By December of 1776, the Continental Army had withdrawn in disarray from New York, across Central New Jersey and the Delaware River into Pennsylvania. The British were in complacent pursuit, confident that it was only a matter of weeks or months before General Washington capitulated. Then, in a remarkable turn of events, on Christmas Day and the day following, the American forces regrouped and launched a surprise counter-attack on Trenton, thereby infusing new life into the Revolutionary cause and changing the course of the war.
The First Battle of Trenton was preceded by Washington's nighttime crossing of the Delaware at McKonkey's Ferry, present-day Washington Crossing, and a nine-mile march to the edge of town. In the early morning of December 26 the American troops caught the British-paid Hessian garrison at the Trenton Barracks unawares and soon forced their surrender. Washington withdrew most of his troops across the Delaware into Pennsylvania again to plan his next move.
A week later, as an advance British contingent entered Trenton, Washington successfully defended the South Broad Street crossing of the Assunpink Creek. This action, the Second Battle of Trenton, bought the American forces valuable time in which to set up another successful surprise attack on the main body of British troops at Princeton the following day. This series of engagements in Trenton and Princeton dramatically boosted American morale and showed the vulnerability of the ponderous British Army to fast-moving and well-chosen assaults by Washington's troops.
Links to learn more - Old Barracks, Trenton; Princeton Battlefield, Princeton; Washington Crossing State Park (New Jersey and Pennsylvania); David Library, Washington Crossing, Pennsylvania