HistoryExam prep15 min read
World War II: Causes, Course and Consequences
A concise overview of the deadliest conflict in human history and the world it produced.
Last updated July 5, 2026
In this guide
1.Causes
The Treaty of Versailles, the Great Depression, the rise of fascism and failed appeasement all contributed to the outbreak of war in 1939.
2.Major theaters
The war spanned Europe, the Pacific, North Africa and the Atlantic, involving more than 30 countries.
3.Aftermath
The war reshaped the world: the UN was founded, decolonization accelerated, and the Cold War began between the US and USSR.