Did your Family Serve?
be aware that wars with native peoples started as early as 1636 in New England and stretched on throughout the 19th century.
Remember to look for military records for ALL the male members of your family. Your many great grandfather may not have served in the American Revolution but if his brother did his records may tell you more about the family.
FamilySearch has these Military Record resources but many of them only provide you with an index.
Fold3 is the best resource for American military records. Some of the records are for free; some require a subscription. They offer a 7 day free trial and if you want it longer it is $7.95 per month; you can stop at at any time.
Ancestry.com also has a very large collection of military resources. It is particularly strong in Civil War research and it is very good for finding soldiers who served on the frontier at military posts you might not normally discover.
U.S. Department of Veterans Affairs now has a Gravesite Locator to National Cemeteries
Ancestry remains one of the best starting points for military research. If you don't have a subscription you might visit the local family history library (see the Archives & Libraries page).
One extremely helpful database at Ancestry is their U.S. Dept. of Veterans Affairs BIRLS File 1850-2010 which has over 8 million names. If you are having trouble finding the person and they lived late enough to have a social security number use the SS Death Index to locate his number. You can then put the number into BIRLS database and he should come right up.
Military Rosters - from Rootsweb (all wars) - currently has 111056 records and keeps growing by contributions
National Archives: Resources for Genealogists - this is where you go to order records. They don't have a lot of online content but they do have a lot of good information and guides.
American Merchant Marines (database of all wars)
Once you know what unit your ancestor served in find more about what they did.
Google terms like:
10th Iowa Infantry company D
or 10th Iowa Infantry unit history
"Captain Dygert's" company
also see if you can find a county history of the place where your family lived because they nearly always devoted a chapter to local involvement in wars.