Fort Delaware is a former harbor defense facility, designed by chief engineer Joseph Gilbert Totten and located on Pea Patch Island in the Delaware River. During the American Civil War, the Union used Fort Delaware as a prison for Confederate prisoners of war, political prisoners, federal convicts, and privateer officers. A three-gun concrete battery of 12-inch guns, later named Battery Torbert, was designed by Maj. Charles W. Raymond and built inside the fort in the 1890s. By 1900, the fort was part of a three fort concept, the first forts of the Coast Defenses of the Delaware, working closely with Fort Mott in Pennsville, New Jersey, and Fort DuPont in Delaware City, Delaware. The fort and the island currently belong to the Delaware Department of Natural Resources and Environmental Control (DNREC) and encompass a living history museum, located in Fort Delaware State Park.

Joseph Gilbert Totten fought in the War of 1812, served as Chief of Engineers and was regent of the Smithsonian Institution and cofounder of the National Academy of Sciences. In 1836, he was elected a member of the American Philosophical Society.