’s operation was located in, started spreading. On high alert, Restany prepared for the worst according to the recommendations of the CDM in case of an occupation of the Free Zone. On 8th November, British and American forces landed in French North Africa, arguably the most important French colony, and one which had remained loyal to the Vichy regime. Restany ordered the hulls that had been produced to be placed in wooden crates and prepared to be buried if needed. All the hulls had been placed in the crates by the 10th of November.

By the evening of 10th November, Restany received the confirmation that the worst he was fearing and preparing for was coming, the Wehrmacht would come kicking in in the Free Zone on 11th November. Unwilling to destroy all of his work, and thinking his men would refuse as well, Restany prepared secret instructions which were issued to each workshop, and only to be opened after a telephone call gave the order to do so. By 4 am on 11th November, liaison personnel were delivering the envelopes around the workshops, all located in proximity to Sarlat. Restany’s orders were to preserve as much of the technical documentation and productions as possible, while at the same time keeping his personnel as safe as possible. Administrative archives were to be destroyed, but the plans were to be kept and hidden. Parts that could easily be identified as of military use were to be buried. The turrets and weapons, in particular, were to be potentially recoverable, if a situation in which this could be done appeared. The weapons were placed in creates and buried in fields and the turrets were walled in the quarry turned workshop of Griffoul. The prototype was disassembled. Meanwhile, in the whole of the Free Zone, the French Army remained in its barracks at the orders of Prime Minister Pierre Laval, and the CDM’s caches were unused. In a single day, the entire “Free” Zone of France disappeared, with the exception of the harbor of Toulon where most of Vichy’s fleet was located, and which was only occupied on 27th November, with the regime’s fleet scuttling to avoid capture.

The telephonic signal to open the envelopes was given by Restany between 9.30 am and 10 am on 11th November. At 11 am, he left Sarlat for Castres, where the operations began back in the spring of 1941, and many of the administrative functions remained. There, he got hold of the plans and met with Mollard who congratulated him for the measures he had taken to conserve the weapons.

Restany under the occupation

From Castres, Restany then moved to another town in Dordogne, Saint-Ceré, where he was to continue managing the dissimulation and destruction operations as much as possible while remaining hidden. However, in Sarlat, an extraordinary German commission was put in place, tasked with the investigation of a large armored vehicle manufacturing scheme German forces had stumbled upon when occupying the town. While residing in Saint-Ceré, Restany still regularly went to Sarlat and Castres to oversee the liquidation of the screen-company that had been set in place to hide his operations. Fearing he may easily be found out due to his regular displacements in the small town of Saint-Ceré, he left for the larger Albi in April of 1943. Restany survived until the liberation, unscathed. He kept writing to Mollard until September of 1943 when he and his son were found out and soon sent to a concentration camp.

Three former workers of the Sarlat workshop were shot in 1944, though it is not known if the reason for their execution was their participation in the armored car production scheme or other actions undertaken in the French resistance.

Despite Restany and his men’s efforts, some of the hidden material was found by German forces. On 12th December 1942, most likely following a denunciation, the exact position of the crates containing the weapons for the armored cars were found, and the crates were dug back out of the soil. Restany suspected an Alsatian worker named Beck for this denunciation, as he had allegedly been seen with German troops following the occupation of the Free Zone, despite having allegedly been enrolled in the Wehrmacht. A truck driver reported the location of the Sousceyrac workshop to German forces and was condemned to 10 years in prison at the end of the war. As a result of the denunciations, and to avoid the owners of the terrains being at risk, the locations of the Griffoul quarry where the turrets were stored, as well as the Vitrac workshops, were leaked to the Germans. Still, some elements, notably a number of armor plates, appear to have remained unfound by the Germans. Most importantly, Restany conserved the plans and shared them in his 1948 book.

