On November 16, early on the morning, Knyphausen opened the attack against Col. Moses Rawlings's Virginia and Maryland riflemen who managed to stall the Germans temporarily. Percy advanced on Lt. Col. Lambert Cadwalader's Pennsylvanians but halted them (to the Americans' surprise) to wait for a signal gun from Cornwallis or Mathew. Washington, Greene, Maj. Gen. Israel Putnam, and Brig. Gen. Hugh Mercer crossed to Fort Washington as the firing commenced, but they could do nothing to help Magaw and so returned to Fort Lee to watch the developing action.
Mathew, who had been somewhat delayed by the tide pushed across the river and established a foothold on Laurel Hill. Cornwallis followed with more troops.
Once the signal had gone out to Percy, pressure on the Americans began to mount. Rawlings was force back and Cadwalader withdrew. Confusion was rampant within the reduced perimeter; the retreating Americans poured into the fort. By 3:00 P.M., the Germans had reached Fort Washington from the north, and the British were in view on the east and south. Despite the original surrender terms, another flag was sent into Magaw to ask for capitulation. Realizing that to stand now would create a bloodbath within the crowded fort, Magaw surrendered. The attack cost the British and Germans 67 killed, 335 wounded, and 6 missing. The Americans suffered 54 killed and 2,858 captured, including probably more than 1,000 wounded. The loss of all their arms and equipment was especially damaging. Fort Lee was now untenable and Washington began transporting the ammunition out of the fort.