Replenishing the camp fires, and leaving the sentinels at their posts, at one o'clock the army filed off to the right in perfect silence and order. The baggage and some spare artillery were sent off to Burlington, to still further mystify the enemy. By one of those sudden changes of weather, not uncommon even in midwinter, the soft ground had become hard frozen during the early part of the night, so that rapid marching was possible, and rapid marching was the only thing that could save the movement from failure, as Cornwallis would have but twelve miles to march to Washington's seventeen, to overtake them--he by a good road, they by a new and half-worked one. Miles, therefore, counted for much that night, and though many of the men wore rags wrapped about their feet, for want of shoes, and the shoeless artillery horses had to be dragged or pushed along over the slippery places, to prevent their falling, the column pushed on with unflagging energy toward its goal. [Sidenote: British in pursuit.] Shortly after daybreak the British, at Trenton, heard the dull booming of a distant cannonade. Washington, escaped from their snares, was sounding the reveille at Princeton. The British camp awoke and listened. Soon the rumor spread that the American lines were deserted. Drums beat, trumpets sounded, ranks were formed in as great haste as if the enemy were actually in the camps, instead of being at that moment a dozen miles away. Cornwallis, who had gone to bed expecting to make short work of Washington in the morning, saw himself fairly outgeneralled. His rear-guard, his magazines, his baggage, were in danger, his line of retreat cut off. There was not a moment to lose. Exasperated at the thought of what they would say of him in England, he gave the order to press the pursuit to the utmost. The troops took the direct route by Maidenhead to Princeton; and thus, for the second time, Trenton saw itself freed from enemies, once routed, twice disgraced, and thoroughly crestfallen and stripped of their vaunted prestige. [Sidenote: Mercer's fight.] Three British battalions lay at Princeton the night before.[7] Two of them were on the march to Trenton when Washington's troops were discovered approaching on a back road. Astonished at seeing troops coming up from that direction, the leading battalion instantly turned back to meet them. At the same time Washington detached Mercer to seize the main road, while he himself pushed on with the rest of the troops. This movement brought on a spirited combat between Mercer and the strong British battalion, which had just faced about.[8] The fight was short, sharp, and bloody. After a few volleys, the British charged with the bayonet, broke through Mercer's ranks, scattered his men, and even drove back Cadwalader's militia, who were coming up to their support.