Conclusion

The large armored car manufacturing scheme undertaken by Emile Mollard’s CDM under Joseph Restany’s lead is a particularly little known and celebrated but particularly interesting part of the French Resistance. In high secrecy, the workers and engineers operating under the lead of Restany managed not only to produce turrets to re-arm 45 Panhard 178 CDMs, but to build an entire armored car from the chassis up, while remaining away from the eyes of Vichy’s higher-ups and the German armistice commission until the occupation of France.

One could definitely argue that the CDM armored car appears to be a primitive basic design It was, without a single doubt, not up to the comparison with any medium or large-sized armored car of the late war such as the German Sd.Kfz 234/2 or a British AEC or even Daimler armored car in terms of capacities. Even some of the more advanced pre-1940 designs, such as the Panhard 178, outclassed it. Nonetheless, the scale of the underground manufacturing scheme undertaken by the CDM remains impressive when taking into account the context of its undertaking. Sadly for the CDM, the whole project had to be urgently dismantled to avoid German capture in November of 1942, and would never bear the fruits of the work, time and materials invested into it. Nowadays, this aspect of the French Resistance remains very lightly touched on and known by the general public and even many enthusiasts. Despite Mollard being sent to concentration camp, he survived, but his son, also involved in the CDM, did not. Mollard remains a little known figure, far overshadowed by military commanders of Free France that earned a reputation in the field, such as Leclerc, Juin or De Lattre.

A view of the CDM armored car,
A view of the CDM armored car, most likely a drawing; source: char-français.net
Illustration of the CDM armored car illustrated by Yuvnashva Sharma and funded by our Patreon campaign.

CDM armored car Specifications

Length 4.6 m long
Width 2.54 m wide
Height 2.23 m high
Armament
(65 turrets)
25 mm R.F gun & two 7.5 mm MAC 31 machine gun + a MAC 31 in storage
Armament
(150 turrets)
13.2 mm Hotchkiss & a 7.5 mm MAC 31 machine gun + a MAC 31 in storage
Armor 10 mm on the hull sides and turret top
20 mm at the superstructure and turret front
15 mm at the radiator and turret sides & rear
5 mm on the bottom and mudguards
15-20 mm at the rear.
Total production 1 completed prototype, 15 completed armored bodies, 65 completed and armed & 15 completed but unarmed turrets, parts for various numbers of vehicles.

Sources

Une entreprise clandestine sous l’occupation Allemande, Joseph Restany, Charles-Laveuzelle & Cie editions, 1948
Char-français.net (photos only)

Categories
WW2 French Prototypes

FCM F4

France (1937)
Heavy Tank – None Built

Back in the 1930s, the tank was still a relatively new weapon. The masterminds of the world’s most powerful tank forces were still debating about its role on the battlefield. Fits of paper fantasy showed engineers and designers putting on as much armor and as big of a gun onto a tank as their imagination could manage. The inventions’ power and potential seemed limitless to the minds of many, leading to the emergence of a type of heavy tank more akin to a land battleship. Most countries capable of building tanks were experimenting with their own models, from the British A1E1, Soviet T-35, to the German Neubaufahrzeug, to name the more “practical” designs.

During the same time period, the Germans were building the infamous Siegfried Line or ‘Westwall’, a fortified defensive line consisting of bunkers, tank traps, and much more arrayed along the western German frontier. Nothing in the French tank arsenal was able to challenge these potent defenses. Combining the multi-turret tank designs – in fashion at the time – and this new threat from the east, the French quickly realized they needed a new powerful breakthrough heavy tank able to withstand anti-tank fire and destroy static defenses.

Breakthrough Heavy Tank

With the doctrine of breaching the Siegfried Line in mind, a heavy tank program was requested by the Conseil Consultatif de l’Armement (Armaments Advisory Council) on 4th May 1936. The specifications for this new program, named “Char de Rupture 1937” (literally breakthrough tank), were released on 12th November 1936. The Conseil Consultatif de l’Armement requested:

“Char lourd, très protégé et très armé, propre en particulier à être utilisé défensivement et offensivement dans la guerre en région fortifiée”.

“A heavy tank, well armored and well armed, suitable for both defensive and offensive purposes in fortified battlefields.”

