One group thought having fewer heavily armored main battle tanks was the way to go. In comparison, the other group wanted to use swarms of lighter tanks to besiege the enemy — much like the Germans, who, instead of placing AFVs with infantry and cavalry tank units, formed whole divisions that would attack targets with overwhelming assaults.
While the Char B1 had 40 mm armor, the upgraded B1 Bis’ front hull had armor that consisted of 60 mm bolted steel plates and was slanted at a 45-degree angle instead of the B1’s 57-degree angle. The sides were upgraded to a 55 mm thickness, the back to 50 mm, and the engine deck to 25 mm. It was virtually impenetrable.
However, all this armor made it incredibly heavy — the B1 was 28 tons (56,000 lbs) and the Bis 31 tons (69,440 lbs). Both were very slow comparatively speaking, with the B1 having a road speed of just 17 mph (13 mph off-road), while the Bis was reportedly even slower.
While France may have lost the war, there were specific battles where the Char B1/B1 Bis, which according to the National Interest, “ate Hitler’s best tanks for breakfast” — and, at least for a short time, struck real fear in the hearts of the German army.