Hello David, The POW's in this particular instance were considered Confederate POW's. While it's true in some cases that the Union deserters duped the Union soldiers and clerks at Fort Delaware into thinking they were former Confederates. The Federal government never did connect the dots with the former Union deserters being former Confederates. In the Federal government eyes these men were former Confederate soldiers and were desirous in joining and as you said some concessions were made. Your statement "I think there was a distinction between a deserter who switched sides and a prisoner of war who switched sides" I'm not clear as to what you mean? If your talking about a former Confederate deserter and a former Confederate POW who became galvanized Yankees I might agree with you somewhat depending upon the time period involved. However if your talking about a former Union deserter joining a Union regiment then I would strongly disagree because if he was not properly discharged from his first enlistment then he would have been in violation of the law and generally brought up on two counts 1) Desertion 2) Enlisting in another Federal unit without being discharged from the 1st. If the Union had recongized him at the time as being a Union deserter then they would have taken appropriate measures and may have taken a trip to Camp Distribution in Alexandria, Virginia assuming he would have been found out about in the Baltimore/Washington DC area.

When the former Confederates filled out the declaration of recruitment papers and their volunteer oath of enlistment papers either with their mark or signed their name and they were mustered into the service of the United States they were considered Union soldiers. If they would have turned around and deserted after that moment in time and some did, they would not have been regarded as former Confederates but as a Union soldier who had deserted. I will agree that when some of them deserted and they faced a court martial and the court felt as if they were sorry for their offence and their age was young, the court sometimes took into consideration of them being former Confederates and cut them some slack.

Generally speaking David, it is my opinion that the Union did not care if they had been former Confederates deserters or just prisoners of war. There were of course a multitude of reasons why the former Confederates joined the Union and also a host of reasons why the Union encouraged former Confederates to join. Some of the reasons were as follows for the Union.
1) To demoralize the South by sending former Confederate troops against them
2) Additional manpower
3) Insofar as the draft it meant that for every former Confederate who enlisted; let's say at Fort Delaware in September of 1863 it meant one less citizen would be drafted in their zone. Needless to say many citizens and some politicians were in favor of galvanized Yankees depending of course on how it affected them.
4) It took away for some over crowding at the various prisons.

Some reasons for the former Confederates might include...........
1) A little better living conditions and not being in prison. For some former prisoners that meant whiskey and women.
2) A little better pay and more consistent pay.
3) A small bounty of perhaps $25.00 due over a time period.
4) If he was a Union deserter who had gone undected than perhaps a reason to get away from his orginal unit and perhaps not being executed.
5) Some of the former Confederates had been drafted into the Confederate service and elected to join the Union by choice.
6) A few of the former Confederates had changed their minds about the South winning after Gettysburg and Vicksburg and elected to join the Union army. Many of these soldiers were not native to their respective Confederate states and had been born either in the North or in a foreign country.
7) Some joined for the purpose of deserting and trying to hide out during the rest of the war. To my surprise a few were successful in doing so.

At Andersonville of course some former Yankees joined the Confederate army; for the most part it was the 10th Tennessee Infantry. Many would desert the first chance they had.