During the Civil War, each side accused the other of mistreating prisoners of war. Today, most historians believe there was systemic and deliberate mistreatment of POWs by one or both sides yet many base their conclusions on anecdotal evidence, much of it from postwar writings. Drawing on prisoner diaries and Union Army documents (some newly discovered), the author presents a fresh and detailed study of supposed prisoner mistreatment at Fort Delaware-one of the largest Union prison camps-and draws some surprising conclusions, some of which have implications for the entire Union prison camp system.