Located on Pea Patch Island at the entrance to the Delaware River, Fort Delaware was built to protect Wilmington and Philadelphia in case of an attack by sea. When the Civil War broke out, Fort Delaware's purpose changed dramatically--it became a prisoner of war camp. By the fall of 1863, about 12,000 soldiers, officers, and political prisoners were being held in an area designed to hold only 4,000--and known as the Andersonville of the North, a place where terrible sickness and deprivation were a way of life despite the commanding general's efforts to keep the prison clean and the prisoners fed.