By late September, Patriot-French forces surrounded Yorktown, trapped the British army, and prevented British reinforcements from Clinton in the North, while the French navy emerged victorious at the Battle of the Chesapeake. The final American offensive was begun with a shot fired by Washington. The siege ended with a British surrender on October 19, 1781; over 7,000 British soldiers were made prisoners of war, in the last major land battle of the American Revolutionary War. Washington negotiated the terms of surrender for two days, and the official signing ceremony took place on October 19; Cornwallis claimed illness and was absent, sending General Charles O'Hara as his proxy. As a gesture of goodwill, Washington held a dinner for the American, French, and British generals, all of whom fraternized on friendly terms and identified with one another as members of the same professional military caste.