Fort Mercer was still in possession of the Continental troops. Howe determined to dislodge them; for, while they remained, the obstructions in the river could not, with safety, be removed. While a portion of his force was beating down Fort Mifflin, he was busy in fortifying Philadelphia. He had extended intrenchments across from the Delaware to the Schuylkill. Having received more re-enforcements from New York, he sent Cornwallis to fall upon Fort Mercer in the rear. That officer, with a detachment of about two thousand men, crossed the Delaware from Chester to Billingsport, where he was joined by some [[November 18, 1777]] troops just arrived from New York. Washington had been apprised of this movement, and had detached General Huntington's brigade to join that of Varnum in New Jersey. He also ordered Major-general Greene to proceed with his division to the relief of the garrison, and to oppose Cornwallis. That able officer, accompanied by La Fayette, who had not yet quite recovered from a wound received in the battle on the Brandywine, crossed the Delaware at Burlington, and marched with a considerable force toward Red Bank. He expected to be re-enforced by Glover's brigade, then on its march through New Jersey, but was disappointed. Ascertaining that the force of Cornwallis was greatly superior to his own in numbers, General Greene abandoned the plan of giving him battle, and filed off toward Haddonfield. Colonel Greene, deprived of all hope of succor, evacuated Fort Mercer, leaving the artillery, with a considerable quantity of cannon-balls and stores, in the hands [[November 20]] of the enemy. Cornwallis dismantled the fort and demolished the works. His army was augmented by re-enforcements, and, with about five thousand men, he took post at and fortified Gloucester Point, whence he might have a supervision of affairs in Lower Jersey. Morgan's rifle corps joined General Greene, but the Americans were not strong enough to venture a regular attack upon Cornwallis. A detachment of one hundred and fifty riflemen, under Lieutenant-colonel Butler, and an equal number of militia, under La Fayette, attacked a picket of the enemy three hundred strong, killed between twenty and thirty of them, drove the remainder quite into the camp at Gloucester, and returned without losing a man. General Greene soon afterward withdrew from New Jersey and joined Washington, and Cornwallis returned to Philadelphia. The American fleet, no longer supported by the forts, sought other places of safety. On a dark night, the galleys, one [[November 21, 1777]] brig, and two sloops, crept cautiously along the Jersey shore past Philadelphia, and escaped to Burlington. Seventeen other vessels, unable to escape, were abandoned by their crews, and burned at Gloucester. ** The American defenses on the Delaware were now scattered to the winds; the obstructions in the river were removed; the enemy had full possession of Philadelphia; Congress had fled to the