World War I: Causes and Impact

2.1 Long-term Causes: MAIN

Historians use the acronym MAIN to summarise WWI's underlying causes.

M — Militarism

All major European powers had engaged in arms races since the 1870s. Germany doubled its army between 1871 and 1914; Britain and Germany were locked in a naval arms race (Dreadnought battleships). The German Schlieffen Plan (1905) — a pre-designed strategy to fight Russia and France simultaneously — showed how militarism had made war planning routine. By 1914, Europe had 6 million soldiers under arms and vast war industries primed for conflict.

A — Alliance System

Two hostile alliance blocs had formed:

• Triple Alliance (1882): Germany, Austria-Hungary, Italy (Italy later switched sides)
• Triple Entente (1907): France, Russia, Britain

This interlocking system meant a local dispute would automatically drag in all great powers — exactly what happened in July–August 1914.

I — Imperialism

European powers competed for colonial empires in Africa and Asia. The Moroccan Crises of 1905 and 1911 showed how imperial rivalries generated direct confrontations. Control of the Balkans was especially contentious — both Austria-Hungary and Russia wanted influence over declining Ottoman territory.

N — Nationalism

Two forms of nationalism were destabilising Europe:

• Pan-Germanism and Pan-Slavism (competing visions of ethnic unity)
• Nationalist separatism in the multi-ethnic Austro-Hungarian Empire — Serbs, Czechs, Slovaks, Croats all sought independence

Serbia was the focal point. After the Balkan Wars (1912–13), Serbia had grown and threatened Austria-Hungary, which sought to crush Serbian nationalism.

2.2 Immediate Cause: The Assassination

On 28 June 1914 in Sarajevo (Bosnia), Archduke Franz Ferdinand — heir to the Austro-Hungarian throne — was assassinated by Gavrilo Princip, a Bosnian-Serb nationalist of the Black Hand secret society. Austria-Hungary blamed Serbia, issued a harsh ultimatum on 23 July 1914, and declared war on Serbia on 28 July 1914.

The alliance system then cascaded:

• Russia mobilised for Serbia
• Germany declared war on Russia (1 Aug) and France (3 Aug)
• Germany invaded Belgium (4 Aug), bringing Britain into the war

2.3 The War: Key Phases and Facts

Phase	Key Events	Dates
Western Front	Trench warfare; Battle of the Marne	Sep 1914
Gallipoli Campaign	Allied attempt on Ottoman; ANZAC troops	Apr–Dec 1915
Battle of Verdun	Longest battle; ~700,000 casualties	Feb–Dec 1916
Battle of the Somme	British offensive; 57,000 British casualties on Day 1	Jul–Nov 1916
US Enters	After German unrestricted submarine warfare	Apr 1917
Russian Exit	Treaty of Brest-Litovsk after Bolshevik Revolution	Mar 1918
Armistice	Germany surrendered; 11th hour, 11th day, 11th month	11 Nov 1918

New Weapons of WWI

• Poison gas — chlorine, mustard gas; first used at Ypres 1915
• Tanks — British invention; first used 1916 Somme
• Aircraft — fighter and bomber development
• Submarines — U-boats; unrestricted warfare
• Machine guns — changed defensive warfare permanently

2.4 Impact of WWI

Political Impact

Four empires collapsed:

• Ottoman Empire — gave rise to modern Turkey and Arab states
• Austro-Hungarian Empire — fragmented into Austria, Hungary, Czechoslovakia, Yugoslavia
• Russian Empire — replaced by USSR after 1917 Revolution
• German Empire — replaced by Weimar Republic

New nations created: Poland, Czechoslovakia, Yugoslavia, Hungary, Finland, Estonia, Latvia, Lithuania. The League of Nations was established (Jan 1920) as the first attempt at collective security.

Economic Impact

• Europe's industrial capacity was devastated; total war cost estimated at $186 billion (1918 dollars)
• Britain borrowed massively from the US, shifting global financial power to New York
• Hyperinflation in Germany (1923): 1 US dollar = 4.2 trillion marks — savings wiped out
• Economic ruin contributed directly to the Great Depression (1929–33)

Social Impact

• Demographic catastrophe: 17 million dead; Spanish flu pandemic (1918–19) killed a further 20–50 million
• Women's roles transformed: UK had 800,000 women in war industries by 1918; US had 1 million women in war work; led to UK women 30+ getting the vote in 1918, equal voting in 1928
• Psychological trauma: "Lost Generation" of writers (Hemingway, Remarque's All Quiet on the Western Front, 1929)
• Rise of anti-war movements and pacifism in the 1920s

Treaty of Versailles 1919 — The Punitive Peace

• Article 231 ("War Guilt Clause"): Germany solely responsible for the war
• Reparations: 132 billion gold marks (~$442 billion in 2021 dollars) — impossible payments
• Territorial losses: Alsace-Lorraine to France; Polish Corridor separating East Prussia; Rhineland demilitarised
• Military limits: Army maximum 100,000; no air force; submarines banned; navy limited
• Colonies lost: All German colonies became League of Nations "mandates" under British, French, Japanese, Australian control
• Result: German humiliation, economic collapse, and the rise of Hitler — the peace that made WWII inevitable

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