Causes of WWII and its effects

World War II (1939–1945) was a global war between the Allies (Britain, France, USSR, USA, China) and the Axis (Germany, Italy, Japan). It ended with Germany's surrender in May 1945 and Japan's surrender in August 1945 after the atomic bombs on Hiroshima and Nagasaki.

Key reasons (causes) of World War II

1. Treaty of Versailles (1919) – Germany was humiliated: it lost territory and colonies, its army was limited and it had to pay huge reparations; this created anger and a desire for revenge.
2. Great Depression (1929) – world economic crisis caused mass unemployment and poverty, helping extremist parties gain power.
3. Rise of Fascism and Nazism – Mussolini in Italy (1922), Hitler in Germany (1933) and militarists in Japan wanted expansion and glorified war.
4. Failure of the League of Nations – it could not stop Japan's invasion of Manchuria (1931) or Italy's attack on Ethiopia (1935); it had no army and the USA was not a member.
5. Policy of appeasement – Britain and France gave in to Hitler (Rhineland 1936, Austria 1938, Sudetenland at Munich 1938), which encouraged more aggression.
6. Expansionism and alliances – Rome–Berlin–Tokyo Axis; Nazi–Soviet Non-Aggression Pact (August 1939).
7. Immediate cause – Germany invaded Poland on 1 September 1939; Britain and France declared war on 3 September 1939. The USA joined after Japan attacked Pearl Harbor (7 December 1941).

Political effects

• United Nations founded in 1945 to maintain peace.
• USA and USSR emerged as superpowers; Britain and France declined.
• Cold War – ideological rivalry between capitalist West (NATO, 1949) and communist East (Warsaw Pact, 1955); nuclear arms race.
• Division of Germany (East and West) and of Korea; Communist China (1949).
• Decolonisation – India and Pakistan (1947), Burma, Indonesia and most African countries gained independence.
• Creation of Israel (1948); Nuremberg and Tokyo war-crime trials; Universal Declaration of Human Rights (1948).

Economic effects

• Massive destruction of industry, cities and transport in Europe and Asia; huge debts and inflation.
• Bretton Woods system (1944) – IMF and World Bank; the US dollar became the world reserve currency.
• Marshall Plan (1948) – US aid rebuilt Western Europe; later "economic miracles" in West Germany and Japan.
• USA became the largest industrial and creditor nation.
• War technologies (jet engines, radar, computers, nuclear power, synthetic rubber) boosted post-war industry.
• Growth of GATT (1947) and free trade; rise of welfare states in Europe.