The Confederate officer in charge of the prison was convicted of war crimes after the war and was hanged. So far as I know he was the only Confederate to suffer that fate, though Cantrell and Mosby and pretty much all of the Kansas terrorists and a few others probably deserved it.
There were a lot - North and South - who committed crimes similar to those which the Americans (sorry, the International War Crimes Tribunals at Nuremburg) gleefully hanged Germans for between 1946 and 1948.
Wirz was actually Swiss. His sense of duty kept him at Andersonville after the rest of the guards - mostly very young boys and superannuated old soldiers - had fled, knowing perfectly well that they would not be smiled upon by the advancing Unionists. It was, at least in part, a bum rap. Wirz had had nothing to work with. There is a lot of evidence that he pleaded repeatedly with Richmond both for them to stop sending prisoners and to provide more resources for the prisoners who were already there. But Richmond had its own problems and, as we all know, the conditions at Andersonville were probably no worse than conditions for the vast majority of Confederate solders in the field in the latter stages of the war. By 1865 there were absolutely no resources to be had: the Confederacy was plumb tuckered out (see, the original meaning!).
The Unionist officer in charge of the execution said to Wirz on the scaffold: "Sir, this is the worst duty I have ever had to perform". Wirz replied that he didn't think it was all that great, either. As well he might.
Talk about picking up trivia!
[Edit: Memory recovery!] Actually Wirz said something like "I am being killed for doing my duty". Can't remember the exact words, but you can see how he might have been a bit upset by it all ...
