Gun in the Hull
Unlike the British, who concentrated on heavy tanks in WWI, the French started out with the medium weight category. The first French tank, the Schneider CA1, belonged to it. In general, the French managed to create the most successful medium tanks of WWI. They were also the most numerous in their class. The British Medium Mk.A Whippet that arrived later was noticeably worse than its French equivalent.
According to a popular version of events, the French then concentrated all of their efforts on the light Renault FT, which later became the most numerous and best tank of WWI. However, that is not entirely true. The Schneider company continued working on a medium tank, taking into account the drawbacks discovered in the Schneider CA1. The tank had a large protrusion in the front, which was supposed to serve as a battering ram for smashing through enemy fortifications, but ended up being a liability. The hull was also to long. Another problem was the placement of the gun on the right side, which limited the arc of fire.
In 1917, work began on a new generation Schneider CA tank.
Schneider CA3 with a 75 mm gun in the hull. The foundation laid by this design will later be used in the development of the Char B.
On May 1st, 1917, several Schneider medium tank projects were demonstrated to the Ministry of War. Their mass ranged from 13.2 to 15.4 tons. They differed in both the armament and its layout. The first variant had a 47 mm gun in a rotating turret, the second had a 75 mm mod. 1897 gun in the front of the hull. The military considered these two variants the most interesting. In total, the commission picked 5 variants, which were presented to the Comité Consultatif de l'Artillerie d'Assaut (Assault Artillery Consulting Committee) on May 11th.
As a result of the meeting, it was decided that an improved tank would be developed on the base of the Schneider #1. The tank retained its turret, but the gun was replaced with a short 75 mm one. On July 5th, 1917, a reworked version of the tank was presented, indexed Schneider CA3. To be safe, the tank was presented in two variants. One was made according to requirements and was similar to the Schneider #1 with an enlarged turret and a 75 mm gun. The second variant had no turret, and the short barreled 75 mm gun was placed in the middle of the hull. To defend itself from infantry, the tank had machineguns in the front and sides of the hull.
Unexpectedly, that variant was selected as preferable. Schneider received an order to produce 400 Schneider CA3 tanks, work began on the production of a prototype, but an order was issued pausing the CA3 program in February of 1918, and it was later completely cancelled. The French army was left without a second generation medium tank.
Medium tank designed by Delaunay-Belleville. It's easy to tell what tank was its predecessor. The mantlet of a 37 mm gun can be seen to the left of the driver's cabin.
Development of French medium tanks continued on personal initiative alone. Delaunay-Belleville was among companies involved in the assembly of the Renault FT. This company was famous for luxury cars, but it couldn't walk past a military contract.
Delaunay-Belleville produced 390 Renault FT tanks. Based on this vehicle, Delaunay-Belleville engineers designed an artillery tractor for the 155 mm Canon de 155 C mle.1917 Schneider howitzer. The gun was transported directly in the tractor, and could fire without being dismounted. The vehicle was sent to trials in October of 1918, but was not mass produced as the war ended.
A larger engine required a roomier engine compartment.
Using their experience with the tractor, Delaunay-Belleville began working on a medium tank on its own initiative. They decided to not reinvent the wheel: the medium tank completed in 1919 looked like an enlarged Renault FT. The front and turret were taken from the predecessor with no changes. The weight increased to 15.8 tons, which required a new engine and a hull that was almost one meter longer. At the same time, the hull was made wider. This was not caused by the engine, but by a 37 mm gun being placed in the front, to the left of the driver.
Delaunay-Belleville engineers managed to bring the Schneider CA3 concept to fruition, albeit in a clumsy way. This design did not go unnoticed. It came to the attention of General Estienne, the father of French tank building.
Together and Apart
The results of WWI were contradictory for French tank building. On one hand, the French created the best tank of the war, having found the optimal layout, later dubbed classical. On the other hand, they did not have time to fully realize their tank industry. Heavy breakthrough tanks, Estienne's brainchild, were too late for the battlefield. They also proved too expensive, which spelled their doom.
