began to be fitted with triple turrets. The first ship to be built with triple turrets was the Italian , although the first to be actually commissioned was the Austro-Hungarian of the . By the beginning of World War II, most battleships used triple or, occasionally, quadruple turrets, which reduced the total number of mountings and improved armour protection. However, quadruple turrets proved to be extremely complex to arrange, making them unwieldy in practice. The largest warship turrets were in World War II battleships where a heavily armoured enclosure protected the large gun crew during battle. The calibre of the main armament on large battleships was typically . The turrets carrying three 460 mm guns of each weighed around 2,500 tonnes. The secondary armament of battleships (or the primary armament of light cruisers) was typically between . Smaller ships typically mounted guns of and larger, although these rarely required a turret mounting, except for large destroyers, like the American and the German Narvik classes. Layout In naval terms, turret traditionally and specifically refers to a gun mounting where the entire mass rotates as one, and has a trunk that projects below the deck. The rotating part of a turret seen above deck is the gunhouse, which protects the mechanism and crew, and is where the guns are loaded. The gunhouse is supported on a bed of rotating rollers, and is not necessarily physically attached to the ship at the base of the rotating structure. In the case of the German battleship Bismarck, the turrets were not vertically restrained and fell out when she sank. The British battlecruiser Hood, like some American battleships, did have vertical restraints. Below the gunhouse there may be a working chamber, where ammunition is handled, and the main trunk, which accommodates the shell and propellant hoists that bring ammunition up from the magazines below. There may be a combined hoist (cf the animated British turret) or separate hoists (cf the US turret cutaway). The working chamber and trunk rotate with the gunhouse, and sit inside a protective armoured barbette. The barbette extends down to the main armoured deck (red in the animation). At the base of the turret sit handing rooms, where shell and propelling charges are passed from the shell room and magazine to the hoists. The handling equipment and hoists are complex arrangements of machinery that transport the shells and charges from the magazine