|Tank, Cruiser, Mk VIII, Cromwell (A27M)|
Cromwell Mk VII in the Kubinka Tank Museum.
|Place of origin||United Kingdom|
|Used by||British Army, Israeli Army, Greek Army, Portuguese Army|
|Wars||World War II, 1948 Arab–Israeli War, Korean War|
|Designer||Leyland, then Birmingham Railway Carriage and Wagon Company from 1942|
|Manufacturer||Nuffield Mechanisation and Aero|
|Weight||27.6 long tons (28 tonnes)|
|Length||20 ft 10 in (6.35 m)|
|Width||9 ft 6 1⁄2 in (2.908 m)|
|Height||8 ft 2 in (2.49 m)|
|Crew||5 (Commander, gunner, loader/radio operator, driver, front gunner)|
|Armour||3 inches (76 mm)|
|Ordnance QF 75 mm
with 64 rounds
|2 x 7.92 mm Besa machine gun
with 4,950 rounds
|Engine||Rolls-Royce Meteor V12 petrol
600 horsepower (450 kW)
|Transmission||Merritt-Brown Z.5 gearbox (five forward and one reverse gear) driving rear sprockets|
|Ground clearance||16 inches|
|Fuel capacity||110 gallons + optional 30 gallon auxiliary|
|170 miles (270 km) on roads, 80 miles cross country|
|Speed||40 miles per hour (64 km/h) with 3.7:1 final reduction drive|
Tank, Cruiser, Mk VIII, Cromwell (A27M),[a] and the related Centaur (A27L) tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second World War. The Cromwell tank, named after the English Civil War leader Oliver Cromwell, was the first tank put into service by the British to combine a dual-purpose gun, high speed from the powerful and reliable Meteor engine, and reasonable armour, in a balanced package. Its design formed the basis of the Comet tank.
The Cromwell and Centaur differed in the engine used. While the Centaur had the Liberty engine of the predecessor cruiser tank, the Crusader (and the interim A24 Cavalier), the Cromwell had the significantly more powerful Meteor. Apart from the engine and associated transmission differences, the two tanks were the same and many Centaurs built were fitted with the Meteor to make them Cromwells.
The Cromwell first saw action in the Battle of Normandy in June 1944. The tank equipped the armoured reconnaissance regiments, of the Royal Armoured Corps, within the 7th, 11th and Guards Armoured Divisions. While the armoured regiments of the latter two divisions were equipped with M4 Shermans, the armoured regiments of the 7th Armoured Division were equipped with Cromwell tanks. The Centaurs were not used in combat except for those fitted with a 95mm howitzer, which were used in support of the Royal Marines during the invasion of Normandy.
- 1 Development
- 2 Production
- 3 Design
- 4 Performance
- 5 Combat service
- 6 Operators
- 7 Variants
- 8 Vehicles based on chassis
- 9 Surviving vehicles
- 10 See also
- 11 Notes
- 12 Notes
- 13 References
- 14 External links
Development of the Cromwell and Centaur dates to 1940, as the Crusader tank was being readied for service. The General Staff was aware that the Crusader would become obsolete, and in late 1940 they set out the specifications for the new tank to replace it. The tank was to be fitted with the QF 6 pounder gun and was expected to enter service in 1942.
Vauxhall responded with the A23, a scaled down version of their A22 Churchill infantry tank. This would have had 75 mm of frontal armour, used a 12 cylinder Bedford engine, carried a crew of five and would have the same suspension as the A22.
Nuffield submitted the A24, heavily based on its Crusader design and powered by its version of the Liberty engine, a V-12 design dating the late days of World War I and now thoroughly outdated. Nevertheless, as the design was based on the Crusader, it was expected it could be put into production rapidly.
The designs were received and examined in January 1941, with Nuffield's A24 being declared the winner on 17 January. Six prototypes of the Cromwell I were ordered for the spring of 1942. These arrived four months late and by this time the design was already outdated. It was put into production anyway, but in service it proved entirely underpowered and only a small number were built.
