Sooo what's the difference between a Char B1, a B1bis and a B1ter?
Technically the Char B1 was the B1 with the smaller turret and stubby gun. There were also minor differences, like the back sprocket wheel. The B1 bis gave the Char B1 its iconic long 47mm SA35 gun in a bigger APX4 turret, also increasing its armor from 40mm to 60mm. The Char B1 ter took its armor to a completely new level, being about 75mm all around, the unreliable transmission was replaced in it, the hull gun was given 5 degrees horizontal aiming, and the turret was different from the previous models, but I cant find any solid information on what was different (if you look at it, you can tell it was more boxy, so maybe thicker armor?)