He was absent from the field during the Battle of Bunker Hill, perhaps due to a quarrel with General Howe, a man with whom Percy could not get along. The following year, Percy commanded a division during the Battle of Long Island and led the storming of Fort Washington. By 1777, he had achieved the rank of lieutenant general, but grew so disgusted with the conduct of the war by General Howe that he resigned his command and left America in 1777 in part after a dispute over a quantity of hay. More substantively, while in command of a detached British force garrisoning Rhode Island he fell into disagreement with General Howe over the feasibility of advancing into the hostile New England hinterland.