The FCM F1 was a super-heavy tank developed in France by the Forges et Chantiers de la Méditerranée company. Twelve were ordered in 1940 to replace the Char 2C, but France was defeated before construction could begin. It was large, and had two turrets with one in front and one in the back. The rear turret was higher so it could shoot over the first one, and the wooden mock-up had a single gun in each turret. The development path of the FCM F1 was extremely complex.
On 4 May 1936 however the Conseil Consulatif de l'Armement under General Dufleux decided to develop a new heavy tank, with the following specifications given on 12 November 1936: a maximum weight of 45 metric tons, immunity to 75 mm AP fire above 200 metres, a speed of 30 km/h, a range of 200 kilometers and an armament consisting of a long 75 mm gun in the hull and a 47 mm gun in a turret. It would thus have resembled an oversized Char B1, of which tank several other development projects were ongoing.
In 1937 three manufacturers, AMX, ARL and FCM, presented prototype proposals; ARL even three of them. All of these however had already a higher projected weight than 45 tons — and threatened to become even heavier during actual construction. In reaction it was first decided by the Conseil Supérieur de la Guerre on 26 March 1937 to build a very small and cheap but heavily armoured (60 mm) vehicle instead, on the lines of the British Matilda I. The first designs featured a 37 mm gun. When a better armament was demanded, it was understood through a study by the Section de l'Armement et des Études Techniques (SAET) on 5 April 1937 that the tank would still weigh a twenty tons, while another tank, the Char G1, was already in development in this weight class. As a result in February 1938 the specifications were again radically changed and now asked for a superheavy tank with a 75 mm gun in a turret; no weight limits were imposed. The new specifications were closest to the original FCM proposal of sixty tons and so the French Supreme Command decided on 6 April 1938 to grant FCM a development contract for a Char F1. It was realised however that this project could be no more than an intermediate step in heavy tank design and already a special commission had been formed in February, headed by the inspector-general of tanks, Martin, to further study the problem of overcoming the new defences of the Westwall being at the time constructed on the western German border.
The French High Command approved of the plans of the commission in April 1938 and now appointed a second commission to work them out in detail. This new commission should also consider the question of whether a 45 ton vehicle might not after all be sufficient. In its first meeting on 9 May 1938, the commission quickly came to the conclusion that to meet the tactical demands a 75 mm gun in a turret was necessary and 120 mm armour allround. This could not be reconciled with a weight of 45 tons. On the other hand to equal the climbing and crossing mobility of even the old Char 2C would likely result in a 150-200 ton behemoth, of which even the modules would be impractical to transport. It was therefore decided to further research the possibility of a 65 ton vehicle, with an empty hull weight of 45 tons.
In its second meeting on 22 July 1938, some troubling data were considered. Most bridges could carry a maximum single vehicle load of 35 tons, so the new tank would have to cross rivers on special pontoons. German tank moats transpired to have a width of about seven metres, so a very long vehicle seemed to be necessary. Existing rail road cars could carry a maximum of 100 tons though. It was also pointed out that 120 mm armour might not be enough in view of the powerful German 88 mm gun. The commission rejected the char minimum proposal of 56 tons as it had insufficient trenchcrossing capacity. It also discarded a proposal by engineer Boirault to build a futuristic 120 ton articulated tank. It retained two options: the char maximum of 89 tons, demountable in two sections, and the char squelette of 110 tons and a trenchcrossing ability of eight metres, on the general lines of the WWI American Skeleton Tank, but with the added feature that the main body could move in relation to the skeleton track frame in order to shift its point of gravity.
In September 1938 the Supreme Command ordered to immediately start research into both possibilities. The ARL company was granted a development contract for the char maximum, the first proposal for which was presented by ARL in May 1939. It had a proposed weight of 120 tons, consisted of two detachable modules and could be armed by either a gun or a flamethrower. The commission decided that only the guntank would be considered, but that a second turret at the back was needed for defence against infantry assault. It also remarked that the project was quite similar to that of the Char F1 and that perhaps both programmes should be merged.
On 22 December 1939 more precise specifications were made. FCM should complete the F1 with a 75 mm gun but also build a F1 hull with a 90 or 105 mm gun in the superstructure, because the 75 mm gun was likely too weak. As the Char F1 was designed with 100 mm armour, this should be enhanced on the front to 120 mm. A secondary turret with a 47 mm gun should protect the back. Both AMX and ARL should build prototypes with 105 and 90 mm guns in a turret — the turrets themselves being independently designed, as usual for French tanks — and a secondary turret with a 47 mm gun. That month both FCM and ARL indicated that they expect to begin construction of the prototypes in the summer of 1940 and series production at the end of 1941; for AMX it is too soon to make any precise predictions. ARL on 17 January 1940 ordered four turrets from the Schneider company, but it agreed only to build two 105 mm gun turrets and refuses the two 90 mm gun turrets, as there was simply no capacity to manufacture them.
In February 1940 the Société d’Études et d’Application Mécanique (SEAM) proposed a tank designed by the Polish engineer Prince Poniatowski. It's a truly gigantic vehicle, weighing 220 tons, to be moved by two Hispano engines of 925 hp each, via a petro-electrical transmission. The project tries to recommend itself by pointing out that the hull is over five meters wide while being only twelve metres long and thus has a superiour length-width ratio, facilitating steering. For transport the vehicle can be split in two sides along its entire length. Unsurprisingly on 20 April 1940 it is refused by the Ministry of Defence.
On 4 March 1940 a new subcommission to supervise the heavy tank design learned that the 90 and 105 mm gun turret designs were ready, i.e. on paper. It decided to abandon the AMX projects as they are hopelessly behind schedule; its Tracteur C could not be ready before July 1941. AMX terminated development on 1 April. It advised to go ahead with both the FCM F1 and the ARL prototypes and already order ten or fifteen of the former. That advice was given to a new overarching Commission of Tank Study, to which ARL presents a wooden mock-up on 11 April 1940 and FCM one on the day after. It transpires that the FCM project is far more advanced and can show the new tank in every detail. The design has a sloped armour front plate, a small turret in front, instead of behind as specified, and a higher turret at the back, able to hold a 90 mm gun instead of the specified 75 mm gun. The tank has a projected weight of 140 metric tons, to be moved at 24 km/h by two 550 hp Renault engines via an electrical transmission. The Commission decides to abandon the ARL projects and make a preliminary order for twelve FCM F1s, to be delivered from May 1941 onward at three or four tanks a month. This expectation to have some tanks ready for the summer of 1941 is a very important consideration, as the entire heavy tank project faces strong opposition from those who see it as a waste of scarce resources, better spent on building more Char B1s. The Commission also asks FCM to bring the armour protection to 120 mm allround, though this will increase weight to 145 tons and reduce maximum speed to 20 km/h. For the commission this is a departure from its earlier decisions about a future Char de Forteresse.