The cruiser tank (sometimes called cavalry tank or fast tank) was a British tank concept of the interwar period for tanks designed as modernised armoured and mechanised cavalry, as distinguished from infantry tanks. Cruiser tanks were developed after medium tank designs of the 1930s failed to satisfy the Royal Armoured Corps. The cruiser tank concept was conceived by Giffard Le Quesne Martel, who preferred many small light tanks to swarm an opponent, instead of a few expensive and unsatisfactory medium tanks. "Light" cruiser tanks (for example the Cruiser Mk I) carried less armour and were correspondingly faster, whilst "heavy" cruiser tanks (such as the Cruiser Mk II) had more armour and were slightly slower. 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 The Crusader was superseded by the A27 Cromwell in 1944.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. The thinking was behind several tank designs which saw action during the Second World War. British armoured operations theory flowed from the decision to build two types of tank and equip two types of unit and 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