Siege of Fort Mifflin - Background

Background

After the British defeated the American army at the Battle of Brandywine on September 11, 1777, Howe failed to follow up Washington's withdrawal to Chester, Pennsylvania. From that town on the Delaware, the Americans marched northeast through Darby to cross the Schuylkill River at the Middle Ferry. From the ferry, the army moved north to present-day East Falls and went into camp. For the next ten days, the two armies sparred while the British won the Battle of Paoli and several skirmishes. On the night of September 22, Howe outmaneuvered Washington and won an unopposed crossing of the Schuylkill near Valley Forge. On September 26, the British army occupied the rebel capital of Philadelphia. In the face of the British advance the Second Continental Congress fled first to Lancaster then to York, Pennsylvania.

During the summer of 1777, Philippe Charles Tronson du Coudray, a French artillery expert, arrived from France. Congress appointed him a major general and inspector general of ordnance, and Washington assigned him the task of strengthening Philadelphia's river defenses. His aristocratic airs soon irritated people. He began to quarrel with another French military engineer, Louis Lebègue Duportail, about how the defenses were to be prepared and even managed to anger Gilbert Motier, marquis de La Fayette. To the relief of many, Coudray drowned on September 16 after he foolishly rode his horse onto a Schuylkill ferry and the animal leaped into the river.

The Mud Island Fort was designed and begun by British engineer Captain John Montresor in 1771. The river front was shielded by a stone face, but then the work stopped due to a shortage of money. After the outbreak of war with Britain, the rest of the fort's defenses were completed with wooden palisades and earthen ramparts, despite the infighting among the French engineer officers. There were wooden barracks for the enlisted men along the west and north sides of the fort. Nearby was a two-story building to accommodate officers. According to one of the defending soldiers, a battery of 18-pound artillery pieces stood at the southeast end of Mud Island. On the southwest end, one 32-pound and four or five 12-pound and 18-pound cannons guarded the river. Three 12-pound guns covered the northwest end of the island. Another account states that ten 18-pound guns made up the main battery while each of the four blockhouses contained four cannons. A bristling set of sharpened logs surrounded the fort while the low ground along the shoreline was infested with trous-de-loups or wolf holes. Chevaux de frise prevented the British navy from ascending the Delaware. Their iron tipped stakes threatened to tear the bottom out of any ship whose master was reckless enough to make the attempt.