Renault R35 Development – Part 2

Author: Yuri Pasholok
Part 1:

Continuing from Part 1:

One thing that needs to be discussed separately is the tanks armament. The thing is, the SA18 gun, used on the Renault FT light tank, was already obsolete by 1926. The reasons why this gun appeared on this new vehicle were purely economic ones. The first reason was that the notoriously underfunded French infantry branch had to save money on practically everything, even on the metal for new tanks production. This was in fact one of the reasons for the appearance of what was basically just an improved version of Renault FT with thicker armor but in roughly the same weight category.

The second reason was that there was a very large number of these guns produced and they were used in the obsolete FT’s. When in 1934 the French started re-arming the FT’s with MAC Mle.1931 machineguns, they didn’t re-arm only the machinegun variants but also the FT variants that carried guns before that. That left them with thousands of “free” guns. At the same time, those Renault FT’s that were too worn-out were phased out as well for scrap. This process also became a source of “free” guns.

Renault R35 – Front

Eventually, the weight of the vehicle was increased even more, something that naturally had influence on its mobility. And finally, another big issue of the vehicle was the fact that it was actually really short, which meant that it had trouble crossing even average-sized trenches. This was eventually “solved” the same way it was nearly two decades ago – the vehicle received a “tail”, the same kind the Renault FT was equipped with.

Regardless of these issues, the modified Renault ZM became the victor of the design competition – not that it was that great of a feat, mind you: Hotchkiss (the same company that was at the birth of the competition for next French light infantry tank) gave up and left the contest and all the other competitors were even worse compared to Renault’s design, requiring many changes and fixes to be suitable. Under the circumstances, the Infantry Command had no choice but to declare Renault the winner. Renault ZM was thus on 29.4.1935 accepted officially in service under the designation of Char léger Modèle 1935 R.

The first production run was to consist of 300 vehicles that had registration numbers starting with 50001. Another production run followed and the French infantry finally received the long-awaited replacement for the obsolete Renault FTs.

Renault R35 quickly became the working horse of French tank units

In the meanwhile however, the vehicle suffered from more issues than just weak armament. Due to the changes made to the vehicle, the initial weight of 6 tons was actually increased to almost 11 tons. The original engine – 85hp Renault 447 – was sufficient to make the original variant mobile, but for nearly 5 extra tons it was woefully inadequate with only 7.7 hp/t.

Renault R35 during Normandy training in 1937

Another issue turned out to be the suspension, originally developed for a cavalry tankette and more suitable for plains and hard surfaces than rough terrain. It clearly had trouble during off-road driving – five roadwheels were obviously not enough, the suspension itself had trouble crossing various ditches and other obstacles. Regardless, the total number of R35s produced was 1540 vehicles. The military actually ordered even more (1800 + 500 immediately after the war began) but these plans were never realized due to complicated circumstances.

The Infantry Command partially “woke up” in 1937 and realized that the Renault R35 wasn’t exactly the best thing on the battlefield. They did not miss the lessons learned from the Spanish Civil War, lessons that would positively haunt them in the future. It turned out that during the war, large numbers of anti-tank guns were used by both sides, especially the German 37mm PaK. In the June of 1937, one R35 underwent firing trials where it was fired at from at first a 25mm AT gun and then from the 37mm PaK. The results were – to put it mildly – a nasty surprise.

Renault R35, shot up by AT guns during testing

The tests have clearly shown that armor thickness by itself cannot guarantee solid protection. The issue with cast armor was that when compared to rolled armor plates of equal thickness, their durability was 10-15 percent lower. From 18 shots by 37mm PaK, 14 ended in penetrations. Neither the hull nor the turret posed a serious problem to the German gun.

What was even worse however was the fact that out of 22 shots from the French 25mm AT gun, 13 also ended in penetrations. It’s no wonder that after such unexpected results, the French Infantry Comnmand started paying much more attention to the FCM 36 – although this vehicle was twice as expensive, it was protected by welded and well-sloped rolled armor plates. In addition to that, the FCM suspension turned out to be more suitable for off-road terrain.

Renault R35, experimentally equipped with a FCM turret (Tourelle FCM)

But the deed was already done and under the circumstances there was no time for significant changes. Even though the FCM 36 would have been nice, it was also expensive and the production capacities of Forges et Chantiers de la Méditerranée were limited. Even Renault itself had issues with fulfilling the military contract, as a result of which the French Infantry Command also ordered 100 Hotchkiss H35 tanks (a roughly similar vehicle to R35).

One of the most common solutions was – after the production of 1350 APX-R turrets – to equip the R35 tanks with FCM turret, originally used on FCM 36, which was considerable more protected than the original APX-R. Another issue came up however.

One of the few R35s equipped with the SA38 gun

With the constant increases in armor, the French suddenly realized that the old SA18 gun cannot penetrate even light tanks on the battlefield. The answer to that was the rushed development of 37mm SA38, penetrating 29mm of armor at 100 meters. Of course, that was too little even for 1938 (by this time, the Germans started producing tanks with 30mm frontal armor) but it was nevertheless more than SA18′s 20mm penetration. Another thing that was later found out was the fact that the welds of the FCM turret would break under intensive shelling.

As a result of these two factors, it was decided to install the new gun into the old APX-R turret. True, even this change took quite long, because apart from the R35, the H35 and H39 tanks by Hotchkiss also required the same re-arming. As a result, the SA38 became available for the R35 only at the end of its production run. One of the tanks that received this new gun was the vehicle registration number 51295. From that number alone, it’s possible to make the conclusion that there were fewer than 250 of these re-armed R35s in total. It’s however likely that there were even fewer than that – the analysis of photoghraphs shows that approximately one half of the vehicles produced after number 51295 were armed with the SA18 still.

R35, destroyed by the Germans in May-June 1940

The results of the obsolete French tank doctrine (based on First World War) became obvious during the French campaign of the Second World War. Interestingly enough, the first soldiers to actually try the R35s in battle were the Polish – the Polish army received 50 such vehicles, but for a number of reasons (including insufficient training) the results of these vehicles in Polish service during the Polish campaign were very poor. A part of these vehicles were captured by the Germans and the Red Army in working condition. Generally it can be said that the Polish 7TP tanks had higher combat value as they were more mobile and were able to penetrate any German tanks of that period.

As for the results of the R35 in France – the R35 was the most common French tank during WW2 (with the exception of the completely obsolete Renault FT), but it was a war it was not ready or suitable for. There were no massive attacks of hundreds of small light tanks against fixed lines like they were in WW1, the enemy the R35 gad ti fight was highly mobile. In reality, the tank battalions equipped with R35s were mostly static with little hanging on their performance. The French fought bravely, but what can you do when your gun can’t penetrate the majority of German tanks and your armor gets penetrated by 37mm AT guns at 300 meters.

And one has to count in the fact that the commander of a French tank was also the gunner, loader and sometimes even the radioman. Even the old D1, considered unsuccessful by the French themselves fared better in combat than the R35. And so the French paid dearly for their failure to prepare for a new type of war.

3 thoughts on “Renault R35 Development – Part 2

  1. Pingback: Renault R35 Development – Part 1 | For the Record

    • Yea, it’s good that Yuri shares his stuff with SS :)
      Interesting read. Hope to see more on R&D in the tank industry