Fort Mifflin, originally called Fort Island Battery and also known as Mud Island Fort was commissioned in 1771 and sits on Mud Island (aka Deep Water Island) on the Delaware River below Philadelphia International Airport. During the American Revolutionary War, the British Royal Navy bombarded and captured the fort as part of their conquest of Philadelphia in autumn 1777. In 1795 the fort was renamed for Thomas Mifflin, a Continental Army officer and the first post-independence Governor of Pennsylvania.