The tank was to have a maximum weight of 45 tonnes (49.6 short tons) and dual armament, with a main gun in the hull and a secondary gun in a rotating turret. The vehicle would need thick armor, capable of resisting incoming fire from anti-tank field guns at a distance of at least 200 m (220 yards). Requirements for the mobility and speed of the design were tight, with a top speed of 30 km/h (18 mph) and a range of 200 km (125 miles) or 10 hours.

A few months later, in 1937, three French companies presented designs, AMX, ARL, and FCM.

Forges et Chantiers de la Méditerranée

The Forges et Chantiers de la Méditerranée (Eng: Foundries and Shipyards of the Mediteranean), better known as just ‘FCM’, was a naval shipyard that specialized in heavy vehicles founded by the British engineer Philip Taylor in 1853. Besides building large warships, like the Paris battleship, they had produced tanks and armored vehicles before, such as the FCM 36 and Char 2C.

One of the FCM shipyards at Seyne-sur-Mer. Source: Wikimaginot.eu

In May 1937 , FCM presented their first design for this competition (FCM was last of the three to present a design), the FCM F4 Variant A. The company already had plenty of experience in building large heavy tanks, as 10 years earlier it had designed the FCM 2C, one of the largest tanks ever made. The company also proposed designs for the program that would eventually become the Char B1, in the form of the FCM 21.

Design

Variant A of the FCM proposal was based on their previous heavy tanks. It had a large, frusto-conical turret located on the front of a long hull, with large idlers and drive sprockets beneath. Its suspension was typical of French heavy tanks of the time. On each side, there were eight bogies with one leaf spring each. To each spring, two road wheels were mounted. In addition, on each end of the track, there were two road wheels connected to bump stops for driving over rough terrain, such as trenches. They did not touch the ground, however, they helped minimize the impact when the tank first came in contact with an obstacle.

The turret housed a 75 mm gun, while a 47 mm gun was mounted in the hull. This allowed for more effective usage of the 75 mm, as it could cover an area of 360° around the tank rather than being restricted by the limited traverse of a hull-mounted weapon. This, however, meant that a larger turret had to be made, pushing the height of the tank to over 3 meters. This turret was frusto-conical, typical of FCM turret designs of the era and had a rotating cupola with a rangefinder on top. The 75 mm gun had a designated gunner and loader in the turret, while the driver was in charge of aiming, shooting and loading the 47 mm. The commander was located in the center of the hull, so it might have been possible for him to assist the driver with loading the 47 mm gun, but this is uncertain as no plans of the crew layout exist. The overall weight would have been around 55 tonnes – far above the requirements.

Armament

While ARL and AMX went with a ‘traditional’ Char B1 layout of a 75 mm howitzer in the hull and a 47 mm gun in the turret, FCM went on its own path. Just like on the Char 2C, they mounted the required 75 mm gun in the turret. It is unclear what 75 mm gun this was supposed to be. Some sources claim it was the same as on the Char 2C, the Model 1897 75 mm howitzer, while others state the 75 mm Model 1929 would have been used. The APX 75 mm model 1929 howitzer was a modified version of the Model 1897 75 gun, with many components, such as the barrel, being the same. It was originally built for the Maginot Line as a static defense, but later modifications allowed it to be mounted on combat vehicles. The later tank destroyer projects ARL-V39 and Somua SAu 40 were also equipped with this gun. Likewise, the designs of FCM’s competitors, ARL and AMX, also mounted the newer howitzer in the hull.

The ammunition used is unknown, however, the same guns in the Maginot Line used HE model 1917 rounds with a muzzle velocity of 577 m/s. Ammunition stowage for all the weapons is unfortunately also unknown.

