Final answer:
Joseph Stalin was the authoritarian leader of the Soviet Union who led his country through World War II and into the Cold War period. His policies transformed the Soviet Union into an industrial superpower and extended its influence into Eastern Europe. The ideological differences between the Soviet Union and the United States emerged post-World War II, leading to the Cold War.
Step-by-step explanation:
The leader of the Soviet Union after Lenin's death, Joseph Stalin, was a pivotal figure during World War II and the subsequent era. Stalin, known for his authoritarian and totalitarian leadership, transformed the Soviet Union from a poor agrarian society into an industrial superpower through forceful policies of rapid industrialization and collectivization.
His regime bore the brunt of the Nazi war machine during the war, with over 25 million Soviets perishing. Stalin's leadership during this time solidified his power and expanded the Soviet sphere of influence into Eastern Europe, ultimately leading to the Cold War rivalry with the United States.
The alliance between the United States and the Soviet Union was based on the need to defeat a common enemy, Hitler, but their fundamental ideological differences resurfaced after the war, setting the stage for the Cold War.
Stalin's legacy continued to influence the trajectory of the Soviet Union and global politics long after World War II, shaped by his dual role as a communist ideologue and autocrat seeking to protect and expand Soviet interests and ideology.