The two divisions could then switch roles if a repeat torpedo attack proved necessary, or alternate roles if barges were encountered, which could be dealt with by the second division's extra guns if necessary. Having learned the harsh lessons of naval combat at night after the Battle of Kolombangara, the Battle of Kula Gulf, and a previous PT boat skirmish, and having finally addressed the technical problems that had plagued their Mark 15 torpedoes since the beginning of the war, the American destroyers did not give away their position with gunfire until their torpedoes started striking their targets.