During the pre-war period , the efficiency and morale of Red Army command staff was low as a result of Stalin 's purges . By August 1941 , Axis forces had achieved overwhelming successes in their advancement deep into Soviet territory . Their successful blitzkrieg strategy disorganized the Soviet defense system , led to the encirclement of numerous Soviet units , including whole field armies
Stalin 's purges
Great Purge
Order No. 270