The most powerful French tank in service in 1940 was already outmoded, its principal ordnance being housed en casemate (armour protection to the front and two sides) which greatly reduced the field of aim.

Nevertheless, at 60mm, its armour could not be penetrated by any enemy tank. It was powerfully armed (two guns, one 75mm and the other 47mm, and two 7.5mm machine-guns) and had good manoeuvrability over rough terrain.

In May 1940, battle tank battalions had less than 400 B1 and B1 bis at their disposal.