With the start of the war, Rolls-Royce ended car production and set up a design team looking for other ways to use their production capacity. The team formed under the direction of Roy Robotham at Clan Foundry near Belper, north of Derby. In October 1940 Robotham met with Henry Spurrier of Leyland Motors to discuss British tank design. They decided to attempt to fit a Rolls-Royce Merlin engine to a Leyland tank for testing. They removed the turbocharger from a Merlin Mk. III and fitted it to a Leyland-built Crusader. Delivered to Aldershot on 6 April 1941, the test team had trouble timing its runs because it was so fast, estimating it reached 50 miles per hour (80 km/h).
Everyone was so impressed by this display that Leyland arranged to start production of 1,000 examples of the engine as the Meteor. They planned to fit this to BRC&W-built versions of their original A24 submission. However, in mid-1941 Leyland changed its mind, concerned about cooling problems. They instead suggested using a diesel engine of their own design, although this would produce only 350 horsepower (260 kW) compared to over 500 from the Rolls design. The Tank Board then placed an order directly with Rolls for the Meteor. The resulting design was ordered as the A27. When Leyland suggested that the tank be designed to fit either the Meteor or the Liberty, the two versions were given the General staff numbers A27M and A27L, respectively, and the names Cromwell III and Cromwell II. The diesel concept was abandoned.
The first prototype of a Meteor-powered Cromwell III was delivered in January 1942, several months before the A24 that was supposed to precede it. With nearly 600 hp (450 kW) it proved to be exceptionally mobile when tested. Orders were placed for both versions, as there were concerns about the production rate of the Meteor. Even when assigned reduced production quotas, BRC&W proved unable to meet demand, and Leyland eventually took over production of both versions.
Rolls was at this time having trouble meeting demand for the Merlin, let alone the Meteor. Meanwhile, Rover was having troubles developing Frank Whittle's Power Jets W.2 jet engine design due to increasing animosity between the engineers at Power Jets and Rover. Things became particularly heated when Whittle learned that Rover had set up a secret lab to develop their own versions of the design. Whittle had, during the same period, contacted Rolls for help delivering some of the required parts that Rover proved unable to produce.
A solution to both their problems was offered by Ernest Hives, a Rolls board member, who had met Whittle and was fascinated by the jet engine. Hives called a meeting with his counterpart at Rover, Spencer Wilks, and the two met late in 1942 at the Swan and Royal pub in Clitheroe. Hives offered to trade the Meteor for the W.2, an offer Wilks jumped at. The official handover took place on 1 January 1943. Rover set up production at their Tyseley factory, and an additional line was set up by Morris Motors in Coventry.
Production began in November 1942. That month, new names were given to all three designs; the original A24 Cromwell I became the Cavalier, the Liberty powered A27L Cromwell II became Centaur, and the Meteor powered A27M kept the name Cromwell. It would take considerable time for Rover to make ready production lines for the Meteor, and it was not until a few months later, in January 1943, that sufficient Meteor engines were available and the A27M Cromwell began production. The Centaur production design allowed for the later conversion to the Meteor engine and many Centaurs were converted to Cromwells before use.
The first real field test of the design was carried out in August–September 1943, when examples of the Centaur, Cromwell, Sherman M4A2 (diesel engine) and Sherman M4A4 (multi-bank petrol engine) were all tested in Exercise Dracula, a 2,000 mile long trip around Britain. The Shermans proved to be the most reliable, by far, requiring 420 hours of specialist fitter attention over a total distance travelled of 13,986 miles (22,508 km). This corresponds to 0.03 hours per mile. In comparison, the Cromwells drove 11,582 miles (18,639 km) and required 814 hours, or 0.07 hours per mile. The Centaur managed only 8,492 miles (13,667 km) due to constant breakdown, and required 742 hours, or 0.087 hours per mile.
The Cromwell and Centaur were given additional time to work out these problems. The Cromwell's problems were mostly related to oil leaks and brake and clutch failures, an observer noted that these were well known and should have been corrected before this point. The crews, however, expressed their love for the design, and especially its speed and handling. The Centaur was largely dismissed, with one observer expressing his hope that units were being equipped with it only for training purposes. The same reviewers unanimously supported the Sherman. A similar test in November demonstrated the Cromwell was improving, while the underpowered Centaur faired no better than the first test.
The production model design was finalized on 2 February 1944 when Leyland released specifications for what they called the "Battle Cromwell". This included a number of minor changes to the basic design, including 6 millimetres (0.24 in) of extra armor below the crew compartment, seam welding all the joints to waterproof and strengthen the tank, and standardizing on the Meteor engine and Merritt Brown transmission.
