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British capture Baghdad
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Germany announces unrestricted submarine warfare
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US severs diplomatic ties with Germany
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Zimmermann Telegram is passed to the US by Britain, detailing alleged German proposal of an alliance with Mexico against the US
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US President Woodrow Wilson requests permission from Congress to arm US merchantmen
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US President Woodrow Wilson's war cabinet votes unanimously in favour of declaring war on Germany
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US declares war on Germany
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Nivelle Offensive (Second Battle of Aisne, Third Battle of Champagne) ends in French failure
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10th, 11th and 12th Battles of Isonzo fought, ending in Italian failure
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Russia opens separate peace negotiations with Germany
