Tank (military)

Introduced in the First World War, a tank is a land combat vehicle that, in its basic form, can travel over a wide range of terrain because it uses tracks rather than wheels, has at least one main main high-velocity gun and one or more machine guns, and some level of armor and other protection. The design of each tank type is a balance among mobility, firepower and protection. A physically heavy tank can carry large guns and thick armor, but may be slow, and civilian bridges may not support its weight. If weight is saved in the gun, the tank may be able to support infantry but not fight other armored vehicles. A lightly armored and maneuverable version may not be able to take hits from even light antitank weapons.

"Tank" was actually a British code word for their first vehicles, intended to break the stalemate by being able to cross barbed wire and trenches, leading the way for infantry. They were first used, in force, at the First Battle of Cambrai (20 November - 3 December 1917), by the British, and, while primitive by modern standards, were so effective that the British were unprepared to exploit the massive hole they opened in the German lines.

There is little physical resemblance between a modern tank and those of the First World War, and there have been many changes in doctrine. Originally, their role was seen as infantry support, but one of the key aspects of the World War II blitzkrieg was the use of teams of tanks, vehicle-borne infantry, mobile artillery, and close air support; the role of the traditional foot-bound infantry was to seal the flanks of the holes the combined arms, tank-led force had opened in enemy lines.

During the Second World War, there was much tank development, and a number of variants proved impractical or usable only in special situations. The British used the terminology of "infantry" tanks and "cruiser" tanks; the more modern terminology would be a heavy tank in direct support of infantry and a medium tank operating in all-motorized formations. Light tanks and even lighter "tankettes" were given scouting roles, but often proved impractical because they were too vulnerable. There are armored scouting vehicles in effective use today, but one of the first things one will encounter in their builders' description is "this is not a light tank". One general principle of a viable tank is that it can fight other tanks, and, the design of many medium or, in modern terms, main battle tanks is that they are optimized for antitank roles and may not be as useful in other roles.

In recent years, with the advent of antitank guided missiles and effective tank-killer aircraft, there have been predictions that the tank will go the way of the armored knight, the heavy gun naval battleship, and other obsolete technologies. Tanks keep evolving, however, as well as variant armored vehicles that complement the true tanks.

Technical issues

Mobility, suspension, drive train

First World War tanks bore very little resemblance to modern tanks. Rather than having a body and turret on top of the treads and drive train, the treads went completely around each side. Weapons were primarily "broadside", in protrusions on the side called sponsons.

Armor

WWI tanks had armor that protected the crew against machine gun fire.

Communications-electronics

At first, there was very little communication among tank crews, and none to the outside. The tank commander would signal the driver to go left by kicking him in the left shoulder.

Gulf War

During the air campaign of the Gulf War, Coalition aircraft frequently attacked Iraqi tanks, the strongest of which was an export version of the Soviet-designed T-72 tank, but also many T-54 tanks, T-55 variants, and Chinese-manufactured Type 59 tanks. In this stage of the war, the attacks tended to be long-range fighter-bombers rather than the armed helicopters, attack aircraft such as the A-10, and attack helicopters such as the AH-64 Apache. An especially destructive technique was called "tank plinking", where F-111 aircraft dropped laser-guided bombs on the least well-armored parts of a tank, detected them by their thermal difference from the terrain, even after the engine was cooling.

In the land campaign, British Challenger tanks, French AMX-30 tanks, and U.S. M1 Abrams tanks and aging M60 Patton tanks used their main guns on enemy tanks. Western 120mm cannon rounds usually achieved catastrophic kills, where the frontal Chobham armor of the British and U.S. tanks were invulnerable to the Iraqi main guns. While the U.S. and Iraqi main gun rounds were both armor-piercing, fin-stabilized, discarding sabot rounds, the Iraqi weapons were tipped with tungsten while the U.S. equivalents were made of depleted uranium, which, much more dense than tungsten, transferred more energy to the target.