28 Jul 1914—11 Nov 1918: World War One World War fought in Europe
2
1917
6 Apr 1917: U.S. Enters WWI United States declares war on the Central Powers (Germany, Austria-Hungry)
3
1939
1 Sep 1939—2 Sep 1945: World War Two war fought on a global scale between the Axis Powers (Germany, Italy, Japan) and the Allied nations (U.S., France, Great Britain)
1908 - 1939 (31 years)