M22 Locust

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Light Tank (Airborne) M22
Light Tank (Airborne) M22 at the Bovington Tank Museum in the UK.
Type	Airborne light tank
Place of origin	United States
Service history
Used by	United Kingdom  Egypt  Israel  Belgium
Wars	World War II 1948 Arab-Israeli War
Production history
Designer	Marmon-Herrington
Manufacturer	Marmon-Herrington
Produced	1942–1945
Number built	830 [1]
Specifications
Weight	7.4 tonnes (16,400 lb)[2]
Length	12 feet 11 inches (3.9 m)[3]
Width	7 feet 1 inch (2.2 m)[3]
Height	6 feet 1 inch (1.9 m)[3]
Crew	3 (Commander/loader, gunner, driver)
Armor	9.5 millimetres (0.37 in)–12.5 millimetres (0.49 in) [3]
Primary armament	1x 37 mm Gun M6 50 rounds [2]
Secondary armament	1 x .30-06 Browning M1919A4 machine gun 2,500 rounds [2]
Engine	Lycoming O-435T 6-cylinder radial gasoline [2] 165-horsepower (123 kW)[2]
Power/weight	25.81 hp/tonne
Suspension	Vertical volute spring suspension (VVSS)
Operational range	135 miles (217 km)[4]
Speed	40 miles per hour (64 km/h)[4]

The Light Tank (Airborne) M22 or Locust was an American designed airmobile light tank which was produced during World War II. The Locust began development in 1941 after a request was made by the British War Office to the American government that it develop a purpose-built airborne light tank, which could be transported by glider into battle to support British airborne forces. The Tetrarch light tank had been selected as the tank to be utilized by the airborne forces, but it had not been designed with this purpose in mind. As such, the War Office believed that a purpose-built airborne light tank was required to eventually replace the Tetrarch. This request was passed onto the United States Ordnance Department, who selected Marmon-Herrington to design and build a prototype airborne tank in May 1941. The prototype was designated the Light Tank T9 (Airborne), and was designed to be transported by being carried underneath a Douglas C-54 Skymaster transport aircraft, although its dimensions also allowed it to fit inside a General Aircraft Hamilcar glider.

The T9 went into production in April 1943 after a series of modifications were made to the initial prototype, but production was significantly delayed when a number of faults were found with the design of the tank. Marmon-Herrington only began to produce significant numbers of the T9 by late 1943 and early 1944, by which time the design was considered to be obsolete; only 830 were built by the time production ended in February 1945. As a result, the Ordnance Department gave the tank the specification number M22 but no combat units were equipped with it. However, the War Office considered that the tank would perform adequately despite its faults, leading to the tank being given the title of 'Locust' and 260 being shipped to Great Britain under the Lend-Lease Act. A small number of Locusts were received by the 6th Airborne Armoured Reconnaissance Regiment in late 1943, but mechanical problems led to the tanks being withdrawn in favour of the Tetrarchs the regiment had previously used.

In October 1944, however, the remaining Tetrarchs of the regiment were replaced by Locusts, and eight of the tanks were used during Operation Varsity in March 1945. The tanks did not perform well in action; several were damaged during the landing process and one was knocked out by a German self-propelled gun. Only two Locusts were able to reach their planned rendezvous point and go into action, occupying a piece of high ground along with an infantry company; the tanks were forced to withdraw from the position after a few hours, however, as they attracted artillery fire that caused the infantry company significant casualties. The Locust never saw active service with the British Army again, and was classified as obsolete in 1946. A number of Locusts were used by foreign militaries in the post-war period, however; the Belgian Army used Locusts as command tanks for their M4 Sherman tank regiments, and the Egyptian Army used a number of the tanks during the 1948 Arab-Israeli War.

