[3] Although Fort Mercer ultimately fell to the British a month later, the victory at the Battle of Red Bank served as a much-needed morale boost to the Patriot cause, delaying British plans to consolidate gains in Philadelphia, and relieving pressure on Washington's Continental Army, which was embedded north of Philadelphia.

The flotilla consisted of sloops, schooners, galleys, an assortment of floating batteries and fourteen old vessels laden with barrels of tar to be used as a means of defending the river.

On just two of the vessels stranded in the river, Howe commanded more officers and men than Commodore Hazelwood had in his entire fleet.

[4] On October 18, General Sir William Howe, the commander of the British Army, evacuated his camp at Germantown, and pulled his forces inside the city of Philadelphia.

[8][7] On October 20, 1777, five British warships under the command of Captain Hamond, made their way through the lower chevaux-de-frise and sailed up the river.

[9] Von Donop divided his force into two groups totaling 1,200 men for a two-pronged attack upon the fort on the morning of October 22.

[7] With five British men-of-war in the river to support the attack, von Donop was convinced that the fort would be in his hands by nightfall.

After a cannonade by the Hessian artillery, Linsing moved against the nine-foot-high southern parapet, and his men were cut down by devastating cannon and musket fire and were forced to retreat.

But when they moved on they were confronted by a tangled mass of felled trees with pointed branches, a kind of abatis, protecting the main wall of the fort.

[10] Suffering heavy casualties, the Hessians began to retreat, falling back to their camp ten miles (16 km) away in the village of Haddonfield which they had taken after landing at nearby Cooper's Ferry.

Fort Mifflin and the Pennsylvania Navy engaged the stranded ships the next morning, with cannons and fire rafts, respectively.

The next morning, a small party of British troops landed unopposed at the deserted fort, tore down the American flag, and ran up the Union Jack.

The bombardment of Fort Mifflin came at minimal cost to the British with only a reported 13 sailors and troops killed, 24 more wounded, and limited damage to some of their warships and land batteries.

Howe then sent Lord Cornwallis with 2,000 men to attack Fort Mercer, landing them by ferry at Billingsport, three miles (4.8 km) to the south.

In June 2022, a mass grave containing the remains of what are believed to be 12 Hessian soldiers was discovered while excavating the outer defensive ditch of Fort Mercer.