Barbettes are several types of gun emplacement in terrestrial fortifications or on naval ships. In recent naval usage, a barbette is a protective circular armour support for a heavy gun turret. This evolved from earlier forms of gun protection that eventually led to the pre-dreadnought. The name barbette ultimately comes from fortification - it originally meant a raised platform or mound, as in the French phrase en barbette, which refers to the practice of firing a cannon over a parapet rather than through an embrasure in a fortification's casemate. The former gives better angles of fire but less protection than the latter. The disappearing gun was a variation on the barbette gun; it consisted of a heavy gun on a carriage that would retract behind a parapet or into a gunpit for reloading. Barbettes were primarily used in coastal defences, but saw some use in a handful of warships, and some inland fortifications. The term is also used for certain aircraft gun mounts. Shipboard barbettes were primarily used in armoured warships - starting in the 1860s during a period of intense experimentation with other mounting systems for heavy guns at sea. In these, gun barrels usually protruded over the barbette edge, so barbettes provided only partial protection, mainly for the ammunition supply. Alternatives included the heavily-armoured gun turret and an armoured, fixed central gun battery. By the late 1880s, all three systems were replaced with a hybrid barbette-turret system that combined the benefits of both types. The armoured vertical tube that supported the new gun mount was referred to as a barbette. Guns with restricted arcs of fire mounted in heavy bombers during World War II—such those in the tail of the aircraft, as opposed to fully revolving turrets—were also sometimes referred to as having barbette mounts, though usage of the term is primarily restricted to British publications. American authors generally refer to such mounts as tail guns or as tail gun turrets. Use in fortifications The use of barbette mountings originated in ground fortifications. The term originally referred to a raised platform on a rampart for one or more guns, enabling them to be fired over a parapet. This gave rise to the phrase en barbette, which referred to a gun placed to fire over a parapet, rather than through an embrasure, an opening in a fortification wall. While an en barbette emplacement offered wider arcs of fire, it