on a displacement in excess of , despite the fact that this violated the established naval treaties. Nevertheless, by the time these ships entered service, the international arms control system had fallen apart and the major naval powers had invoked the "escalator clause" that allowed for ships up to displacement. General characteristics The ships of the class varied slightly in dimensions. Littorio and Vittorio Veneto were long between perpendiculars and long overall, while Roma and Impero were long overall. All four ships had a draft of and a beam of . Littorio displaced as designed and at full load. Vittorio Veneto displaced and , respectively. Romas displacement increased slightly as compared to the other ships, to and , respectively. As Impero was not completed, her final displacement is unknown. As built, the ships were fitted with bulbous bows to increase their speed, but they were found to cause serious vibration, which forced a modification to the bow. Littorio and Vittorio Veneto had a standard crew of 80 officers and 1,750 enlisted men; while serving as a flagship, the crew was increased by a command staff of between 11 and 31 additional officers. The standard crew for Roma and Impero was increased by 100 enlisted men. Aircraft facilities were located on the quarterdeck, where it was initially planned to base six La Cierva autogyros. Instead, a single catapult was fitted. The ships were equipped with three Ro.43 reconnaissance seaplanes or navalized Re.2000 fighters. The Re.2000 fighter was a wheeled aircraft and had to land on an airfield. The ships' propulsion system consisted of four Belluzzo geared steam turbines powered by eight oil-fired Yarrow boilers. The engines were rated at and a top speed of . On sea trials, both Littorio and Vittorio Veneto exceeded the design specifications for their power plant. Littorio reached and , while Vittorio Veneto made and , both at light loadings. In service, however, the ships averaged . Figures for Romas speed trials have not been recorded. The ships carried of fuel oil, which enabled a maximum range of at a cruising speed of . At , the ships' range increased slightly to . The entire machinery system accounted for about 5.6 percent of the total displacement. Armament The ships' main battery consisted of nine 381 mm L/50 Ansaldo 1934 guns in three triple turrets, two in a superfiring pair forward and one aft. These long-barrel, high-velocity