As Sherman moved north through the Carolinas, starving Union POW's joined the CSA army. They were assigned to guard mills, etc. Needless to say, the hapless Yanks in gray surrendered without firing a shot.
Captors hardly knew what to do with what were turncoats, after all. The war was obviously winding down. The immediate fate of the gray coated Yankees seems to have depended on how much tolerance for paperwork their captors had. In the end, no matter how indifferent or vindictive their captors were, not starving in a filthy disease ridden POW camp was an improvement.
The CSA "galvanized yankees" who signed up with the proviso that they be sent to the Western Frontier were appalled to discover that they had signed regular 3 year papers. When the war ended, many of them thought they would be free to go home.
Plan 'A' was to hang around with a real chance of contributing your hair to a Lakota Dog Soldier's coupe stick or plan "B" beat feet for parts unknown. It is impossible to exaggerate just how bleak western garrison duty was in the 1860's. At Fort Hartsuff in the Nebraska Sand Hills, the guardhouse had more accommodations than the barracks.
Like their Yankee peers, their fate depended very much on the tolerance for paperwork as much as anything. Desertion rates upwards of 40% were common on the frontier. Men who had been brevet lieutenant colonels were reduced to their permanent rank of sergeant or lieutenant served time to qualify for a pension. Many were so debilitated by war wounds that they couldn't dress without aide. Applying for medical discharges was a constant occupation. The commander of Fort Hartsuff NB wasted away & died of his war wounds still firing off volleys of paperwork in his medical discharge attempt.
Because of the connection with Stones River, I have taken a particular interest in the Fetterman Massacre. At that time, soldiers would run off from what now seem absolutely preposterous places.
Note: Fort Hartsuff Nebraska State Historical Park is in Valley County NB. The fort's structures are in remarkable condition. A dedicated group of living historians portray all aspects of service on the frontier. It was partly maned by US Regular veterans of Stones river.