Virginia, Cornwallis complied with Clinton's orders and withdrew to Yorktown, where he constructed strong defenses and awaited evacuation. An agreement by the Spanish navy to defend the French West Indies allowed Admiral de Grasse to relocate to the Atlantic seaboard, a move Arbuthnot did not anticipate. This provided Lafayette naval support, while the failure of previous combined operations at Newport and Savannah meant their co-ordination was planned more carefully. Despite repeated urging from his subordinates, Cornwallis made no attempt to engage Lafayette before he could establish siege lines. Even worse, expecting to be withdrawn within a few days he abandoned the outer defenses, which were promptly occupied by the besiegers and hastened British defeat. On August 31, a British fleet under Thomas Graves left New York for Yorktown. After landing troops and munitions for the besiegers on August 30, de Grasse had remained in Chesapeake Bay and intercepted him on September 5; although the Battle of the Chesapeake was indecisive in terms of losses, Graves was forced to retreat, leaving Cornwallis isolated. An attempted breakout over the York River at Gloucester Point failed due to bad weather. Under heavy bombardment with dwindling supplies, Cornwallis felt his situation was hopeless and on October 16 sent emissaries to Washington to negotiate surrender; after twelve hours of negotiations, these were finalized the next day. Responsibility for defeat was the subject of fierce public debate between Cornwallis, Clinton and Germain. Despite criticism from his junior officers, Cornwallis retained the confidence of his peers and later held a series of senior government positions; Clinton ultimately took most of the blame and spent the rest of his life in obscurity. Subsequent to Yorktown, American forces were assigned to supervise the armistice between Washington and Clinton made to facilitate British departure following the January 1782 law of Parliament forbidding any further British offensive action in North America. British-American negotiations in Paris led to preliminaries signed November 1782 acknowledging US independence. The enacted Congressional war aim for British withdrawal from its North American claims to be ceded to the US was completed for the coastal cities in stages. In the South, Generals Greene and Wayne loosely invested the withdrawing British at Savanna and Charleston. There they observed the British finally taking off their regulars from Charleston December 14, 1782. Loyalist provincial militias of whites and free blacks, as well as Loyalists with their slaves were transported in a