Wars ranked by total number of U.S. military deaths Rank War Years Deaths Deaths per Day US Population in First Year of War Deaths per Population 1 American Civil War 1861–1865 625,000 420 31,443,000 1.988% (1860) 2 World War II 1941–1945 405,399 297 133,402,000 0.307% (1940) 3 World War I 1917–1918 116,516 279 103,268,000 0.110% (1920) 4 Vietnam War 1961–1975 58,209 11 179,323,175 (1960) 0.030% (1970) 5 Korean War 1950–1953 36,516 45 151,325,000 0.020% (1950) 6 American Revolutionary War 1775–1783 25,000 11 2,500,000 0.899% (1780) 7 War of 1812 1812–1815 15,000 15 8,000,000 0.207% (1810) 8 Mexican–American War 1846–1848 13,283 29 21,406,000 0.057% (1850) 9 War on Terror 2001–present 6,717 1.57 294,043,000 0.002% (2010) 10 Philippine–American War 1899–1902 4,196 3.8 72,129,001 0.006% (1900)