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June 28 - Archduke Franz Ferdinand, heir to Austria-Hungary's throne, and his wife, Sophie, are assassinated by Serbian nationalist Gavrilo Princip while the couple were visiting Sarajevo.
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July 28 - Austria-Hungary declares war on Serbia.
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August 1 - Germany declares war on Russia.
August 3 - Germany declares war on France. -
September 5 - The First Battle of the Marne begins. Trench warfare begins as soldiers on both sides dig in.
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April 22 - The Second Battle of Ypres begins. It is during this battle that the Germans first use poison gas.
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February 21 - 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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February 21 - 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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April 6 - The United States declares war on Germany.
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November 11 - Germany signs the armistice at Compiegne, France. Fighting ends on the 11th hour of the 11th day of the 11th month (i.e. 11 a.m. on November 11).
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June 28 - The Treaty of Versailles officially ends WWI.
