I had a g-grandfather from Muscogee County, GA who joined the Union army (Co. I, 2nd Regt. U S Vol Inf) and was sent west. He did not return home (settled in TN) for fifteen years after the war. From your post I am guessing you have already checked for a U.S. pension application.....if not you should check for one. My g-gf received a U.S. pension and it is full of genealogical tidbits.