The Tank

A **tank** is a large, heavily armoured fighting vehicle with tracks and a large tank gun that is designed for front-line combat. Modern tanks are mobile land weapon platforms, mounting a large-calibre cannon in a rotating gun turret. They combine this with heavy vehicle armour which provides protection for the crew, the vehicle's weapons, and its propulsion systems, and operational mobility,
 due to its use of tracks rather than wheels, which allows the tank to
move over rugged terrain and be positioned on the battlefield in
advantageous locations. These features enable the tank to perform well
in a tactical situation: the combination of powerful weapons fire from their tank gun
 and their ability to resist enemy fire means the tank can take hold of
and control an area and prevent other enemy vehicles from advancing. In
both offensive and defensive roles, they are powerful units able to perform key primary tasks[*which?*] required of armoured units on the battlefield.[1]
 The modern tank was the result of a century of development from the
first primitive armoured vehicles, due to improvements in technology
such as the internal combustion engine,
 which allowed the rapid movement of heavy armoured vehicles. As a
result of these advances, tanks underwent tremendous shifts in
capability during the World Wars of the 20th century.

Tanks in World War I were developed separately and simultaneously by Great Britain [2] and France as a means to break the deadlock of trench warfare on the Western Front. Their first use in combat was by the British Army in September 1916 during the Battle of the Somme.
 The name "tank" was adopted by the British during the early stages of
their development, as a security measure to conceal their purpose (see etymology).
 While the French and British built thousands of tanks in WWI, Germany
was unconvinced of the tank's potential, and built only twenty.
Tanks of the interwar period evolved into the much larger and more powerful designs of World War II. Important concepts of armoured warfare were developed; the Soviet Union launched the first mass tank/air attack at Khalkhin Gol (Nomonhan) in August 1939,[3] which later resulted in the T-34, a predecessor of the main battle tank. Less than two weeks later, Germany began their large-scale armoured campaigns that would become known as blitzkrieg ("lightning war") – massed concentrations of tanks supported by motorised and mechanized infantry, artillery and air power designed to break through the enemy front and collapse enemy resistance.

The widespread introduction of high-explosive anti-tank warheads during the second half of WWII led to lightweight infantry-carried anti-tank weapons such as the Panzerfaust, which could destroy some types of tanks. Tanks in the Cold War were designed with these weapons in mind, and led to greatly improved armours during the 1960s, especially composite armour.
 Improved engines, transmissions and suspensions allowed tanks of this
period to grow larger. Aspects of gun technology changed significantly
as well, with advances in shell design and aiming technology.
During the Cold War, the main battle tank concept arose and became a key component of modern armies.[4] In the 21st century, with the increasing role of asymmetrical warfare and the end of the Cold War, that also contributed to the increase of cost-effective Russian anti-tank weapons worldwide, the importance of tanks has waned. Modern tanks seldom operate alone, as they are organized into combined arms units which involve the support of infantry, who may accompany the tanks in infantry fighting vehicles. They are also usually supported by reconnaissance or ground-attack aircraft.[5]

### Conception

Play media

Film clip of World War I-era tanks

The tank is the 20th century realization of an ancient concept: that
of providing troops with mobile protection and firepower. The internal combustion engine, armour plate, and the continuous track were key innovations leading to the invention of the modern tank.
Armoured trains appeared in the mid-19th century, and various
armoured steam- and petrol-engined vehicles were also proposed. The
first armoured car
 was produced in Austria in 1904. However, all were restricted to rails
or reasonably passable terrain. It was the development of a practical caterpillar track that provided the necessary independent, all-terrain mobility.

Model of Leonardo's proposed vehicle

Many sources imply that Leonardo da Vinci and H.G. Wells
 in some way foresaw or "invented" the tank. Leonardo's late 15th
century drawings of what some describe as a "tank" show a man-powered,
wheeled vehicle with cannons all around it. However the human crew would
 not have enough power to move it over larger distance, and usage of
animals was problematic in a space so confined.
The machines described in Wells's 1903 short story *The Land Ironclads*
 are a step closer, in being armour-plated, having an internal power
plant, and being able to cross trenches. Some aspects of the story
foresee the tactical use and impact of the tanks that later came into
being. However, Wells's vehicles were driven by steam and moved on pedrail wheels,
 technologies that were already outdated at the time of writing. After
seeing British tanks in 1916, Wells denied having "invented" them,
writing, "Yet let me state at once that I was not their prime
originator. I took up an idea, manipulated it slightly, and handed it
on."[6] It is, though, possible that one of the British tank pioneers, Ernest Swinton, was subconsciously or otherwise influenced by Wells's tale.[7][8]

The "caterpillar" track arose from attempts to improve the mobility
of wheeled vehicles by spreading their weight, reducing ground pressure,
 and increasing their adhesive friction. Experiments can be traced back
as far as the 17th century, and by the late nineteenth they existed in
various recognizable and practical forms in several countries.
It is frequently claimed that Richard Lovell Edgeworth created a
caterpillar track. It is true that in 1770 he patented a "machine, that
should carry and lay down its own road", but this was Edgeworth's choice
 of words. His own account in his autobiography is of a horse-drawn
wooden carriage on eight retractable legs, capable of lifting itself
over high walls. The description bears no similarity to a caterpillar
track.[9] The first combinations of the three principal components of the tank appeared in the decade before World War One. In 1903, a Captain Levavasseur
 of the French Artillery proposed mounting a field gun in an armoured
box on tracks. Major W.E. Donohue, of the British Army's Mechanical
Transport Committee, suggested fixing a gun and armoured shield on a
British type of track-driven vehicle.[10] In 1911, a Lieutenant Engineer in the Austrian Army, Günther Burstyn, presented to the Austrian and Prussian War Ministries plans for a light, three-man tank with a gun in a revolving turret.[11] In the same year an Australian civil engineer named Lancelot de Mole submitted a basic design for a tracked, armoured vehicle to the British War Office.[12] In Russia, Vasiliy Mendeleev designed a tracked vehicle containing a large naval gun.[13]

All of these ideas were rejected and, by 1914, forgotten, although it
 was officially acknowledged after the War that de Mole's design was at
least the equal of the tanks that were later produced by Great Britain,
and he was voted a cash payment for his contribution. Various
individuals continued to contemplate the use of tracked vehicles for
military applications, but by the outbreak of the War no one in a
position of responsibility in any army had any thoughts about tanks.[*citation needed*]

### World War I

Main article: Tanks in World War I

British World War I Mark V\* tank

**Great Britain**
From late 1914 a small number of middle-ranking British Army
 officers tried to persuade the War Office and the Government to
consider the creation of armoured vehicles. Amongst their suggestions
was the use of caterpillar tractors, but although the Army used many
such vehicles for towing heavy guns, it could not be persuaded that they
 could be adapted as armoured vehicles. The consequence was that early
tank development in Great Britain was carried out by the Royal Navy.

