Ever since 1935, France was working on a new medium tank, intended to replace the ageing Char D2. It was supposed to weight 20 tons and was to be armed with a 47mm gun in the turret and one 75mm short-barrel gun in the hull. As a result, in 1938, the medium tank "Char G" program expanded already to 30 tons, catching up to the Char B in weight.

That didn't sit well with the infantry the tanks were supposed to be supporting and in early 1939, their representatives turned to the Atelier de Construction d'Issy-les-Moulineaux (AMX) company with a request for a 20 ton tank. AMX saw designing a new tank from scratch as completely pointless and therefore they proposed a project consisting of parts of two tanks: AMX 38 and medium tank AMX Tracteur B, projected at the same time. This 35 ton vehicle served as a basis for this new 20 ton "medium" tank.

From the outside, this new 20 ton tank resembled a bigger AMX 38. It was to use the same suspension, that was in the end mass-produced for Renault R 40 tanks. The hull however resembled Tracteur B more than the original AMX 38, especially the suspension part, covered with plates of armor from the outside, which was maintenance-wise far from ideal. The frontal armor was supposed to be 70mm thick and the sides and rear 60mm thick - quite a good armor for a tank of this class, especially for 1939. Just like the Char D2, this vehicle too had two crewmen in the hull - driver and radioman.

The turret of the vehicle was two-man (even though some sources mention only the commander) with the loader sitting actually behind the commander (while the commander was also the gunner). The turret ring was rather small and there was not much room for head inside either, the turret was actually quite flat. What was really good about it however was the proposal to install the new 47mm SA37 gun instead of the usual SA35. SA37 was quite powerful for its time, more than capable of knocking out pretty much anything the enemies (Germans) would throw at it. This would have made the tank a force to be reckoned with.

Unfortunately, we don't know much about the engine, as the project never passed beyond the proposal stage. One of the major candidates would be the 220hp 6-cylinder Aster diesel from 1940, as AMX didn't want to install anything that would give the tank less than 10 hp/t. The vehicle was to be 5960mm long, 2920mm wide and 2560mm tall and was more than adequate for its time. Unfortunately, it was never built due to the wartime events.