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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
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August 3 - Germany declares war on France.
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August 4 - The United Kingdom declares war on Germany, after Germany invades Belgium.
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August 6 - Austria-Hungary declares war on Russia
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August 19 - U.S. President Woodrow Wilson announces the U.S. will remain neutral.
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December 24 The unofficial Christmas truce is declared.
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February 4 - 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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July 1 - The Battle of the Somme begins. During the Battle of the Somme, tanks are first introduced into battle.
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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.