As the result of an approach by Royal Naval Air Service officers who had been operating armoured cars on the Western Front, the First Lord of the Admiralty, Winston Churchill[14] formed the Landships Committee, on 20 February 1915. The Director of Naval Construction for the Royal Navy, Eustace Tennyson d'Eyncourt,
 was appointed to head the Committee in view of his experience with the
engineering methods it was felt might be required; the two other members
 were naval officers, and a number of industrialists were engaged as
consultants. So many played a part in its long and complicated
development that it is not possible to name any individual as the sole
inventor of the tank.[15] However leading roles were played by Major Walter Gordon Wilson who designed the gearbox and developed practical tracks and by William Tritton whose agricultural machinery company, William Foster & Co., built the prototypes;.[16] The committee's first design, Little Willie,
 ran for the first time in September 1915 and served to develop the form
 of the track but an improved design, better able to cross trenches,
swiftly followed and in January 1916 the prototype, nicknamed "Mother",
was adopted as the design for future tanks. Production models of "Male" tanks (armed with naval cannon and machine guns) and "Females" (carrying only machine-guns) would go on to fight in history's first tank action at the Somme in September 1916.[14][17] Great Britain produced about 2,600 tanks of various types during the war.[18]
The first tank to engage in battle was designated *D1*, a British Mark I Male, during the Battle of Flers-Courcelette (part of the wider Somme offensive) on 15 September 1916.[19]

Renault FT
 tanks, here operated by the US army, pioneered the use of a fully
traversable turret and served as pattern for most modern tanks.

**France**

Whilst several experimental machines were investigated in France, it was a colonel of artillery, J.B.E. Estienne,
 who directly approached the Commander-in-Chief with detailed plans for a
 tank on caterpillar tracks, in late 1915. The result was two largely
unsatisfactory types of tank, 400 each of the Schneider and Saint-Chamond, both based on the Holt Tractor.
The following year, the French pioneered the use of a full 360° rotation turret in a tank for the first time, with the creation of the Renault FT
 light tank, with the turret containing the tank's main armament. In
addition to the traversible turret, another innovative feature of the FT
 was its engine located at the rear. This pattern, with the gun located
in a mounted turret and the engine at the back, has become the standard
for most succeeding tanks across the world even to this day.[20] The FT was the most numerous tank of the War; over 3,000 were made by late 1918.

**Germany**
Germany fielded very few tanks during World War I, and started development only after encountering British tanks on the Somme. The A7V, the only type made, was introduced in March 1918. with just 20 being produced during the war.[21] The first tank *versus* tank action took place on 24 April 1918 at the Second Battle of Villers-Bretonneux, France, when three British Mark IVs met three German A7Vs.
 Captured British Mk IVs formed the bulk of Germany's tank forces during
 World War I; about 35 were in service at any one time. Plans to expand
the tank programme were under way when the War ended.

**Other nations**

The United States Tank Corps
 used tanks supplied by France and Great Britain during World War I.
Production of American-built tanks had just begun when the War came to
an end. Italy also manufactured two Fiat 2000s
 towards the end of the war, too late to see service. Russia
independently built and trialed two prototypes early in the War; the
tracked, two-man Vezdekhod and the huge Lebedenko, but neither went into production. A tracked self-propelled gun was also designed but not produced.[22]

Although tank tactics developed rapidly during the war, piecemeal
deployments, mechanical problems, and poor mobility limited the military
 significance of the tank in World War I, and the tank did not fulfil
its promise of rendering trench warfare obsolete.
 Nonetheless, it was clear to military thinkers on both sides that tanks
 in some way could have a significant role in future conflicts.[23]

### Interwar period

Main article: Tanks of the interwar period

French Hotchkiss H-39 light tank of 1939

In the interwar period tanks underwent further mechanical development. In terms of tactics, J.F.C. Fuller's doctrine of spearhead attacks with massed tank formations was the basis for work by Heinz Guderian in Germany, Percy Hobart in Britain, Adna R. Chaffee, Jr., in the U.S., Charles de Gaulle in France, and Mikhail Tukhachevsky in the USSR. Liddell Hart
 held a more moderate view that all arms - cavalry, infantry and
artillery - should be mechanized and work together. The British formed
the all-arms Experimental Mechanized Force to test the use of tanks with supporting forces.
In the Second World War
 only Germany would initially put the theory into practice on a large
scale, and it was their superior tactics and French blunders, not
superior weapons, that made blitzkrieg so successful in May 1940.[24] For information regarding tank development in this period, see tank development between the wars.

Germany, Italy and the Soviet Union all experimented heavily with tank warfare during their clandestine and “volunteer” involvement in the Spanish Civil War, which saw some of the earliest examples of successful mechanised combined arms — such as when Republican troops, equipped with Soviet-supplied tanks and supported by aircraft, eventually routed Italian troops fighting for the Nationalists in the seven-day Battle of Guadalajara in 1937.[25] However, of the nearly 700 tanks deployed during this conflict, only about 64 tanks representing the *Franco* faction and 331 from the *Republican* side were equipped with cannon, and of those 64 nearly all were World War I vintage Renault FT tanks, while the 331 Soviet supplied machines had 45mm main guns and were of 1930s manufacture.[26] The balance of *Nationalist*
 tanks were machine gun armed. The primary lesson learned from this war
was that machine gun armed tanks had to be equipped with cannon, with
the associated armor inherent to modern tanks.

The five-month-long war between the Soviet Union and the Japanese 6th Army at *Khalkhin Gol* (Nomonhan) in 1939 brought home some lessons[*which?*]. In this conflict, the Soviets fielded over two thousand tanks, to the around 73 cannon armed tanks deployed by the Japanese,[27] the major difference being that Japanese armor were equipped with diesel engines as opposed to the Russian tanks equipped with petrol engines.[28] After General Georgy Zhukov
 inflicted a defeat on the Japanese 6th Army with his massed combined
tank and air attack, the Soviets learned a lesson on the use of gasoline engines, and quickly incorporated those newly found experiences into their new T-34 medium tank during World War II.[29]

### World War II

Main article: Tanks in World War II

Soviet T-34 tank column advancing near Leningrad, 1942

Cutaway of an M4A4 Sherman tank, the primary tank used by the United States and a number of the other western allies during the Second World War.

