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Austro-Hungarian throne and his wife Sophie, Duchess of Hohenberg were assassinated in Sarajevo
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Austria-Hungary declares war on Serbia, effectively beginning the First World War.
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Great Britain declared war on Germany at 11:00 p.m. for violating Belgian neutrality.
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the British ocean liner Lusitania is torpedoed without warning by a German submarine off the south coast of Ireland.
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France lost 48,320 casualties while Great Britain lost 61,713.
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The British intercept a telegram sent by Alfred Zimmermann in the German Foreign Office to the German embassies in Washington, D.C., and Mexico City.
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the United States formally declared war against Germany and entered the conflict in Europe.
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The Nivelle Offensive in April and May had failed to achieve its more grandiose aims, had led to the demoralisation of French troops and confounded the Anglo-French strategy for 1917.
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Although fighting continued elsewhere, the armistice between Germany and the Allies was the first step to ending World War I.
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Germany and the Allies signed the Treaty of Versailles, formally ending World War I and providing for the creation of the League of Nations.