The influential leader of the Soviet Union during the Great Patriotic War against Nazi Germany was Joseph Stalin. His leadership during World War II was marked by significant military decisions and political strategies. Although initially caught off guard by the German invasion, Stalin's regime ramped up production and mobilization efforts, facilitating key victories such as the Battle of Stalingrad. Stalin's use of propaganda fostered a spirit of resistance among the Soviet populace, ultimately contributing to the defeat of Nazi Germany and establishing the Soviet Union as a major world power post-war.