Contents 1 Development history 1.1 Background 1.2 Development 1.3 Faults 2 Operational history 2.1 World War II 2.2 Post-war 3 Footnotes 4 References 5 External links

[edit] Development history

[edit] Background

The Light Tank (Airborne) M22, also known as the Locust, began development in late 1941 in response to a request by the British military in early 1941 for an airmobile light tank which could be transported onto a battlefield by a glider.^[5] At the time the request was made, the War Office was considering the equipment to be used by Britain's fledgling airborne forces, which had been formed in June 1940 under the orders of the Prime Minister, Winston Churchill.^[6] When the equipment that would be required for a British airborne division had been examined, it had been decided by officials at the War Office that gliders would be an integral component of such a force; these would be used to transport glider-borne troops and heavy equipment, which by 1941 was to include artillery and some form of tank.^[7] Plans to transport an airborne tank went through a number of revisions, but by May 1941 it was considered feasible for a tank weighing 5.5 tons could be carried for 300 miles (480 km) to 350 miles (560 km) in a glider, although it would have to be specifically designed for the task. In a conference held on 16 January 1941, it was decided that the General Aircraft Hamilcar, currently under development, would be used to transport a single tank, or two Universal Carriers.^[8][9]

The War Office chose the Tetrarch light tank, produced by Vickers-Armstrong, as a decision had recently been made that light tanks were no longer to be used in the British Army; light tanks as a whole had performed poorly during the Battle of France and were considered to be a liability due to their thin armour and inadequate armaments.^[10] However, although the Tetrarch provided a short-term solution to provide armoured support to British airborne units, it had not been designed specifically as an airborne tank or to be airmobile, and it also possessed a number of faults. Its size limited the possible crew to three—a driver in the hull and a gunner and commander in the turret—which was found to be too few crew members to effectively operate the Tetrarch effectively.. The gunner or commander, in addition to their own duties, had to act as loader for the 2-pounder, which caused delays in combat; a report on the tank written in January 1941 stated that since the commander had to both fight and control the tank, controlling a troop of Tetrarchs during combat would be almost impossible.^[11] The War Office also considered that the tank had a faulty cooling system that made the Tetrarch unsuitable for service in hotter climates, such as the Middle East and North Africa.^[12]

A purpose-built airborne light tank was therefore required to replace the Tetrarch, but the decision was taken by the War Office not to produce the tank in Britain due to a lack of production capacity; instead the American government was approached with a request that it produce a replacement for the Tetrarch.^[2] This request was made by the British Air Commission in Washington, D.C., with a proposal calling for a tank of between 9 metric tons (8.9 long tons) and 10 metric tons (9.8 long tons) to be developed, this being the maximum weight the War Office had decided could be carried by current glider technology. The proposed tank was to have a primary armament of a 37-millimetre (1.5 in) main gun and secondary armament of a .30-06 Browning M1919A4, and a crew of three. The specification also called for a maximum speed of 40 miles per hour (64 km/h) and an operational radius of 200 miles (320 km). The turret and front of the hull were to have an armour thickness of between 40 millimetres (1.6 in) and 50 millimetres (2.0 in), and the sides of the tank a thickness of 30 millimetres (1.2 in).^[13] The United States Ordnance Department was given the task of developing the proposed tank, and in turn requested designs from three American companies: General Motors, J. Walter Christie and Marmon-Herrington.^[4] At a conference in May 1941, the Department chose the Marmon-Herrington design and requested that the company produce a prototype tank, which was completed in late 1941; it was designated the Light Tank T9 (Airborne) by the company and the Ordnance Department.^[2]

[edit] Development

The T9 had a crew of three and weighed 6.7 metric tons (7.4 short tons). It was armed with a 37-millimetre (1.5 in) main gun and a coaxial .30-06 Browning M1919A4 machine-gun, as well as two further machine-guns on the right-hand side of the bow. The main gun and coaxial machine-gun were mounted in a powered turret, which also had a gyro stabilizer installed to allow the gun to be fired when the tank was moving.^[2] The T9 was powered by a 162 horse-power six-cylinder, air-cooled Lycoming engine, and the thickness of the armour varied; the front, rear and sides of the hull had a thickness of 12.5 millimetres (0.49 in) whilst the sloped portions of the hull had a thickness of 9.5 millimetres (0.37 in).^[2] The engine in the T9 was able to give the tank a maximum speed of 40 miles per hour (64 km/h), as originally requested by the War Office.^[4] The T9 was not primarily designed to be transported by glider, a significant change from the original request, but instead was to be carried under the belly of a Douglas C-54 Skymaster transport aircraft, using four lifting brackets welded onto each side of the hull of the tank. The turret was designed to be removable so that it could be detached and transported inside the C-54 and reattached once on the battlefield. However, the T9 was of the correct shape, weight and size to be carried inside a Hamilcar glider, suggesting that these dimensions had been chosen deliberately so that the tank could be transported inside a glider if required.^[4][14]

