The Soviet Union ended the 1930s with a huge fleet of tanks almost completely derived from foreign designs , but before 1941 developed some of the most important trend-setting tanks of the war . The problem the Soviet tank force faced in 1941 was not primarily the technical quality of its vehicles , but the very poor state of maintenance , the appalling lack of readiness , and the poor command situation brought on by the purges of the officer class . The Red Army had adopted in 1940 an advanced doctrine that it was simply incapable of executing
purges of the officer class
Great Purge
Tanks in World War II