Char G1
The Char G1 was a French replacement project for the Char D2 medium tank. Several prototypes from different companies were developed from 1936 onwards, but not a single one had been fully completed at the time of the Fall of France in 1940. The projects represented some of the most advanced French tank design of the period and finally envisaged a type that would have been roughly equal in armament and mobility to later World War II standard tanks of other nations, such as the Soviet T-34 and the American M4 Sherman, but possessing several novel features, such as gun stabilisation, a semi-automatic loader and an optical rangefinder.
Development
The twenty tonne tank
By 1935 the French Infantry had not yet developed a satisfactory medium tank. Whereas a reasonably effective heavy breakthrough tank was available, the Char B1, and several light infantry support tanks were on the brink of being taken into production – the Renault R35, Hotchkiss H35 and the FCM 36 – a good medium tank had still to be designed, as the Char D1 was a manifest failure and the Char D2 only a slight improvement over its ancestor. Such a medium tank was needed in a minimal number of 250 to serve in the planned organic tank battalion of the five Mechanised Infantry Divisions, the main Infantry force capable of executing strategic offensive or defensive movements. A good medium tank was already under development by the French Cavalry, the SOMUA S35, but the Infantry rejected this type, both because of technological reasons – its climbing capacity was limited – and because the Infantry wanted to assert its dominance over the Cavalry in the field of tank design.On 18 December 1935 the first specifications were issued by the Infantry for a Char Moyen d'Infanterie de 20 tonnes. They called for a tank with a road speed of 50 km/h, an off-road speed of 20 km/h, a range of 400 kilometres, a trench crossing capacity of two metres, a wading capacity of 120 centimetres, a climbing capacity of eighty centimetres and 45° slope, a 47 mm gun and 7.5 mm machine-gun, an armour thickness of 40 mm, a gas-proof hull and the possession of a radio set. The weight limit of twenty metric tonnes was chosen because of railroad, bridge carrying and pontoon constraints. Overall these features were close to those of the SOMUA S35.
New specifications
In May 1936, the Conseil Consultatif de l'Armement accordingly decided that French industry would be invited to initiate studies on the design of a tank having sufficient protection and armament to fight other armour, but light enough 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. A twenty-tonne tank would be lighter, swifter, cheaper, more easily produced and require less training. It was 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 ; 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 fulfill 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 to instead 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, only made sense if German-style armoured divisions would be created and a definite decision about its production could only be made when the role-of-the-Infantry 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 that the industry badly needed during the period of the Great Depression. In 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 issued its report on each proposal on 20 February 1937. For two of these, the report forms the 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 the commission had 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 francs, 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 a 50% increase in armour protection caused another two-tonne weight rise. All designs on 20 February 1937 failed to meet the original twenty-tonne weight limit and were projected at 23–25 tonnes.
Renault's tank could easily be adapted, however, to hold a 75 mm gun in the turret. In 1936 Renault proposed this as an alternative, and it was well received. Encouraged by this, in 1937 he retook the initiative from Poniatowski by, through an intermediary, bribing a high-ranking officer of the Direction de l'Infanterie; the latter again manipulated the commission to change the design policy. He convinced the commission that a 75 mm gun in the turret should be not merely an option, but mandatory. This gave Renault an enormous advantage over all his rivals who now were forced to completely redesign their projects, leading to inevitable large and, as Renault hoped, perhaps fatal delays.
In late 1937, the project had been renamed Char G1 and all prototypes then authorised had received an official designation: Lorraine: G1L; Renault: G1R; Baudet Donon Rousel: G1B, Fouga: G1F and SEAM: G1P. The SOMUA and FCM projects were discontinued for being too vague or lacking innovation; also the production capacity of these two companies had already been directed to the manufacture of other types.
On 1 February 1938 the Direction de l'Infanterie issued new specifications, the third major change in the project concept: a maximum weight increased to 35 tonnes, necessitated by the fitting of an L/32 75 mm gun in a turret.
These new demands caused most companies to slow the design process: they were unwilling to invest much money in an ever more complex system with uncertain prospects. Therefore, the French government ordered on 8 June 1938 that ARL military engineer Maurice Lavirotte be detached to guide their efforts, in order to speed the proceedings; if the companies could not obtain armour plate, they should be allowed to use boiler plate to construct prototypes. At that moment Renault was unable to give any indication about a possible production date; the Fouga and BDR projects seemed to become prohibitively heavy; SEAM thought to be able to commence manufacture in the middle of 1940 and Lorraine in 1941.
On 12 July 1938 a much more detailed list of specifications was given. In general they called for a tank that was to be powerfully armed, immune to standard anti-tank guns, and possessing an excellent tactical and strategic mobility. In detail they demanded a long high velocity semi-automatic 75 mm main armament; a 7.5mm machine-gun in the turret that could also serve as an AA-weapon; a machine-gun in the front of the hull or the turret; a minimal ammunition load of a hundred rounds for the gun and thirty magazines for the machine-gun; an empty weight of thirty and a combat weight of thirty-two tonnes. The engine was to be able to be both electrically and manually started, and the tracks were to be fully accessible. An on-road speed capability was required of 40 km/h maximum and 30 km/h average over a long journey, with an off-road capability of 20 km/h. Two fuel tanks were to allow a range of two hundred kilometres or eight hours off-road. The climbing capacity was to be ninety centimetres and 85% on a solid or 65% on a wet slope. The trench-crossing capacity was to be 250 centimetres and the wading capacity, 120 centimetres. For the first time, dimensional limits were included: the width was not to exceed 294 centimetres to facilitate rail transport, and the absolute height of the fighting compartment was not to exceed 120 cm, but yet be sufficient to hold a side-door.
As regards specifications for the gas-tight armour, the required thickness remained at sixty millimetres, but a requirement was added that appliqué armour construction techniques not be used, along with a detail requirement that the armour could be cast – with the sections connected by bolts or, preferably, gudgeons – or electrically welded. A requirement that automatic fire-extinguishers be present also was added.
The crew was to have advanced vision and fire-control equipment. The cupola, armed with the secondary 7.5 mm machine gun, was to have a large episcope to which the main turret was to be slaved, allowing the commander to lay the 75 mm gun on the target himself, allowing for the possibility that the commander would double as gunner. The cupola also was to be fitted with an optical telemetric rangefinder. The main gun was to be an L/32 75 mm gun, providing, despite its limited caliber-length compared to anticipated comparable AFV main weapons of other major military powers, a good muzzle velocity through the use of Brandt tungsten armour-piercing subcalibre ammunition.
None of the projects in the summer of 1938 could meet these specifications without a fundamental redesign.