With New York City in British hands, Forts Washington and Lee on the Hudson River (North River) fell to British attack November 16 & 19, 1776, respectively. General George Washington moved his army south through New Jersey, crossing the Delaware River into Pennsylvania. The British Army and German auxiliaries followed, reaching Princeton on December 7th and Trenton on December 8th.
With the American Army temporarily out of reach, British and German troops fortified and garrisoned towns along the main road, including Princeton and Trenton. This arrangement allowed the British to gather provisions over a wider area but made mutual support difficult if attacked. Washington took advantage of this vulnerability by crossing the Delaware River Christmas night, attacking the next morning the garrison closest to his army, the German Regiments at Trenton.