||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (April 2010)|
A light tank is a tank variant initially designed for rapid movement, and now primarily employed in the reconnaissance role, or in support of expeditionary forces where main battle tanks cannot be made available. Early light tanks were generally armed and armored similar to an armored car, but used tracks in order to provide better cross-country mobility.
The fast light tank was a major feature of the pre-WWII buildup, where it was expected they would be used to exploit breakthroughs in enemy lines created by slower, heavier tanks. Numerous small tank designs and "tankettes" were developed during this period and known under a variety of names, including Combat Car.
The light tank has been one of the few tank variants to survive the development of the main battle tank, and has seen use in a variety of roles including support of light airborne or amphibious forces and reconnaissance. Modified IFVs are assuming these roles in many militaries due to their immediate availability, a cheaper alternative to developing and fielding a pure light tank.
World War I 
In World War I Industrial initiative also led to swift advances. The car industry, already used to vehicle mass production and having much more experience in vehicle layout, in 1916 designed the first practical light tanks, a class largely neglected by the British. It would be Renault's small tank design the FT-17, incorporating a proper climbing face for the tracks, that was the first tank to incorporate a top-mounted turret with a full rotation. In fact the FT was in many respects the first truly 'modern' tank having a layout that has been followed by almost all designs ever since: driver at the front; main armament in a fully rotating turret on top; engine at the rear. Previous models had been "box tanks", with a single crowded space combining the role of engine room, fighting compartment, ammunition stock and driver's cabin. The FT-17 would have the largest production run of any tank of the war - with over 3,700 built (most of those in 1918) it was more numerous than all British tanks combined.
The Carden Loyd tankette and its derivatives was adopted by several nations as a small tracked vehicle. In 1928, the British firm of Vickers started promoting another design by John Carden and Vivien Loyd as the "6 Ton" tank. Although rejected by the British Army, it was bought by a large number of nations in small numbers. It formed the basis of the Soviet T-26 (around 10,000 built) and the Polish 7TP tank and influenced the Italian Fiat M11/39. The British Army did not use the design as a light tank themselves but a developed version of the Carden-Loyd tankette as the starting point for a series of British light tanks intended for use in Imperial policing.
In general, French tanks of the 1930s were well-armored, innovative vehicles that owed little to foreign designs. However, the light tanks lacked firepower and almost all French tanks were handicapped by their one-man turrets, even the larger tanks such as the Char B overworked the commander who besides directing the vehicle, or even a troop, had to load and aim the turret gun. The lack of radios with the light tanks was not seen as a major drawback, since French doctrine called for slow-paced, deliberate maneuvers in close conformance to plans. The role of small unit leaders was to execute plans, not to take the initiative in combat. In 1939 a belated effort was made to improve flexibility and increase the number of radios.
Throughout the interwar period the US produced only a few hundred tanks. From the end of World War I to 1935, only 15 tanks were produced. Most were derivatives or foreign designs or very poor quality private designs. The Christie designs were among the few bright spots, but the US Army acquired only three Christies and did not pursue the idea any further. Budget limitations and the low priority given to the Army meant that there were few resources for building tanks. The US Army instead developed and tested tank components such as suspensions, tracks, and transmissions. This paid off when production had to be initiated on the outbreak of war.
World War II 
The Soviet BT tanks were the most advanced in the 1930s, extremely fast and mounting high velocity 45 mm cannons. Their only drawback were their petrol engines which caught fire often and easily during the Nomonhan fighting which lasted from about May through September 1939. The Japanese Type 95 Ha-Go light tank was equipped with a diesel engine, and although mounting a 37 mm cannon, it was a low velocity gun with only a maximum effective range of about 700 meters. However, this conflict would be instrumental in developing the famous T-34 medium tank.
Germany's armored Panzer force was not especially impressive at the start of the war. In the invasions of Poland and of France the German forces were mostly made up of the Panzer I and Panzer II light tanks. The Panzer I was little more than a training vehicle armed only with machine guns, the Panzer II with a 20 mm cannon. The Panzer division also included some Czech designed light tanks - the Panzer 35(t) and the Panzer 38(t).
On the American side, the M2 Light Tank series was the most important. These light tanks were mechanically very reliable, with good mobility. However, they had a high silhouette and only a few saw combat. The M3 Stuart series was an improvement of the M2, with better armor and a 37 mm gun. The new medium tank just entering production in 1940 was the M2A1. This was a poor design with thin armor and a high silhouette.
The M3 Stuart saw use in the North African Campaign but was relegated to reconnaissance as soon as US-built medium tanks became available. Further light tank development in the war included the M24 Chaffee.