Tank gun mount of the 75mm mle 1929 howitzer, the same was used on the later Somua SAu 40 and ARL V39 tank destroyer projects. Source: Wargaming

As secondary armament, FCM used the 47 mm model 1934 gun, firing APX mle 1936 Obus de Rupture (Armour-Piercing High-Explosive, APHE) shells. Originally, just like the APX mle 1929, this gun was intended for the Maginot Line. These shells had a muzzle velocity of 880 m/s (2890 fps) and could penetrate 77 mm (3 inch) of armor angled at 30° at 500 m (547 yards) and 56 mm (2.2 inch) of armor at 1000 m (1094 yards). The shell weighed 1.670 kg (mock warhead, translation from the French “fausse ogive”) and the charge weighed 610 g. This gun would have been aimed and loaded by the driver. This was common in French tanks and was done to reduce the number of crewmen needed per vehicle. However, naturally, this put the crew under a lot of strain and required more training. In addition, maintaining the tank with a smaller crew was more strenuous.

Version A was equipped with 2 machine guns (later versions would have up to 6) and these were the 7.5 mm MAC (Manufacture d’Armes de Châtellerault) model 1931. Originally built for use in static defences on the Maginot Line, it could also be mounted on tanks and other Armored Fighting Vehicles (AFVs). It was gas operated and fired the 7.5 mm MAS cartridge from a 150-round drum magazine. These rounds had a muzzle velocity of 830 m/s (2,700 ft/s). Its weight of nearly 12 kg (26,45 lb) meant that it had to be mounted on a heavy steel mount.


The 7.5 mm MAC 31 with a tank mount. The large 150-round side-mounted drum magazine meant that storage inside of vehicles (in this case tank) was simple and allowed for continuous fire, without the crew having to reload very often. This was crucial in French tanks as the crew already had a lot of tasks to fulfill. Source: Wikipedia

Engine

There is very little information on the mechanical parts of the FCM design. It is known that it was to be equipped with two V12 diesel engines. It is unclear what engine this would have been, but may be assumed this engine was being purpose-designed for this tank project and got canceled simultaneously. Each engine drove an electric generator that was connected to the final drive, similar to the later British TOG 1 and 2, and the German Elephant tank destroyer and Maus super-heavy tank. These engines were supposed to have allowed the 55 tonne tank to reach 30 km/h.

Armor

Like many other statistics about this vehicle, the armor thickness is mostly unknown. However, considering that the AMX design had 100 mm (3.94 in) at the front around the turret, it is relatively safe to assume that the FCM F4 would have had similar armor thickness. French tanks also tended to have the same armor thickness all around the turret. The frontal hull plate was well angled, and so was the turret, which increased its effectiveness.

Other Variants

After presenting the first version, FCM showed a second one, the FCM F4 Variant B. It was identical but had the transmission and exhaust moved centrally and an FCM 36 turret equipped with 2 machine guns was added, facing the rear. This increased the weight to 57 tonnes and the crew to 5. There are no images of this design.

In August 1937, FCM proposed 2 new designs. Version C had a new turret, also armed with a 75 mm gun. Version D had the 47 mm gun in the hull moved into the little turret in the back. In October, Version E was designed with 5 additional machine guns. Finally, in December, Version F was shown mounting a flamethrower and the total weight was pushed to 59 tonnes.

From Heavy to Super Heavy

All 3 companies – ARL, AMX and FCM – had their designs rejected because the tanks would have been too expensive and could only be produced in small numbers, therefore they would not have any large effect on the battlefield. To solve this, the Conseil Supérieur de la Guerre (Eng: Superior War Council) decided on 26th March 1937 to build a smaller and cheaper yet heavily armored tank. However, after testing, the Section de l’Armement et des Études Techniques (Eng: Section for technical and armaments studies) claimed that this would be redundant, as there was already such a tank under development – the Char G1.

Due to this evolution, the requirements were changed in February 1938. There was to be no weight limit and a 75 mm gun had to be mounted in the turret. The same companies presented designs once again, however, these new specifications were very close to those of the original FCM design, so the Supreme Command gave FCM a contract to build the tank. This would eventually lead to the FCM F1, a 140 tonne monster with 2 massive turrets and a 90 mm gun. However, by the time a mockup was ready in 1940, France had been occupied by Germany and, consequently, all super-heavy tank designs were halted, meaning no French Char Lourd (heavy tank) would ever get the chance to batter the Siegfried Line.