A number of changes were made to the prototype during testing, primarily the addition of supporting steel beams to improve and strengthen the suspension of the tank, which increased the weight to 7.05 metric tons (7.77 short tons), which was the maximum weight that could be carried by a Hamilcar glider.^[1] Two new prototypes were ordered by the Ordnance Department in January 1942 and were delivered by Marmon-Herrington in November 1942, both designated the T9E1. The new tanks incorporated a number of requested changes. The turret was altered in shape and lightened with the power traverse mechanism being removed, as was the gyro stabilizer for the main armament.^[3] The front of the hull was altered from a stepped appearance to a more sloped shape which would provide for a better ballistic shape, and the two .30-06 machine-guns were removed from the bow of the tank, and the suspension was altered to try and reduce the weight of the design.^[1] However, contrary to normal practice, the Ordnance Department had placed an order for the original T9 design in April 1942, before the T9E1 models were delivered in November 1942; 500 were ordered in April, with this order rapidly increased to a total of 1900, with deliveries to begin in November. However, production difficulties and design changes caused this date to be delayed several times, and it was not until April 1943 that production on the T9 actually began.^[1] Production of the T9 peaked at 100 tanks being produced per month between August 1943 and January 1944; however, this number rapidly declined when the results of the British and American testing programmes were reported to the Ordnance Department, and only 830 T9s were ever produced.^[15] The faults discovered with the design led to the Ordnance Department giving it the specification number M22, but classing it as 'limited standard'. No American combat units were equipped with the tank, although some of those produced were used for training purposes.^[3] However, the British still required the M22 as a replacement for the Tetrarch, and the first prototype Locust was shipped to Britain in May 1942 for testing, followed by the second prototype T9E1 in July 1943.^[16] Although of the opinion that the M22 possessed a number of faults, the War Office believed it would perform adequately as an airborne tank, resulting in the tank receiving the official title of "Locust" and 260 being shipped to Britain under the Lend-Lease Act.^[3] The majority of the Locusts ended up being placed in tank parks until they were scrapped at the end of the conflict, and only eight of the models ever saw action with British airborne forces.^[17]

[edit] Faults

Extensive testing of the M22 began in 1943 and 1944, and was conducted by both the United States Ordnance Department and the British Armoured Fighting Vehicle School at Lulworth. These tests uncovered a number of faults and problems with the Locust.^[15] The AFV School noted that the process of loading the M22 into a C-54 transport aircraft took considerable time and involved the use of complex equipment, with the process taking six untrained men twenty-four minutes, although it was believed this could be shortened with sufficient training.^[15] Unloading was also a long process, taking approximately ten minutes; it was noted that the time it took to unload the M22 from a C-54 on the battlefield meant that both the tank and aircraft would make excellent targets for enemy fire whilst the tank was being unloaded.^[18] Operational use of the tank would therefore be restricted to the availability of airfields large enough to accommodate a fully-laden C-54, which might not be in the right geographical location or might even have to be captured in advance of a planned airborne operation.^[18] By 1944, it was also realized that the design of the tank was actually obsolete. The armour of the M22 in several areas was found to be so thin that it was incapable of resisting even the armour-piercing ammunition of a .50 caliber machine-gun, and the main armament was not powerful enough to penetrate the armour of most tanks used by the Axis powers.^[15][4] There were also mechanical problems with the design, which was proving to be unreliable in that area; the engine was also found to be underpowered, possibly due to problems with the torque characteristics of the engine or an inefficient transmission system.^[15] Complaints were also made about the main armament of the Locust. A report made on 13 March 1944 by elements of the 6th Airborne Armoured Reconnaissance Regiment complained that the 37mm gun was underpowered; when a high-explosive shell had been fired from a Locust, the resulting shell-burst was so weak that observers had difficulty in seeing where it had impacted.^[19]

