The leader of the Soviet Union during the Great Patriotic War (World War II) was Joseph Stalin. His leadership was marked by a brutal but effective approach to governance and military strategy. Stalin played a crucial role in the Soviet Union's defense against Nazi Germany, orchestrating significant battles such as the Battle of Stalingrad that turned the tide in favor of the Allies. Despite facing immense challenges, including purges within the military, Stalin's regime successfully mobilized the economy for war efforts, ultimately contributing to the defeat of the Axis powers. His legacy remains complex, entwined with both industrial progress and pervasive repression.