FCM F4 Version A. The large turret and the rangefinder can be seen. Note the 4 holes in the sideskirts acting as mud shoots, to release mud from under the sideskirt.
Source: Pinterest


Illustration of the FCM F4 produced by the Author, Pavel Alexe, and funded by our Patreon campaign.

Specifications

Dimensions 7.5 x 2.94 meters
(24.6 x 9.65 ft)
Weight 55+ tonnes
(60.63 tons)
Crew 4 (commander, driver, loader, radio operator)
Propulsion 2 x V12 diesel engines connected to electrical generators
Maximum speed 30 km/h* (18 mph)
Suspension Leaf springs
Range 200 km* (125 miles)
Armament 75 mm model 1929
47 mm SA35
7.5 mm MAC

*These numbers are what was requested by the Conseil Consultatif de l’Armement . Actual numbers are unknown.

Sources

Chars-francais.net
DGA Châtellerault
TNT number 11
Chars De France, Jean-Gabriel Jeudy
Memoiredeshommes.sga.defense.gouv.fr
Wikimaginot.eu
Modernfirearms.net


Categories
WW2 French Prototypes

AMX 37 ‘Char de Rupture’

France (1937)
Heavy Tank – None Built

During the mid-1930s, Germany started construction of the Westwall, otherwise known as the Siegfried Line. This fortification spanned across the German border with France up until their border with Denmark and was equipped with numerous bunkers and cannons. The French authorities were alarmed by this and figured that they would have to overcome this defensive line. However, no tank in the French arsenal at the time was able to combat such an obstacle. Therefore, they quickly started a heavy breakthrough tank program, named ‘Char de Rupture 1937’.

Specifications

On the 4th of May, 1936, the Conseil Consultatif de l’Armement (Armaments Advisory Council) requested plans for a new heavy breakthrough tank that would be able to charge the Siegfried Line while being able to knock out static defenses and enemy tanks. A quote from the Council:

“Char lourd, très protégé et très armé, propre en particulier à être utilisé défensivement et offensivement dans la guerre en région fortifiée”.

“A heavy tank, well armored and well armed, suitable for both defensive and offensive purposes in fortified battlefields.”

The exact specifications were released on the 12th of November 1936. The tank was to have a maximum weight of 45 tonnes (49.6 short tons) and be equipped with two main armaments, a 75 mm gun and a 47 mm one. As it was supposed to lead the charge against bunkers and fortifications, it was to have thick armor, namely to withstand anti-tank fire from 200 m (220 yards). The mobility aspect was optimistic for a tank of the time, as it was supposed to reach 30 km/h (18 mph) while having a range of 200 km (125 miles) or 10 hours of operation.

By May 1937, 3 companies presented their designs, ARL, FCM, and AMX.

Construction d’Issy-les-Moulineaux

Construction d’Issy-les-Moulineaux (AMX) was created when the French government took over the Renault factories in 1936, ultimately meaning that the Char de Rupture AMX was one of their very first tank projects. AMX went on to design and build some of the most famous post-war French tanks, like the AMX-13, AMX-50 and AMX-30.

Production line of AMC-34 on the left and Renault D1 on the right, in the Ateliers de construction d’Issy-les-Moulineaux (Renault) before nationalization, 1935. Source: Wikipedia Commons

Design

In March of 1937, AMX presented its preliminary concept for the program. This was essentially an enlarged Char B1 Bis. Their design was elongated, with a 75 mm gun mounted in the hull to the right of the driver. On the roof, a small turret with a 47 mm gun and a machine gun were placed. There were two turret designs, the first one having the gun mounted on the right side and an unusual polygonal shape. The second turret was much more similar to that of the Char B1 bis and Somua S35, the APX-1, however, the armor on it had been increased considerably. As a matter of fact, the entire tank was covered in thick armor and, in typical French fashion, long side skirts were hiding the suspension, leaving only the massive tracks exposed. It had a crew of 4, driver, tank commander (located in the turret, manning the 47 mm gun) a loader and a radio operator. To reach the desired top speed, two V12 engines were to be used, each engine being coupled to an electrical transmission which, in turn, drove four electric engines, two per sprocket.

