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assassination of Archduke Franz Ferdinand
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Austria-Hungary declares war on Serbia
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Germany declares war on Russia.
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Germany declares war on France.
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The United Kingdom declares war on Germany, after Germany invades Belgium
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Austria-Hungary declares war on Russia and Serbia declares war on Germany
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U.S. President Woodrow Wilson announces the U.S. will remain neutral
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The First Battle of the Marne begins. Trench warfare begins as soldiers on both sides dig in.
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Battle of Ypres begins
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The unofficial Christmas truce is declared.
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Germany declares a "war zone" around Great Britain, essentially effecting a submarine blockade where even neutral merchant vessels were to be potential targets.
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The Second Battle of Ypres begins. It is during this battle that the Germans first use poison gas.
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The British ocean liner RMS Lusitania is sunk by German U-boat, U-20
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The Battle of Verdun begins. The Battle of Verdun was the longest battle of World War I and was one of the bloodiest.
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The Battle of the Somme begins. During the Battle of the Somme, tanks are first introduced into battle.
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Germany sends the secret Zimmerman Telegram to Mexico in an effort to entice Mexico to join the war. The British intercept and decipher the coded message.
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The United States declares war on Germany.
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Russia signs the Treaty of Brest Litovsk, which is a peace treaty between Russia and the Central Powers.
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German Kaiser Wilhelm II abdicates and flees Germany.
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Germany signs the armistice at Compiegne, France. Fighting ends on the 11th hour of the 11th day of the 11th month
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The Treaty of Versailles officially ends WWI.