Final answer:
The primary causes of World War II were Adolf Hitler's personal obsession with expanding the German empire, nationalism, and international tensions. The war involved numerous nations and became a global conflict. Germany, Italy, and Japan were the Axis powers, while Britain, the US, and the USSR were the Allies.
Step-by-step explanation:
The primary causes of World War II were Adolf Hitler's personal obsession with creating a vastly expanded German empire, nationalism, and international tensions. Hitler's ideology of Nazism and fascism, along with Germany's rebellion against the restrictive sanctions from World War I, led Germany to launch a war of aggression. This war involved numerous nations and eventually became a global conflict. The Axis powers, including Germany, Italy, and Japan, initiated the war, while the Allies, including Britain, the US, and the USSR, opposed them.