Artist’s impression of the AMX 37, most likely made to promote the design. Like many images of the kind, the proportions and details are off. The turret is of the late-type. Source: aviarmor.net

Original blueprints of the AMX 37. The resemblance to the Char B1 can be seen, with the large sprocket, side skirts and weapon placement. Note that the turret seen is the early type. Source: memoiredeshommes.sga.defense.gouv.fr
Front view of the tank. The mounting of the 75 mm model 1929 howitzer and the turret’s location can be seen. Source: memoiredeshommes.sga.defense.gouv.fr

Top view. Note the large, exposed tracks and odd polygonal turret shape. Source: memoiredeshommes.sga.defense.gouv.fr

Armaments

Just like in the Char B1, AMX mounted a 75 mm howitzer in the hull and a 47 mm gun in the turret. The 75 mm gun was the APX 75 mm model 1929 howitzer, a modified version of the famous Model 1897 75 mm gun, with many components, such as the barrel, being the same. It was originally built for the Maginot line as a static defense gun, but later modifications allowed it to be mounted on combat vehicles. The later tank destroyer projects ARL-V39 and Somua SAu 40 were also equipped with this gun. It was mounted to the right-hand side of the driver who was also the gunner. The main drawback was the poor gun traverse, only 6° to the left and right.

The APX 75 mm Mle 1929 on the mount designed for tanks and other AFVs. Source: Wargaming.net

The gun mounted in the turret was most likely the 47 mm SA35, the same gun used in the turret of the Char B1 Bis. It would have shot the same type of ammunition, the Obus de Rupture Mle 1935 (AP model 1935) weighing 1.620/1.625 kg (3.6 pounds). The entire shell was 325 mm long (13 inches) while the projectile was 145 mm long (5.7 inches) and the case was 193 mm long (7.6 inches). On the Char B1 Bis, the muzzle velocity of the SA35 was 660 to 680 m/s (22 feet per second) with a penetration of 40 mm angled at 30° at 400 m.

Side views of the SA35 from a B1 Bis. The mantlet mounted at the base of the barrel would be different on the AMX 37. Source: Warspot

The machine guns used on the tank were the 7.5 mm MAC (Manufacture d’Armes de Châtellerault) model 1931. Like many other French weapons of the time, it was developed to be mounted on the Maginot line, but was later adapted to be mounted on armored fighting vehicles and tanks. It was gas-operated and fired the 7.5 mm MAS cartridge from a 150-round drum magazine mounted on the left side of the gun. This large magazine meant that the crew did not have to reload as often compared to other machine guns (the German MG-34, when mounted on tanks and AFVs, had a 50 to 75 round magazine). Such a large magazine was crucial in the already overworked French tank crews, of which the AMX 37 certainly was not an exception. These machine guns were attached independently, next to the 75 mm and the 47 mm. Two more MAC machine guns were placed in ball mounts, next to the entrance doors on the sides of the tank, to better protect from infantry sneaking up on the tank. Due to the large suspension of the tank, the side machine guns had restricted traverse.

The 7.5 mm MAC Mle 1931 with a tank mount. The large 150-round magazine can be seen. Source: Wikipedia

Crew

Despite a large number of weapons, the tank only had a crew of four; driver, commander, loader and radio operator. In a similar fashion to the Char B1, the driver was also the gunner for the 75 mm howitzer. Since the gun only had 6° of traverse, the driver had to turn the entire tank to better aim the gun. The loader was loading the 75 mm and was located in the hull. He was also responsible for loading and firing the MAC machine guns to the right of the tank and the one coaxial to the 75 mm. Behind the driver was the turret and that was where the commander sat. He was responsible for searching for targets, firing and loading the 47 mm and, to top it all off, fire and load the co-axial MAC machine gun. The radio operator, located behind the commander, was in charge of the radio of unknown type, and the machine gun to the left of the tank. He could have also assisted the commander, giving him ammunition from the hull up and into the turret.