During World War II,
 the first conflict in which armoured vehicles were critical to
battlefield success, the tank and related tactics developed rapidly.
Armored forces proved capable of tactical victory in an unprecedentedly
short amount of time, yet new anti-tank weaponry showed that the tank was not invulnerable.
Prior to World War II, the tactics and strategy of deploying tank forces underwent a revolution. In August 1939, Soviet General Georgy Zhukov used the combined force of tanks and airpower at Nomonhan against the Japanese 6th Army;[30] Heinz Guderian,
 a tactical theoretician who was heavily involved in the formation of
the first independent German tank force, said "Where tanks are, the
front is", and this concept became a reality in World War II.[31] During the Invasion of Poland, tanks performed in a more traditional role in close cooperation with infantry units, but in the Battle of France
 deep independent armoured penetrations were executed by the Germans, a
technique later called blitzkrieg. Blitzkrieg used innovative combined arms
 tactics and radios in all of the tanks to provide a level of tactical
flexibility and power that surpassed that of the Allied armour. The French Army,
 with tanks equal or superior to the German tanks in both quality and
quantity, employed a linear defensive strategy in which the armoured
cavalry units were made subservient to infantry as "support weapons".[24] In addition, they lacked radios in many of their tanks and headquarters,[32] which limited their ability to respond to German attacks.

In accordance with blitzkrieg methods, German tanks bypassed enemy strongpoints and could radio for close air support to destroy them, or leave them to the infantry. A related development, motorized infantry, allowed some of the troops to keep up with the tanks and create highly mobile combined arms forces.[24]
 The defeat of a major military power within weeks shocked the rest of
the world, spurring tank and anti-tank weapon development.

German general Erwin Rommel in North Africa, June 1942

The North African Campaign
 also provided an important battleground for tanks, as the flat,
desolate terrain with relatively few obstacles or urban environments was
 ideal for conducting mobile armoured warfare. However, this battlefield
 also showed the importance of logistics, especially in an armoured force, as the principal warring armies, the German Afrika Korps and the British Eighth Army,
 often outpaced their supply trains in repeated attacks and
counter-attacks on each other, resulting in complete stalemate. This
situation would not be resolved until 1942, when during the Second Battle of El Alamein, the Afrika Korps, crippled by disruptions in their supply lines, had 95% of its tanks destroyed[33] and was forced to retreat by a massively reinforced Eighth Army, the first in a series of defeats that would eventually lead to the surrender of the remaining Axis forces in Tunisia.

Battle of Kursk was the largest tank battle ever fought, with each side deploying nearly 3,000 tanks.

When Germany launched its invasion of the Soviet Union, Operation *Barbarossa*, the Soviets had a superior tank design, the T-34.[34] A lack of preparations for the Axis
 surprise attack, mechanical problems, poor training of the crews and
incompetent leadership caused the Soviet machines to be surrounded and
destroyed in large numbers. However, interference from Adolf Hitler,[35]
 the geographic scale of the conflict, the dogged resistance of the
Soviet combat troops, and the Soviets' massive advantages in manpower
and production capability prevented a repeat of the Blitzkrieg of 1940.[36]
 Despite early successes against the Soviets, the Germans were forced to
 up-gun their Panzer IVs, and to design and build both the larger and
more expensive Tiger heavy tank in 1942, and the Panther medium tank the following year. In doing so, the *Wehrmacht*
 denied the infantry and other support arms the production priorities
that they needed to remain equal partners with the increasingly
sophisticated tanks, in turn violating the principle of combined arms
they had pioneered.[4]
 Soviet developments following the invasion included upgunning the T-34,
 development of self-propelled anti-tank guns such as the SU-152, and deployment of the IS-2
 in the closing stages of the war, with the T-34 being the most produced
 tank of World War II, totalling up to some 65,000 examples by May 1945.

Sherman tanks joining the U.S. Fifth Army forces in the beachhead at Anzio during the Italian Campaign, 1944

Much like the Soviets, when entering World War II six months later (December 1941), the United States' mass production capacity enabled it to rapidly construct thousands of relatively cheap M4 Sherman
 medium tanks. A compromise all round, the Sherman was reliable and
formed a large part of the Anglo-American ground forces, but in a
tank-versus-tank battle was no match for the Panther or Tiger.[37]
 Numerical and logistical superiority and the successful use of combined
 arms allowed the Allies to overrun the German forces during the Battle of Normandy. Upgunned versions with the 76 mm gun M1 and the 17 pounder
 were introduced to improve the M4's firepower, but concerns about
protection remained — despite the apparent armor deficiencies, a total
of some 42,000 Shermans were built and delivered to the Allied nations
using it during the war years, a total second only to the T-34.
Tank hulls[38] were modified to produce flame tanks, mobile rocket artillery, and combat engineering vehicles for tasks including mine-clearing and bridging. Specialised self-propelled guns, most of which could double as tank destroyers, were also both developed by the Germans — with their *Sturmgeschütz*, *Panzerjäger* and *Jagdpanzer* vehicles — and the *Samokhodnaya ustanovka* families of AFV's for the Soviets: such turretless, casemate-style tank destroyers and assault guns
 were less complex, stripped down tanks carrying heavy guns, solely
firing forward. The firepower and low cost of these vehicles made them
attractive but as manufacturing techniques improved and larger turret
rings made larger tank guns feasible, the gun turret
 was recognised as the most effective mounting for the main gun to allow
 movement in a different direction from firing, enhancing tactical
flexibility.[24]

### Cold War arms race

Main article: Tanks in the Cold War

At one time, the Soviet T-72 was the most widely deployed main battle tank across the world.[39]

During the Cold War, tension between the Warsaw Pact countries and North Atlantic Treaty Organisation (NATO) countries created an arms race
 that ensured that tank development proceeded largely as it had during
World War II. The essence of tank designs during the Cold War had been
hammered out in the closing stages of World War II. Large turrets,
capable suspension systems, greatly improved engines, sloped armour
 and large-calibre (90 mm and larger) guns were standard. Tank design
during the Cold War built on this foundation and included improvements
to fire control, gyroscopic gun stabilisation, communications (primarily radio) and crew comfort and saw the introduction of laser rangefinders and infrared night vision equipment. Armour technology progressed in an ongoing race against improvements in anti-tank weapons, especially antitank guided missiles like the TOW.

