In early July, Washington suggested an attack be made at the northern part of Manhattan Island, but his officers and Rochambeau all disagreed. Washington continued to probe the New York area until August 14, when he received a letter from de Grasse stating he was headed for Virginia with 28 warships and 3,200 soldiers, but could only remain there until October 14. De Grasse encouraged Washington to move south so they could launch a joint operation. Washington abandoned his plan to take New York, and began to prepare his army for the march south to Virginia.