Cruiser tank

The British cruiser tank series started in 1938 with the A9 and A10 cruiser tanks, followed by the A13, A13 Mark II, the A13 Mark III Covenanter in 1940 and the A15 Crusader which entered service in 1941. The Crusader was superseded by the A27 Cromwell in 1944. The A34 Comet, a better-armed development of Cromwell, began to enter service in late 1944. The Centurion tank of 1946 became the "Universal tank" of the United Kingdom, transcending the cruiser and infantry tank roles and becoming one of the first main battle tanks (MBT).

Background

Dissatisfaction with experimental medium tank designs of the mid-1930s led to the development of specialised fast cruiser tanks, where armour thickness was sacrificed for speed and infantry tanks, in which speed was sacrificed for heavier armour. Financial constraints had made it impossible to produce a vehicle suitable for close support and for exploitation. British armoured operations theory flowed from the decision to build two types of tank and equip two types of armoured formation. Cruisers were operated by armoured regiments of the Royal Armoured Corps, established on 4 April 1939, in armoured divisions, some regiments coming from the Royal Tank Regiment (RTR) and some from cavalry regiments converted during the war. Infantry tanks went to Army Tank Battalions, sometimes grouped administratively into Army Tank Brigades of the RTR. Small, fast, lightly armed tanks like the Light Tank Mk VI operated as reconnaissance vehicles.

Giffard Le Quesne Martel originated the cruiser concept while Assistant Director and then Deputy Director of Mechanisation at the War Office in the 1930s. Martel considered that medium tanks were too complicated and expensive for infantry support where they would be too vulnerable to anti-tank weapons and rejected claims that they could fire accurately when moving, so would gain no benefit from their speed. Martel preferred a large number of smaller and simpler tanks to swamp an opponent, instead of a few comparatively expensive medium tanks. Work should continue on a universal tank in the long term but from 1936 to 1939, Martel gave much thought to the infantry tank; he did not want medium tank development to be split but saw the logic of it, given the constraints on tank development. Tanks were necessary for mobile operations in armoured divisions and for infantry support in attacks on fortified defensive positions; a vehicle satisfactory for both tasks appeared to be impossible to attain. Two types of vehicle led to two theories and procedures, infantry tank thinking coming from the experience of tank operations from 1916 to 1918, when British tanks had been used for infantry support. Armoured division theory emphasised the speed of cruiser tanks and independent action to protect flanks, attack the opponent's flanks and rear, to counter-attack and conduct pursuit operations.

Interwar

In 1936, the War Office decided on a light tank for the cavalry, a cruiser tank, a medium tank and an infantry or assault tank. By 1938, the medium tank had stagnated as a research project, in favour of heavier cruiser and infantry tanks and after the outbreak of war, the move towards heavy infantry tanks capable of breaking through the Siegfried Line (Westwall) on the German border.

In 1934, Sir John Carden of Vickers-Armstrongs had produced a "Woolworth" medium tank to a 1934 specification (General Staff number A.9) for a close support tank, using elements of the Medium Mk III design (which had been abandoned due to financial reasons) but lighter and using a commercial engine to be cheaper. It was accepted as an interim design for limited production as the Cruiser Tank Mark I. It was expected to be replaced by a Christie suspension design. From 1937–1938, 125 A9s were built. The A9 was lightly armoured but capable of 25 mph (40 km/h) and carried a highly-effective 2-pounder anti-tank gun.

The Cruiser Mk II (A10), was designed by Carden as an infantry tank, built to the same design with added armour for 30 mm (1.2 in) of protection. It was insufficiently armoured for the role but as a "heavy cruiser", it was put into production in July 1938 as another interim design. It had the same gun as the A9, was the first to be equipped with the Besa machine gun and 175 Mk IIs were produced by September 1940. Experience with the A9 during the Battle of France in 1940 revealed shortcomings, including inadequate armour and a lack of space for the crew, but it saw useful service in France, the Western desert and Greece in 1941. Orders for the Mk I and Mk II Cruisers were limited, for an advanced and faster cruiser tank which would incorporate Christie suspension designed by J. Walter Christie and have better armour.

In 1936, General Giffard LeQuesne Martel, a pioneer in tank design who had published works on armoured warfare and pioneered the lightly armoured "tankette" concept to enhance infantry mobility, became Assistant Director of Mechanization at the War Office. Later that year, Martel had watched Soviet tanks at the Red Army's autumn manoeuvres including the BT tank, which they had developed from Christie's work. He urged the adoption of a tank that would use the suspension system and also follow the Christie practice of using a lightweight aircraft engine such as the Liberty L-12 engine or a Napier Lion. The government authorised purchase and licensing of a Christie design via the Nuffield Organization.

The tank A13 E1 was rudimentary and too small for British use but the Nuffield suspension was most effective and this became the basis of the Cruiser Mk III (A13). Following testing of two Nuffield-built prototypes (A13E2 and A13E3), the A13 was ordered into production and 65 were manufactured by mid-1939. The Mk III weighed 31,400 pounds (14.2 t), had a crew of 4, a 340 hp engine which gave a top speed of 30 mph (48 km/h) and was armed with a 2-pounder (40 mm) gun and a machine gun. When it was introduced in 1937, the army still lacked a formal tank division. The trackless element of the Christie suspension was discarded as adding little value for the extra complexity. The Cruiser Mk IV (A13 Mk II) had heavier armour than the Mk III and production started in 1938.