A tank gun is the main armament of a tank. Modern tank guns are high-velocity, large-caliber artilleries capable of firing kinetic energy penetrators, high-explosive anti-tank, and cannon-launched guided projectiles. Anti-aircraft guns 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. History World War I The first tanks were used to break through trench defences in support of infantry actions particularly machine gun positions during the First World War and they were fitted with machine guns or high explosive firing guns of modest calibre. These were naval or field artillery pieces stripped from their carriages and mounted in sponsons or casemates on armored vehicles. The early British Mark I tanks of 1916 used two naval 57 mm QF 6 pounder Hotchkiss mounted either side in sponsons. These guns proved too long for use in the British tank designs as they would come into contact with obstacles and the ground on uneven terrain, and the succeeding Mark IV tank of 1917 was equipped with the shortened 6 pounder 6 cwt version which can be considered the first specialised tank gun. The first German tank, the A7V, used British-made 57 mm Maxim-Nordenfelt fortification guns captured from Belgium and Russia, mounted singly at the front. The early French Schneider CA1 mounted a short 75 mm gun in a sponson on the right hand side, while the Saint-Chamond mounted a standard 75 mm field gun in the nose. The thin armour of the tanks meant that such weapons were effective against other vehicles, though the Germans fielded few tanks anyway and the Allied tanks concentrated on anti-infantry and infantry support activities. World War II This thinking remained pervasive into the dawn of World War II, when most tank guns were still modifications of existing artillery pieces, and were expected to primarily