My GGrandfather J.D. Calaway Sgt. Oates 15th Ala Inf, wounded and captured Jul 2 ,1863 at Gettysburg was sent to Fort Delaware Prison. He spent about 15 months there and was exchanged Oct 30, 1864, along with 3 thousand plus. They were checked by a doctor and ruled unable to render any further service. They were placed on a ship sent down the Delaware River to the sea, they picked up more prisoners at Point Lookout, Md, then made their way down the coast to Venus Point, Georgia, Savanah River and turned over to confederate authority. The three thousand plus prisoners was the total haul, quiet a logistic chore I'm sure.