Joseph Stalin led the Soviet Union during World War II. Assuming power in the 1920s, he transformed the USSR into a major industrial and military power despite the costs of his policies, including widespread purges and famine. Stalin's leadership was instrumental during the war, as he rallied the nation to resist Nazi Germany following the invasion in 1941. The Red Army's resilience was pivotal in major battles such as Stalingrad, contributing significantly to the defeat of Nazi forces in 1945. Stalin emerged as one of the dominant figures in post-war geopolitics, shaping the Cold War landscape.