As for the Renault FT, even though it was the best tank in the world, it was not devoid of faults. It was protected from only rifle caliber bullets, and equipping it with anything bigger than a 37 mm infantry cannon proved a difficult task. Eventually, Estienne came to a reasonable conclusion: medium tanks were the future. Their size allowed for sufficiently thick armour and powerful armament, and they were much cheaper than heavy tanks.
According to Estienne's theories, the Renault FT would be gradually replaced by the "battle tank" (char de bataille, or Char B). Their mass would be between 13 and 14.5 tons, and the overall concept was similar to the Schneider CA3. Their main armament would be a 75 mm gun, as the smallest caliber capable of effectively fighting against light fortifications. It was to be housed in the front of the hull. The rotating turret was optional, and in any case, would not contain a weapon more powerful than a machinegun.
Estienne began preparations for the project in 1920. A year later, in late 1921, the general initiated a program for a new tank. Aside from Delaunay-Belleville, Estienne involved FAMH, FCM, Renault, and Schneider. According to the preliminary agreement, the first order would be made for 120 Char B tanks. Delaunay-Belleville received an order for 10 tanks, FAMH for 15, FCM for 15, and Schneider and Renault 30 each.
Estienne proposed that the companies develop the Char B together. In reality, this did not happen, and almost every company picked its own route. Delaunay-Belleville was the first to build their concept in metal, but also quickly dropped out of the competition. Its tank matched the requirements in mass alone, in every other way it was obsolete. There were four competitors left.
According to Estienne, the FAMH design was the best match for the requirements of the Char B concept.
FAMH (Compagnie des Forges et Acieries de la Marine et d'Homecourt), whose tanks are better known under the name Saint-Chamond, developed the tank that met Estienne's requirements. It was the shortest (overall length was 5.2 meters) and the gun was in the exact center of the hull, according to requirements. This was little consolation to the driver. Even though her had a separate cabin, the gun was still located near his legs. The pneumatic control system also added problems and required additional efforts from the driver.
As required, the crew consisted of three men. Aside from the driver and his assistant (who also serviced the gun), the crew included a commander in the turret. His duty was also unenviable: aside from his direct responsibilities, he had to aim and load the dual Hotchkiss Mle.1914 machineguns. Their service required extraordinary ability. It's worth noting that the crew layout was the same in all tanks created according to the Char B concept.
The same tank from the front. It's hard to envy the driver.
At 17 tons, the FAMH Char B had a 120 hp Panhard engine. It was enough to accelerate up to 18.2 kph, almost twice as fast as the Renault FT. As with all other vehicles presented in the tender, the engine and transmission were in the rear.
A progressive decision was to use pneumatic shock absorbers in the suspension. As for the track links, they had British roots. The French used Philip Johnson's designs from the Medium Tank Mk.D. Like the Americans on their Medium Tank M.1922, FAMH engineers equipped the tank with wooden pads that could get more grip on uneven terrain.
FCM (Forges et chantiers de la Méditerranée) engineers also used tracks from the Medium Tank Mk.D, and also the rest of the suspension, along with the original decision to use a cable for the elastic element. It's likely that the company eventually received news about how unreliable it was, as the cable was replaced with a Galls chain.
The tank, which is sometimes called FCM 21, also used the Panhard engine, but the higher mass reduced the top speed to 17.5 kph. On the other side, the larger fuel tanks increased the range to 175 km compared to FAMH's 70.
FCM medium tank. The similarities to the FCM 2C are striking, especially since the commander's turret is the rear turret from the heavy tank.
FCM's medium tank was reminiscent of the FCM 2C breakthrough tank. Despite a different suspension and tracks, the overall design of the running gear changed little. The hull design was similar as well. FCM's tank was the longest (6.5 meters) and tallest (2.5 meters). The height was due to the commander's cupola, which, just like the turret, had its roots in the FCM 2C design.
The armour was the same as the FAMH variant: 25 mm. Poor comfort for the driver was another thing it had in common with its competitor. He was placed on the left side of the hull, the gun on the right. It's unlikely that this neighbour improved his work conditions, and his visibility decreased. On the other hand, the commander of the FCM tank felt like a king. Not only did he have a cupola, but the turret was much larger than that of his competitors.
Experimental SRA (Renault JZ) tank on the assembly line. The suspension can be seen in this photo.
