World War I  Causes, Events, Aftermath
MAIN causes, assassination, trench warfare, new weapons, Versailles Treaty, seeds of WW2.
World War I  Causes, Events, Aftermath
World War I (1914–1918)
What you'll learn
- The causes of WW1 — MAIN factors.
- How the war was fought — trenches, new weapons.
- Why WW1 ended and the peace settlement (Versailles).
- How WW1 reshaped the world — new nations, Russian Revolution, seeds of WW2.
Key concepts
Causes of World War I — MAIN
| Factor | Detail |
|---|---|
| Militarism | Arms race between European powers, especially Germany vs Britain (navy) |
| Alliance system | Triple Alliance (Germany, Austria-Hungary, Italy) vs Triple Entente (Britain, France, Russia) — a war between two would drag in all |
| Imperialism | Competition for colonies in Africa and Asia; rivalry and resentment |
| Nationalism | Pan-Slavism (Russia, Serbia); German nationalism; desire of nationalities to break free from Austria-Hungary |
| Assassination | 28 June 1914: Archduke Franz Ferdinand (heir to Austro-Hungarian throne) assassinated in Sarajevo by Gavrilo Princip (Serbian nationalist, member of Black Hand) |
Outbreak and spread
- Austria-Hungary blamed Serbia → issued ultimatum → Serbia partially accepted.
- Austria declared war on Serbia (28 July 1914).
- Alliance chain activated: Russia mobilised → Germany declared war on Russia → France entered → Germany invaded neutral Belgium → Britain declared war on Germany (4 August 1914).
- By August 1914: Europe at war.
The two sides
| Allied Powers | Central Powers |
|---|---|
| Britain, France, Russia (later USA, Italy) | Germany, Austria-Hungary, Ottoman Empire, Bulgaria |
How the war was fought
Western Front — trench warfare
- Armies dug 600+ km of trenches from English Channel to Switzerland.
- No Man's Land: muddy, barbed-wire strip between opposing trenches; crossing it meant death.
- Battle of the Somme (1916): 57,000 British casualties on the first day alone; ~1 million total casualties.
- Battle of Verdun (1916): ~700,000 casualties; neither side gained meaningful ground.
- Stalemate — neither side could advance.
New weapons
| Weapon | Significance |
|---|---|
| Machine guns | Made frontal attacks suicidal |
| Poison gas | Chlorine, mustard gas; caused horrific casualties; first used by Germans at Ypres (1915) |
| Tanks | Introduced by Britain (1916, Somme); broke through barbed wire and trenches |
| Aeroplanes | Reconnaissance; then aerial combat (dogfights); strategic bombing |
| Submarines (U-boats) | Germany blockaded Britain; sank supply ships including RMS Lusitania (1915, 1,198 killed) |
Eastern Front
- More mobile than Western Front; Russia suffered enormous casualties.
- Russia's army poorly equipped; internal unrest growing.
End of the war
- 1917 — Two turning points:
- Russian Revolution (March + November 1917): Tsar Nicholas II abdicated; Bolsheviks (Lenin) seized power; Russia signed Treaty of Brest-Litovsk (March 1918) with Germany and exited the war.
- USA entered the war (April 1917): Reason — German U-boats sinking US ships; Zimmermann Telegram (Germany tried to get Mexico to attack USA).
- Fresh US troops + resources tipped the balance against Germany.
- 11 November 1918 (11 am): Armistice signed — war ended.
The Paris Peace Conference and Treaty of Versailles (1919)
- "Big Four": USA (Woodrow Wilson), Britain (Lloyd George), France (Clemenceau), Italy (Orlando).
- Woodrow Wilson's Fourteen Points: self-determination, open diplomacy, freedom of seas, League of Nations.
- France wanted to punish Germany severely; Britain more moderate; USA idealistic.
Treaty of Versailles (June 1919) terms for Germany:
| Clause | Detail |
|---|---|
| War Guilt (Article 231) | Germany accepts full blame for the war |
| Reparations | £6.6 billion to be paid to Allies |
| Territory | Lost Alsace-Lorraine (to France), Polish Corridor, all overseas colonies |
| Military | Army limited to 100,000; no air force; no submarines |
| Rhineland | Demilitarised zone |
Legacy and consequences
| Consequence | Detail |
|---|---|
| Casualties | ~17 million dead; 20 million wounded; 1918 Spanish Flu (linked to war) killed 50–100 million more |
| New nations | Austria-Hungary and Ottoman Empire broke up; Poland, Czechoslovakia, Yugoslavia, Hungary, Austria created |
| Russian Revolution | 1917; Bolshevik state; eventually became USSR (1922) |
| League of Nations | Created 1920; first attempt at international peace organisation; USA never joined; weak |
| Seeds of WW2 | German humiliation + reparations → economic crisis → extremism → Hitler |
| End of empires | Ottoman Empire gone; British and French empires extended but weakened |
| India's role | ~1.5 million Indian soldiers served; ~74,000 died; Indian nationalists hoped for self-rule in return |
Quick check
- What does MAIN stand for in the causes of WW1?
- Who was assassinated in 1914? How did this start WW1?
- What was trench warfare? Why was it a stalemate?
- Name three new weapons used in WW1 and their significance.
- What were the key terms of the Treaty of Versailles? How did they lead to WW2?
Open the Practice tab for graded questions on World War I.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Quick check
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