When the day closed, and Cornwallis encamped on the north bank of the Assanpink, his pickets could see the Americans at work throwing up intrenchments behind the bridge, and at one point further up the stream. All along the American lines immense camp-fires burned, and these were abundantly replenished, during the night, by fence-rails from the country near by. The British and Hessians also maintained their camp-fires. A sudden freeze made these fires comfortable. It also hardened the ground, so that the American artillery and baggage-wagons could move more readily than on the previous day. Washington hurried a messenger to General Putnam, at Philadelphia, advising him of his proposed movement, and instructing him to send troops to occupy Crosswicks, a short distance above Bordentown, and thus take charge of some baggage which has been sent in that direction. All this time, the army, except its wide-awake and conspicuous sentries at the bridge, and its active fire-builders along the Assanpink, was on the march for Princeton. When the vanguard reached Stony Brook, Washington re-formed his columns, and sent General Mercer, who had served with him in the Indian War of 1756–66, to the left, by the Quaker Road, intending to advance with the main army directly to the village, by a lower road, under cover of rising ground, and thus expedite his march upon Brunswick, now weakened in its garrison by the presence of Cornwallis at Trenton. But General Mercer’s small command was suddenly confronted by a part of Colonel Mawhood’s British regiment hastening to reënforce Cornwallis. This precipitated the action, known as the “Battle of Princeton.” As soon as firing was heard, Washington hastened to the scene and took part in the fight. A British bayonet charge was too much for the American advance guard. The officers in vain attempted to rally the men. Washington at once appreciated the ruin that would result from protracted battle; and, as at Kipp’s Bay, dashed into the thickest of the fight, and with bared head urged the men to rally. He passed directly across the fire of the British troops, and the Americans responded to his appeal. Stirling, St. Clair, Patterson and others promptly brought their troops into action; cut off the retreat of a portion of the enemy to Princeton, and fought them again, just south of Nassau Hall, Princeton College.