The major causes of World War II were numerous. They include the impact of the Treaty of Versailles following WWI, the worldwide economic depression, failure of appeasement, the rise of militarism in Germany and Japan, and the failure of the League of Nations.

The war in Europe concluded with the liberation of German-occupied territories, and the invasion of Germany by the Western Allies and the Soviet Union, culminating in the fall of Berlin to Soviet troops, the suicide of Adolf Hitler and the German unconditional surrender on 8 May 1945.

These were: the lack of productivity of its war economy, the weak supply lines, the start of a war on two fronts, and the lack of strong leadership. Following the invasion of the Soviet Union, using the Blitzkrieg tactic, the German Army marched far into Russia.