Play media

1974 news report about tank warfare on the Golan

Medium tanks of World War II, evolved into the *main battle tank*
 (MBT) of the Cold War and took over the majority of tank roles on the
battlefield. This gradual transition occurred in the 1950s and 1960s due
 to anti-tank guided missiles, sabot ammunition and high explosive anti-tank
 warheads. World War II had shown that the speed of a light tank was no
substitute for armour and firepower and medium tanks were vulnerable to
newer weapon technology, rendering them obsolete.[*citation needed*]
In a trend started in World War II, economies of scale
 led to serial production of progressively upgraded models of all major
tanks during the Cold War. For the same reason many upgraded post-World
War II tanks and their derivatives (for example, the T-55 and T-72)
 remain in active service around the world, and even an obsolete tank
may be the most formidable weapon on battlefields in many parts of the
world.[40] Among the tanks of the 1950s were the British Centurion and Soviet T-54/55 in service from 1946, and the US M48 from 1951.[41]
 These three vehicles formed the bulk of the armoured forces of NATO and
 the Warsaw Pact throughout much of the Cold War. Lessons learned from
tanks such as the Leopard 1, M48 Patton series, Chieftain, and T-72 led to the contemporary Leopard 2, M1 Abrams, Challenger 2, C1 Ariete, T-90 and Merkava IV.

Tankers drive an M1A1 Abrams tank in Germany.

Tanks and anti-tank weapons of the Cold War era saw action in a number of proxy wars like the Korean War, Vietnam War, Indo-Pakistani War of 1971, Soviet war in Afghanistan and Arab-Israeli conflicts, culminating with the Yom Kippur War. The T-55, for example, has seen action in no fewer than 32 conflicts. In these wars the USA or NATO countries and the Soviet Union or China consistently backed opposing forces. Proxy wars were studied by Western and Soviet military analysts and provided a contribution to the Cold War tank development process.

### 21st-century conflicts

Main article: Tanks of the post–Cold War era

Type 10 Japanese main battle tank

The role of tank vs. tank combat is becoming diminished. Tanks work
in concert with infantry in urban warfare by deploying them ahead of the
 platoon. When engaging enemy infantry, tanks can provide covering fire
on the battlefield. Conversely, tanks can spearhead attacks when
infantry are deployed in personnel carriers.[42]
Tanks were used to spearhead the initial US invasion of Iraq in 2003. As of 2005, there were 1,100 M1 Abrams used by the United States Army in the course of the Iraq War, and they have proven to have an unexpectedly high level of vulnerability to roadside bombs.[43] A relatively new type of remotely detonated mine, the explosively formed penetrator has been used with some success against American armoured vehicles (particularly the Bradley fighting vehicle).
 However, with upgrades to their armour in the rear, M1s have proven
invaluable in fighting insurgents in urban combat, particularly at the Battle of Fallujah, where the US Marines brought in two extra brigades.[44] Britain deployed its Challenger 2 tanks to support its operations in southern Iraq.

Israeli Merkava tanks contain features that enable them to support infantry in low intensity conflicts (LIC) and counter-terrorism operations. Such features are the rear door and rear corridor, enabling the tank to carry infantry and embark safely; the IMI APAM-MP-T multi-purpose ammunition round, advanced C4IS systems and recently: TROPHY active protection system which protects the tank from shoulder-launched anti-tank weapons. During the Second Intifada further modifications were made, designated as "Merkava Mk. 3d Baz LIC".[*citation needed*]

### Research and development

Graphic representation of the US Army's cancelled XM1202 Mounted Combat System

In terms of firepower, the focus of current R&D is on increased detection capability such as thermal imagers, automated fire control systems and increased muzzle energy from the gun to improve range, accuracy and armour penetration.[45] The most mature future gun technology is the electrothermal-chemical gun.[46] The XM291 electrothermal-chemical tank gun has gone through successful multiple firing sequences on a modified M8 Armored Gun System chassis.[47]

To improve tank protection, one field of research involves making the tank invisible to radar by adapting stealth technologies originally designed for aircraft. Improvements to camouflage or and attempts to render it invisible through active camouflage is being pursued. Research is also ongoing in electromagnetic armour systems to disperse or deflect incoming shaped charge jets,[48][49] as well as various forms of active protection systems to prevent incoming projectiles from striking the tank at all.
Mobility may be enhanced in future tanks by the use of diesel-electric or turbine-electric series hybrid drives — first used in a primitive, gasoline-engined form with Porsche's *Elefant* German tank destroyer of 1943 — improving fuel efficiency while reducing the size and weight of the power plant.[50] Furthermore, advances in gas turbine technology, including the use of advanced recuperators,[51] have allowed for reduction in engine volume and mass to less than 1 m3 and 1 metric ton, respectively, while maintaining fuel efficiency similar to that of a diesel engine.[52]

In line with the new doctrine of network-centric warfare, the modern battle tank shows increasing sophistication in its electronics and communication systems.

## Design

The three traditional factors determining a tank's capability effectiveness are its *firepower*, *protection*, and *mobility*.
 Firepower is the ability of a tank's crew to identify, engage, and
destroy enemy tanks and other targets using its large-calibre cannon.
Protection is the degree to which the tank's armor, profile and
camouflage enables the tank crew to evade detection, protect themselves
from enemy cannon fire, and retain vehicle functionality during and
after combat. Mobility includes how well the tank can be transported by
rail, sea, or air to the operational staging area; from the staging area
 by road or over terrain towards the enemy; and tactical movement by the
 tank over the battlefield during combat, including traversing of
obstacles and rough terrain.

### Offensive capabilities

Main article: Tank gun

Rifling of a 105 mm Royal Ordnance L7 tank gun (which has been cut open to show the interior of the barrel).

