Char B1
The Char B1 was a French heavy tank manufactured before World War II.
The Char B1 was a specialised break-through vehicle, originally conceived as a self-propelled gun with a 75 mm howitzer in the hull; later a 47 mm gun in a turret was added, to allow it to function also as a Char de Bataille, a "battle tank" fighting enemy armour, equipping the armoured divisions of the Infantry Arm. Starting in the early twenties, its development and production were repeatedly delayed, resulting in a vehicle that was both technologically complex and expensive, and already obsolescent when real mass-production of a derived version, the Char B1 "bis", started in the late 1930s. A further up-armoured version, the Char B1 "ter", was only built in two prototypes.
Among the most powerfully armed and armoured tanks of its day, the type was very effective in direct confrontations with German armour in 1940 during the Battle of France, but low speed and high fuel consumption made it ill-adapted to the war of movement then being fought. After the defeat of France, captured Char B1 would be used by Germany, with some rebuilt as flamethrowers, Munitionspanzer, or mechanised artillery.
Development and production
The Char B1 had its origins in the concept of a Char de Bataille conceived by General Jean Baptiste Eugène Estienne in 1919, e.g. in his memorandum Mémoire sur les missions des chars blindés en campagne. It had to be a "Battle Tank" that would be able to accomplish a breakthrough of the enemy line by destroying fortifications, gun emplacements and opposing tanks. In January 1921 a commission headed by General Edmond Buat initiated a project for such a vehicle. To limit costs, it had to be built like a self-propelled gun, with the main weapon in the hull. To minimise the vehicle size this gun should be able to move only up and down, with the horizontal aiming to be provided by turning the entire vehicle. The specifications included: a maximum weight of thirteen tonnes; a maximum armour thickness of 25 millimetres; a hull as low as possible to enable the gun to fire into the vision slits of bunkers; a small machine gun turret to fend off enemy infantry attacks, at the same time serving as an observation post for the commander and a crew of at most three men. Two versions should be built, one a close support tank armed with a 75 mm howitzer, the other an anti-tank vehicle with a 47 mm gun instead.French industry was very interested in the project. In the past, this had led to much non-constructive rivalry. Estienne, who in the war had personally witnessed the dismal effects of such a situation, was determined to avoid a repetition. He used his position as Inspector-General of the Tanks to enforce the so-called "Estienne accord" on the industrialists, ordering them to "reach a mutual understanding, free from any spirit of industrial competition". To be allowed to join, they had to agree beforehand to relinquish any patents to the Army, which would be free to combine all projects into a single type. In exchange, to the industry very large orders of no less than a thousand vehicles were promised.
On these conditions four projects were started in 1921: two by a cooperation between Renault and Schneider, the SRA and the SRB; one by Forges et Aciéries de la Marine et d'Homécourt, more commonly known as "Saint Chamond" from its location; and the last by Forges et Chantiers de la Méditerranée, the FCM 21. Renault and Schneider would each get to produce 250 units, FAMH and FCM each 125. A fifth producer, Delaunay-Belleville, whose project had been rejected beforehand, would be allowed to make 83 tanks; the remaining 167 would be allotted at the discretion of the French State, which would be the owner of the design.
On 13 May 1924, the four prototypes were presented at the Atelier de Rueil, where they were compared, each having to drive over a twenty kilometre test course. Immediately it became evident that their technical development had been insufficient, most breaking down; the SRA even started to fall apart. Maintenance was difficult because the engines were inaccessible. All projects used a three-man crew but differed considerably in size, form and the solution chosen to laterally point the gun.
The SRA was the heaviest vehicle at 19.5 tonnes. Its length was 5.95 metres, its height 2.26m and its width 2.49m. It had a 75 mm howitzer in the right side of the hull and a cast, 30 mm thick, turret with two machine guns. It was steered by an epicyclical transmission combined with hydraulically reinforced brake disks, which failed to provide the desired precision during tests.
Seen from the front it was very similar to the final model, but its side-on profile was more like that of the British Medium Mark D, including the snake track-system, with the drive wheel higher than the idler in front. The suspension used leaf springs. A Renault six-cylinder 180 hp engine allowed for a maximum speed of 17.5 km/h; a four hundred litre fuel tank for a range of 140 kilometres.
The SRB, also using leaf springs, was a somewhat larger vehicle, six metres long, 2.28 metres high and 2.5 metres wide. It was nevertheless lighter at 18.5 tonnes, a result of having a smaller 47 mm gun—it thus was the antitank version. Using the same engine, its speed was accordingly slightly higher at 18 km/h. More limited fuel reservoirs holding 370 litres decreased the range to 125 kilometres. It used an advanced hydraulic suspension system and the hydraulic Naeder-transmission from the Chaize company combined with a Fieux clutch and Schneider gear box. It used modified Renault FT tracks. The upper track run was much higher, creating enough room for a side door on the left.
The FAHM prototype was 5.2 metres long, 2.4 m high and 2.43 m wide. It used a hydropneumatic suspension. Despite a less powerful Panhard engine of 120 hp it still attained a speed of 18.2 km/h. Fuel reservoirs of just 230 litres limited its range to a mere seventy kilometres. The 75 mm howitzer was placed in the middle of the hull and steered by providing each snake track with its own hydraulic Jeanny transmission. On top there was a riveted machine gun turret with 25 mm armour.
