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Assassination of Franz Ferdinand
The heir to Austria-Hungary is killed in Sarajevo.
This causes tensions between countries in Europe. -
Austria-Hungary Declares War on Serbia
The war officially begins between European powers. -
World Powers Join the War
Germany, France, Russia, and the UK enter the conflict. -
Battle of the Marne
France and Britain stop Germany near Paris. -
Poison Gas Used at Ypres
Germany uses poison gas for the first time in battle. -
Sinking of the Lusitania
A German submarine sinks a ship with U.S. citizens on board. -
Battles of Verdun and the Somme
Two of the deadliest battles of the war happen this year. -
Zimmermann Telegram Intercepted
Germany’s secret offer to Mexico prompts U.S. outrage. -
USA Joins the War
The United States declares war on Germany. -
Russia Leaves the War
Russia signs peace with Germany after the revolution. -
Treaty of Versailles Signed
Germany accepts blame and pays reparations.
This officially ends the war and reshapes Europe.