Gen Washington sought to launch a surprise attack against British forces spread across New Jersey. His target was Trenton, a town garrisoned by 1,500 Hessian mercenaries hired by the British government. Washington’s plan involved dividing his army into three sections and crossing the Delaware River to attack the British forces: one section was to assault the British outpost at Bordentown to prevent reinforcements from arriving from the South, another’s objective was to seize the bridge spanning the Assunpink Creek to prevent the enemy from escaping, while the main thrust was to be launched against Trenton itself. The weather deteriorated the night of 25 January, and only Washington’s main force was able to successfully cross the Delaware River. Despite freezing temperatures, Washington’s army endured a nine-mile march before separating into three columns to attack Trenton from the West, North, and Northeast. The Continental Army achieved initial surprise, but the Hessians managed to rally and form a line of battle; however, because of the confusion, the Hessian commander— Col Johann Rall—believed his position to be surrounded and launched a failed counterattack as opposed to retreating. Washington was able to successfully counter any Hessian attempt to outmaneuver his flanks and within an hour the Hessians forces were in complete disarray with their commander mortally wounded. Those who could not flee were forced to surrender. After concluding his victory at Trenton, Washington chose to withdraw back across the Delaware River into Pennsylvania.

On 29 December 1776, Washington’s army again crossed the Delaware River to assume a defensive position at Trenton. His victory against the Hessians three days earlier had aroused the attention of British Gen Lord Cornwallis, who departed New York with an army of 9,000 men. After leaving 1,200 men in Princeton, NJ, Cornwallis advanced toward Washington’s position at Trenton. After a series of delaying actions impeded their advance, the British reached the outskirts of Trenton on the night of 2 January 1777. That night, Washington sent his baggage train to return to Pennsylvania. Leaving a small holding force to keep Cornwallis in place, Washington’s army used backroads to outflank the British and launch an attack at their supply base in Princeton. On the morning of 3 January, the British forces at Princeton had begun to march toward Trenton to reinforce Cornwallis’s main force. The two forces ran into each other south of the town. Upon seeing the American army, the British commander, Col Charles Mawhood, sent skirmishers to delay Washington’s advance as he withdrew his forces toward Princeton.   Washington’s initial advance against the British, commanded by BGen Hugh Mercer, was repulsed by a bayonet charge from Mawhood’s men who succeeded in routing the Americans and mortally wounding their commander. Washington then ordered a militia brigade, commanded by BGen Cadwalader, to check the British advance, but they too were routed. By this point, Washington arrived on the field with reinforcements of riflemen and Virginian Continentals and proceeded to rally Cadawalder’s men for a counterattack. Washington’s counterattack assailed the British on the front and both flanks, successfully routing them from the field. A few remaining British soldiers barricaded themselves within the Princeton University campus, but their positions were successfully assailed by an American assault. Following the battle, Washington remained in Princeton long enough to loot the British supply trains before marching to Morristown for winter quarters.