The main weapon of modern tanks is a single, large-calibre cannon mounted in a fully traversing gun turret. The typical modern tank gun is a smoothbore weapon capable of firing a variety of ammunition, including armor-piercing kinetic energy penetrators (KEP), also known as armour-piercing discarding sabot (APDS), and/or armour piercing fin stabilised discarding sabot (APFSDS) and high explosive anti-tank (HEAT) shells, and/or high explosive squash head (HESH) and/or anti-tank guided missiles (ATGM) to destroy armoured targets, as well as high explosive (HE) shells for engaging soft targets or fortifications. Canister shot may be used in close or urban combat situations where the risk of hitting friendly forces with shrapnel from HE rounds is unacceptably high.[44]
A gyroscope
 is used to stabilise the main gun, allowing it to be effectively aimed
and fired at the "short halt" or on the move. Modern tank guns are also
commonly fitted with insulating thermal jackets to reduce gun-barrel warping caused by uneven thermal expansion, bore evacuators to minimise fumes entering the crew compartment and sometimes muzzle brakes to minimise the effect of recoil on accuracy and rate of fire.

Traditionally, target detection relied on visual identification. This was accomplished from within the tank through telescopic periscopes;
 occasionally, however, tank commanders would open up the hatch to view
the outside surroundings, which improved situational awareness but
incurred the penalty of vulnerability to sniper fire, especially in
jungle and urban conditions. Though several developments in target
detection have taken place especially recently, these methods are still
common practice.

A Merkava Mk IIID Baz firing

In some cases spotting rifles
 were used confirm proper trajectory and range to a target. These
spotting rifles were mounted co-axially to the main gun, and fired tracer ammunition
 ballistically matched to the gun itself. The gunner would track the
movement of the tracer round in flight, and upon impact with a hard
surface, it would give off a flash and a puff of smoke, after which the
main gun was immediately fired. However these have been mostly
superseded by laser rangefinding equipment.

Modern tanks also use sophisticated light intensification and thermal imaging
 equipment to improve fighting capability at night, in poor weather and
in smoke. The accuracy of modern tank guns is pushed to the mechanical
limit by computerised fire-control systems. A fire-control system uses a laser rangefinder to determine the range to the target, a thermocouple, anemometer and wind vane
 to correct for weather effects and a muzzle referencing system to
correct for gun-barrel temperature, warping and wear. Two sightings of a
 target with the range-finder enable calculation of the target movement vector. This information is combined with the known movement of the tank and the principles of ballistics to calculate the elevation and aim point that maximises the probability of hitting the target.
Usually, tanks carry smaller calibre armament for short-range defence
 where fire from the main weapon would be ineffective, for example when
engaging infantry, light vehicles or close air support aircraft. A typical complement of secondary weapons is a general-purpose machine gun mounted coaxially with the main gun, and a heavier anti-aircraft
 machine gun on the turret roof. Some tanks also have a hull-mounted
machine gun. These weapons are often modified variants of those used by
infantry, and so utilise the same kinds of ammunition.

### Protection and countermeasures

The Russian T-90 is fitted with a "three-tiered" protection systems:
**1:** Composite armour in the turret
**2:** Third generation Kontakt-5 ERA
**3:** Shtora-1 countermeasures suite.

See also: Anti-tank warfare

The measure of a tank's protection is the combination of its ability
to avoid detection (due to having a low profile and through the use of
camouflage), to avoid being hit by enemy fire, its resistance to the
effects of enemy fire, and its capacity to sustain damage whilst still
completing its objective, or at least protecting its crew. This is done
by a variety of countermeasures, such as armour plating and reactive
defences, as well as more complex ones such as heat-emissions reduction.

In common with most unit types, tanks are subject to additional
hazards in wooded and urban combat environments which largely negate the
 advantages of the tank's long-range firepower and mobility, limit the
crew's detection capabilities and can restrict turret traverse. Despite
these disadvantages, tanks retain high survivability against previous-generation rocket-propelled grenades in all combat environments by virtue of their armour.

However, as effective and advanced as armour plating has become, tank survivability against newer-generation tandem-warhead anti-tank missiles is a concern for military planners.[53] For example, the RPG-29 from 1980s is able to penetrate the frontal hull armour of the Challenger II[54][55] and also managed to damage a M1 Abrams.[56] As well, even tanks with advanced armour plating can have their tracks damaged by RPGs, which may render them immobile.

#### Avoiding detection

Further information: Military deception

PLA's Type 99a tank with disruptive camouflage painting

A tank avoids detection using the doctrine of countermeasures known as CCD: camouflage (looks the same as the surroundings), concealment (cannot be seen) and deception (looks like something else).
Working against efforts to avoid detection is the fact that a tank is a large metallic object with a distinctive, angular silhouette that emits copious heat
 and noise. Consequently, it is difficult to effectively camouflage a
tank in the absence of some form of cover or concealment (e.g., woods)
it can hide
 its hull behind. The tank becomes easier to detect when moving
(typically, whenever it is in use) due to the large, distinctive
auditory, vibration and thermal signature of its power plant. Tank
tracks and dust clouds also betray past or present tank movement.
Switched-off tanks are vulnerable to infra-red detection due to differences between the thermal conductivity and therefore heat dissipation
 of the metallic tank and its surroundings. At close range the tank can
be detected even when powered down and fully concealed due to the column of warmer air above the tank and the smell of diesel.

Thermal blankets slow the rate of heat emission and camouflage nets
use a mix of materials with differing thermal properties to operate in
the infra-red as well as the visible spectrum. Camouflage attempts to break up the distinctive appearance and silhouette of a tank. Adopting a turret-down or hull-down position reduces the visible silhouette of a tank as well as providing the added protection of a position in defilade.
The Russian Nakidka camouflage kit was designed to reduce the Optical, Thermal, Infrared, and Radar
 signatures of a tank, so that acquisition of the tank would be
difficult. According to Nii Stali, the designers of Nakidka, Nakidka
would reduce the probabilities of detection via "visual and near-IR
bands by 30%, the thermal band by 2-3 fold, radar band by 6 fold, and
radar-thermal band to near-background levels.[57]

#### Armour

Main article: Vehicle armour

The British Challenger II is protected by second-generation Chobham armour

To effectively protect the tank and its crew, tank armour must counter a wide variety of antitank threats. Protection against kinetic energy penetrators and high explosive anti-tank (HEAT) shells fired by other tanks is of primary importance, but tank armour also aims to protect against infantry rocket-propelled grenades, anti-tank guided missiles, anti-tank mines, bombs, direct artillery hits, and (less often) nuclear, biological and chemical threats, any of which could disable or destroy a tank or its crew.
Steel armour plate was the earliest type of armour. The Germans pioneered the use of face hardened steel during World War II and the Soviets also achieved improved protection with sloped armour technology. World War II developments led to the obsolescence of homogeneous steel armour with the development of shaped-charge warheads, exemplified by the Panzerfaust and bazooka infantry weapons which were effective, despite some early success with spaced armour. Magnetic mines led to the development of anti-magnetic paste and paint.
British tank researchers took the next step with the development of Chobham armour, or more generally composite armour, incorporating ceramics and plastics in a resin matrix between steel plates, which provided good protection against HEAT weapons. High explosive squash head warheads led to anti-spall armour linings, and kinetic energy penetrators led to the inclusion of exotic materials like a matrix of depleted uranium into a composite armour configuration.