[edit] Operational history

[edit] World War II

By 1942 specifically-trained airborne units had been raised to conduct airborne operations, the largest being the 1st Airborne Division, and on 19 January 1942 the War Office took the decision that a light tank unit would be amongst the support units attached to the division. This unit, designated the Light Tank Squadron, was to be formed of nineteen light tanks and would operate to the fore of the division, with the tanks using their speed to capture objectives and then hold them until relieved by other units.^[20] The unit chosen for conversion into the Light Tank Squadron was 'C' Special Services Squadron, which had seen service as an independent tank unit during Operation Ironclad, the invasion of Madagascar in mid-1942; the squadron was also equipped with Tetrarchs, which had recently been re-designated as an airborne tank by the War Office. 'C' Squadron was officially transferred to the 1st Airborne Division on 24 June 1942, bringing with it seven Tetrarchs amongst the other vehicles it was equipped with.^[21] The unit immediately began training, but did not stay attached to the 1st Airborne Division for very long; during mid-1943, the division was transported to the Middle East, where it would eventually participate in Operation Husky, the Allied invasion of the island of Sicily. 'C' Squadron remained in Britain, however, as not enough Hamilcar gliders had been built to transport and then deploy the Tetrarchs belonging to the squadron by the time the division left for the Middle East.^[22]

The squadron was then transferred to the 6th Airborne Division, which had been raised in April 1943, and was the division that 'C' Squadron would remain with for the rest of the conflict. After it had been transferred, the squadron continued to train as an air-portable unit, and from 1943 onwards participated in a number of exercises intended to familiarize it with the duties it would perform, including reconnaissance of enemy positions and performing counter-attacks against enemy infantry and armour.^[23] On 25 October, the squadron received a shipment of seventeen Locusts, and during November the new tanks were issued to the squadron, replacing a majority of the Tetrarchs; however a small number of Tetrarchs fitted with a 76.2-millimetre (3.00 in) infantry support howitzer, which were designated as Tetrarch 1 CS (Close Support), were retained.^[24] Several of the Locusts were fitted with Littlejohn adaptors to increase the range and penetration power of its main armament, although it is not clear how many were fitted with the adaptor or if the Locusts were fitted with the adaptors when they were manufactured or after they reached the squadron.^[24] The squadron was expanded into the 6th Airborne Armoured Reconnaissance Regiment in December 1943, and as late as March 1944, plans were made for the regiment to be equipped with seventeen Locusts and three Tetrarchs when it took part in Operation Tonga, the British airborne landings in Normandy. However, records indicate that by April the Hamilcar gliders of the regiment were being refitted to only carry Tetrarchs, and by late March the Locusts appear to have been completely replaced in favour of Tetrarchs. The reason behind this replacement appears to have been mechanical and gunnery problems with the Locusts, as well as specific problems with the design of the gearbox in the Locust.^[24]

