Frank, another group of Galvanized Yankees includes those Confederate POWs who enlisted in the U.S. Navy. I don't know if any from Camp Butler joined the Navy, but quite a few from Camp Douglas did. In fact, the U.S. Navy established a Naval Rendezvous there, and POWs at Camp Douglas, Alton and Rock Island Barracks who applied to enlist in the Navy were sent there for examination.

I haven't done much research on this group, so this pretty much taps my limited store of knowledge of the subject.