in 1930, during the london naval conference, chief of naval operations admiral william v. pratt, successfully argued for an additional class of naval surface combatants that would not be limited in number that could be constructed. defined as a sloop, per article viii(b) of the treaty. the ships could neither exceed of displacement nor a maximum cruising speed of 20 knots and their armament was limited to up to four guns above in caliber, but not to exceed in caliber, and they could not mount torpedo tubes.