page_title: Char B1
section_title: Development and production
hierarchical_section_title: Char B1 / Development and production
caption_attribution_description: Nederlands: Elektronische reproductie van foto van houten maquette Char B-tank
context_page_description: The Char B1 was a French heavy tank manufactured before World War II.
  The Char B1 was a specialised break-through vehicle, originally conceived as a self-propelled gun with a 75 mm howitzer in the hull; later a 47 mm gun in a turret was added, to allow it to function also as a Char de Bataille, a "battle tank" fighting enemy armour, equipping the armoured divisions of the Infantry Arm. Starting in the early twenties, its development and production were repeatedly delayed, resulting in a vehicle that was both technologically complex and expensive, and already obsolescent when real mass-production of a derived version, the Char B1 "bis", started in the late thirties. Although a second up-armoured version, the Char B1 "ter", was developed, only two prototypes were built.
  Among the most powerfully armed and armoured tanks of its day, the type was very effective in direct confrontations with German armour in 1940 during the Battle of France, but slow speed and high fuel consumption made it ill-adapted to the war of movement then being fought.
context_section_description: The Char B1 had its origins in the concept of a Char de Bataille conceived by General Jean Baptiste Eugène Estienne in 1919, e.g. in his memorandum Mémoire sur les missions des chars blindés en campagne. It had to be a "Battle Tank" that would be able to accomplish a breakthrough of the enemy line by destroying fortifications, gun emplacements and opposing tanks. In January 1921 a commission headed by General Edmond Buat initiated a project for such a vehicle. To limit costs, it had to be built like a self-propelled gun, with the main weapon in the hull. To minimise the vehicle size this gun should be able to move only up and down, with the horizontal aiming to be provided by turning the entire vehicle. The specifications included: a maximum weight of thirteen tonnes; a maximum armour thickness of 25 millimetres; a hull as low as possible to enable the gun to fire into the vision slits of bunkers; a small machine gun turret to fend off enemy infantry attacks, at the same time serving as an observation post for the commander and a crew of at most three men. Two versions should be built, one a close support tank armed with a 75 mm howitzer, the other an anti-tank vehicle with a 47 mm gun instead.
  French industry was very interested in the project. In the past, this had led to much non-constructive rivalry. Estienne, who in the war had personally witnessed the dismal effects of such a situation, was determined to avoid a repetition. He used his position as Inspector-General of the Tanks to enforce the so-called "Estienne accord" on the industrialists, ordering them to "reach a mutual understanding, free from any spirit of industrial competition". To be allowed to join, they had to agree beforehand to relinquish any patents to the Army, which would be free to combine all projects into a single type. In exchange, to the industry very large orders of no less than a thousand vehicles were promised.
  On these conditions four projects were started in 1921: two by a cooperation between Renault and Schneider: the SRA and the SRB, one by FAMH (Forges et Aciéries de la Marine et d'Homécourt, better known as Saint Chamond) and the last by FCM (Forges et Chantiers de la Méditerranée), the FCM 21. Renault and Schneider would each get to produce 250 units, FAMH and FCM each 125. A fifth producer, Delaunay-Belleville, whose project (an improved FT 17) had been rejected beforehand, would be allowed to make 83 tanks; the remaining 167 would be allotted at the discretion of the French State.
  On 13 May 1924, the four prototypes were presented at the Atelier de Rueil, where they were compared, each having to drive over a twenty kilometre test course. Immediately it became evident that their technical development had been insufficient, most breaking down; the SRA even started to fall apart. Maintenance was difficult because the engines were inaccessible. All projects used a three-man crew but differed considerably in size, form and the solution chosen to laterally point the gun.
  The SRA was the heaviest vehicle at 19.5 tonnes. Its length was 5.95 metres, its height 2.26m and its width 2.49m. It had a 75 mm howitzer in the right side of the hull and a cast, 30 mm thick, turret with two machine-guns. It was steered by an epicyclical transmission combined with hydraulically reinforced brake disks, which failed to provide the desired precision during tests.
  Seen from the front it was very similar to the final model, but its side-on profile was more like that of the British Medium Mark D, including the snake track-system, with the drive wheel higher than the idler in front. The suspension used leaf springs. A Renault six-cylinder 180 hp engine (a bisected 12V aircraft engine) allowed for a maximum speed of 17.5 km/h; a four hundred litre fuel tank for a range of 140 kilometres.
  The SRB, also using leaf springs, was a somewhat larger vehicle, six metres long, 2.28 metres high and 2.5 metres wide. It was nevertheless lighter at 18.5 tonnes, a result of having a smaller 47 mm gun—it thus was the antitank version. Using the same engine, its speed was acc
caption: The wooden mock-up
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