Cruiser Mk I / A9

The Tank, Cruiser, Mk I (A9) was a British cruiser tank of the interwar period. It was the first cruiser tank: a fast tank designed to bypass the main enemy lines and engage the enemy's lines of communication, along with enemy tanks. The Cruiser Mk II was a heavier armoured adaptation of the Mark I, developed at much the same time.

In 1936, the British War Office designated two different kinds of tanks for future development: heavily armoured infantry tanks to be used in close co-operation with infantry during attacks, and fast mobile cruiser tanks designed to make forays deep into enemy territory.

In 1934, Sir John Carden of Vickers-Armstrong was asked to provide a "reasonably cheap tank" as a replacement for some of the medium models then in use. The pilot model of his design was finished in 1936 and given the designation A9E1.

It incorporated the best features of the earlier Mk III Light Tank, and was powered by a commercial petrol engine. However, this was still in the time of the Great depression and the tank had a number of cost-cutting measures applied. It was the first British tank to have a centrally located turret and to have powered traverse. 

The system was by Nash & Thompson and similar to that being introduced on the Vickers Wellington bomber aircraft. The armour was light, with a maximum of 14 mm thickness. Many armour faces were vertical, and there were numerous shot traps, but it could achieve 25 mph and carried the new high velocity QF 2-pounder (40 mm) gun.

The driver's compartment and the fighting compartments were not separated. As well as the turret armament, which consisted of a Ordnance QF 2 pounder gun and a coaxial Vickers machine gun, there were two small turrets either side of the driver's compartment, each with a Vickers machine-gun. Both these smaller turrets were permanently manned, which gave the tank a total crew of 6 (Commander, gunner, loader, driver and two machine-gunners).

The A9E1 was tested against other designs and -although lacking in some areas - it was accepted in 1937 as an interim design until a Christie suspension cruiser tank could be delivered. An order was placed for 125. 

Seventy-five were built by Harland and Wolff, and the other 50 were built by Vickers. 
Originally, a Rolls-Royce car engine was used, but this proved underpowered and was replaced by an AEC bus engine.

The later Valentine Infantry tank essentially used the same lower hull and suspension, though with considerably more armour.

The A9 weighed 12 tons, was 5.8 metres long, 2.65 metres high, 2.5 metres wide, and had a top speed of 25 mph on road and 15 mph off. Its maximum road range was 150 miles. The ammunition load was 100 2-pounder rounds and a total of 3,000 rounds for the three Vickers machine guns.

The Mark I cruiser began to be delivered in January 1939.

The Cruiser was an effective tank in the French, Greek and early North African campaigns. The 2 pdr gun was lethal against the early Italian tanks encountered during the North African campaign and could hold its own against Rommel's early Panzer IIs and IIIs. The A9's 2-pounder gun could also breach the 20 – 30 mm of protective steel on later opponents, such as the Panzer III ausf D and the Panzer IV ausf D variants. It was effective until the Germans introduced the more thickly armoured Panzer IV ausf E variant to the desert in the Spring of 1941.

However, its minimal armour made the A9 very vulnerable against most Axis anti-tank weapons. Also problematic was the lack of high explosive shells for the 2 pdr gun, and even worse the lack of armor-piercing shells for the 95 mm gun on the Close Support version. Another issue was that the areas around the front machine gun turrets created a frontal surface that was more vulnerable to enemy fire than it would have been had it been a flat plate, let alone a sloped glacis.

The mechanical unreliability of the Cruiser was also a disadvantage. In particular, tracks were easily slewed causing difficulties.

Mark I (A9) used by the 1st Armoured Division in the Battle of France (1940). 

Used by the 2nd and 7th Armoured Divisions in North Africa until 1941.

Mark I CS, had a 3.7 inch (94 mm) /L15 breech-loaded mortar instead of the 2-pounder gun. 40 rounds, mostly smoke, were carried.

Tank, Cruiser, Mk I (A9)
Tank, Cruiser, Mk I (A9)
Type	Cruiser tank
Place of origin	United Kingdom
Service history
In service	1938–1941
Used by	British Army
Wars	Second World War
Production history
Designer	Sir John Carden
Manufacturer	Vickers
Produced	1936–1941
Number built	125
Specifications
Weight	12 tons
Length	19 ft (5.8 m)
Width	8 ft 4 in (2.5 m)
Height	8 ft 8 in (2.65 m)
Crew	6 (Commander, gunner, loader, driver, 2x MG gunners)
Armour	6 - 14 mm
Main armament	QF 2-pdr 100 rounds
Secondary armament	3 x 0.303 Vickers machine gun 3,000 rounds
Engine	AEC 179 6-cylinder petrol[1] 150 hp (110 kW)
Suspension	sprung triple wheel bogie
Operational range	150 miles (240 km)
Speed	25 mph (40 km/h)