Washington decided to attack the troops at Trenton. His men fit for duty did not exceed five thousand, and of these nearly two thousand were militia. The troops under Rahl consisted of three battalions of Hessians, having with them six field-pieces, fifty chasseurs, and twenty dragoons,—twelve hundred in all. Circumstances favored the plan which Washington now adopted. Colonel Griffin, with two companies of Virginians and some militia, had driven a party of Hessians, who had penetrated as far south as Moorestown and Haddonfield, back to Mount Holly, where they had been reinforced by Donop, who was thus too far removed from Trenton to support Rahl in case of an emergency. The success of Griffin made the militia at Bristol anxious for service, and it was decided by Cadwalader and Reed, who was with him, to gratify them by supporting Griffin. To this Washington assented, and at the same time confided to Reed and Cadwalader his contemplated movement against Trenton. On the morning of the 23d he wrote to them asking if the plan had been carried out, and informed them that one hour before day on the morning of the 26th was the time he had fixed upon for attacking Rahl. "For heaven's sake", he wrote, "keep this to yourselves as the discovery of it may prove fatal to us. Our numbers, sorry I am to say, being less than I had any conception of; but necessity, dire necessity, will, nay must justify an attack. Prepare and concert with Griffin; attack as many of their posts as you possibly can with a prospect of success; the more we can attack at the same instant the more confusion we shall spread, and the greater good will result from it."
Washington was informed that it was impracticable to act with Griffin; and Reed repaired to Philadelphia to urge Putnam to create a diversion by crossing the river at Cooper's Ferry. He found, however, that little could be expected from Putnam, and returned to Bristol on the 25th, where Cadwalader was preparing to carry out the part which Washington had assigned to him. It was the intention of Washington to cross the Delaware above Trenton with about one half of his command, and attack the enemy, while Ewing and Cadwalader should cross opposite Trenton and Bristol, and not only cut Rahl's line of retreat but prevent Donop from reinforcing him.
Notwithstanding the fact that no aid could be expected from Putnam, Washington determined to proceed, and urged Cadwalader to do all in his power to support him. The boats had been gathered at McKonkey's Ferry, nine miles above Trenton, and as the men marched to them the footprints they left in the snow were here and there tinged with blood from the feet of those who wore broken shoes. The boats were promptly manned by Glover's regiment from Marblehead, and at dark the crossing began. It was three o'clock before the artillery was landed, and four before the troops took up the line of march. The attack was to have been made about five, and against a more vigilant enemy this delay would have proved fatal. But Rahl was not vigilant. He despised his opponents, and refused to protect his position with redoubts as instructed by Donop. He had been informed of Washington's intended movement, but paid no attention to the report. It so happened that on the morning of the attack his outposts had been fired upon by a body of strolling militia, and this he supposed was the attack he was to look for. Washington had with him two thousand four hundred men. These he divided into two columns. One was commanded by Sullivan, and marched by the river road which entered the town on the northwest. The other, under Greene, took the Pennington road which approached the town from the north. The Americans advanced in a violent storm of snow and hail. Greene's command arrived at the outskirts of the town three minutes before Sullivan's. The attacks of both parties were almost simultaneously. Many of the guns were rendered useless by the storm, and the men were ordered to charge. Those who had bayonets fixed them and rushed upon the pickets, who retired. The Hessians were taken entirely by surprise. For a while Rahl was allowed to remain undisturbed in bed, but when matters grew serious he was aroused and hurriedly assumed command. Some of his half-formed regiments were advanced towards the Americans, but were driven back, throwing those in their rear into inextricable confusion. Two lines of retreat were open to Rahl. One lay over the bridge which crossed the Assanpink, south of the town; the other was the road to Brunswick. But Sullivan's attack was so spirited that the Hessians were driven past the road which led to the bridge, and as they attempted to escape towards Brunswick, Washington intercepted them with Hand's riflemen and held them in check. A battery under Captain Thomas Forrest created great havoc in their ranks, and two of their guns were turned against it. These were immediately charged by the Americans, who were led by Captain William Washington and Lieutenant James Monroe. Both were wounded, but the guns were captured. Rahl was mortally wounded in trying to rally his men, and shortly after he fell his command surrendered. All was over in three quarters of an hour. With the exception of the horse and a small number of the infantry which escaped over the Assanpink or to Brunswick, Rahl's entire force was either killed or captured. The prisoners numbered nine hundred and eighteen. The killed, Washington thought, did not exceed twenty or thirty. The Americans had two privates killed, one frozen to death, and two officers and four men wounded. As the enemy were supposed to be in force at Princeton and Bordentown, and the Americans were in no condition to withstand an attack, it was thought best not to risk the advantage which had been gained, and as soon as the men were rested the army, with its prisoners, returned to Pennsylvania.
