| 1914 | - U.S. Marines occupy Veracruz, Mexico.
- Archduke Franz Ferdinand assassinated.
- Austria-Hungary declares war on Serbia.
- Germany attacks Russia and France.
- Great Britain declares war on Germany.
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| 1915 | |
| 1916 | - Pancho Villa attacks Americans in Mexico and New Mexico.
- Wilson reelected.
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| 1917 | - Zimmermann telegram intercepted.
- United States declares war on Germany.
- Committee on Public Information created.
- Selective Service Act.
- Espionage Act and Trading with the Enemy Act.
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| 1918 | - Wilson gives Fourteen Points speech.
- Russia arranges separate peace with Germany.
- Sedition Act.
- U.S. Marines see first major combat.
- Armistice signed ending World War I.
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| 1919 | - Paris peace conference begins.
- Treaty of Versailles signed.
- Wave of labor strikes.
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| 1920 | - American Civil Liberties Union founded.
- Prohibition begins.
- Palmer raids.
- Senate votes against ratification of Treaty of Versailles.
- Women get the vote.
- Warren G. Harding elected president.
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