strength, Greene offered Cornwallis open battle at Hillsboro, North Carolina, in March. Although he lost the Battle of Guilford Court House, Greene inflicted significant casualties on Cornwallis while retaining his own army intact. Cornwallis moved to Wilmington, North Carolina, to regroup, and then made the controversial decision to bring his army into Virginia, which he saw as the supply base for Greene's army. Joining with the army of Phillips, he maneuvered against the growing Continental presence led by Lafayette, while continuing to raid and destroy economic and military targets in the state. Eventually his decision to enter Virginia reached Clinton, who was surprised at the move. After a series of confusing and sometimes contradictory suggestions, Clinton in late July issued firm orders to Cornwallis to establish a fortified deep-water port in Virginia. Cornwallis informed Clinton that he would do so at Yorktown. Siege and victory Admiral de Grasse received the dispatches of Washington and Rochambeau in mid-July. He immediately sent dispatches north indicating that he would be sailing for the Chesapeake Bay to assist in operations there. When Washington learned of this decision, he reluctantly abandoned the idea of attacking New York. In a brilliant but risky strategic move, he marched 6,000 soldiers from New York to Virginia, leaving the New York highlands only lightly defended. Washington would in later years claim that early preparations to operate against New York were intended to deceive Clinton, but the documentary record of 1781 did not support him. Later operations, as the march got underway, did involve deliberate deception. As part of the march troops appeared to establish camps and other works on the west side of the Hudson, as if preparing for an attack on New York. By the time Clinton saw through the deception, Washington had already crossed the Delaware. De Grasse sailed north with his entire fleet (28 ships of the line), while his British counterpart, Admiral Rodney (not expecting de Grasse to take his entire fleet) sent only 15 ships in pursuit. In early September, while the French and Continental armies marched south, de Grasse and the British fleet (enlarged by the inclusion of ships from New York to 19 ships) met in the Battle of the Chesapeake. The French victory was strategically vital, for it denied the British control of the Chesapeake and set the stage for the encirclement of Cornwallis at Yorktown. Upon his arrival at Yorktown