The British withdrew their light tank designs from their armoured divisions early in the war, but used some later designs for minor amphibious operations and airborne operations. In general they used armoured cars for reconnaissance and the last of the light tank designs, the Light Tank Mk VIII "Harry Hopkins", was produced in small numbers.
The Japanese made extensive use of light tanks that were much better suited to jungle warfare than larger designs.
Cold War 
Light tanks continued to be built, but for very limited roles such as amphibious reconnaissance, support of Airborne units, and in rapid intervention forces that were not expected to face enemy tanks. The Soviet PT-76 is a specialized light tank -amphibious with sufficient firepower to engage other reconnaissance vehicles, but very lightly armored. The US fielded small numbers of the M41 Walker Bulldog with a high velocity 76mm gun, and better armor, but it suffered from range limits, and its weight was too heavy for most air transport of the day. The US M551 Sheridan had similar strengths and weaknesses, but could also be airdropped, either by parachute or LAPES.
The British FV101 Scorpion, the fire support variant of the Combat Vehicle Reconnaissance (Tracked) series of vehicles that replaced armoured cars in British service has been described as a light tank and was sold to many smaller nations.
Post Cold War 
Light tanks, such as the PT-76, continue to play a small role in tank warfare, although many are losing favor to cheaper, faster, lighter armoured cars. The light tank still fills an important niche in many armies, especially for nations with airborne divisions, or those without the resources and funding for main battle tanks. They have important advantages over heavier tanks in Southeast Asia and other nations in the Equatorial region. Their size lets them maneuver through thick rain forests, and their weight reduces the risk of getting stuck in mud. This makes the light tank the preferred choice for infantry support in Equatorial nations. Post cold war light tanks include the Stingray light tank, M8 AGS, 2S25 Sprut-SD and light tanks based on infantry fighting vehicles such as the CV90120T and ASCOD LT 105.
Modern light tank design 
Typically, the armor in contemporary light tanks is modular, sometimes up to three configurations.
The flat hull necessary for amphibious light tanks to plane across the surface of the water is not nearly as blast-resistant as the V-shape hull. It has been suggested that underbelly armor appliqué could be applied after the light tanks come ashore and before they encounter explosive devices.
Weapons suite 
Guns capable of defeating modern tanks at reasonable ranges requires a large vehicle to carry them. Gun weight is typically the product of caliber and muzzle velocity. Large caliber guns on light tanks often sacrifice muzzle velocity in interest of saving weight. These guns can make and disable close-quarter targets but lack the power and/or accuracy to effectively engage heavier vehicles at a distance. Alternately, high muzzle velocity guns often sacrifice gun caliber in interest of saving weight. These guns can hit long-distance targets but lack the explosive power to disable some tanks.
- Tactical mobility
Some light tanks such as the PT-76 are amphibious, typically being propelled in the water by hydrojets or by their tracks. Most amphibious light tanks weigh little and often utilize aluminum armor. Some light tanks require no modifications for river crossings. Crews simply raise the easily accessible cloth sides around the hull, cover the hatches, turn on the bilge pump and shift the transmission to water operations. Often a fold down trim vane is erected to stop water from flooding into the hatch. Some amphibious tanks, such as the PT-76, are able to transition from land to water with little to no preparation and fire from the main gun while afloat.
- Strategic mobility
Some light tanks, such as the M551 Sheridan Armored Reconnaissance vehicle, could be rigged for low-velocity airdrop from cargo aircraft. With this method the tank is pulled out of the aircraft by brake chutes and skids to a stop. The crew does not ride in the tank during extraction, but parachutes from another plane. Upon landing, they go to their tank, release the lines, and drive it away.
The modern light tank supplements the Main battle tank in expeditionary roles and situations where all major threats have been neutralized and excess weight in armor and armament would only hinder mobility and cost more money to operate.
See also 
- Coox, Alvin D. Nomonhan; Japan Against Russia, 1939. Two volumes, 1985. Stanford University Press. ISBN 0-8047-1160-7.
- Zaloga, Steven. Japanese Tanks 1939-45. Osprey 2007. ISBN 978-1-84603-091-8.
- Coox p. 437, 998
- Flint, Keith (2006). Airborne Armour: Tetrarch, Locust, Hamilcar and the 6th Airborne Armoured Reconnaissance Regiment 1938–1950. Helion & Company Ltd. ISBN 1-874622-37-X p13
- John Pike (2005-04-27). "M8 Armored Gun System". Globalsecurity.org. Retrieved 2010-04-11.
- JSF Not Too Hot For Carriers
- RS22947 The Marines Expeditionary Fighting Vehicle (EFV): Background and Issues for Congress
- "M551 Armored Reconnaissance/Airborne Assault Vehicle". Gary's Combat Vehicle Reference Guide. Inetres.com. Retrieved 2010-03-31.
|Wikimedia Commons has media related to: Light tanks|