Cruiser Tank Mk VIII, Cromwell (A27M)

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The Cruiser Tank Mk VIII Cromwell (A27M) was the most important British produced tank during the campaign in north-western Europe in 1944-45 by which time it had evolved into a reliable if somewhat under-gunned tank that performed well in the 'great swan' across France.

The basic design for the Cromwell emerged from an under-used Rolls Royce design team led by W A (Roy) Robotham. This team would normally have been working on designs for new Rolls Royce cars, but the company had cancelled all car production at the start of the war and were focusing entirely on the Merlin aircraft engine. Robotham and his team took over the Clan Foundry near Belper and began to look around for suitable war work. In October 1940 Robotham met with Henry Spurrier, the general manager of Leyland Motors and an old friend. The two men discussed the problems with British tank designs.

After this meeting Robotham and his team began to examine the possibility of fitting a Rolls-Royce engine in a cruiser tank. After testing a variety of Rolls Royce engines they settled on the Merlin Mk III, produced an unsupercharged version of the engine, and installed it in a Crusader tank. This was delivered to Aldershot for trials on 6 April 1941, three months after the A24 had been ordered. The Meteor powered Crusader excelled in its trials, going so fast that the time-keepers failed to time it properly, and on its first run it failed to take a corner and crashed into some trees! It was later estimated that the tank had reached around 50mph.

The new Meteor engine was clearly a major step up from the Liberty, but soon after being given a contract to build 1,000 of them Leylands changed their minds and asked to be allowed to return to Liberty production. Fortunately the funds were quickly found to pay Rolls Royce to begin production of the Meteor.  Leyland's decision did have one negative result. Robotham had worked with the Birmingham Railway Carriage and Wagon Company to produce a design for a tank to use his new engine. This was adopted as the A27, but instead of focusing entirely on a Meteor powered version, the decision was made to allow Leyland to produce the A27L Centaur, powered by a Liberty engine, while the BRC&W developed the A27M Cromwell. At this stage both were called the Cromwell, with the Liberty powered version being the Cromwell II and the Meteor powered version the Cromwell III. The more familiar names were adopted in November 1942.

The first prototype of the Meteor-engined heavy cruiser tank was running at the BRC&W works on 20 January 1942, two months ahead of the A24. In the same month production of the A24 was scaled back, but there was still a belief that there would be a shortage of Meteor engines, while Leyland was still committed to producing the Liberty. It was decided to modify the A27 design so that it could take either engine. Leyland was to control production of the Liberty-powered A27L, while BRC&W took on the A27M. This arrangement didn’t last for long - the BRC&W proved unable to cope with the demanding task and Leyland took over control of both projects.

The A27M was similar in appearance to the A24 and the earlier Crusader. It has a low flat rectangular hull with a stepped front to all for a hull machine gun. All of the sides were vertical, with no sloped armour. The turret was also flat sided, and had a welded substructure with the armour bolted on from inside. The engine was at the rear and the fighting compartment at the front. The turret had power traverse. The 6pdr version had manual gun elevation but the 75mm armed versions had geared elevation (reducing the amount of effort required to move the gun up or down, but because of the poor quality of the gearing making it harder to hit accurately).

The Cromwell was very similar in appearance to the Centaur. The only obvious visual difference was just behind the turret. On the Centaur the rear deck was level all the way from the turret to the back of the tank. On the Cromwell there was a raised armoured louvre just behind the turret, looking like a raised rectangle somewhat narrower than the turret itself.

In August 1943 the Cromwell had its first serious test. This was Exercise Dracula, a 2,300 mile long trip around Britain that was intended to compare the Cromwell, Centaur, Sherman M4A2 and Sherman M4A4. The Sherman came out as the most reliable, both on the move and in gunnery exercises. The Centaur was a near total failure. The Cromwell did a little better, but still needed far more maintenance on the road than the Sherman. As a result of this trial the Centaur was relegated to a secondary role, but the Cromwell designers were given more time to improve their product. A second longer test in November showed that the Cromwell was increasingly reliable but the Centaur still failed. 

On 2 February 1944, with the D-Day landings getting closer, Leyland issued a specification for the Battle Cromwell, setting out a set of features that any individual tank would have before it would be considered combat ready. Battle ready tanks would have to have the correct versions of the Meteor engine and Merritt Brown transmission, 6mm extra amour below the crew compartment and all major riveted joints in the front hull and on the outer turret skin plates seam welded, making them stronger and more water proof. The 6pdr armed Cromwell I and Cromwell III were removed from the front line. Only tanks that satisfied this Final Specification were to be issued to the units fighting in Normandy, and as a result they had a reliable tank.