The lightest prototype was the FCM 21 at 15.64 tonnes. It resembled a scaled-down Char 2C, the giant tank produced by the same company. It was very elongated with a length of 6.5 metres and width of 2.05 metres. A rather large riveted turret with a stroboscopic cupola, adopted from the Char 2C, brought its height to 2.52 metres. Like the superheavy tank it had no real spring system for the twelve small wheels per side. Separate clutches for each snake track enabled it to horizontally point the 75 mm howitzer in the middle of the hull. It used the same Panhard engine as the FAHM type and its speed was the lowest of all at 17.4 km/h. However, its 500-litre fuel tanks allowed for the best range at 175 kilometres.
In March 1925, Estienne decided to base the future production type on the SRB, as regarded the general form and mechanical parts. However, it would be fitted with the 75 mm gun, a Holt-track to be developed by FCM, which company had completed a special research programme aimed at optimising weight distribution, and the FAMH-suspension. Estienne also had some special requirements: a track tension wheel should be fitted, adjustable from the inside, and a small gangway from the fighting room should improve the accessibility of the engine compartment. Furthermore, the front armour should be increased to 40 millimetres.
In November 1925 Renault was given the order to build a wooden mock-up, that was finished early 1926. On 27 January 1926, it was decided to build three prototypes of what was provisionally called a Tracteur 30, a final design by engineer Alleaume of the Schneider company, cooperating with the Section Technique des Chars de Combat. The first was to be delivered by Renault, the other two by FCM and FAHM respectively.
The same year, the Direction de l'Infanterie in the Plan 1926 redefined the concept of a Char de Bataille. There would be a greater emphasis on infantry support, implying that the antitank-capacity was secondary and no armour increase was necessary. The weight was to be limited to 22 tonnes and the speed might be as low as 15 km/h. However, a radio set would have to be fitted to better direct and coordinate its actions; therefore a fourth crew-member was needed.
On 18 March 1927, the contracts for the three prototypes were signed. The hull of first Renault vehicle, made of soft boiler plate instead of armour steel to simplify changes, was finished apart from the armament in January 1929; it was delivered in March. The separately produced cast turret was delivered on 23 April. The howitzer could only be fitted in April 1930. This prototype was allotted the series number No. 101. No. 102, the production of which FAMH had shifted to Renault, was delivered soon after; in September 1930 FCM delivered No. 103, constructed by the Atelier de Mépanti at Marseille. One of the vehicles was fitted with an alternative 75 mm Schneider gun instead of the 75 mm St Chamond M 21 from FAMH.
Testing on the first prototype had already begun before the other two were delivered, or even its main armament was fitted. At the weight was more than specified but could nevertheless reach a top speed of. From 6 May until August 1930 the Commission d'Experiences des Matériels de Chars carried out a further test programme on what was now officially called the Char B—the "B" not referring to Bataille but to a general classification code. The commission was largely satisfied with the vehicle, though many smaller problems were detected that had to be improved. The FCM prototype featured several alternative technologies: a Winterthur transmission, a Citroën clutch and a Sulzer diesel engine, later replaced by a Clerget diesel. All of these systems would prove to be more unreliable than the original concept and were ultimately rejected.
The three vehicles were not only used for technological, but also tactical experimentation. Together with the Char D1 pre-series, they represented the only modern tanks in France and the Army was naturally very interested in what lessons could be learned from them about future warfare, outlining the concept of a Char de Manoeuvre. Neither Char de Bataille nor Char de Manoeuvre are official type designations; they refer to the tactical concepts only. In October 1931 a small unit was formed, the Détachement d' Experimentation in which the prototypes were united from December, using the Camp de Châlons as a base to see how they could be used in winter conditions. Afterwards, they drove on their own power to the Atelier de Rueil for repairs. In September they took part in the summer manoeuvres in Champagne as a Détachement Mécanique de Combat; from 4 May 1933 No. 102 and 103 together formed a Détachement d'Engins Blindés to perform tactical experiments in the army bases of Coëtquidan and Mourmelon as part of a motorised light division, followed by comparable experiments in April 1934 at Sissonne. Technical aspects were not forgotten during these tests and it was established they could attain an average road speed of 19 km/h, cross a trench wide, and wade through a deep stream.
The prototypes were again extensively altered to meet changes in specifications. On 6 April 1934, the first order was made for seven tanks of a Char B1. The "B1" refers to the fact that there were other simultaneous projects to develop improved types: the Char B2, B3 and B B.
The Char B1 was manufactured by several firms: Renault, AMX, FCM, FAMH and Schneider. Although it was the main producer, Renault had not exclusively designed the tank. Therefore, the official name was not Renault B1 as often erroneously given. It was a very expensive tank to build: the cost per vehicle was about 1.5 million French francs. In France at the time two schools of thought collided: the first wanted to build very powerful heavy tanks, the other a lot of cheap light tanks. Both sides managed to influence procurement policy to the end that not enough tanks were built of either category, to the exasperation of men like Colonel Charles de Gaulle, who wanted to build more of the medium Char D2 at a third of the cost of the Char B1 bis, but with the same 47 mm anti-tank gun.