Blazer explosive reactive armour (ERA) blocks on an Israeli M-60

Reactive armour
 consists of small explosive-filled metal boxes that detonate when hit
by the metallic jet projected by an exploding HEAT warhead, causing
their metal plates to disrupt it. Tandem warheads
 defeat reactive armour by causing the armour to detonate prematurely.
Modern Reactive armour protects itself from Tandem warheads by having a
thicker front metal plate to prevent the precursor charge from
detonating the explosive in the reactive armour. Reactive armours can
also reduce the penetrative abilities of kinetic energy penetrators
 by deforming the penetrator with the metal plates on the Reactive
armour, thereby reducing its effectiveness against the main armour of
the tank.
Grenade launchers which can rapidly deploy a smoke screen that is opaque to Infrared light, to hide it from the thermal viewer of another tank. The modern Shtora countermeasure systems provides additional protection by interfering with enemy targeting and fire-control systems.

#### Active protection system

IDF Merkava Mk4 tank with Trophy APS ("מעיל רוח") during training

The latest generation of protective measures for tanks are active protection systems, particularly "hard-kill". The Soviet Drozd, the Russian Arena, the Israeli Trophy and Iron Fist, Polish ERAWA, and the American Quick Kill systems show the potential to dramatically improve protection for tanks against missiles, RPGs and potentially kinetic energy penetrator attacks, but concerns regarding a danger zone for nearby troops remain.[*citation needed*] As for 2011, only the Israeli Trophy system, installed on the Merkava
 Mk4, has been combat-proven, as it successfully intercepted
Rocket-propelled Grenades and various anti-tank missiles during
operational missions on the Gaza Strip border.[58][59]

### Mobility

Play media

Two German Army Leopard 2s demonstrate their deep-wading capabilities

The mobility of a tank is described by its battlefield or tactical
mobility, its operational mobility, and its strategic mobility. Tactical
 mobility can be broken down firstly into agility, describing the tank's
 acceleration, braking, speed and rate of turn on various terrain, and
secondly obstacle clearance: the tank's ability to travel over vertical
obstacles like low walls or trenches or through water. Operational
mobility is a function of manoeuvre range; but also of size and weight,
and the resulting limitations on options for manoeuvre.

#### Tactical mobility

M1 Abrams offloading from Landing Craft Air Cushioned vehicle.

Tank agility is a function of the weight of the tank due to its inertia while manoeuvring and its ground pressure, the power output of the installed power plant and the tank transmission and track design. In addition, rough terrain effectively limits the tank's speed through the stress it puts on the suspension
 and the crew. A breakthrough in this area was achieved during World War
 II when improved suspension systems were developed that allowed better
cross-country performance and limited firing on the move. Systems like
the earlier Christie or later torsion-bar suspension developed by Ferdinand Porsche dramatically improved the tank's cross-country performance and overall mobility.[60]

Tanks are highly mobile and able to travel over most types of terrain due to their continuous tracks and advanced suspension. The tracks disperse the weight of the vehicle over a large area, resulting in less ground pressure.
 A tank can travel at approximately 40 kilometres per hour (25 mph)
across flat terrain and up to 70 kilometres per hour (43 mph) on roads,
but due to the mechanical strain this places on the vehicle and the
logistical strain on fuel delivery and tank maintenance, these must be
considered "burst" speeds that invite mechanical failure of engine and
transmission systems. Consequently, wheeled tank transporters and rail infrastructure
 is used wherever possible for long-distance tank transport. The
limitations of long-range tank mobility can be viewed in sharp contrast
to that of wheeled armoured fighting vehicles.
 The majority of blitzkrieg operations were conducted at the pedestrian
pace of 5 kilometres per hour (3.1 mph), and that was only achieved on
the roads of France.[61]

The M1 Abrams is powered by a 1,500 shaft horsepower (1,100 kW) Honeywell AGT 1500 gas turbine engine, giving it a governed top speed of 45 mph (72 km/h) on paved roads, and 30 mph (48 km/h) cross-country.

The tank's power plant supplies kinetic energy to move the tank, and electric power via a generator to components such as the turret rotation motors
 and the tank's electronic systems. The tank power plant has evolved
from predominantly petrol and adapted large-displacement aeronautical or
 automotive engines during World Wars I and II, through diesel engines to advanced multi-fuel diesel engines, and powerful (per unit weight) but fuel-hungry gas turbines in the T-80 and M1 Abrams.

#### Strategic mobility

Strategic mobility is the ability of the tanks of an armed force to
arrive in a timely, cost effective, and synchronized fashion. For good
strategic mobility transportability by air is important, which means
that weight and volume must be kept within the designated transport
aircraft capabilities.

Nations often stockpile enough tanks to respond to any threat without
 having to make more tanks as many sophisticated designs can only be
produced at a relatively low rate. The US Military for instance keeps
6000 MBTs in storage.[62]

In the absence of combat engineers, most tanks are limited to fording
 rivers. The typical fording depth for MBTs is approximately 1 metre
(3.3 ft), being limited by the height of the engine air intake and
driver's position. Modern tanks such as the Russian T-90 and the German Leopard 1 and Leopard 2 tanks can ford to a depth of 3 to 4 metres when properly prepared and equipped with a snorkel
 to supply air for the crew and engine. Tank crews usually have a
negative reaction towards deep fording but it adds considerable scope
for surprise and tactical flexibility in water crossing operations by opening new and unexpected avenues of attack.
Amphibious tanks are specially designed or adapted for water operations, but they are rare in modern armies, being replaced by purpose-built amphibious assault vehicles or armoured personnel carriers in amphibious assaults. Advances such as the EFA mobile bridge and MT-55 scissors bridge have also reduced the impediment to tank advance that rivers posed in World War II.[63]

### Crew

*Tank commander redirects here. For other meanings see Tank commander (disambiguation).*
The tank commander's position in an AMX Leclerc

Most modern tanks most often have four crew members, or three if an auto-loader is installed. These are the:

* Commander

 - The commander is responsible for commanding the tank, most often in
conjunction with other tanks and supporting infantry. The commander is
provided with all-round vision devices rather than the limited ones of
the driver and gunner.

