Fort Mifflin, on Mud Island, is a British built fortification. The Americans had secured it that by the fall of 1777 approximately 200 men were garrisoned at this fort, charged with the duty of holding the British off so that Gen. Washington and his army could successfully move into winter quarters.
On November 15, 1777, the British land batteries, commanded by Captain Montresor, and together with a British naval squadron under Vice Admiral Lord Howe, overcame the American revolutionaries and captured this fort on the Delaware River commanded by Lt. Colonel Samuel Smith. The Americans evacuated the fort on the night of November 15.