New Specifications
In May 1936 the Conseil Consultatif de l'Armement accordingly decided that French industry be invited to initiate studies on the design of a tank having sufficient protection and armament to fight other armour, but light enough (twenty tons or less) to be both cheap and mobile. However, during this period it began to be increasingly realised that the Char B1 was overly complex and expensive and two tonnes heavier than necessary because of using riveted armour plate instead of cast or welded armour. The twenty tonne tank would be lighter, swifter, cheaper, more easily produced and require less training. It is therefore also decided that the new twenty tonne tank should be able to serve as a future battle tank, eventually replacing the older heavy tank.
In October a special commission revealed to the French industry the changed specifications for the "twenty tonne tank": a maximum speed of at least 40 km/h; a range of 200 km; a protection level equal to that of the Char B1 bis (i.e. 60 mm all around); a trench crossing capacity of 250 cm; a complete protection against gas attack; the dimensions should not impede rail transport and the armament should consist of a high velocity gun capable of destroying all expected enemy medium tanks, combined with two machine guns.
The specifications implied that the vehicle would have been the most potent and modern French tank yet developed. It also entailed that its introduction would not take place in the near future, as it was simply too advanced. This way it was avoided that a decision would have to be reached about the future course the Infantry tank weapon should take. At the time there were officers, like Charles de Gaulle, who proposed that the Infantry raise armoured divisions that were similar in organisation to the Divisions Légères Mécaniques of the French Cavalry or the German Panzerdivisionen, i.e. balanced forces with much organic mechanised infantry and motorised artillery, that would be flexible enough to fulfil all possible tactical roles. Other officers however considered it redundant to imitate the Cavalry and thought the Infantry should stick to its proper task: the break-through only. Some of them wanted that the money to be spent on armoured divisions would go to the production of a sufficient number of light infantry tanks to give each division its own organic battalion, as the best way to ensure an effective execution of combined arms tactics. Some wanted only heavy tanks to be built. The Char G, mobile, but heavily armoured enough to function as a break-through tank, made only sense if German-style armoured divisions would be created and a definite decision about its production could only be made when the debate had produced a clear winner.
Despite this uncertainty about its future the project generated enormous interest among French industrialists, as it had a real potential to become France's main AFV building programme, leading to large state investments the French industry badly needed during the period of the Great Depression. Late 1936 and early 1937 seven companies submitted plans: Baudet-Donon-Roussel; FCM; Fouga; Lorraine de Dietrich; Renault; SEAM and SOMUA. One company, Batignolles, announced a plan, but did not actually submit one.
The commission on 20 February 1937 issued its reports on each proposal. For two of these this report forms our main source of information because they would be discontinued within a year: the SOMUA design resembled a cross between the SOMUA S40 and the Sau 40 self-propelled gun; it was basically a SOMUA S35 with better climbing capacity. Of the FCM design no details are known but it seemed to have had the general outline of the FCM 36, though with its dimensions about 20% larger and equipped with a FCM F4 fortification turret.
Of the other proposals, those of Baudet-Donon-Roussel, Fouga and Lorraine de Dietrich were being kept under consideration until further information could be provided about their feasibility. The SEAM and Renault projects were sufficiently advanced to approve the construction of a prototype of each. The last two firms' good contacts with the French military had allowed them to begin design work even before the specifications were officially revealed. In Renault's case this advantage had turned into a disadvantage when in November it had been decided that a hull-based 75 mm main armament was to be preferred on instigation of Prince André Poniatowski, head of a design bureau subcontracted by SEAM, whose proposal unsurprisingly had this feature. The SEAM prototype was to be delivered before 31 October 1937 at a price of 1.2 million French franc, twenty percent of which was advanced by the State.
The new demand for a 75 mm gun in the hull posed many problems for most contenders as in their first designs no room had been provided to mount such a large weapon; it would likely add a mass of two tonnes. The requirement for an 50% increase in armour protection caused another two tonne weight raise. All designs on 20 February 1937 failed to meet the original twenty tonne weight limit and were projected at 23-25 tonnes.
Read more about this topic: Char G1, Development