Family Tree Magazine posted on their Pinterest board an easy-to-use general guideline military records chart to help you know which wars to research based on birth year.

For example: If your ancestor was born in 1819, then research the Civil War and the Mexican War.

See the military records chart.  Note: You don’t have to be a member of Pinterest to view any boards, but you must be a member to repin, like pins, or comment on pins.