After the destruction of Forts Clinton and Montgomery in 1777, it had been determined to construct the fortifications intended for the future defense of the North river at West Point, a position which being more completely embosomed in the hills was deemed more defensible. The works had been prosecuted with unremitting industry but were far from being completed.

King's Ferry, some miles below West Point, where the great road, the most convenient communication between the middle and eastern States, crossed the North river, is completely commanded by two opposite points of land. That on the west side, a rough and elevated piece of ground, is denominated Stony Point; and the other, on the east side, a flat neck of land projecting far into the water, is called Verplanck's Point. The command of King's Ferry was an object worth the attention of either army, and Washington had comprehended the points which protect it within his plan of defense for the Highlands. A small but strong work called Fort Fayette was completed at Verplanck's and was garrisoned by a company commanded by Captain Armstrong. The works on Stony Point were unfinished. As the season for active operations approached Sir Henry Clinton formed a plan for opening the campaign with a brilliant coup de main up the North river and toward the latter end of May made preparations for the enterprise.

These preparations were immediately communicated to Washington who was confident that Clinton meditated an attack on the forts in the Highlands or designed to take a position between those forts and Middlebrook, in order to interrupt the communication between the different parts of the American army, to prevent their reunion and to beat them in detail. Measures were instantly taken to counteract either of these designs. The intelligence from New York was communicated to Generals Putnam and M'Dougal, who were ordered to hold themselves in readiness to march, and on the 29th of May (1779) the army moved by divisions from Middlebrook toward the Highlands. On the 30th the British army commanded by Clinton in person and convoyed by Sir George Collier proceeded up the river, and General Vaughan at the head of the largest division, landed next morning about eight miles below Verplanck's. The other division under the particular command of General Patterson, but accompanied by Clinton, advancing further up, landed on the west side within three miles of Stony Point.

That place being immediately abandoned, General Patterson took possession of it on the same afternoon. He dragged some heavy cannon and mortars to the summit of the hill in the course of the night (June 1, 1779), and at five next morning opened a battery on Fort Fayette at the distance of about 1,000 yards. During the following night two galleys passed the fort and anchoring above it prevented the escape of the garrison by water while General Vaughan invested it closely by land. No means of defending the fort or of saving themselves remaining the garrisons became prisoners of war. Immediate directions were given for completing the works at both posts and for putting Stony Point in particular in a strong state of defense.

Washington determined to check any further advance of the enemy, and before Clinton was in a situation to proceed against West Point, General M'Dougal was so strengthened and the American army took such a position on the strong grounds about the Hudson that the enterprise became too hazardous to be further prosecuted.

After completing the fortifications on both sides of the river at King's Ferry, Clinton placed a strong garrison in each fort and proceeded down the river to Philipsburg. The relative situation of the hostile armies presenting insuperable obstacles to any grand operation they could be employed offensively only on detached expeditions. Connecticut, from its contiguity to New York and its extent of sea coast, was peculiarly exposed to invasion. The numerous small cruisers which plied in the sound, to the great annoyance of British commerce, and the large supplies of provisions drawn from the adjacent country for the use of the Continental army, furnished great inducements to Clinton to direct his enterprises particularly against that State. He also hoped to draw Washington from his impregnable position on the North river into the low country and thus obtain an opportunity of striking at some part of his army or of seizing the posts which were the great object of the campaign. With these views he planned an expedition against Connecticut, the command of which was given to Governor Tryon, who reached New Haven bay on the 5th of July (1779) with about 2,600 men.

Washington was at the time on the lines examining in person the condition of the works on Stony and Verplanck's Points, in consequence of which the intelligence which was transmitted to headquarters that the fleet had sailed could not be immediately communicated to the Governor of Connecticut, and the first intimation which that State received of its danger was given by the appearance of the enemy. The militia assembled in considerable numbers with alacrity, but the British effected a landing and took possession of the town. After destroying the military and naval stores found in the place, they re-embarked and proceeded westward to Fairfield which was reduced to ashes. The spirited resistance made by the militia at this place is attested by the apology made by General Tryon for the wanton destruction of private property which disgraced his conduct. "The village was burnt," he says, "to resent the fire of the rebels from their houses and to mask our retreat."

From Fairfield the fleet crossed the sound to Huntington bay where it remained until the 9th (July, 1779), when it recrossed that water. The troops were landed in the night on a peninsula on the east side of the Bay of Norwalk. About the same time a much larger detachment from the British army directed its course towards Horse Neck and made demonstrations of a design to penetrate into the country in that direction.

On the first intelligence that Connecticut was invaded, General Parsons, a native of that State, had been directed by Washington to hasten to the scene of action. Placing himself at the head of about 150 Continental troops who were supported by considerable bodies of militia, he attacked the British on the morning of the twelfth as soon as they were in motion and kept up an irregular distant fire throughout the day. But, being too weak to prevent the destruction of any particular town on the coast, Norwalk was reduced to ashes, after which the British re-embarked and returned to Huntington bay there to await for reinforcements. At this place, however, Tryon received orders to return to Whitestone where in a conference between Clinton and Sir George Collier it was determined to proceed against New London with an increased force.

On the invasion of Connecticut, Washington was prompt in his exertions to send Continental troops from the nearest encampments to its aid, but before they could afford any real service Clinton found it necessary to recall Tryon to the Hudson.