other armies, huge wartime losses and reorganisation based on war experience reversed the trend during the later war years. Thus, for example, the Soviet Tank Corps was equivalent in armored vehicle power to an American armored division, and a Soviet rifle (infantry) division, unless specifically reinforced, was often equivalent to an American infantry regiment. The Soviets developed their armament factories under the assumption that during the war they would have to rebuild the whole equipment of the ground and air forces many times over. This assumption was indeed proven correct during the four-year-long war. The Red Army's focus on mobile operations in the early 1930s was gravely disrupted by Stalin's purge of the military's leadership. Since the new doctrines were associated with officers who had been declared enemies of the state, the support for them declined. Many large mechanised formations were disbanded, with the tanks distributed to support the infantry. After the German blitzkrieg proved its potency in Poland and France, the Red Army started a frantic effort to rebuild the large mechanised corps, but the task was only partly finished when the Wehrmacht attacked in 1941. The huge tank forces, powerful only on paper, were mostly annihilated by the Germans in the first months of Operation Barbarossa. Another factor contributing to the initial defeat was that the Soviet post-World War I rearmament effort was started too early, and in 1941 the majority of Soviet equipment was obsolete and inferior to that of the Wehrmacht. In the initial period of the war, in the face of catastrophic losses, the Red Army drastically scaled down its armored formations, with the tank brigade becoming the largest commonly deployed armored unit, and reverted to a simpler mode of operations. Nevertheless, the revolutionary doctrines of the 1930s, modified by combat experience, were eventually successfully used at the front starting in 1943 after the Red Army regained the initiative. Practical deployment of the Soviet military Interwar period Following the death of Lenin, the Soviet Union was enmeshed in a struggle for succession that pitted Trotsky and his policy of "world revolution" against Stalin and his policy of "socialism in one country." Thanks to his control over and support from the Party and state bureaucracy, Stalin prevailed and Trotsky was removed as war commissar in 1925, resulting in a turn away from the policy of spreading the revolution abroad in favour of focusing on domestic issues