Mk VII Tetrarch (A17)

The Tetrarch was first developed in 1937 by Vickers-Armstrongs as a private venture to be sold to either the British Army or foreign militaries. It was the latest of the series of light tank produced and was designed to overcome the shortcomings of the earlier versions, particularly the insufficient armaments on the earlier tanks. Thus a 2-pounder 40mm main gun with a 9.92mm Besa machine-gun were mounted in a two man turret. The first light tank was nicknamed the Purdah and put through a series of trials by the War Office, being tested a possible light cruiser as the light tank needs were already met by its predecessor the Mk. VI. The tank was not accepted as a light cruiser, with the the Nuffield produced A13 being accepted due to better speed and obstacle crossing performance. However, it was decided that is was essential for some Tetrarchs to be produced, thus they were brought in at the end of the light tank program. It was given specification number A17 and was accepted for production in November 1938. Some minor changes were requested such a the fitting of an external fuel tank to increase the tanks range. Originally 70 of the tank were to be produce, but this was increased to 120 after a 3-day conference in November.Production began in 1940 and the order was temporarily returned to the original 70 before being changed to 100, and later to 220. However, due to a number of reasons, thus only a total of between 100 to 177 were made. The last batch of tanks were built and delivered by the end of 1942. By 1941, however, then the War Office and Army concluded that the light tanks were a liability and vulnerable for use in further combat. Those destined to be deployed to for the North African Campaign were left in Britain as their cooling systems were determined unable to cope with the heat. The complete removal of the Tetrarch was prevented when the War Office decided in mid-1941 were it was considered equipment to be used by Britain’s fledgling airborne forces. The General Aircraft Hamilcar (which was still under development) were to carry either a single Tetrarch tank, or 2 Universal Carriers. As the Tetrarch was already an obsolete design, it was chosen as it would be immediately available for use by airborne forces. Although successful, the limited number of tanks available for use caused problems with deployment. 20 were already sent to the USSR under the Lend-Lease Act and some were lost during Operation Ironclad (the invasion of Madagascar). Only about 50 were available for use in December 1942. Thus, as about 287 tanks were needed total for the Airborne Divisions, the Tetrarch was eventually replaced by the US made M22 Locust.
It first saw action in 1942 during the campaign in Madagascar. Later, it became the first airborne tank, the Hamilcar glider being specifically designed to carry it. A few Tetrarchs were carried at the Normandy landings and across the Rhine, but saw only limited action.
However with the development of Airborne Forces, the vehicle proved ideal for deployment by Hamilcar gliders and production of 177 vehicles commenced in 1941. These formed part of the 6th Airborne Division efforts during the Normandy Landings and others were sent to Russian Forces, which proved unpopular.

The unarmed P.R. prototipe as completed in may 1938. The turret shape differs from the production version.

The original prototype Mk VII Purdah A17E1 (WD NT5757), carrying an angular turret with Vickers machine gun and 40mm gun (not the British 2-pdr but a Vickers-Armstrongs semi-automatic weapon of slightly inferior performance).

The same hull from the same angle but now fitted with wooden representations of the approved War Offce armament; the Ordnance Quick Firing Two-Pounder (40mm) and a co-axial 7.92mm Besa air-cooled machine gun.

Light tank Mk VII Tetrarch.

A floating variant of the Tetrarch was made. Called the Tetrarch Duplex Drive (DD), it used the Duplex Drive system which allowed a tank to ‘swim’ through water and participate in amphibious operations. It functions by erecting a large waterproof canvas screen around the tank above its tracks, giving the tank the ability to float. The tank would then be propelled along by a small propeller powered by the tank’s engine and a small explosive charge would be used to collapse the screen when it reached land. It was used on the Tetrarch as it was the lightest tank at the time. Successful tests in lakes and reservoirs allowed for the system to be tested on heavier tanks, ultimately being used on M4 Sherman medium tanks during Operation Overlord.

A Tetrarch fitted with the Duplex Drive System.

Photo of a Tetrarch DD Light tank with screen lowered, and showing details of the Duplex drive

The General Aircraft Limited GAL. 49 Hamilcar Mark I was a large British military glider produced during the Second World War, which was designed to carry heavy cargo, such as the Tetrarch light tank.

Loading a Tetrarch tank into a General Aircraft Hamilcar gliderWhen the Tetrarch switched to an airborne tank, a few changes were made. Firstly, some had their guns replaced by a 76.2mm infantry support howitzer and re-designated the Tetrarch I CS (Close Support). Those which still had their 2-pounder guns were fitted with Littlejohn adapters to increase muzzle velocity and armour penetration.

Light tank Mk VII Tetrarch Mk I CS (Close Support) fitted with a 3 in. howitzer.

Light tank Mk VII Tetrarch Mk I with a Littlejohn adapter fitted to the end of its barrel.