Germany, constrained by the terms of the Treaty of Versailles, was not allowed to produce tanks of any kind and only a few armoured cars. In 1926 an unofficial program of tank construction was initiated by Hans von Seeckt, the commander of the "Reichswehr". Built by Rheinmetall-Borsig the first "Grosstraktor" ("big tractor") was similar to the existing British Mk II Medium Tank, 20 tons with a 75 mm gun. This, and other designs, were tested with Soviet co-operation at Kama tank school in the Russian Urals. In Germany proper dummy tanks were used in training, apparently at the instigation of then-Major Heinz Guderian, a staff tactical instructor. Guderian had read Fuller, Liddell-Hart and other tank warfare theorists and he had the support of his commanders to develop his theories into reality.