The ship left Danzig at 12:30 pm on 30 January 1945, accompanied by the passenger liner "Hansa", also filled with civilians and military personnel, and two torpedo boats. "Hansa" and one torpedo boat developed mechanical problems and could not continue, leaving "Wilhelm Gustloff" with one torpedo boat escort, "Löwe". The ship had four captains ("Wilhelm Gustloff"'s captain, two merchant marine captains, and the captain of the U-boat complement housed on the vessel) on board, and they disagreed on the best course of action to guard against submarine attacks. Against the advice of the military commander, Lieutenant Commander Wilhelm Zahn (a submariner who argued for a course in shallow waters close to shore and without lights), "Wilhelm Gustloff"'s captain, Friedrich Petersen, decided to head for deep water which was known to have been cleared of mines. When he was informed by a mysterious radio message of an oncoming German minesweeper convoy, Petersen decided to activate his ship's red and green navigation lights so as to avoid a collision in the dark, making "Wilhelm Gustloff" easy to spot in the night.