6.12 Causes of World War I

Long-Term Causes: MAIN Factors

Historians summarize WWI's causes as MAIN: Militarism (arms races, glorification of military power), Alliances (Triple Alliance vs. Triple Entente created a rigid bloc system), Imperialism (colonial rivalries, e.g., Morocco Crises), and Nationalism (Pan-Slavism, Franco-German tensions over Alsace-Lorraine, ethnic unrest in the Balkans). These created deep tensions across Europe by 1914.

The Balkan Powder Keg

The declining Ottoman Empire left the Balkans unstable, with Austria-Hungary and Russia competing for influence. Serbia sought to unite South Slavs, threatening Austria-Hungary's multi-ethnic empire. The Balkan Wars (1912-1913) increased Serbian confidence and Austrian anxiety, setting the stage for a crisis.

The Trigger: Assassination and Escalation

On June 28, 1914, Gavrilo Princip, a Serbian nationalist, assassinated Archduke Franz Ferdinand in Sarajevo. Austria-Hungary issued Serbia an ultimatum, backed by Germany's 'blank check' pledge of support. Rigid alliance systems and mobilization plans (like Germany's Schlieffen Plan) turned a regional dispute into a continental war within weeks.

Key terms

MAIN causes of WWI

Militarism, Alliances, Imperialism, Nationalism — the four long-term causes historians use to explain WWI's origins.

Gavrilo Princip

Serbian nationalist who assassinated Archduke Franz Ferdinand in Sarajevo in June 1914, triggering the July Crisis.

'Blank check' pledge

Germany's promise of unconditional support to Austria-Hungary for any action against Serbia after the assassination.

Schlieffen Plan

Germany's strategy to swiftly defeat France through Belgium before turning to face Russia, escalating the war rapidly.

Balkan instability

Decline of the Ottoman Empire and rise of Serbian/Pan-Slavic nationalism made the Balkans a flashpoint for Austro-Russian rivalry before WWI.

Try an AP-style question

The alliance system before WWI divided Europe into…

1. the Axis and the Allies
2. the Triple Alliance and Triple Entente
3. NATO and the Warsaw Pact
4. the Holy Alliance and Concert