Total A27 production consisted of 4,016 tanks, 950 of which were Centaurs and 3,066 Cromwells. In addition, 375 Centaur hulls were built to be fitted with an anti-aircraft gun turret; only 95 of these were completed.
The frame was of riveted construction, though welding was used later. The armour plate was then bolted to the frame; large bosses on the outside of the plate were used on the turret. Several British firms besides Leyland contributed to production of the Cromwell and Centaur, including LMS Railway, Morris Motors, Metro-Cammell, Birmingham Railway Carriage and Wagon Company and English Electric. Some variants were produced with 14-inch-wide (360 mm) tracks; later, 15.5-inch tracks were used.
The suspension was of the Christie type, with long helical springs (in tension) angled back to keep the hull sides low. Of the five road wheels each side, four had shock absorbers. The tracks were driven by sprocketed wheels at the rear and tension adjusted at the front idler, this being standard British practice. As with previous Christie-suspension cruiser tanks, there were no track return rollers, the track being supported instead on the tops of the road wheels. The side of the hull was made up of two spaced plates, the suspension units between them, and the outer plate having cutouts for the movement of the road-wheel axles. The gearbox had five forward and one reverse gears. The first gear was for "confined spaces, on steep inclines or...sharp turns". The Meteor engine delivered 540 hp at 2,250 rpm. This was the maximum rpm, which was limited by governors built into the magnetos. Fuel consumption on "pool" petrol (67 octane) was between 0.5 and 1.5 miles per gallon depending on terrain.
The driver sat on the right in the front of the hull, separated from the hull gunner by a bulkhead. The driver had two periscopes and a visor in the hull front. The visor could be opened fully or a small "gate" in it opened; in the latter case a thick glass block protected the driver. A bulkhead with access holes separated the driver and hull gunner from the fighting compartment. A further bulkhead separated the fighting compartment from the engine and transmission bay. The engine compartment drew cooling air in through the top of each side and the roof and exhausted it to the rear. To allow fording through up to 4 ft (1.2 m) deep water, a flap could be moved to cover the lowermost air outlet. Air for the engine could be drawn from the fighting compartment or the exterior; it was then passed through oil bath cleaners.
The Cromwell had revisions to make before service, changing from the QF 6-pounder (57 mm) to the ROQF 75 mm gun, which was an adaptation of the 6-pounder design to fire the ammunition of the US M3 75 mm gun, which gave it a better HE round to use in infantry support. This meant that the 75 mm used the same mounting as the 6 pounder. In June 1944, the Cromwell saw action during Operation Overlord, the Allied invasion of Normandy. It had a mixed reception by crews, being faster, with a lower profile than the Sherman tank and thicker frontal armour plate 3 in (76 mm) as against the 2 in (51 mm) on the glacis of the early Shermans, though it was unsloped and hence less effective. On later Cromwells this was increased, first to 3 1⁄4 in (83 mm), then to 4 in (100 mm). The 75 mm gun, though able to fire a useful HE shell, was not as effective against armour as the 6-pounder or the Ordnance QF 17 pounder gun. A derivative of Cromwell, the Cruiser Mk VIII Challenger, was built to take the 17-pounder but only a small number were built. Most 17-pounder armed tanks to see service in the war were the Sherman Firefly variant of the Sherman.
There was a 7.92 mm Besa machine gun mounted co-axially to the main armament, operated by the gunner. A second was "gimbal" mounted in the front of the hull. The mounting gave 45 degrees of coverage to the front (it had 25 degrees of vertical movement as well) and sighting was by a No. 35 telescope, which was connected through a linkage to the mounting. In the top of the turret was a 2 inch "bombthrower" angled to fire forward and thirty smoke grenades were carried for it.
