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Fort Mifflin, Pennsylvania

Fort Mifflin, Pennsylvania

FORT MIFFLIN, PENNSYLVANIA. 23 September-16 November 1777. Located opposite Fort Mercer (Red Bank, Gloucester County, New Jersey) on Mud Island, Fort Mifflin anchored the American defenses of the Delaware River and protected the final band of obstructions (chevaux de frise) and the anchorage of the Continental-state naval squadron. In concert with Fort Mercer and the squadron, Washington hoped the forts could keep the river sealed and thus force the British to evacuate Philadelphia by choking off the flow of supplies. Continental regulars took over the responsibility for the fort from Pennsylvania on 23 September. A 450-man garrison consisted of detachments rotated in and out during the course of the siege. The first commandant, Colonel Henry baron d'Arendt of the army's German Battalion, fell ill from overwork and passed command to Maryland's Lieutenant Colonel Samuel S. Smith. Both men worked feverishly with two French volunteers, Major Thomas-Antoine du Plessis, chevalier de Mauduit, and Major François Teisseydre, marquis de Fleury, to augment the fortifications as the British began clearing the river.

Americans assumed that nearby Province and Carpenter's Islands, which had been flooded earlier in the summer, were too marshy for enemy artillery use, and concentrated their efforts on the threat posed by warships approaching upstream. On 23 October, the day after Donop's unsuccessful attack on Fort Mercer, the guns of Fort Mifflin, a mobile battery on the riverbank, and the American squadron achieved the war's greatest triumph over the Royal Navy when they pummeled six men-of-war trying to work upstream. The sixty-four-gun ship of the line Augusta and the sixteen-gun sloop of war Merlin ran aground and were destroyed, the former by accident and the latter by its own crew to prevent capture. But that was the last bright moment for the Americans.

Loyalists headed by Joseph Galloway told Howe where to find suitable sites on Province and Carpenter's for siege batteries, and on 5 October a detachment crossed to Province to begin construction. Despite a number of American nighttime raids, the British were able to open fire from four of them on 15 October; more batteries followed over the following weeks, and at about 7:30 on the morning of 10 November, the full complement started reducing the earth and timber fort to rubble. On 15 November, Admiral Howe brought up HM Armed Ship Vigilant, a specialized shore bombardment vessel mounting fourteen heavy twenty-four-pounders but with a shallow draft, to take up a position raking the defenders. A wounded Lieutenant Colonel Samuel Smith was evacuated and Major Simeon Thayer succeeded in command of Fort Mifflin. By nightfall the fort had no guns left in working order and no walls capable of defense, so Thayer evacuated the survivors to Fort Mercer. Showing remarkable tenacity, the Americans had stuck to their guns despite 250 casualties. It is highly significant that Smith would reprise these same tactics in 1814 as a militia major general when he successfully defended Baltimore.

SEE ALSO Philadelphia Campaign.


Dorwart, Jeffery M. Fort Mifflin of Philadelphia: An Illustrated History. Philadelphia: University of Pennsylvania Press, 1998.

Jackson, John. The Pennsylvania Navy, 1775–1781: The Defense of the Delaware. New Brunswick, N.J.: Rutgers University Press, 1974.

                    revised by Robert K. Wright Jr.

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