Towards the end of May, Washington broke up his cantonments at Morristown, and shifted his camp to Middlebrook, within ten miles of Brunswick. His whole force fit for duty was now about seven thousand three hundred men, all from the States south of the Hudson. There were forty-three regiments, forming ten brigades, commanded by Brigadiers Muhlenberg, Weedon, Woodford, Scott, Smallwood, Deborre, Wayne, Dehaas, Conway, and Maxwell. These were apportioned into five divisions of two brigades each, under Major-generals Greene, Stephen, Sullivan, Lincoln and Stirling. The artillery was commanded by Knox. Sullivan, with his division, was stationed on the right at Princeton. With the rest of his force, Washington fortified himself in a position naturally strong, among hills, in the rear of the village of Middlebrook. His camp was, on all sides, difficult of approach, and he rendered it still more so by intrenchments. The high grounds about it commanded a wide view of the country around Brunswick, the road to Philadelphia, and the course of the Raritan, so that the enemy could make no important movement on land without his perceiving it.
On the 31st of May, reports were brought to camp that a fleet of a hundred sail had left New York and stood out to sea. Whither bound and how freighted was unknown. If they carried troops, their destination might be Delaware Bay. Eighteen transports also had arrived at New York, with troops in foreign uniforms, which proved to be Anspachers, and other German mercenaries; there were British reinforcements also; and, what was particularly needed, a supply of tents and camp equipage. Sir William Howe had been waiting for the latter, and likewise until the ground should be covered with grass. The country was now in full verdure, affording "green forage" in abundance, and all things seemed to Sir William propitious for the opening of the campaign. Early in June, therefore, he gave up ease and gayety and luxurious life at New York, and crossing into the Jerseys set up his head-quarters at Brunswick.
As soon as Washington ascertained that Sir William's attention was completely turned to this quarter, he determined to strengthen his position with all the force that could be spared from other parts, so as to be able, in case a favorable opportunity presented, to make an attack upon the enemy; in the meantime, he would harass them with his light militia troops, aided by a few Continentals, so as to weaken their numbers by continual skirmishes. With this view he ordered General Putnam to send down most of the Continental troops from Peekskill, leaving only a number sufficient, in conjunction with the militia, to guard that post against surprise.
Arnold, in this critical juncture, had been put in command of Philadelphia, a post which he had been induced to accept, although the question of rank had not been adjusted to his satisfaction. His command embraced the western bank of the Delaware with all its fords and passes, and he took up his station there with a strong body of militia, supported by a few Continentals, to oppose any attempt of the enemy to cross the river. He was instructed by Washington to give him notice by expresses, posted on the road, if any fleet should appear in Delaware Bay; and to endeavor to concert signals with the camp of Sullivan at Princeton, by alarm fires upon the hills.
On the night of the 13th of June, General Howe sallied forth in great force from Brunswick, as if pushing directly for the Delaware, but his advanced guard halted at Somerset court-house, about eight or nine miles distant. Apprised of this movement, Washington at daybreak reconnoitred the enemy from the heights before the camp. He observed their front halting at the court-house, but a few miles distant, while troops and artillery were grouped here and there along the road and the rear-guard was still at Brunswick. It was a question with Washington and his generals, as they reconnoitred the enemy with their glasses, whether this was a real move toward Philadelphia, or merely a lure to tempt them down from their strong position. In this uncertainty, Washington drew out his army in battle array along the heights, but kept quiet. In the present state of his forces it was his plan not to risk a general action, but should the enemy really march toward the Delaware, to hang heavily upon their rear.
The British took up a strong position, having Millstone Creek on their left, the Raritan all along their front, and their right resting on Brunswick, and proceeded to fortify themselves with bastions.
The American and British armies, strongly posted, remained four days grimly regarding each other; both waiting to be attacked. The Jersey militia which now turned out with alacrity, repaired, some to Washington's camp, others to that of Sullivan. The latter had fallen back from Princeton, and taken a position behind the Sourland Hills.
Howe pushed out detachments and made several feints, as if to pass by the American camp and march to the Delaware, but Washington was not to be deceived. Baffled in these attempts to draw his cautious adversary into a general action, Howe, on the 19th, suddenly broke up his camp, and pretended to return with some precipitation to Brunswick, burning as he went several valuable dwelling houses. Washington's light troops hovered round the enemy as far as the Raritan and Millstone, which secured their flanks, would permit; but the main army kept to its stronghold on the heights.
On the next day came warlike news from the North. Amesbury, a British spy, had been seized and examined by Schuyler. Burgoyne was stated as being arrived at Quebec to command the forces in an invasion from Canada. While he advanced with his main force by Lake Champlain, a detachment of British troops, Canadians and Indians, led by Sir John Johnson, was to penetrate by Oswego to the Mohawk River, and place itself between Fort Stanwix and Fort Edward. If this information was correct, Ticonderoga would soon be attacked. The force there might be sufficient for its defence, but Schuyler would have no troops to oppose the inroad of Sir John Johnson, and he urged a reinforcement. Washington forthwith sent orders to Putnam to procure sloops, and hold four Massachusetts regiments in readiness to go up the river at a moment's warning.
On the 22d, Sir William again marched out of Brunswick, but this time proceeded towards Amboy, again burning several houses on the way; hoping, perhaps, that the sight of columns of smoke rising from a ravaged country would irritate the Americans and provoke an attack. Washington sent out three brigades under General Greene to fall upon the rear of the enemy, while Morgan hung upon their skirts with his riflemen. At the same time the army remained paraded on the heights ready to yield support if necessary. Finding that Howe had actually sent his heavy baggage and part of his troops over to Staten Island, Washington, on the 24th, left the heights and descended to Quibbletown (now New Market), six or seven miles on the road to Amboy, to be nearer at hand for the protection of his advanced parties.