Mr.Hodge, Thank you very much for the great information and insights.

Looking at my CW ancestor's records more closely, I am very shocked and not a little disturbed that it says "Enlisted at Rock Island Barracks, Ill., in the US Army for frontier service, October 15, 1864." For some reason, I had not read that before (only recently obtained his record, and that of a good number of other CW soldier ancestors)

Another of the cards says "To what point forwarded" and handwritten is "Louisville, Ky. December 5, 1863." Then, beside "remarks" is handwritten "for exchange". This is why I thought he'd been exchanged very soon after the battle at Missionary Ridge. There was no further record of him in the service records and I had assumed that he'd been released quickly and then deserted. Don't know if it's better to have been a deserter or to have enlisted in the US army to kill Native Americans! :\

Glenda