A principal figure during the Bolshevik Revolution and the establishment of communist rule in the Soviet Union, Joseph Stalin served as general secretary of the central committee of the communist party for more than 30 years. He led the Soviet Union during World War II as the Red Army defended the country against the invasion by German forces that began on June 22, 1941. After initial setbacks, the Soviets assumed the offensive and drove the Germans westward hundreds of miles, capturing Berlin in 1945. Stalin ruled with an iron fist and was responsible for the deaths of millions. His ruthlessness was particularly evident during a bloody purge of the Soviet military leadership in the 1930s. He expanded communist rule into Eastern Europe following World War II and opposed his former Allies during the early days of the Cold War. He died of a stroke in 1953 at the age of 74.