The only companies that worked together like Estienne wished were Schneider and Renault. On October 21st, 1921, an agreement of cooperation was signed. Competition remained, and each company took its own path in some respects. Nevertheless, both companies moved in parallel and shared identical parts and components in their designs.
Both tanks had identical turrets, designed by Schneider, containing a pair of Hotchkiss machineguns. Later, this turret (known as the ST1) and its improved version (ST2) were used on Renault D1 light tanks. The unification also included the engine: both tanks used a 180 hp Renault design. The armour, increased to 30 mm, was also similar, as was the weight: 19 tons. The hulls were also similar, including the placement of the armament and the driver's position. The tanks even had similar names: SRA and SRB, where SR stood for Schneider-Renault.
SRA on trials.
The SRA also had an internal index at Renault: Renault JZ. This tank was almost entirely developed at Boulogne-Billancourt. The length of the tank was between FAMH and FCM at 5.95 meters. It couldn't go faster than 17.5 kph, but no top speed was specified in the requirements. Like other competitors, the tank used Medium Tank Mk.D type tracks, but the suspension used bogeys (2 bogeys of 6 wheels each per side) and leaf springs. Overall, the suspension was more reliable than its competitors'.
This is what the tank looked like after trials. The wear on the tracks, especially the wooden pads, can be clearly seen.
The main feature of the Renault tank was the armament. The 75 mm short barreled gun was shifted to the right, and the ability to aim the gun horizontally was completely absent. This reduced the mobility of fire, but was a boon when it came to protection. In addition, the SRA's driver was housed much more comfortably. Even though he still served as the gunner, his life was much easier than on the FAMH or FCM variants of the Char B. The same could be said about visibility. The presence of servos reduced his efforts.
The SRB, designed by Schneider, had a similar front hull, with one exception. Instead of a short barreled 75 mm gun, it had a long barreled 47 mm gun. It also had the NAEDER turning system, which made aiming the gun horizontally much easier for the driver. The SRB also had servos.
The SRB was the only tank with a different gun than its competitors, but in the same mount as the SRA.
The running gear was a noticeably different between the SRB and SRA. The tank used a similar suspension, which the designers wanted to replace with a hydropneumatic one. Instead of Medium Tank Mk.D type tracks, a more traditional design was used. Renault FT tracks were taken as the basis, and seriously redesigned. Similar tracks were later developed for the Renault NC. With an identical engine, the SRB was slightly faster than the SRA.
As the tanks had to be designed from scratch, work dragged on. All four vehicles were presented on May 13th, 1924, in Rueil-Malmaison. Trials began, which lasted until March of 1925.
The tanks had to have a special trailer which carried 800 L of fuel or 8 men.
The result of the trials came as a shock to General Estienne. He assumed that out of the competitors, one vehicle could be selected as the superior and put into production. In practice, each of the tanks had its own drawbacks.
The FAMH tank was difficult to drive, and broke down many times. The Achilles Heel of the FCM design was the gearbox, which also broke. Similar problems pursued the SRA. In addition, Philip Johnson's tracks were deemed not the best. Initially, everything was fine, but tracks with wooden pads quickly wore down. It was clear that fully metallic tracks were the best option, but even they needed improvements.
Char B by Renault, FCM, and FAMH on trials, 1924.
The SRB was a clear favourite, as its suspension turned out to be the best and the NAEDER system showed itself well. However, Estienne wasn't completely satisfied with this tank either. As a result, no company was awarded the contract for production. Instead, Estienne issued new requirements which had different conditions. Instead of four tanks, only one would be built, and the concept would be designed by Schneider and Renault. The tank would use a Renault engine, a Schneider double differential, a Fieux clutch, and the NAEDER turning mechanism. Individual suspension elements would be taken from the FCM and FAMH tanks.
The armour requirement was increased to 40 mm in the front, 30 mm in the sides, 20 mm in the roof and 15 mm in the floor. The mass was estimated at 19-22 tons. Overall control over the project was given to Renault, who cooperated closely with the STCC (Section technique des chars de combat, Tank Technical Section). Schneider engineers would also take an active role in the development.
After almost four years in development, the second generation medium tank project was launched a second time. Nine long years remained until the adoption of the Char B1.