* Driver - The driver drives the tank, and often also serves as the tank's day-to-day mechanic.
* Gunner - The gunner is responsible for laying the gun.
* Loader - The loader loads the gun, with a round appropriate to the target. In tanks with auto-loaders this position is omitted.

A view in a M1A1 Abrams tank of the gunner's station (bottom left) and commander's station (top right)

Historically, crews have varied from just two members to a dozen. For
 example, pre–World War II French tanks were noted for having a two-man
crew, in which the overworked commander had to load and fire the gun in
addition to commanding the tank. First World War tanks were developed
with immature technologies; in addition to the crew needed to man the
multiple guns and machine guns, up to four crewmen were needed to drive
the tank: the driver, acting as the vehicle commander and manning the
brakes, drove via orders to his gears-men; a co-driver operated the
gearbox and throttle; and two gears-men, one on each track, steered by
setting one side or the other to idle, allowing the track on the other
side to slew the tank to one side.

With World War II the multi-turreted tanks proved impracticable, and
as the single turret on a low hull design became standard, crews became
standardized around a crew of four or five. In those tanks with a fifth
crew member, usually three were located in the turret (as described
above) while the fifth was most often seated in the hull next to the
driver, and operated the hull machine gun in addition to acting as a
co-driver or radio operator.

Well designed crew stations, giving proper considerations to comfort
and ergonomics, are an important factor in the combat effectiveness of a
 tank, as it limits fatigue and speeds up individual actions.

### Engineering constraints

The Indian Arjun MBT's hydropneumatic suspension at work, while moving over a bump track.

A noted author on the subject of tank design engineering, Richard M Ogorkiewicz,[64] outlined the following basic engineering sub-systems that are commonly incorporated into tank's technological development:

* Mobility of tanks (through chassis design)
* Tank engines
* Tank transmissions
* Suspensions and running gear
* Soil-vehicle mechanics
* Tank guns and ammunition
* Ballistics and mechanics of tank guns
* Vision and sighting systems
* Illuminating and night vision systems
* Fire control systems for main and auxiliary weapons
* Gun control systems
* Guided weapons
* Armour protection
* Configuration of tanks

To the above can be added unit communication systems and electronic
anti-tank countermeasures, crew ergonomic and survival systems
(including flame suppression), and provision for technological
upgrading. Few tank designs have survived their entire service lives
without some upgrading or modernisation, particularly during wartime,
including some that have changed almost beyond recognition, such as the
latest Israeli Magach versions.

The characteristics of a tank are determined by the performance
criteria required for the tank. The obstacles that must be traversed
affect the vehicles front and rear profiles. The terrain that is
expected to be traversed determines the track ground pressure that may
be allowed to be exerted for that particular terrain.[65]

Tank design is a compromise between its technological and budgetary
constraints and its tactical capability requirements. It is not possible
 to maximise firepower, protection and mobility simultaneously while
incorporating the latest technology and retain affordability for
sufficient procurement quantity to enter production. For example, in the
 case of tactical capability requirements, increasing protection by
adding armour will result in an increase in weight and therefore
decrease in mobility; increasing firepower by installing a larger gun
will force the designer team to increase armour, the therefore weight of
 the tank by retaining same internal volume to ensure crew efficiency
during combat. In the case of the Abrams MBT which has good firepower,
speed and armour, these advantages are counterbalanced by its engine's
notably high fuel consumption, which ultimately reduces its range, and
in a larger sense its mobility.
Since the Second World War, the economics of tank production governed
 by the complexity of manufacture and cost, and the impact of a given
tank design on logistics and field maintenance capabilities, have also
been accepted as important in determining how many tanks a nation can
afford to field in its force structure.

Some tank designs that were fielded in significant numbers, such as Tiger I and M60A2
 proved to be too complex or expensive to manufacture, and made
unsustainable demands on the logistics services support of the armed
forces. The *affordability of the design* therefore takes
precedence over the combat capability requirements. Nowhere was this
principle illustrated better than during the Second World War when two
Allied designs, the T-34 and the M4 Sherman,
 although both simple designs which accepted engineering compromises,
were used successfully against more sophisticated designs by Germany
that were more complex and expensive to produce, and more demanding on
overstretched logistics of the Wehrmacht. Given that a tank crew will
spend most of its time occupied with maintenance of the vehicle,
engineering simplicity has become the primary constraint on tank design
since the Second World War despite advances in mechanical, electrical
and electronics technologies.
Since the Second World War, tank development has incorporated
experimenting with significant mechanical changes to the tank design
while focusing on technological advances in the tank's many subsystems
to improve its performance. However, a number of novel designs have
appeared throughout this period with mixed success, including the Soviet
 IT-1 and T-64 in firepower, and the Israeli Merkava and Swedish S-tank in protection, while for decades the USA's M551 remained the only light tank deployable by parachute.

Further information: Tank classification

## Command, control, and communications

German Army Leopard 2A6M incorporates networked battlefield technology

Commanding and coordinating
 tanks in the field has always been subject to particular problems,
particularly in the area of communications, but in modern armies these
problems have been partially alleviated by networked, integrated systems that enable communications and contribute to enhanced situational awareness.

### Early

Armoured bulkheads,
 engine noise, intervening terrain, dust and smoke, and the need to
operate "buttoned up" are severe detriments to communication and lead to
 a sense of isolation for small tank units, individual vehicles, and
tank crewmen. Radios were not then portable or robust enough to be
mounted in a tank, although Morse code transmitters were installed in some Mark IVs at Cambrai as messaging vehicles.[66]
 Attaching a field telephone to the rear would become a practice only
during the next war. During World War I when these failed or were
unavailable, situation reports were sent back to headquarters by some
crews releasing carrier pigeons through loopholes or hatches[67] and communications between vehicles was accomplished using hand signals, handheld semaphore flags which continued in use in the Red Army/Soviet Army through the Second and Cold wars, or by foot or horse mounted messengers.[68]

### Modern

See also: Military communications and C4ISTAR

Merkava Mark 4 main battle tank is equipped with a digital C4IS battle-management system.

