Fort Mifflin is the oldest fortification continually used in the United States. Almost 350 Americans died in November 1777 when British forces relentlessly bombed the site from ships. But the Americans’ valor at Fort Mifflin gave George Washington time to regroup at Valley Forge.
The fort is named for General Thomas Mifflin, who later became governor of Pennsylvania and was known for standing up against Virginia slave catchers.
During the Civil War, the facility held civilians as well as Confederate and Union prisoners.