The ARL 44 was being developed, but this vehicle, although to be armed with a powerful 90 mm gun, could hardly be called modern, as its suspension system was obsolete.

[1] The same year the Ateliers de construction d'Issy-les-Moulineaux (AMX) company presented its projet 141, a project to build the so-called M 4 prototype, armed with a 90 mm Schneider gun with a 1000 m/s muzzle velocity and comparable in performance to the German 8.8 cm KwK 43.

[3] Part of the project was to study whether a modern torsion bar suspension should be used or the height lowered by ten centimetres through a fitting of leaf or coil springs.

To save weight it was decided to install a novel oscillating turret, designed by the Compagnie des forges et aciéries de la marine et d'Homécourt (FAMH).

[4] The prototypes had a length, with gun, of 10.43 m, a width of 3.40 m and a height of 3.41 m. It was intended to fit a 1,200 hp engine to attain a speed much superior to all existing medium tank types.

They consisted of Argus disk brakes of the type developed by Hermann Klaue [de], similar to those previously used in the German Tiger and Panther tanks.

[4] Ten preseries vehicles were to be built by DEFA (Direction des Études et Fabrications d'Armement, the state weapon design bureau),[8] the first being delivered in 1953.

The type was armed with a 120 mm gun, also with a 1,000 m/s muzzle velocity,[2] in response to the perceived threat posed by the Soviet heavy tanks, such as the IS-3[2] and the T-10.

To accommodate the larger gun, an enormous turret was fitted; originally planned in a conventional form, eventually it was decided to also make it of the oscillating type.

From 1954 to 1955 this type was made even heavier, creating the surblindé ("Uparmoured") version with a lower turret and a higher hull with a pointed glacis like the IS-3, bringing weight to about 64 tonnes and the line-of-sight thickness of the armour to 200 mm.

As problems with the preferred Maybach engine persisted, despite limiting the desired output to 1,000 hp, from 1955 onwards a special design team, brought over from Germany, cooperated with the AMX factory to solve them.

As it was already obvious in the early 1950s that the AMX 50 might well turn out to be too heavy — the eventual weight of 53.7 tonnes came as a shock — a parallel medium tank project was initiated in 1952: the Lorraine 40t.

The hull and suspension recalled both the German Tiger and the Panther tanks which, having entered French service after the war,[10] were well known and deliberately imitated.

Therefore, the road wheels were made smaller, compared to the first design proposal, both to save weight and lower the profile of the tank, which was quite high due to a deep hull, a problem only changed in the fifth prototype.

This proved to be unrealistically ambitious, given the level of technological development at the time; in reality not even a ratio of thirty was reliably attained.

Above the massive hull, there was the oscillating turret, smaller, lighter and more compact than that of the Tiger; the sloped face of the upper part had a thickness of 85 mm.

For the production vehicles it was considered to install a coaxial 20 mm gun;[8] lighter armoured targets could then be engaged without depleting the limited ammunition stock in the turret magazines.

Expectations were high: as General Molinié recounted to express his irony, it was hoped to create a tank with the protection of the Panther, the firepower of the Tiger, the mobility and abundance of the T-34, the reliability of the M4 Sherman and all that weighing less than the M26 Pershing.

[4][8] At that time France hoped to regain its position as a Great Power; rebuilding its armaments industry served this goal.

[8] The project was only an independent development in the technological sense: it was hoped that the Americans would fund such a tank, as the financial position of the European states would not allow them to rearm.

[8] In the early 1950s, NATO tacticians were worried by the strong armour of the Soviet vehicles, that seemed to be immune to the guns of the existing Western types.

Room could in fact only be found by increasing the height of the lower turret half, negating the advantages of the oscillating concept and creating a dangerous shot trap.

The "uparmoured" version, with its deeper hull and flatter turret, was specially designed to counter this and make the vehicle immune in long range fire engagements, but further increased weight.

[4] This decision had to be delayed however, due to the fact the engine problems had not been solved: reliability could only be assured if the output was limited to 850 hp, causing a mediocre hp/tonne ratio of about 13:1.

[8] As a result, the project was changed again in intention, now trying to present itself as an agile main battle tank,[8] with the same gun as the Conqueror but much lighter and more powerful.

Only in the early 1980s would France again attempt to combine heavy armour and armament in its tank designs, beginning with the later AMX 32 prototypes.