Confederate In The Attic is a great read. Of the 180 Confederates that joined the Union Army, 152 were from the 10th Tennessee (Irish). Of the rest, a few joined the Union Army, deserted and went back to their old unit. I found one Confederate POW that joined a Union regiment, was captured by the Confederates and died at Andersonville. With the choice of "dying in Chicago" or joining the 23rd Illinois and discretion being the better part of valor, I can understand why some would do anything to get out of the Union POW camps.

If you run across any Shiloh Confederates that escaped from Fort Doneleson, please let me know.