United States War Casualties War Killed From To Days KIA/Day American Revolution 25,324 04/19/1775 09/03/1783 3059 8.3 War of 1812 2,260 06/18/1812 02/18/1815 975 2.3 Mexican War 13,283 05/13/1846 02/02/1848 630 21.1 Civil War 863,153 04/12/1861 04/09/1865 1458 592.0 Union 498,332 1458 341.8 Confederacy 364,821 1458 250.2 Spanish-American War 2,446 04/25/1898 08/12/1898 109 22.4 World War I 116,516 4/6/1917 11/11/1918 584 199.5 World War II 405,399 12/7/1941 9/2/1945 1365 297.0 Korean War 54,246 6/25/1950 7/27/1953 1128 48.1 Vietnam War 56,244 8/7/1964...