On the modern battlefield an intercom mounted in the crew helmet provides internal communications and a link to the radio network,
 and on some tanks an external intercom on the rear of the tank provides
 communication with co-operating infantry. Radio networks employ radio voice procedure to minimize confusion and "chatter".
A recent[*when?*] development in AFV equipment and doctrine is integration of information from the fire control system, laser rangefinder, Global Positioning System and terrain information via hardened military specification electronics and a battlefield network to display information on enemy targets and friendly units on a monitor in the tank. The sensor data can be sourced from nearby tanks, planes, UAVs or, in the future infantry (such as the US Future Force Warrior project). This improves the tank commander's situational awareness and ability to navigate
 the battlefield and select and engage targets. In addition to easing
the reporting burden by automatically logging all orders and actions,
orders are sent via the network with text and graphical overlays. This
is known as Network-centric warfare by the US, Network Enabled Capability (UK) or Digital Army Battle Management System צי"ד (Israel).

## Etymology

The word *tank* was first applied to the British "landships" in 1915, before they entered service, to keep their nature secret.

On 24 December 1915, a meeting took place of the Inter-Departmental
Conference (including representatives of the Director of Naval
Construction's Committee, the Admiralty, the Ministry of Munitions, and
the War Office). Its purpose was to discuss the progress of the plans
for what were described as "Caterpillar Machine Gun Destroyers or Land
Cruisers." In his autobiography, Albert Gerald Stern (Secretary to the Landships Committee, later head of the Mechanical Warfare Supply Department) says that at that meeting "Mr. (Thomas J.) Macnamara (M.P., and Parliamentary and Financial Secretary to the Admiralty) then suggested, for secrecy's sake, to change the title of the Landships Committee. Mr. d'Eyncourt
 agreed that it was very desirable to retain secrecy by all means, and
proposed to refer to the vessel as a "Water Carrier." In Government
offices, committees and departments are always known by their initials.
For this reason I, as Secretary, considered the proposed title totally
unsuitable.\* In our search for a synonymous term, we changed the word
"Water Carrier" to "Tank," and became the "Tank Supply" or "T.S."
Committee. That is how these weapons came to be called Tanks," and
incorrectly added, " and the name has now been adopted by all countries
in the world."[69]

(\* The initials W.C. are a British abbreviation for a water closet;
 in other words, a toilet. Unfortunately, later in the War a number of
Mk IV Tanks were fitted with grapnels to remove barbed wire. They were
designated "Wire Cutters" and had the large letters "W.C." painted on
their rear armour.)[70]

Colonel Ernest Swinton, who was secretary to the meeting, says that
he was instructed to find a non-committal word when writing his report
of the proceedings. He later discussed it with a Lt-Col W. Dally Jones,
and they chose the word 'tank.' "That night, in the draft report of the
conference, the word 'tank' was employed in its new sense for the first
time." [71] Swinton's *Notes on the Employment of Tanks*, in which he uses the word throughout, was published in January 1916.

In July 1918, *Popular Science Monthly* reported, "Because a fellow of the Royal Historical Society has unintentionally misled the British public as to the origin of the famous "tanks," Sir William Tritton,
 who designed and built them, has published the real story of their
name ... Since it was obviously inadvisable to herald "Little Willie's"
reason for existence to the world he was known as the "Instructional
Demonstration Unit." "Little Willie's" hull was called in the shop
orders a "water carrier for Mesopotamia;" no one knew that the hull was
intended to be mounted on a truck. Naturally, the water carrier began to
 be called a "tank." So the name came to be used by managers and foremen
 of the shop, until now it has a place in the army vocabulary and will
probably be so known in history for all time."[72]

D'Eyncourt's account differs from Swinton's and Tritton's: " . . .
when the future arrangements were under discussion for transporting the
first landships to France a question arose as to how, from a security
point of view, the consignment should be labelled. To justify their size
 we decided to call them 'water-carriers for Russia' - the idea being
that they should be taken for some new method of taking water to forward
 troops in the battle areas. Lt.-Col. Swinton . . . raised a humorous
objection to this, remarking that the War Office pundits would probably
contract the description to 'W.C.'s for Russia', and that we had better
forestall this by merely labelling the packages 'Tanks'. So tanks they
became, and tanks they have remained."[73]
 This appears to be an imperfect recollection. He says that the name
problem arose "when we shipped the first two vehicles to France the
following year" (August, 1916), but by that time the name "tank" had
been in use for eight months. The tanks were labelled "With Care to
Petrograd," but the belief was encouraged that they were a type of
snowplough.

In saying that the word *tank* was adopted worldwide, Stern was wrong. In France, the second country to use tanks in battle, the word *tank* or *tanque* was adopted initially, but was then, largely at the insistence of Colonel J.B.E. Estienne, rejected in favour of *char d'assaut* ("assault vehicle") or simply *char* ("vehicle"). During World War I German sources tended to refer to British tanks as *Tanks*[74][75] and to their own as *Kampfwagen*.[76] Later, tanks became referred to as "Panzer" (lit. "armour"), a shortened form of the full term "*Panzerkampfwagen*", literally "armoured fighting vehicle". In Israel, tanks are called "Shiryon", meaning "armoured", while in the Arab world, tanks are called *Dabbāba* (after a type of siege engine). In Italian, a tank is a "*carro armato*" (lit. "armed wagon"), without reference to its armour. Norway uses the term *stridsvogn* and Sweden the similar *stridsvagn* ("chariot", lit. "battle wagon"), whereas Denmark uses *kampvogn* (lit. battle wagon). Finland uses *panssarivaunu* (armoured wagon), although *tankki* is also used colloquially. The Polish name *czołg*, derived from verb *czołgać się* ("to crawl"), is used, depicting the way of machine's movement and its speed. In Hungarian the tank is called *harckocsi* (combat wagon), albeit *tank* is also common. In Japanese, the term *sensha* (戦車?, lit. "battle vehicle") is taken from Chinese and used, and this term is likewise borrowed into Korean as *jeoncha* (전차/戰車); more recent Chinese literature uses the English derived 坦克 *tǎnkè* (tank) as opposed to 戰車 *zhànchē* (battle vehicle) used in earlier days.