"When researching in military records, it is helpful to determine when and where in the armed service a soldier served, and whether he or she was in the enlisted ranks or an officer. Clues may be found in family stories, old newspaper clippings, correspondence, scrapbooks, journals or diaries, service medals and memorabilia, and photographs of the soldier in uniform. The grave marker of a veteran may contain information about military service as well. Military records may have been created in peacetime or during time of war, depending on the record type, and you may even find military records for ancestors who never served. For example, the U.S. World War I Draft Registrations include records for 24 million men, both immigrant and U.S. citizens, who were born between about 1872 and 1900. Many of these men were never called up for service.
Military records...may include dates of birth and death, residence, names and addresses of family members, military rank and affiliation, among other details. The types of records you’ll find in this category include draft records, service records, pension records, bounty land records, claim records, and military histories." - Ancestry Library
Honolulu, HI National Cemetery of the Pacific (Punchbowl), 1941-2011U.S. WWI Draft Registration Cards, 1917-18
Japanese Internment Camp Rosters, 1942-1946
U.S. WWII Draft Registration Cards, 1942
WWI, WWII, and Korean War Casualty Listings
U.S. Vietnam War Military Casualties
U.S. Civil War Soldiers, 1861-1865
U.S. Veterans Gravesites, ca. 1775-2006
U.S. American Red Cross Nurse Files, 1916-1959
And much more...