Russian revolutionary, Soviet political, state, military and party leader. From January 21, 1924 to March 5, 1953 - the leader of the USSR . Marshal of the Soviet Union (1943) . Generalissimo of the Soviet Union (1945) .. The Tehran Conference is the first conference of the "big three" - the leaders of three countries: I. V. Stalin (USSR), F. D. Roosevelt (USA), W. Churchill (Great Britain) during the Second World War ), held in Tehran on November 28 - December 1, 1943.