American Battle Monuments Commission – has a searchable database for military serving in 20th century wars
Daughters of the American Revolution – free publicly accessible resources
Family Search – U.S. Revolutionary War Compiled Service Records 1775-1783 – free, but only an index
National Archives Military Records – Find out what is held in the national archives related to military service.
National Park Service Soldiers and Sailors – Civil War database
Nationwide Gravesite Locator – locate any person buried in a U.S. national cemetery
Online Military Indexes and Records – links to all major U.S. military actions. Links include those with free access and those requiring a subscription