Ewing and Cadwalader had been unable to carry out the parts assigned them, on account of the ice. The latter sent a portion of his infantry over the river, but recalled it when he found he could not land his artillery. With no definite news of Washington's success, Cadwalader recrossed on the morning of the 27th, supposing Washington to be at Trenton. He soon learned his mistake, but discovered that Donop had retreated towards Brunswick when he heard of the action at Trenton. Cadwalader then moved on to Burlington, and on the 29th marched to Crosswicks. The desperate condition of affairs previous to the battle had stimulated the people to extraordinary efforts, and the news of the victory raised their spirits in proportion to the depression they had so lately suffered. Ignorant of the victory Washington had achieved, Congress on the 27th vested him with powers that virtually constituted him a military dictator for the period of six months. To convince the people of the reality of the victory, the Hessians were marched through the streets of Philadelphia, and one of their standards was hung up in the chamber of Congress at Baltimore. Public rejoicings broke forth on every side. "The Lord of Hosts has heard the cry of the distressed, and sent an angel to their assistance", exclaimed Muhlenberg, the patriarch of the Lutherans. On the 27th and 28th of December, fifteen hundred militia under Mifflin followed Cadwalader into New Jersey, while the Jerseymen gathered at Morristown and other points. In the face of this feeling it was necessary that the offensive should be resumed, and on the 30th Washington occupied Trenton. The service of the New England troops expired on the first of the year; but through the efforts of Robert Morris money was raised to offer bounties, which, with appeals to their patriotism, induced them to remain six weeks longer with the army.
As soon as Cornwallis heard of the surprise at Trenton, he gave up his visit to England and hastily joined Grant at Brunswick. On the 30th, with 8,000 men, he marched towards Trenton, with the determination of driving Washington over the Delaware or capturing his entire force. Washington immediately ordered Cadwalader and Mifflin to Trenton, and sent forward a detachment under General Fermoy to retard the advance of Cornwallis. On the night of January the 1st this detachment was at Five Mile Run, between Trenton and Princeton. Early on the morning of the 2d Cornwallis set out from Princeton, where he had halted the night previous. The Americans retired before him, disputing every foot of ground. Hand's riflemen, Scott's Virginians, and Forrest's battery bore the brunt of the fighting. It was nearly noon by the time Shabbakong Creek was reached, and two hours passed before the British succeeded in crossing it. The main portion of the American army was strongly posted on the south side of the Assanpink, the banks being sufficiently high to enable the men in the rear to fire over the heads of those in front of them. As the British approached Trenton, troops were sent forward by Washington to support the Americans. A battery placed on a hill beyond Trenton held the British in check for a short time, but the Americans were soon driven into the town and across the bridge. The cannonading on both sides was heavy, but the British were unable to force their way across the stream, and as night approached Cornwallis, against the advice of his officers, withdrew his troops, determined to renew the conflict in the morning. "If ever there was a crisis in the affairs of the Revolution", wrote Wilkinson, "this was the moment. Thirty minutes would have sufficed to have brought the two armies into contact, and thirty minutes more would have decided the combat." Washington's position was indeed critical. It was hardly possible that with his raw levies he could continue to hold in check the well-disciplined troops of Cornwallis, which in the morning would be reinforced with troops he had left at Maidenhead and Princeton. The Delaware behind Washington was full of floating ice, and to cross it in that condition was impossible. If Cornwallis should force the Americans' position, the victory of the British would be decisive. Immediately after dark a council of war was held. It was then decided to turn the left flank of the enemy, strike a blow at Princeton, where the garrison was small, and march on Brunswick, the depository of the British stores. The sentries of both armies were posted along the banks of the Assanpink, and at some points were within one hundred and fifty yards of each other. Working parties were sent within hearing distance of the enemy to throw up intrenchments, the guards were doubled, and everything was done to indicate that Washington intended to defend his position to the last. But at midnight the fires were replenished and the troops silently withdrawn. Marching by the Quaker road, Washington turned the left flank of Cornwallis, and by daybreak reached a point directly south of Princeton. With the main body he moved directly on the town, and ordered a detachment under Mercer to march to the left and demolish the bridge over Stony Brook, thus destroying direct communication with Cornwallis. The garrison at Princeton consisted of the 17th, 40th, and 55th regiments and three companies of light horse. The 17th and 55th, with a few dragoons, started at sunrise on the morning of the 3d to join Cornwallis. The 17th, under Colonel Mawhood, had crossed the bridge over Stony Brook, that Mercer was to destroy, and was some distance beyond it, when Mawhood discovered Mercer on his flank and rear, moving north on the east side of the stream. He at once recrossed the bridge, and both parties endeavored to gain the high ground east of the stream. As the Americans had the shortest distance to march, they were successful, and with their rifles they poured a