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World History Unit 7: Global conflict (c. 1900–present)

Two world wars and a global depression reshaped politics, ended empires and produced mass atrocities.

Covers: Shifting power, World War I, the interwar period, the Great Depression, World War II, mass atrocities

Study guide

In the early 1900s, older land empires collapsed. The Qing fell in 1911, the Mexican Revolution began in 1910, the Russian Revolution of 1917 ended the tsars and brought the Bolsheviks under Lenin to power, and the Ottoman Empire collapsed after World War I.

World War I (1914–1918) was caused by militarism, alliances, imperialism and nationalism (often remembered as MAIN), and it was triggered by the assassination of Archduke Franz Ferdinand. It was a total war, with governments mobilizing entire economies and using propaganda. Trench warfare, machine guns, poison gas and tanks caused enormous casualties. Colonies supplied soldiers and resources. The Treaty of Versailles (1919) blamed Germany, demanded reparations and created the League of Nations, while the mandate system gave former Ottoman lands to Britain and France.

The Great Depression began with the 1929 US stock market crash and spread worldwide. Governments responded differently: the US New Deal used Keynesian government spending, while economic crisis helped fascism rise in Italy (Mussolini) and Germany (Hitler). Stalin's Soviet Union pursued five-year plans and collectivization, causing famine. World War II (1939–1945) began with Germany's invasion of Poland; Japan's expansion in Asia and its attack on Pearl Harbor brought the US into the war. The Allies (Britain, the Soviet Union, the US and others) defeated the Axis (Germany, Italy, Japan), and the US dropped atomic bombs on Hiroshima and Nagasaki. The war included mass atrocities: the Holocaust killed six million Jews and millions of others, and genocides also occurred in Armenia (1915), and later in Cambodia and Rwanda.

In the 1930s, Japan invaded Manchuria (1931) and then China (1937), Italy conquered Ethiopia, and Germany rearmed and annexed Austria, while the League of Nations failed to stop them. Britain and France tried appeasement, letting Hitler take the Sudetenland at Munich (1938). The Nazi-Soviet Pact (1939) cleared the way for Germany's invasion of Poland. The peace treaties broke up Austria-Hungary and the Ottoman Empire and created new states such as Poland, Czechoslovakia and Yugoslavia, guided partly by Woodrow Wilson's principle of self-determination. Colonized peoples also invoked that principle.

Sun Yat-sen (Sun Yixian), whose Three Principles called for nationalism, democracy and the people's livelihood, led the movement that founded the Republic of China in 1912. The Nationalists (Guomindang) under Chiang Kai-shek later fought Mao's Communists for control. Out of the Ottoman collapse, Mustafa Kemal Atatürk founded the Republic of Turkey (1923) and pushed secular, Western-style reforms. The Mexican Revolution rose against dictator Porfirio Díaz. Leaders like Emiliano Zapata and Pancho Villa demanded land reform, and the revolution produced the Constitution of 1917.

Stalin's Great Purge in the late 1930s used show trials, executions and Gulag labor camps against suspected enemies, including peasants, officials and army officers.

Key ideas

• The Qing, Russian and Ottoman empires collapsed in the early 1900s.
• WWI was a total war caused by militarism, alliances, imperialism and nationalism.
• The Treaty of Versailles punished Germany and created the League of Nations.
• The Great Depression helped fascism rise.
• WWII included the Holocaust and ended with atomic bombs.

Formulas and rules

Common mistakes

• Thinking the League of Nations included the US; the US never joined.
• Confusing fascism (extreme nationalism, one-party rule) with communism.

Words to know

Total war

War that mobilizes a nation's entire economy and population.

MAIN

Causes of WWI: militarism, alliances, imperialism, nationalism.

Trench warfare

Fighting from long ditches, leading to stalemate in WWI.

Propaganda

Information used to promote a political cause.

Treaty of Versailles

1919 treaty that ended WWI and punished Germany.

League of Nations

International organization created after WWI.

Mandate system

Former Ottoman and German lands governed by Britain and France after WWI.

Russian Revolution

1917 revolution that ended the tsars and brought the Bolsheviks to power.

Great Depression

Worldwide economic collapse beginning in 1929.

Keynesian economics

Using government spending to fight recessions.

Fascism

Extreme nationalist, one-party rule that suppresses opposition.

Collectivization

Stalin's forced merging of farms into state-controlled collectives.

Holocaust

Nazi genocide of six million Jews and millions of others.

Genocide

The deliberate killing of a national, ethnic or religious group.

Armenian genocide

Ottoman mass killing of Armenians in 1915.

Sample practice questions

5 more questions like these, from level 1 to 5, are in the practice set.