At the end of March a strong French fleet under de Grasse sailed from Brest for the West Indies. After a few weeks’ operations among the islands, and taking Tobago, de Grasse made for Cap François in Hayti and found dispatches from Washington. Taking on board 3,500 French soldiers, he sailed for the North American coast and reached the Chesapeake at the end of August. The object was to co-operate with Washington and de Rochambeau in blockading Cornwallis and compelling him to surrender. Meanwhile a French squadron at Newport in Rhode Island, under de Barras, put out to sea with a convoy containing the siege train, making a wide circuit in order to escape detection by the English ships and join de Grasse in Chesapeake Bay. On land Lafayette, strengthened by a body of Pennsylvanians, already harassed Cornwallis, especially charged to prevent as far as possible a retreat to the south; while de Rochambeau from Rhode Island joined Washington who was facing New York, and the combined army, after threatening an attack on Clinton, crossed the Hudson in August, marched through New Jersey to Philadelphia, and passing on to Virginia, with the help of French transports appeared before Yorktown in the latter end of September. Cornwallis was now besieged by 16,000 men on land and an overwhelming fleet at sea. [Sidenote: Ineffective movements of the English fleet.] The movement had been well planned and skilfully executed. Clinton at New York had been misled by a feint of attack, and on the sea the English had been found wanting. When Rodney learnt that de Grasse had left the West Indies for the North American coast, in ill health himself and about to leave for England, he dispatched Sir Samuel Hood in pursuit with fourteen ships of the line. A stronger force was needed and had apparently been intended by Rodney. Hood reached the Chesapeake three or four days before de Grasse arrived, and passing on to New York came under the orders of a senior officer, Admiral Graves, who had at the time but five ships with him. The combined squadron sailed for the Chesapeake, and found that de Grasse had forestalled them with a stronger fleet. They attacked on the 5th of September, with no decisive result on either side: for three or four days longer the two fleets faced each other, then Graves returned to New York and de Grasse went back to block Cornwallis, his manœuvres having enabled de Barras in the meantime to bring in his ships in safety to the Chesapeake. [Sidenote: Cornwallis surrenders at Yorktown.]