It was typical for French tanks to have one-man turrets, or to have overworked crews. The sheer amount of work that the commander had to do in the AMX 37, and many other French tanks of the time, was huge. He did not only have to command the tank and spot targets for the 75 mm gunner through his cupola, but he also had to aim, load and fire his 47 mm and, when necessary, the machine gun as well. This lead to an overworked soldier, having to complete so many tasks at once and doing neither very well. The reasoning behind this design was to decrease the amount of manpower needed to operate tanks. The fewer men you need per tank, the more tanks you can have. The shortage of men was deemed an issue in France during the 30s, as the population still had not recovered from the First World War. In practice, the French had overworked crews, and too few tanks, getting the worst out of both.

Top view of the crew compartment. The four crewmen’s position can be clearly seen with the driver, commander and radio operator sitting in a row with the loader on the far right. Note the two hull MGs overlooking the sides. Another interesting detail is the floor escape door most likely used by the driver or when another door was damaged, as the other three crewmen have their own doors. Separating the crew compartment and the engines is a pneumatic, waterproof, firewall door, which could be used to access the engine from within the tank. Source: memoiredeshommes.sga.defense.gouv.fr

Turret

The tank had two different turrets during its development process. The early version had an octagonal faced, frustoconical shape, with the SA35 47 mm gun mounted on the right side and the 7.5 mm MAC on the left. Its armor values are unknown, however, they are probably similar to those of the second design turret. This second design was much more similar to that of the Char B1 Bis, a nonagon with the 47 mm mounted more centrally and the machine gun mounted slightly to the left. The armor was 100 mm all around and 43 mm on the roof. While it can be hard to distinguish the two turrets from one another, the second design has large bulb-like protrusions on the sides for periscopes, which are not shown in many contemporary line-drawings and illustrations. The periscopes were surrounded by thick armor, doubled around the holes, as seen in the blueprints. This turret was designed in August, after AMX had submitted the first design. The reasoning behind why a new turret was made is unknown, and why it was re-done after the tank had been presented.

Several angles of the second version turret. Note the rear hatch for the tank commander. Source: memoiredeshommes.sga.defense.gouv.fr

Armor

The armor on the AMX design was very impressive. To be able to withstand AT fire, the frontal plate was angled at 50° and was 100 mm thick. It is a well-known fact that French tanks had thick armor, but this was another level for 1937. The turret was just as impressive, 100 mm thick angled at 85° all around. The top of the turret and hull were 43 mm thick. To put this in perspective, the Somua S35 had 47 mm of armor at the thickest, while the Char B1 Bis had 60 mm and the Tiger tank – yet to even be conceptualized – was ‘just’ 80 mm all around the turret and not sloped! However, all of this armor came with additional weight and made the 7.25-meter long tank weigh above 45 tonnes, the maximum weight allowed.

Original blueprints of the late turret. Besides the gun, traverse mechanism and more, the extremely thick armored walls of the turret can be seen. Source: memoiredeshommes.sga.defense.gouv.fr

Propulsion

When the tank was designed, there were no engines in production in France powerful enough to move such a heavy vehicle at the required 30 km/h. This meant that completely new engines had to be designed. The tank was to be equipped with two V12 engines with a horsepower of 550 hp (600 hp according to other sources). As per the blueprints, two companies were taken into consideration in the production of these engines; Aster and CLM (Compagnie Lilloise des Moteurs). These engines were to be mounted horizontally along the length of the tank, right behind the ammunition storage. Each engine was coupled to an unknown type of electrical generator connected to two electric engines (total 4, 2 per side) that drove the sprockets. For traverse, each sprocket had a diagonally mounted traverse motor. Neither CLM nor Aster produced such large engines at any point.

