A fantastic example of a late 1800s GAR photo. The GAR was a fraternal organization of Union Civil War veterans founded in 1866. This photo, accompanied by John's Civil War diary are real American treasures. I'm sure your family is very proud. Excellent post, Kathleen.
Edit: If you haven't already, Kathleen, you should acquire John's entire Civil War Pension File from Fold-3 (there are $ charges but also a free trial). Here is an Index card from John's file at FamilySearch that gives his disability and death reference and the name of his spouse/widow, Deborah.