Siege of Fort Mifflin - Siege - Climax

Climax

Beginning on October 26 a Nor'easter struck the area and the storm lasted for three days, bringing with it high winds and torrential rain. With two feet of water over most of Mud Island and similar conditions on Province and Carpenter's Islands, the mutual cannon fire stopped as both sides tried to find a dry place. By November 1, the Americans had the British army in Philadelphia effectively under blockade. Howe's troops were short of food, rum, clothing, and money. Montresor complained that he lacked adequate artillery and ammunition. The British were compelled to send supplies into Philadelphia via convoys of flatboats. To avoid being sunk by the guns of Fort Mifflin and the Pennsylvania Navy, the boats had to make the attempt in the night and maintain total silence. Hessian Captain Johann von Ewald noted that in order to hold the sailors to their dangerous work, they were made completely drunk.

After a council of war on October 29, Washington ordered Brigadier General James Mitchell Varnum to assume responsibility for the defense of the Delaware. The two Rhode Island regiments of Varnum's brigade were already manning the forts. Soon the last two units of his brigade were committed to the battle. On November 3, Varnum sent the 4th and 8th Connecticut Regiments to garrison Fort Mifflin.

On November 10, Montresor was finally prepared to batter down the fort. By that date he had ready for action two 32-pound, six 24-pound, and one 18-pound cannons plus two 8-inch howitzers, two 8-inch mortars, and one 13-inch mortar. On the 10th, the two sides blazed away at each other at a range of 500 yards (457 m). No casualties were suffered by the Americans but large parts of the palisades on the western side of the island were wrecked. On the 11th, Captain Treat was killed by the concussion of a near miss as he talked with Smith. Later that day as Smith was in the barracks, a cannonball smashed through the chimney and struck him in the left hip. Though covered in bricks from the collapsed chimney and suffering from a dislocated wrist, Smith survived because the round was spent.

The wounded Smith was ferried across to Red Bank, leaving the garrison leaderless. Varnum reported that the troops would welcome a British infantry assault, but that the constant barrage was taking its toll on the men. Fleury wrote to Washington that all the guns were dismounted except two but that the soldiers of the garrison were able to repair the damage to the palisades every night. The only safe place in the fort was a ditch on the east side and Fleury would go there to round up men for work details, lashing out at the laggards with his cane. The next in command after Smith was Lieutenant Colonel Giles Russell of Connecticut, but he declined and asked to be recalled. On November 12 Major Thayer accepted command of the fort.

Sir William Howe began assembling a detachment of light infantry and Foot Guards on November 9, placing them under the command of Lieutenant Colonel Sir George Osborn, 4th Baronet. These troops were ready by the 13th and were to be supported by the 27th Foot and 29th Foot. By November 14, the British had planted two additional batteries containing four 32-pound guns and six 24-pound guns, which added to the furious daily bombardment. That night Fort Mifflin fired on a supply convoy but missed.

The British brought the HMS Vigilant (20) upriver to attack the fort. Vigilant was originally the naval transport Empress of Russia. She had been converted in June 1777 into a vessel designed for shore bombardment. For this purpose, the ship carried 14 24-pound cannons, two 9-pounders, and four 6-pounders. Before the attack, the British strengthened the vessel's sides, added 24 sharpshooters and 50 gunners to the crew, and transferred two extra guns to her starboard side. To maintain the ship's stability, water casks were positioned on the port side. Lieutenant John Henry was the commanding officer. Favored by a high tide, the Vigilant worked its way into the shallow channel between Mud Island and the north bank at 8:00 AM on November 15. Accompanied by the sloop Fury with three 18-pound guns, the converted transport hurled a barrage at Fort Mifflin from a distance of 20 yards (18 m). Out in the main channel, the HMS Somerset (70), Isis, Roebuck, and Pearl added the weight of their broadsides from a greater distance.

Thayer ordered his 32-pound cannon to be moved to the place of danger. Before Vigilant reached her station, the gun crew claimed to have fired 14 shots into her. After the floating battery came to anchor, the fort was subjected to a terrific point blank fire. A single shot killed five American gunners at one cannon. A defender wrote that men were, "split like fish to be broiled". Thayer ordered a distress signal to be hoisted requesting help from Hazelwood, but to do so the fort's flag had to be lowered first. When the British gunners ceased fire and began to cheer in anticipation of victory, Thayer's officers demanded that the flag be immediately raised again. The bombardment resumed and the artillery sergeant detailed to haul the flag was the next casualty, cut in half by a cannonball. That afternoon, a chunk of wood from the smashed barracks struck down artillery Captain James Lee and knocked Fleury unconscious. When Hazelwood's ships tried to attack the Vigilant and Fury, fire from the British naval squadron drove them back. By this time the interior of the fort was furrowed with the tracks of cannonballs and the barracks and blockhouses were wrecked.

Osborn planned to send eight flatboats each with 35 soldiers in the first wave of his assault. Howe declined to give the order for the 400-man storming party to attack, waiting for a high tide and hoping that the garrison would evacuate the fort. That evening, Thayer gave the order to abandon Fort Mifflin. The 300 survivors and what equipment could be salvaged were rowed across to Red Bank. Thayer held back a detail of 40 men. These troops burned down the barracks at midnight and soon joined the others in New Jersey. Thayer was the last to leave.