World War I was caused by rising nationalism, ethnic conflicts, and imperial rivalries in Europe that led countries to take sides in the war. Germany was defeated and the Treaty of Versailles punished Germany by forcing it to pay reparations, take responsibility for the war, and lose territory. This humiliation of Germany led to resentment and created an environment where Hitler could rise to power by promising to restore Germany to greatness. The economic and social disruptions of the war spread worldwide and contributed to the conditions that caused the Great Depression.
