Gun turret in the context of "Leopard 2A6"

A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and battlefield mobility provided by tracks and a powerful engine; their main armament is often mounted within a turret. They are a mainstay of modern 20th and 21st century ground forces and a key part of combined arms combat.

Modern tanks are versatile mobile land weapons platforms whose main armament is a large-calibre tank gun mounted in a rotating gun turret, supplemented by machine guns or other ranged weapons such as anti-tank guided missiles or rocket launchers. They have heavy vehicle armour which provides protection for the crew, the vehicle's munition storage, fuel tank and propulsion systems. The use of tracks rather than wheels provides improved operational mobility which allows the tank to overcome rugged terrain and adverse conditions such as mud and ice/snow better than wheeled vehicles, and thus be more flexibly positioned at advantageous locations on the battlefield. These features enable the tank to perform in a variety of intense combat situations, simultaneously both offensively (with direct fire from their powerful main gun) and defensively (as fire support and defilade for friendly troops due to the near invulnerability to common infantry small arms and good resistance against heavier weapons, although anti-tank weapons used in 2022, some of them man-portable, have demonstrated the ability to destroy older generations of tanks with single shots), all while maintaining the mobility needed to exploit changing tactical situations. Fully integrating tanks into modern military forces spawned a new era of combat called armoured warfare.

A weapons platform is generally any structure, vehicle or mechanism on which a weapon can be installed (via various mounting mechanisms) for optimal stability and performance. The mounted weapons, the platform and all other associated supporting equipments together form the weapon system.

In more general use, a weapons platform could be structured around a gun, such as a gun turret on a ship, or bracing on an aircraft. For example, a jet aircraft is a weapons platform for missiles, bombs or autocannons, and the resultant weapon system is the fighter jet; a motorboat can serve as a weapons platform for automatic weapons, torpedoes and flamethrowers, resulting in weapon systems such as gunboats and fast attack crafts. Land vehicles, either wheeled, tracked or mixed, are also considered weapons platforms for grenade launchers, machine guns, recoilless guns and some missile launchers, which transform the vehicles into weapon systems such as armored cars (such as the Humvee), IFVs and technicals (improvised from civilian pickup trucks). In addition, artificial satellites have been proposed as potential space weapon platforms. These satellites could carry an arsenal of weapons, such as to threaten other countries with the possibility of an orbital nuclear strike (see Rods from God).

The M3 Lee, officially Medium Tank, M3, was an American medium tank used during World War II. The turret was produced in two different forms, one for US needs and one modified to British requirements to place the radio next to the commander. In British Commonwealth service, the tank was called by two names: tanks employing US-pattern turrets were called "Lee", named after Confederate general Robert E. Lee, while those with British-pattern turrets were known as "Grant", named after Union general Ulysses S. Grant.

Design commenced in July 1940, and the first M3s were operational in late 1941. The US Army needed a medium tank armed with a 75 mm gun and coupled with the United Kingdom's immediate demand for 3,650 medium tanks, the Lee began production by late 1940. The design was a compromise meant to produce a tank as soon as possible and serve only until replaced by the following M4 Sherman tank. The M3 was reliable, had considerable firepower, good armor, and high mobility but had serious drawbacks in its general design and shape, including a high silhouette, an archaic sponson mounting of the main gun preventing the tank from taking a hull-down position, and riveted construction.

A tank gun or tank cannon is the main armament of a tank. Modern tank guns are high-velocity, large-caliber artillery capable of firing kinetic energy penetrators, high-explosive anti-tank, and cannon-launched guided projectiles. Additional weapons, such as anti-aircraft guns, heavy machine guns and rocket launchers can also be mounted to tanks.

As the tank's primary armament, they are almost always employed in a direct fire mode to defeat a variety of ground targets at all ranges, including dug-in infantry, lightly armored vehicles, and especially other heavily armored tanks. They must provide accuracy, range, penetration, and rapid fire in a package that is as compact and lightweight as possible, to allow mounting in the cramped confines of an armored gun turret. Tank guns generally use self-contained ammunition, allowing rapid loading (or use of an autoloader). They often display a bulge in the barrel, which is a bore evacuator, or a device on the muzzle, which is a muzzle brake.

Pre-dreadnought battleships were sea-going battleships built from the mid- to late- 1880s to the early 1900s. Their designs were conceived before the appearance of HMS Dreadnought in 1906 and their classification as "pre-dreadnought" is retrospectively applied. In their day, they were simply known as "battleships" or else more rank-specific terms such as "first-class battleship" and so forth. The pre-dreadnought battleships were the pre-eminent warships of their time and replaced the ironclad battleships of the 1870s and 1880s.

In contrast to the multifarious development of ironclads in preceding decades, the 1890s saw navies worldwide start to build battleships to a common design as dozens of ships essentially followed the design of the Royal Navy's Majestic class. Built from steel, protected by compound, nickel steel or case-hardened steel armor, pre-dreadnought battleships were driven by coal-fired boilers powering compound reciprocating steam engines which turned underwater screws. These ships distinctively carried a main battery of very heavy guns upon the weather deck, in large rotating mounts either fully or partially armored over, and supported by one or more secondary batteries of lighter weapons on broadside.

A main battery is the primary weapon or group of weapons around which a warship is designed. As such, a main battery was historically a naval gun or group of guns used in volleys, as in the broadsides of cannon on a ship of the line. Later, this came to be turreted groups of similar large-caliber naval rifles. With the evolution of technology the term has come to encompass guided missiles and torpedoes as a warship's principal offensive weaponry, deployed both on surface ships and submarines.

A main battery features common parts, munition and fire control system across the weapons which it comprises.

A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position.

In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles.