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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 Battle of Tannenberg begins.
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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 United Kingdom announces that the North Sea is a military area, effectively creating a blockade of goods into Germany.
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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.