The Cruiser Tank Mk I (A9) was designed to replace the Medium Mk III that had been cancelled due to its high cost, and saw limited service in the first years of the Second World War.
The A9 was designed in response to a General Staff specification of June 1934 that called for a tank with the same firepower and armour as the Vickers Medium Mk III, but that must be cheaper than the A7 or A8 designs. Sir John Carden of Vickers Armstrong responded by reducing the weight of the tank by enough to allow it to be powered by commercially available engines instead of a more expensive purpose-built tank engine. The intention was to use the 7.67litre Rolls-Royce Phantom II but a combination of a higher than hoped weight for the tank and lower than expected power from the engine meant that Vickers had to use a 9.64litre AEC bus engine instead. At this stage it was known as the Medium Mk IV, and would only become the Cruiser Tank Mk I in 1938.
Originally the A9 was to use a smaller gun, but in November 1934 the specification was modified to include the new 2pdr gun. The 2pdr gun had a higher muzzle velocity than the gun it replaced, and thus a flatter trajectory, so was both a more powerful anti-armour weapon and easier to aim. Its only flaw was that its high explosive shell carried a very small charge. The A9 was also the first British tank to have a powered turret traverse, although gun elevation was manually controlled.
The tank carried three .303in machine guns, one mounted in the turret and two in auxiliary turrets mounted at the front of the tank. This was a very outdated design feature even by 1934, but was used because the War Office demanded a very wide field of fire for the hull mounted machine guns.
The prototype underwent trials from July 1936. It was three tons over-weight, had problems with its new suspension design and tended to shed its tracks. Vickers spent most of the next year working on these problems, and when production began in 1937 the A9 was a reliable vehicle.
In 1937 an order was placed with Vickers for 50 Cruiser Tank Mk Is. Eventually 125 were built, fifty by Vickers and seventy five by Harland and Wolff (Vickers moved on to the Cruiser Tank Mk II). Production of both the Mk I and Mk II was limited because the War Office decided to adopt Christie suspension and work moved on to the A13 Cruiser Tank Mk III.
Deliveries began in 1939 and by 3 September 1939 there were 77 Cruiser Tanks Mk I and Mk II in service. This rose to 117 by October, and by May 1940 there were 158 Cruiser Tanks Mk I, Mk II and Mk III in service in France. About a third of the A9s were delivered as the close support Cruiser Tank Mk ICS, armed with a 3.7in howitzer.
The Cruiser Mk I first saw combat in France in May 1940, at which point it was still a new and largely untried machine. It was part of the equipment of 1st Armoured Division, where it was used alongside the A10 Cruiser Tank Mk II, the A13 Cruiser Tank Mk III and a number of light tanks. The division arrived in France in late May. 3rd Royal Tank Regiment was sent to Calais, where it was isolated from the rest of the division and wiped out. The rest of the division landed further west, at Cherbourg. It was then rushed forward to the new front line on the Somme, where it launched an unsuccessful attack on the German lines. On 5 June the Germans attacked the new French line on the Somme, and soon broke through. 1st Armoured Division was forced to race back to Cherbourg,
The first ten A9s reached Egypt in October 1939 and was allocated to the 6th Royal Tank Regiment. By June 1940, when Italy entered the war, all four tank regiments in the 7th Armoured Division had at least one squadron of cruiser tanks, with a mix of Mk Is (A9), Mk IIs (A10) and Mk IIIs (A13). More arrived in September when the 2nd Royal Tank Regiment reached Egypt, equipped with a mix of A9s, A10s and A13s (mainly A13s).
The A9 was used at the battles of Sidi Barrani, Beda Fomm and during Operation Battleaxe, although always in small numbers. In December 1940 at Sidi Barrani the cruiser tanks were used to sweep around the Italian flank, get behind them and prevent reinforcements from reaching the front. At Beda Fomm (January-February 1941) the cruiser tanks took part in the dash across the desert that helped trap large parts of the retreating Italian army. After these two battles the A9 was praised for its reliable engine, the exact opposite of the feedback after the fighting in France in May-June 1940!
In June 1941 the 2nd Royal Tank Regiment (7th Armoured Brigade, 7th Armoured Division) had two mixed squadrons of A9 and A10 cruisers, and one squadron of A13s. Their job during Operation Battleaxe was to break through the Axis front line on Rommel's southern flank, capture Hafid Ridge and drive towards Tobruk. The A9s and A10s were used to make the initial breakthrough. The A13s were then sent through the gap and attacked Hafid Ridge, but were repulsed. Soon after this the last A9s were withdrawn from front line service.
During 1940 the prototype A9E1 was used to test out the idea of an amphibious tank. While the production tanks had been of riveted construction the prototype had used bolts, many of which were missing. The two machine gun turrets added extra problems, and the light-weight tank was surprisingly buoyant. Despite these problems the A9 successfully crossed the River Stour underwater on 24 May 1940.
Cruiser Tank Mk I (A9)
Hull Length: 19ft
Hull Width: 8ft 2.5in
Height: 8ft 8.5in
Crew: 6 (commander, gunner, loader, driver, two machine gunners)
Max Speed: 25mph (road), 15mph (cross-country)
Max Range: 150 road radius
Armament: One 2pdr OQF, three .303in Vickers machine guns
Armour: 14mm maximum, 6mm minimum