The regiment took part in Operation Tonga as part of 6th Airlanding Brigade in June 1944, equipped with twenty Tetrarchs.^[25] However, the tanks performed poorly during the operation due to their thin armour and underpowered armament, proving to be completely outclassed by the tanks and self-propelled guns being deployed by German forces, such as the Panzer IV and the Sturmgeschütz III.^[26] By August, in preparation for the 6th Airborne Division to participate in the planned breakout from the Normandy bridgehead, the majority of Tetrarchs in 'A' Squadron were replaced with Cromwell fast cruiser tanks; only three Tetrarchs were retained, remaining with the Headquarters troop of 'A' Squadron.^[27] During the first week of October 1944, the 6th Airborne Armoured Reconnaissance Regiment underwent an extensive reorganization, which completely restructured the regiment and retired all the remaining Tetrarch tanks it was equipped with, replacing them with Locusts.^[28] In March 1945, the 6th Airborne Division was informed that it would be participating in Operation Varsity, an airborne operation in support of 21st Army Group crossing the River Rhine during Operation Plunder. The division, in conjunction with the American 17th Airborne Division, would be dropped by parachute and glider near the city of Wesel, where it would capture the strategically important village of Hamminkeln, several important bridges over the River Ijssel and the southern portion of a major forest, the Diersfordter Wald.^[29] Six Locusts from the regiment, divided into two troops of three, would land with the 6th Airlanding Brigade in landing-zone 'P' east of the Diersfordter Wald and west of Hamminkeln, acting as a divisional reserve; the rest of the regiment would arrive by road after crossing the Rhine with 21st Army Group.^[30]

The eight Locusts were loaded into eight Hamilcar gliders between 17–20 March, and on the morning of 24 March the gliders were towed from the airfield by eight Handley Page Halifax heavy bombers to join the rest of the gliders and transport aircraft carrying the two airborne divisions. Weather conditions for the operation were excellent, with clear visibility, and all eight gliders arrived in the vicinity of the landing zone without incident; during their attempts to land, however, the small force was severely depleted. One glider broke away from the Halifax towing it and disintegrated, apparently as a result of structural failure, with the Locust inside it falling to the ground.^[31] Three more gliders came under heavy German anti-aircraft fire and crashed as they landed; one tank survived with a damaged machine gun, another crashed through a house which put its wireless radio set and main armament out of action, and the third broke loose of the glider as it landed and was flipped over onto its turret, rendering it useless.^[32] Six Locusts landed intact on the landing zone, including several with significant damage, but two of these tanks would never reach the rendezvous point chosen for the regiment. One undamaged tank came to the aid of a group of American paratroopers who were under fire from a German self-propelled gun but was rapidly knocked out by the German vehicle, wounding two crewmembers. A second tank broke down as it attempted to tow a jeep out of a crashed glider, immobilizing it, although the crew remained with the tank and supported British airborne troops in the area.^[33] Of the four Locusts that reached the rendezvous point, only two were undamaged and fully fit for action; these two were immediately deployed to the high ground east of the Diersfordter Wald, being covered by the two damaged tanks. The two tanks were soon engaged by German troops and had to be supported by an infantry company, but were forced to withdraw from the high ground after several hours because they were attracting a great deal of artillery and anti-tank fire; although neither of the tanks were hit, a number of infantrymen were killed or wounded by the German fire. The four tanks and remaining infantry formed a small force that repelled several German attempts to attack their position, and were eventually relieved at 10:30 by a tank squadron from the 44th Royal Tank Regiment and elements of the rest of the 6th Airborne Armoured Reconnaissance Regiment.^[34]

[edit] Post-war

Operation Varsity was the only time that the Locust would see action with the 6th Airborne Armoured Reconnaissance Regiment or the British Army as a whole.^[35] A report issued at the end of a conference held by the Director (Air) of the War Office in January 1946 confirmed that the Locust design was considered to be obsolete, and any light tanks to be used in post-war airborne formations would be completely new designs.^[36] It appears that a small number of Locusts were disposed of by the British Army by transferring them to foreign militaries. Several had their main armaments removed and were used by the Belgian Army as command tanks for their M4 Sherman regiments, and a few Locusts even found their way to the United States of America, where they had their turrets removed and served as agricultural tractors.^[37] A larger number of Locusts served with the Egyptian Army, replacing a number of older tank models, such as the Vickers-Armstrong Mk V light tank, that the Egyptian military had acquired during the interwar period.^[38] Several company-sized units of Locusts were used by the Egyptians during the 1948 Arab-Israeli War.^[39]

[edit] Footnotes

[edit] References

[edit] External links

Wikimedia Commons has media related to: M22 Locust

• AFV database
• WWII vehicles
• OnWar
• Armor penetration table of US 37 mm guns
• M22 Locust Restoration Project

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