...hase, at Columbus, Ohio; and the Barracks, at Elmira, New York. The Gratiot Street Prison in St. Louis had been an old medical college, and Myrtle Street Prison had been used as a negro market. Fort Delaware , on an island in the Delaware River, had been constructed by General McClellan while a member of the Engineer Corps. A dike kept out the tide which would otherwise have washed over the island, and ...