deadly fire into the 17th and 55th, as they advanced to drive them from their position. They had no bayonets, however, and were unable to stand the charge of the British. They fled through an orchard in their rear, leaving their commander mortally wounded on the ground. It was not until Mawhood emerged from the orchard that he was aware that the whole American army was within supporting distance of the troops he had just engaged. On hearing the firing on his left, Washington halted his column, and with the Pennsylvania militia moved to the support of Mercer. Encouraged by the irresolution of the militia, Mawhood charged them, but other regiments coming up and the militia gaining confidence, the British halted, and then fled, as the Americans in turn advanced against them. The 55th retreated to Princeton and joined the 40th. They made a mere show of defending the town, took refuge in the college building, deserted it, and were soon seen in full retreat across the Millstone towards Brunswick. Washington's troops had been under arms for over eighteen hours, and were too much fatigued to follow them. Having dispersed the 17th regiment, he destroyed the bridge over Stony Brook and Millstone as the head of Cornwallis's rear-guard came in sight. It was commanded by Leslie, who had marched from Maidenhead as soon as he heard the firing in his rear. Washington turned north at Kingston, and proceeded to Somerset Court-House, where he rested his men. Cornwallis was not aware that the Americans had been withdrawn from his front until he heard the sound of the guns at Princeton. Realizing at once that he had been outgeneralled, and that his stores were in danger, he ordered a retreat. Failing to reach Princeton in time to be of service, he continued his march to Brunswick, and made no attempt to follow Washington. The losses of the British in these engagements were severe; those on the 2d of January were never known. At Princeton, Washington estimated that one hundred men were left dead upon the field, and that the killed, wounded, and prisoners amounted to five hundred. Ensign Inman, of the 17th, wrote that of the two hundred and twenty-four rank and file of his regiment, which set out on the morning of the 3d, one hundred and one were either killed or wounded, and that he was the only officer of the right wing not injured. The Americans lost only twenty or thirty privates, but many officers. Bravely had they urged their men on in the thickest of the fight. That Washington escaped seemed a miracle to those who saw him lead the troops which drove Mawhood back. Hazlet, Morris, Neal, and Shippin fell upon the field. Mercer, mortally wounded, died upon the 12th, lamented by the whole country. From Somerset Court-House Washington marched to Morristown, where he went into winter-quarters. The British troops were soon all withdrawn to Amboy and Brunswick. In less than three weeks Washington had turned back the tide of adversity, and had compelled his opponents to evacuate West Jersey.
Washington remained at Morristown from the 7th of January until the 28th of May, during which time no military movement of importance took place. His men left for their homes as soon as their terms of service expired, and as few militia entered the camp to take their places, at times it seemed as if the army would be so reduced as to be unworthy of the name. It was not until late in the spring that the new levies reached headquarters. On the 28th of May the Americans marched to Middlebrook, and took position behind the Raritan. On the 13th of June Howe marched from Brunswick and extended his line to Somerset Court-House, and Arnold was sent to Trenton to take measures to prevent his crossing the Delaware. The militia turned out in a spirited manner, and Howe did not care to advance in the face of the opposition they could offer, with Washington on his flank. He endeavored to bring on a general engagement with the latter, but Washington refused to leave the strong position he occupied, and Howe retired to Amboy.
Early in April Howe had settled upon a campaign having for its object the capture of Philadelphia. He determined to embark his troops and transport them to the banks of the Delaware or Chesapeake, and march directly on the city. With the object of reaching the fleet he started to cross to Staten Island; but learning that Washington was at Quibbletown, he recalled his men and proceeded to Westfield, hoping to outflank him. But, as Washington retired, Howe was unsuccessful, and finally passed over to Staten Island, totally evacuating New Jersey.
For over six weeks Washington was ignorant of Howe's intentions. Supposing that he would endeavor to coöperate with Burgoyne, and would sail up the Hudson, Washington moved his army to Ramapo, in New York. On the 23d of July, after Howe's troops had been three weeks on the vessels, the fleet sailed, shaping its course southwesterly. Its departure was promptly reported to Congress. Signal fires were lighted along the Jersey coast as it was seen from time to time by those who were watching for it, and messengers carried inland the news of its progress. At last, on the 30th, it was spoken off the capes of Delaware, but Lord Howe deemed it too hazardous to sail up that river, and after consulting with his brother, the general, continued on his course southward. On the 15th of August he entered Chesapeake Bay, and on the 25th the troops were landed at Elk Ferry.
On the 24th of July Washington heard that the fleet had sailed southward, and in consequence marched his army from Ramapo to Coryell's Ferry. He continued his march to Philadelphia, when he learned that the fleet was off the capes of Delaware; but as it was soon lost sight of, he retraced his steps, and halted in Bucks County, Pennsylvania, twenty miles from Philadelphia. While there, Lafayette, De Kalb, and Pulaski joined the army.