1) Do you have a copy of his Obitaury that tells of any military service?
2) There is a possibilty that he may have served in Union Army-possibly as a servant or a cook.
3) Have you tried the National Archives website for copies of any Pension Applications (civil War Union only) possibly by ancestor or his
wife? (Can be ordered online I Think(link below)
4) The SUVCW is an org of male descendants of Union soldiers.
One Project is an online gallery of union soldier pictures "Photos from the Past". Type in "SUVCW" in Internet search engine.