Cornwallis was diligently fortifying himself at York and Gloucester. Lafayette was in a position on James river to prevent his escape into North Carolina, and the combined army was hastening southward to attack him. In order to cooperate against Cornwallis De Grasse detached four ships-of-the-line and some frigates to block up the entrance of York river, and to carry the land forces which he had brought with him, under the Marquis de St. Simon, to Lafayette's camp. The rest of his fleet remained at the entrance of the bay.

Sir George Rodney, who commanded the British fleet in the West Indies, was not ignorant that the count intended to sail for America, but knowing that the merchant vessel which he convoyed from Cape Francois were loaded with valuable cargoes the British admiral believed that he would send the greater part of his fleet along with them to Europe and would visit the American coast with a small squadron only.

Accordingly, Rodney detached Sir Samuel Hood with fourteen sail-of-the-line to America as a sufficient force to counteract the operations of the French in that quarter. Admiral Hood reached the capes of Virginia on the 25th of August (1781), a few days before de Grasse entered the bay and finding no enemy there sailed for Sandy Hook, where he arrived on the 28th of August.

Admiral Graves, who had succeeded Admiral Arbuthnot in the command of the British fleet on the American station, was then lying at New York with seven sail-of-the-line; but two of his ships had been damaged in a cruise near Boston and were under repair. At the same time that Admiral Hood gave information of the expected arrival of de Grasse on the American coast, notice was received of the sailing of de Barras with his fleet from Newport. Admiral Graves, therefore, without waiting for his two ships which were under repair, put to sea on the 31st of August with nineteen sail-of-the-line and steered to the southward.

On reaching the capes of the Chesapeake, early on the morning of the 5th of September (1781), he discovered the French fleet, consisting of twenty-four ships-of-the-line, lying at anchor in the entrance of the bay. Neither admiral had any previous knowledge of the vicinity of the other till the fleets were actually seen. The British stretched into the bay and soon as Count de Grasse ascertained their hostile character he ordered his ships to slip their cables, form the line as they could come up without regard to their specified stations and put to sea. The British fleet entering the bay and the French leaving it, they were necessarily sailing in different directions, but Admiral Graves put his ships on the same tack with the French and about four in the afternoon a battle began between the van and centre of the fleets which continued till night. Both sustained considerable damage. The fleets continued in sight of each other for five days, but de Grasse's object was not to fight unless to cover Chesapeake Bay, and Admiral Graves, owing to the inferiority of his force and the crippled state of several of his ships, was unable to compel him to renew the engagement.

On the 10th (September, 1781), de Grasse bore away for the Chesapeake and anchored within the capes next day when he had the satisfaction to find that Admiral de Barras with his fleet from Newport and fourteen transports laden with heavy artillery and other military stores for carrying on a siege had safely arrived during his absence. That officer sailed from Newport on the 25th of August, and making a long circuit to avoid the British, entered the bay while the contending fleets were at sea. Admiral Graves followed the French fleet to the Chesapeake, but on arriving there he found the entrance guarded by a force with which he was unable to contend. He then sailed for New York and left de Grasse in the undisputed possession of the bay.

While these naval operations were going on the land forces were not less actively employed in the prosecution of their respective purposes. The immediate aim of Washington was to overwhelm Cornwallis and his army at Yorktown; that of Clinton, to rescue him from his grasp. As soon as Clinton was convinced of Washington's intention of proceeding to the southward with a view to bring him back, he employed the infamous traitor Arnold, with a sufficient naval and military force, on an expedition against New London. The "parricide," as Jefferson calls him, had not the slightest objection to fill his pockets with the plunder of his native State. He passed from Long Island and on the forenoon of the 6th of September (1781) landed his troops on both sides of the harbor; those on the New London side being under his own immediate orders and those on the Groton side commanded by Lieutenant-Colonel Eyre. As the works at New London were very imperfect, no vigorous resistance was there made, and the place was taken possession of with little loss. But Fort Griswold, on the Groton side, was in a more finished state and the small garrison made a desperate defense. The British entered the fort at the point of the bayonet.

Col. William Ledyard, brother of the celebrated traveler, commanded the fort. Colonel Eyre and Major Montgomery having fallen in the assault, the command had devolved on Major Bromfield, a New Jersey Tory. After the works had been carried, Ledyard ordered his men to lay down their arms. Bromfield called out, "Who commands in this fort?" Ledyard advanced and presenting his sword, replied, "I did, but you do now." Bromfield seized the sword and ran Ledyard through the body. This was the signal for an indiscriminate massacre of a greater part of the garrison by the Tories, refugees, and Hessians, of which the army of Arnold was very appropriately composed. Seventy were killed and thirty-five desperately wounded. The enemy lost 2 officers and 46 men killed, 8 officers and 135 soldiers wounded. Few Americans had fallen before the British entered the works.

The loss sustained by the Americans at New London was great, but that predatory incursion had no effect in diverting Washington from his purpose or in retarding his march southward. From Philadelphia the allied armies pursued their route, partly to the head of Elk river, which falls into the northern extremity of Chesapeake Bay, and partly to Baltimore, at which places they embarked on board transports furnished by the French fleet, and the last division of them landed at Williamsburgh on the 25th of September (1781). Washington, Rochambeau, and their attendants proceeded to the same place by land, and reached it ten days before the troops. Virginia had suffered extremely in the course of the campaign; the inhabitants were clamorous for the appearance of Washington in his native State, and hailed his arrival with acclamations of joy.

Washington and Rochambeau immediately repaired on board de Grasse's ship in order to concert a joint plan of operations against Cornwallis. De Grasse, convinced that every exertion would be made to relieve his lordship, and being told that Admiral Digby had arrived at New York with a reinforcement of six ships-of-the-line, expected to be attacked by a force little inferior to his own, and, deeming the station which he then occupied unfavorable to a naval engagement, he was strongly inclined to leave the bay and to meet the enemy in the open sea. Washington, fully aware of all the casualties which might occur to prevent his return and to defeat the previous arrangements, used every argument to dissuade the French admiral from his purpose, and prevailed with him to remain in the bay.