Combat

The 7th Armoured Division (the Desert Rats) was the main user of the Cromwell. It had one reconnaissance regiment and three regiments making up 22nd Armoured Brigade, all of which used the Cromwell. At the end of June the VIIIth King's Royal Irish Hussars were the reconnaissance regiment, while the 22nd Armoured Brigade was made up of the 1st Royal Tank Regiment, 5th Royal Tank Regiment and 4th County of London Yeomanry. In July this last regiment suffered heavy losses at Villers Bocage and was replaced by the 5th Royal Inniskilling Dragoon Guards. At the end of June 1944 the division had 201 Cromwells with the 75mm gun, 25 with the 95mm gun and eight OP tanks. 

11th Armoured Division and the Guards Armoured Division both used the Cromwell in their Armoured Recce Regiments. For the Guards this was 2nd Battalion the Welsh Guard, who had 59 with the 75mm gun and six with the 95mm gun at the end of June 1944. In 11th Armoured this was the 2nd Northampton Yeomanry in June 1944, ending the month with 62 75mm and six 96mm tanks. In August the Northamptons were replaced by the 15th/19th King's Royal Hussars.

The Cromwell was used by the 10th Mounted Rifle Regiment of the 1st Polish Armoured Division, and by three regiments in the 1st (Czechoslovak) Independent Armoured Brigade, although their tanks arrived after June 1944.

In June 1944 Cromwell regiments at full strength had 70% 75mm tanks, 10% 95mm tanks and 20% Sherman Fireflys (some used the British Challenger).

The Cromwell suffered during the fighting in Normandy, where the boccage meant its high speed couldn't be used. After the Falaise Gap closed in mid-August the Allies broke out of Normandy, and the Cromwell came into its own (August was the second most costly month for Cromwell regiments, with 143 lost). It's high speed and surprisingly good reliability meant that it was able to keep up with the faster moving parts of the army, and inspired Montgomery to claim that the great advance was only possible because of the British cruiser tanks and wouldn't have been possible with Panthers and Tigers. The Allies reached Antwerp on 4 September and the fast moving Cromwells were with them.

Another period of largely static warfare followed. October saw the worst casualty figures, with 174 Cromwells lost, although replacements were still arriving in large numbers – by 30 December there were 1,063 Cromwell Mk IVs in Europe.

In combat the Cromwell was praised by its users for its reliability, but it was vulnerable to mines (because of its limited belly armour), and the 75mm gun wasn't good enough for use against the heavily armoured Panthers and Tigers. The tank was also rather under-armoured for the period, but this at least was deliberate – protection was meant to come from the tank's speed, fine during the 'great swan' but not during the close-quarters fighting in Normandy. Despite its flaws the Cromwell was a vast improvement on previous British cruiser tanks, and was only beaten by the Comet, which entered service in small numbers after the crossing of the Rhine and by the Centurion, which arrived just after the end of the fighting.

Variants

Cromwell I

6pdr gun, two Besa MGs, riveted hull, bolted turret, 14in track

Cromwell II

The Cromwell II would have been armed with the 6pdr gun and used 15.5in tracks. The Cromwell II never entered production. It was to have been produced by Vauxhall after production of the Churchill ended but that tank performed better than expected and remained in production.

Cromwell III

The Cromwell III was the designation given to the Centaur I (6pdr gun) when equipped with a Meteor engine.

Cromwell IV

The Cromwell IV was the designation given to Centaur IIIs (armed with the 75mm gun) that were either re-engined or built from scratch (by companies in the Centaur pool) using the Meteor engine.

Cromwell V

The Cromwell V was armed with a 75mm gun, and was the most numerous version of the tank. It was also produced with a welded hull as the Mk Vw.

Cromwell VI

The Cromwell VI was a close-support version of the tank, armed with a 95mm howitzer. This designation was given both to newly built Cromwells and to Centaurs completed with the Meteor engine.

Cromwell VII/ Cromwell 7

The Cromwell VII was a post-war modification of the tank. It was armed with the 75mm gun, had a low-speed final drive, 15.5in wide tracks and heavy duty front axles. It was produced by modifying Mk IV and V tanks, and was also produced as the Mk 7w which was based on the Mk Vw.

Cromwell VIII/ Cromwell 8

The Cromwell VIII was similar to the Mk VII, but was based on the 95mm armed Cromwell VI.

Stats
Production: 2,494-2,607 (Roughly 1800 75mm gun, 340 CS, 350 6pdr)
Hull Length: 20ft 10in
Hull Width: 9ft 6.5in
Height: 8ft 2in
Crew: 5
Weight: 27-28 tons
Engine: 600hp Meteor
Max Speed: 32-40mph
Armament: Varied – see above
Armour: 8-76mm

How to cite this article: Rickard, J (7 March 2012), Cruiser Tank Mk VIII, Cromwell (A27M) , http://www.historyofwar.org/articles/weapons_cruiser_tank_mk_VIII_cromwell.html

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