Washington, uncertain of General Howe's next step, spread his troops thinly along the shores of York Island and the Westchester shore, and actively sought intelligence that would yield clues to Howe's plans. He also ordered an attempt against , the flagship of General Howe's brother and commander of the Royal Navy at New York, Admiral Richard Howe. On September 7, in the first documented case of submarine warfare, Sergeant Ezra Lee, volunteered to pilot the submersible to "Eagle" and attach explosives to the ship; the submersible's drill struck an iron band it could not penetrate, and Lee was unable to attach the required explosives. Lee was able to escape, although he was forced to release his explosive payload to fend off small boats sent by the British to investigate when he surfaced to orient himself. The payload exploded harmlessly in the East River.