With the capture of Fort Washington, the project of obstructing the navigation of the Hudson, at that point, was at an end. Fort Lee, consequently, became useless, and Washington ordered all the ammunition and stores to be removed, preparatory to its abandonment. This was effected with the whole of the ammunition and a part of the stores, and every exertion was making to hurry off the remainder, when, early in the morning of the 20th, intelligence was brought that the enemy, with two hundred boats, had crossed the river and landed a few miles above. General Greene immediately ordered the garrison under arms, sent out troops to hold the enemy in check, and sent off an express to Washington, at Hackensack.
The enemy had crossed the Hudson, on a very rainy night, in two divisions, one diagonally upward from King's Bridge, landing on the west side, about eight o'clock; the other marched up the east bank, three or four miles, and then crossed to the opposite shore. The whole corps, six thousand strong, and under the command of Lord Cornwallis, were landed, with their cannon, by ten o'clock, at a place called Closter Dock, five or six miles above Fort Lee, and under that line of lofty and perpendicular cliffs known as the Palisades. "The seamen," says Sir William Howe, "distinguished themselves remarkably on this occasion, by their readiness to drag the cannon up a very narrow road for nearly half a mile to the top of a precipice, which bounds the shore for some miles on the west side."
Washington arrived at the fort in three quarters of an hour. Being told that the enemy were extending themselves across the country, he at once saw that they intended to form a line from the Hudson to the Hackensack, and hem the whole garrison in between the two rivers. Nothing would save it but a prompt retreat to secure the bridge over the Hackensack. No time was to be lost. The troops sent out to check the enemy were recalled. The retreat commenced in all haste. There was a want of horses and wagons; a great quantity of baggage, stores and provisions, therefore, was abandoned. So was all the artillery excepting two twelve-pounders. Even the tents were left standing, and camp-kettles on the fire. With all their speed they did not reach the Hackensack River before the vanguard of the enemy was close upon them. Expecting a brush, the greater part hurried over the bridge, others crossed at the ferry and some higher up. The enemy, however, did not dispute the passage of the river.
From Hackensack, Colonel Grayson, one of Washington's aides-de-camp, wrote instantly, by his orders, to General Lee; informing him that the enemy had crossed into the Jerseys, and, as was reported, in great numbers. "His Excellency," adds Grayson, "thinks it would be advisable in you to remove the troops under your command on this side of the North River, and there wait for further commands."
At Hackensack the army did not exceed three thousand men, and they were dispirited by ill success, and the loss of tents and baggage. They were without intrenching tools, in a flat country, where there were no natural fastnesses. Washington resolved, therefore, to avoid any attack from the enemy, though, by so doing, he must leave a fine and fertile region open to their ravages; or a plentiful store-house, from which they would draw voluntary supplies. A second move was necessary, again to avoid the danger of being enclosed between two rivers. Leaving three regiments, therefore, to guard the passes of the Hackensack, and serve as covering parties, he again decamped, and threw himself on the west bank of the Passaic, in the neighborhood of Newark.
His army, small as it was, would soon be less. The term of enlistment of those under General Mercer, from the flying camp, was nearly expired; and it was not probable that, disheartened as they were by defeats and losses, exposed to inclement weather, and unaccustomed to military hardships they would longer forego the comforts of their homes, to drag out the residue of a ruinous campaign. In addition, too, to the superiority of the force that was following him, the rivers gave the enemy facilities, by means of their shipping, to throw troops in his rear. In this extremity he cast about in every direction for assistance. Colonel Reed was despatched to Burlington with a letter to Governor William Livingston, describing his hazardous situation, and entreating him to call out a portion of the New Jersey militia; and General Mifflin was sent to Philadelphia to implore immediate aid from Congress and the local authorities.
His main reliance for prompt assistance, however, was upon Lee. On the 24th came a letter from that general, addressed to Colonel Reed. Washington opened it, as he was accustomed to do, in the absence of that officer, with letters addressed to him on the business of the army. Lee was at his old encampment at Northcastle. He had no means, he said, of crossing at Dobbs' Ferry, and the round by King's Ferry would be so great that he could not get there in time to answer any purpose. "I have therefore," added he, "ordered General Heath, who is close to the only ferry which can be passed, to detach two thousand men to apprise his Excellency, and await his further orders; a mode which I flatter myself will answer better what I conceive to be the spirit of the orders than should I move the corps from hence. Withdrawing our troops from hence would be attended with some very serious consequences, which at present would be tedious to enumerate; as to myself," adds he, "I hope to set out to-morrow."
On the following day he writes to Washington: "I have received your orders, and shall endeavor to put them in execution, but question whether I shall be able to carry with me any considerable number; not so much from a want of zeal in the men as from their wretched condition, with respect to shoes, stockings, and blankets, which the present bad weather renders more intolerable. I sent Heath orders to transport two thousand men across the river, apprise the general, and wait for further orders; but that great man (as I might have expected) intrenched himself within the letter of his instructions, and refused to part with a single file, though I undertook to replace them with a part of my own."
Scarce had Lee sent this letter when he received one from Washington, informing him that he had mistaken his views in regard to the troops required to cross the Hudson; it was his (Lee's) division that he wanted to have over. The force under Heath must remain to guard the posts and passes through the Highlands, the importance of which was so infinitely great that there should not be the least possible risk of losing them. Lee's reply explained that his idea of detaching troops from Heath's division was merely for expedition's sake, intending to replace them from his own. The want of carriages and other causes had delayed him. From the force of the enemy remaining in Westchester County, he did not conceive the number of them in the Jerseys to be near so great as Washington was taught to believe. He had been making a sweep of the country to clear it of the tories. Part of his army had now moved on, and he would set out on the following day.
The situation of the little army was daily becoming more perilous. In a council of war, several of the members urged a move to Morristown, to form a junction with the troops expected from the Northern army. Washington, however, still cherished the idea of making a stand at Brunswick on the Raritan, or, at all events, of disputing the passage of the Delaware; and in this intrepid resolution he was warmly seconded by Greene. Breaking up his camp once more, therefore, he continued his retreat towards New Brunswick; but so close was Cornwallis upon him that his advance entered one end of Newark just as the American rear-guard had left the other.