The British followed up their success on Long Island with a series of landings on Manhattan Island which compelled Washington to retire northward to avoid entrapment. When Forts Washington and Lee on the Hudson above Manhattan were lost in mid-November 1776, Washington retreated across New Jersey with General Howe in close pursuit, escaping finally over the Delaware into Pennsylvania with about 3,000 men. Howe then went into winter quarters in New York City, leaving garrisons at Newport, R. I., and in several New Jersey towns. In December 1776, Washington determined to make a surprise attack on the British garrison in Trenton, a 1,400-man Hessian force, in the hope that a striking victory would lift the badly flagging American morale. Reinforcements had raised Washington's army to about 7,000 and on Christmas night (25-26 December) he ferried about 2,400 men of this force across the ice-choked Delaware. At 0800 hours they converged on Trenton in two columns, achieving complete surprise. After only an hour and a half of fighting, the Hessians surrendered. Some 400 of the garrison escaped southward to Bordentown, N. J., when two other American columns failed to get across the Delaware in time to intercept them. About 30 were killed and 918 captured. American losses were only 4 dead and a like number wounded.

After the successful coup at Trenton, Washington recrossed the Delaware into Pennsylvania with his Hessian prisoners. But he reoccupied Trenton on 30 - 31 December 1776, and collected there a force of 5,200 men, about half militia. Meanwhile, Maj. Gen. Charles Cornwallis, British commander in New Jersey, who was in New York at the time of the attack on Trenton, returned gathering troops as he came. He entered Trenton with some 6,ooo British regulars on 2 January and faced Washington's forces, which had withdrawn southward behind Assunpink Creek. The Americans were in a most precarious position with their backs to the Delaware. Fortunately, Cornwallis delayed his attack until the following morning. This gave Washington's men an opportunity to steal off quietly by a side road during the night of 2 - 3 January, leaving their campfires burning brightly. They slipped southward and eastward undetected around the enemy's flank and by morning of the 3rd had arrived at Princeton, where they encountered a column of British regulars led by Col. Charles Mawhood just leaving the town to join Cornwallis. In a brief engagement the Americans defeated the British, inflicting losses of 400-600 killed, wounded, and prisoners at a cost of 30 patriots killed and wounded. Mawhood's force retired in disorder toward Trenton and New Brunswick while Washington moved on north to Morristown, where thickly wooded hills provided protection against a British attack. Here he established his winter headquarters on the flank of the British line of communications, compelling General Howe to withdraw his forces in New Jersey back to New Brunswick and points eastward.