1. Background Causes (Before 1914)
- Nationalism – Pride in one’s nation created rivalry (e.g., Germany vs. France, Slavs vs. Austria-Hungary).
- Imperialism – Competition for colonies increased tension between European powers.
- Militarism – Countries built powerful armies and navies, preparing for war.
- Alliance System – Two main alliances formed:
- Triple Alliance: Germany, Austria-Hungary, Italy.
- Triple Entente: Britain, France, Russia.
- This created a “powder keg” situation in Europe.
2. The Spark (June 1914)
- Archduke Franz Ferdinand of Austria-Hungary was assassinated in Sarajevo by a Serbian nationalist.
- Austria-Hungary declared war on Serbia.
- Alliances pulled other nations into the conflict.
3. Outbreak of War (July–August 1914)
- Russia supported Serbia.
- Germany declared war on Russia, then on France.
- Germany invaded Belgium (Schlieffen Plan) to reach France.
- Britain declared war on Germany for violating Belgian neutrality.
- By August 1914, much of Europe was at war.
4. Stalemate on the Western Front (1914–1917)
- Germany’s advance was stopped at the Battle of the Marne (1914).
- Both sides dug trenches from the North Sea to Switzerland.
- Life in the trenches was harsh (mud, disease, constant shelling).
- New weapons: machine guns, poison gas, tanks, submarines, and airplanes.
- Battles like Verdun (1916) and Somme (1916) caused millions of casualties but little territorial change.
5. Other Fronts & Global Involvement
- Eastern Front: Germany and Austria-Hungary fought Russia; fighting was more mobile.
- Middle East: The Ottoman Empire joined Germany; Arabs revolted with British support (Lawrence of Arabia).
- Colonial Fronts: Fighting spread to Africa and Asia.
- Naval Warfare: German submarines attacked Allied shipping; Britain blockaded German ports.
6. Turning Points (1917)
- Russia withdrew after the Bolshevik Revolution (Treaty of Brest-Litovsk, 1918).
- United States entered the war (April 1917) after repeated German submarine attacks and the Zimmerman Telegram.
- U.S. troops boosted Allied strength and morale.
7. The End of the War (1918)
- Germany launched a final offensive in spring 1918 but failed.
- Allied forces counterattacked with fresh U.S. troops.
- Central Powers collapsed one by one: Bulgaria, Ottoman Empire, Austria-Hungary.
- Germany faced revolution at home; Kaiser Wilhelm II abdicated.
- Armistice signed on November 11, 1918 – fighting stopped.
8. Aftermath
- The Treaty of Versailles (1919) blamed Germany for the war, imposed heavy reparations, and redrew European borders.
- League of Nations was created to prevent future wars (but was weak).
- The war caused around 16 million deaths and changed global politics forever.