four o'clock
The Yorktown arrived off the mouth of the Baler river , April 11 , as scheduled . Ensign Stanley went ashore , under a flag of truce , where , to his surprise , he was cordially received by the Filipino officers ; but their exceptionally good behavior and the twinkle of their eyes told only too plainly to the ensign that something was wrong . He therefore returned to the Yorktown without having accomplished anything in particular . The next morning , at four o'clock , Lieutenant Gilmore and sixteen brave associates left the Yorktown in a row boat , and entered the mouth of the river . Ensign Stanley and Quartermaster Lysac were put ashore to reconnoiter . In a few minutes daylight broke forth and those left in the boat were discovered by the Filipino sentry who was walking his beat along the shore . He gave the alarm .