Cutout view of AMX 37 showing the V12 Aster motors, however, only one can be seen as they are mounted parallel one to the other. In this image, the crew compartment and other details can be seen. Note the traverse motor mounted diagonally by the final drive. The armor thickness can also be seen.
Front view of the V12 Aster motors. Note the gigantic coil springs from the suspension.
The in-line CLM engines. It was a much shorter alternative compared to the Aster engine however, it was much taller. It is unclear if these engines had fewer pistons, usually in-line engines need to be significantly longer than V shape engines to have the same number of pistons.
Front view of in-line CLM engines. Due to the narrow, tall shape, it is safe to assume these were in-line piston engines. The large plate-like shape over the engines is the radiator, of which this tank had 3. Source for these 4 images: memoiredeshommes.sga.defense.gouv.fr

Suspension

The suspension was very similar to that of the Char B1, with 16 small steel road wheels per track. Two wheels in the front (in between the idler and road wheels) and one in the back (in between the sprocket and road wheels) were not touching the ground and, when tensioned, moved diagonally. This was done to decrease the shock when the tank crossed over large obstacles. On each side, there were 4 large springs connected to a bogie. Each bogie then had two smaller bogies in turn connected to two wheels. In addition, every single wheel had its own spring. This was a very complex system, however, it allowed for a lot of motion from the wheel to the hull itself, meaning that the ride quality would have been rather smooth. At the top of the tracks, 10 return rollers were mounted. This was rather unusual for French tanks, as the Char B1, for example, still used skids.

Cutout showing the suspension layout. This system was very similar to the British Matilda Mk.II tank. The track tensioning system can also be seen.

Aftermath

Despite all the efforts, the Conseil Consultatif de l’Armement rejected all the designs presented by FCM, ARL, and AMX. All three companies presented very complex and expensive tanks, thus limiting their production output to a very small number; making them insignificant on the battlefield. To add insult to injury, every company exceeded the 45-tonne mark, even on paper. The AMX 37 weighed around 50 tonnes on paper, however, a battle-ready tank would have even exceeded this already high number. In response to this issue, the Conseil Supérieur de la Guerre (Eng: Superior War Council) decided on the 26th March 1937 that a much smaller, cheaper yet heavily armored tank be designed. This in turn went south as well, when the Section de l’Armement et des Études Techniques (Eng: Section for technical and armaments studies) made a study which showed that a tank fulfilling those criteria was already under development, and there would not be a need of a new program. This tank was the Char G1.

This was not the end of the road for AMX designed heavy tanks. In February of 1938, the requirements changed. Amongst others, the weight limits were removed. This would eventually lead to the AMX Tracteur C super heavy tanks, but like its predecessor, it remained on paper only.



Illustration of the AMX 37 ‘Char de Rupture’ (Breakthrough Tank), produced by the author, Pavel Alexe, and funded by our Patreon campaign.

Specifications

Dimensions 7.25 x 2.70 x 2.94 meters
(24.6 x 8.9 x 9.65 ft)
Weight 50+ tonnes
(55 tons)
Crew 4 (commander, driver, loader, radio operator)
Propulsion 2 x V12 or in-line diesel engines connected to electrical generators connected to electrical motors
Maximum speed 30 km/h* (18 mph)
Suspension Coil springs
Range 200 km* (125 miles)
Armament 75 mm model 1929
47 mm SA35
4 x 7.5 mm MAC
Armor 100 mm in front hull (3.9 inches)
100 mm side skirts
100 mm all around the turret
43 mm top of the hull and turret (1.7 inches)

*These numbers are what was requested by the Conseil Consultatif de l’Armement . Actual numbers are unknown.

Sources

Chars-francais.net
DGA Châtellerault
TNT number 11
Chars De France, Jean-Gabriel Jeudy
Memoiredeshommes.sga.defense.gouv.fr
Wikimaginot.eu
Modernfirearms.net
Tbof.us