Josef Stalin, the Soviet Union's war leader during World War II (the Great Patriotic War to the Soviets), came to power after the death of Vladamire Lenin in the late 1920s. He was a harsh and brutal dictator. In 1937-38, he purged his military of its best officers, an act that would deprive him of competent leadership once the war started. In 1939, Stalin and Adolf Hitler signed the Nazi-Soviet Non-aggression Treaty that, besides declaring one country would not go to war with the other, divided Poland between Germany and the Soviet Union.
When the Germans launched Operation Barbarossa (its invasion of the Soviet Union) in 1941, Josef Stalin was caught completely off guard and caused him to have a nervous breakdown.
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