On January 3, Hugh Mercer, leading the American advance guard, encountered British soldiers from Princeton under the command of Charles Mawhood. The British troops engaged Mercer and in the ensuing battle, Mercer was mortally wounded. Washington sent reinforcements under General John Cadwalader, which were successful in driving Mawhood and the British from Princeton, with many of them fleeing to Cornwallis in Trenton. The British lost more than one quarter of their force in the battle, and American morale rose with the great victory.