1775-1783--Revolutionary War (Was your male ancestor 10-45 years of age in 1775?)
1812-1814--War of 1812 (Was your male ancestor 15-45 years of age in 1812?)
1846-1848--Mexican-American War (Was your male ancestor 16-45 years of age in 1846?)
1861-1865--Civil War (Was your male ancestor 13-45 years of age in 1861?)
1898--Spanish-American War (Was your male ancestor 18-45 years of age in 1898?)
1917-1918--World War I (Was your ancestor 17-45 years of age in 1917?)
1941-1945--World War II (Was your ancestor 13-45 years of age in 1941?)
1950-1953--Korean War (Was your ancestor 15-45 years of age in 1950?)
1964-1973--Vietnam War (Was your ancestor 9-45 years of age in 1964?)
1990-1991--Gulf War (Was your ancestor 17-45 years of age in 1990?)
If you know when an American man (or woman) was born, it is fairly easy to figure out in which war(s) he may have served. Just figure that men have generally been liable for military service between the ages of 18-45, with those between the ages of 18-35 being the ones most likely to enlist/be drafted. Also be aware that it would have been hard for men 18-35 to avoid serving in several of these wars, notably the Revolutionary War, the Civil War, and World War II, while it would have been relatively easy to avoid serving in the Mexican-American War, the Spanish-American War, and the Gulf War.
Men who have served in America’s wars have been eligible at various times for special government programs, including bounty land grants and military pensions. Bounty land warrants were granted at various times during the period 1788-1855. Warrantees could receive up to 160 acres each (privates or seamen), all of which need not have been awarded under the provisions of one particular piece of legislation. A soldier’s heirs could also receive a grant for land based on his service, so long as total acreage awarded to that man and his heirs did not exceed 160 acres.
Land warrants initially would have been redeemable in specially earmarked military districts: men receiving warrants in 1847 and after could redeem them for any open public lands, not just land in military districts. Civil War Union soldiers did not receive bounty lands, although they could deduct time in service from the residency requirements of the 1862 Homestead Act.
Most bounty land was located in the present-day states of Ohio, Kentucky, Tennessee, and Illinois, with smaller amounts in the present-day states of New York, Pennsylvania, Arkansas, South Carolina, Georgia, and Missouri. Most land warrants were issued by the federal government, although some state governments, notably Pennsylvania and New York, also rewarded Revolutionary War soldiers with land grants.
Immediately after each of these wars, pensions were available only to those men permanently disabled by their service, and to widows or orphans of men killed in the war. Pensions would become available later to any man who had served in the war who was unable to support himself and/or his family due to age and/or infirmity; then at some later point would be available to any surviving soldier of a particular war. For example, Revolutionary War vets became eligible in 1818 for pensions if they had financial need for support, and if they had either 9 months total service or had served to the end of the war.
Civil War Union soldiers received pensions from the federal government, while Confederate soldiers received pensions directly from the Southern or border state they were living in after the war (surviving Confederate widows only became eligible for federal pensions in 1959--after the last Confederate vet had passed on).
Men entering military service sometimes received one-time payments for enlisting (bounties were more widely available in the North than in the South). These payments could come from the soldier’s town, county, state, or the federal government, or from all four (some soldiers enlisting in the Union Army in late 1864/early 1865 received bonuses of up to $1,200, a very substantial sum at the time).
Certain types of aid to soldiers and/or their families were made only by state/local governments. While in service, a man’s family (in some states) could receive relief payments if receipt of a soldier’s meager pay ($13.00/month) was causing family hardship. Victims of amputation could receive artificial limbs from some states (1/3 of Mississippi’s budget in 1866 consisted of payments for artificial limbs and eyes).
Families of deceased veterans were also eligible for certain forms of aid. The family of a Union soldier killed during the war received a one-time payment of $100 from the federal government. The man’s body could be buried by the U.S. Army on or near the place where he fell, or the family could pay to transport the body home. The U.S. government furnished a headstone to a veteran’s family free of charge (and maintains a list of veterans for whom a headstone was furnished).