In July 1781, Rochambeau's army left Rhode Island and marched across Connecticut to join Washington's army on the Hudson River at Dobbs Ferry, New York. From there the combined forces marched overland to Virginia. During this time, Admiral de Grasse managed to defeat a British fleet sent from New York City to evacuate British General Charles Cornwallis at the Battle of the Chesapeake on September 5, trapping Cornwallis on the Yorktown peninsula. On September 22, Rochambeau and Washington combined forces with those of Marquis de Lafayette and began the siege of Yorktown. The siege ended with the surrender of Cornwallis on October 19, 1781.