In the summer of 1781, during the seventh year of the Revolutionary War, the allied American and French armies of Generals Washington and Rochambeau were encamped at Dobbs Ferry, Ardsley, Hartsdale, Edgemont and White Plains. Washington chose lower Westchester for encampment because of its proximity to the British forces which controlled Manhattan, and which Washington intended to attack.On August 14 Washington and Rochambeau received a communication from French Admiral de Grasse, who suggested a joint sea and land campaign against General Cornwallis's British troops in Virginia. Washington risked all on this march. Its success depended on precise timing and coordination of multiple naval and land movements including those of Generals Washington, Rochambeau and Lafayette, and of French Admirals de Grasse and Barras. Success also required the utmost secrecy, and an elaborate deception was prepared by Washington in order to convince the British that Manhattan remained the target of the allied armies. Two months later, at Yorktown, Virginia, Cornwallis surrendered his entire army to the American and French forces.