The Twentieth Century: World Wars, Cold War, Decolonization

World War I (1914–1918)

Triggered by the June 1914 assassination of Archduke Franz Ferdinand in Sarajevo and the subsequent July Crisis. Allied Powers (initially France, Britain, Russia, Serbia; joined later by Italy 1915, US 1917) fought the Central Powers (Germany, Austria-Hungary, Ottoman Empire, Bulgaria). Distinctive features: trench warfare on the Western Front; industrial-scale casualties (~17 million deaths); the 1917 Russian Revolutions removing Russia from the war; US entry (April 1917) contributing to eventual Allied victory. Ended with the Armistice November 11, 1918 and the Treaty of Versailles June 1919 (with a punitive settlement toward Germany that would shape the interwar order).

Interwar period (1918–1939)

Key developments:

• Russian Revolution and Soviet Union — Bolshevik seizure of power October 1917; Russian Civil War 1918–1922; Stalin's consolidation and rapid industrialization Five-Year Plans from 1928 with substantial human cost.
• Global Depression from 1929 producing widespread unemployment and political radicalization. Responses varied: New Deal (US), Beveridge-tradition welfare-state planning (UK), fascist state-directed economics (Germany, Italy), Stalin's Five-Year Plans (USSR).
• Rise of fascism — Mussolini's Italy from 1922, Hitler's Germany from 1933, with extreme nationalism, cult of the leader, mobilization through mass rallies and propaganda.
• League of Nations (1920–1946) failed to prevent Japanese, Italian, and German aggression that led to WWII.

World War II (1939–1945)

Began in Europe with German invasion of Poland September 1, 1939 (following the Molotov-Ribbentrop Pact); in the Pacific with Japanese expansion, formalized by the December 7, 1941 Pearl Harbor attack. Key features:

• Massive military mobilization on multiple fronts.
• Total-war economies with civilian industries converted to military production.
• Deliberate targeting of civilian populations through strategic bombing.
• The Holocaust — systematic murder of approximately six million European Jews and millions of other victims by Nazi Germany.
• Atomic bombing of Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945).
• Approximately 70–85 million deaths total — the deadliest conflict in human history.

The Cold War (1947–1991)

Structured global politics for four decades:

• US-led capitalist West vs USSR-led communist East, without direct hot war between them.
• Ideological, economic, and cultural competition.
• Proxy wars — Korean War (1950–1953), Vietnam War (1955–1975), various African and Latin American conflicts.
• Nuclear arms race — US atomic bomb 1945, Soviet 1949, hydrogen bombs early 1950s, ICBMs, doctrine of Mutual Assured Destruction.
• Cuban Missile Crisis (October 1962) as closest approach to nuclear war.
• Ended 1989–1991: Berlin Wall falls November 9, 1989; Central European revolutions; Soviet Union formally dissolves December 25, 1991.

Decolonization

Post-WWII independence spread across Asia and Africa:

• India and Pakistan (August 1947) with catastrophic Partition violence.
• Southeast Asia — Indonesia 1949 (after four-year struggle vs Dutch), Vietnam through the Indochina Wars, Philippines 1946.
• Africa — Ghana (1957) as first sub-Saharan colony, with 17 African states independent in 1960 alone (the "Year of Africa") and most others by late 1960s.
• Mostly retained colonial-era borders (later codified as OAU principle) despite ethnic mismatches.

CBE skill focus

20th-century questions often test specific dates and sequences. Build a mental timeline of major events. Also expect comparative analysis — parallel WWI and WWII causes, or compare Chinese and Russian Communist revolutions.