Sekenr said:
Actually some sort of early tanks were used by the British in WWI. The Germans followed shortly with a prototype manned by 20 or so soldier crew, where people often suffocted due to engine exaust
The tank first fought on the Somme, IIRC- and they were British tanks. The Germans attempted to come up with a version- the A7V- but only ever built a couple of dozen. In addition to the exhaust, apparently after the tank's engine had been running for a few minutes, the internal temperature rose to around 50 degrees centigrade. I think the crew was no more than 10, though. The Germans had more success with captured British tanks.
The French produced a lot of light tanks in the last two years of the war, the Renault FT-17. A six tonne tank armed with either a machine gun or a 37mm gun. A lot were used by Americans in the war (who didn't produce tanks domestically until too late for use in the war). Something like 3,000 FT-17s and their variants were produced, and many were still in service in 1940, though they were even less reliable by that time.