The Cromwell was the fastest British tank to serve in the Second World War, with a top (ungoverned) speed of 40 mph (64 km/h). However, this speed proved too much for even the Christie suspension and the engine was governed to give a top speed of 32 mph (51 km/h), which was still fast for its time. Thanks to its excellent engine power and Christie parentage the Cromwell was very agile on the battlefield. The dual purpose 75 mm main gun fired the same ammunition as the US 75 mm gun and therefore it had around the same HE and armour-piercing capabilities as the 75 mm equipped Sherman tank. The armour on the Cromwell ranged from 8 mm up to 76 mm thick overall. However, on all-welded vehicles built by BRCW Co. Ltd, the weight saved by the welding allowed for the fitting of appliqué armour plates on the nose, vertical drivers' plate and turret front, increasing the maximum thickness to 102 mm. These vehicles are identified by their War Department numbers carrying the suffix W, e.g. T121710W. This armour compared well with that of the Sherman, although the Cromwell did not share the Sherman’s sloped glacis plate. The Cromwell crews in North-West Europe succeeded in outflanking the heavier and more sluggish German tanks with superior speed, manoeuvrability and reliability. However, the Cromwell was still not a match for the best German armour and British tank design would go through another stage, the interim Comet tank, before going ahead in the tank development race with the Centurion tank.[original research?]
The Centaur was chiefly used for training; only those in specialist roles saw action. The Close Support version of the Centaur with a 95 mm howitzer, saw service in small numbers as part of the Royal Marine Armoured Support Group on D-Day and a number were used as the chassis for combat engineering vehicles such as an armoured bulldozer.
The Sherman remained the most common tank in British and Commonwealth armoured units. Cromwells were used as the main tank in the armoured brigades of only the 7th Armoured Division, although the Cromwell was used in the armoured reconnaissance regiments of the other British armoured divisions (Guards Armoured Division and 11th Armoured Division) in North-west Europe, because of its speed and relatively low profile. The Cromwell in turn was succeeded by small numbers of the Comet tank, which was similar to the Cromwell, being based on it and shared some components but had a superior gun in the 77 mm gun (a version of the 17 pounder with different ammunition).
The Cromwell was found to be very reliable with excellent speed and manoeuvrability, though it required more maintenance than the Sherman. It was modified so that the exhaust fumes were redirected so that they were not drawn into the fighting compartment, a problem found when tanks were drawn up together, preparing to advance. In northern Europe, the Cromwell was used by Allied units of the 1st Polish Armoured Division (10th Mounted Rifle Regiment) and 1st Czechoslovak Armoured Brigade. After the war, the Cromwell remained in British service, and saw service in the Korean War with 7 RTR and the 8th King's Royal Irish Hussars.
The Cromwell/Centaur had the distinction of being the first tank to go into service with the Greek Army during the re-formation following the Second World War. Fifty-two Centaur I tanks were donated early in 1946, during the opening stages of the Greek Civil War but they were kept in storage due to the lack of trained personnel. In 1947, the first Greek officers returned from training courses in the United Kingdom and training of tank crews began. The Centaur saw limited service in the civil war as in 1949 battles were fought on mountains. Centaurs formed the core of the Greek Armour Corps during the 1950s and were retired in 1962, having been replaced by US-built M47s. Finland used the Charioteer version of the Cromwell post war.
The modifications and developments of the Cromwell were classified under "Type" and "Mark". A single Mark could cover up to four Types and a Type up to six Marks making classification complex.
The Types ran from A (the earliest Cavaliers, Centaurs and Cromwells) to F (a late model Cromwell with driver's side escape hatch).
- Centaur I
- First draft. Armed with the Royal Ordnance QF 6 pounder (57 mm) gun (with 64 rounds of ammunition). It was used only for training. 1,059 produced.
- Centaur II
- Mark I with wider tracks and no hull machine gun. Experimental only.
- Centaur III
- Centaur armed with the 75 mm ROQF Mk V gun. In 1943, most Centaur I were converted to IIIs, but a few remained as such. 233 produced.
- Centaur IV
- Centaur armed with a 95 mm howitzer (with 51 rounds of ammunition). This is the only version of the Centaur known to have seen combat, in service with the Royal Marines Armoured Support Group. The vehicles were fitted with wading gear to get them ashore. Trunking waterproofed the engine inlets and covers were fitted to the guns. 114 produced.
- Centaur, AA Mk I
- Used a Crusader III, Anti-Aircraft Mk II turret fitted with twin 20 mm Polsten guns. Were originally deployed in Normandy, but withdrawn as unnecessary due to Allied air superiority. 95 were produced.
- Centaur, AA Mk II
- Used a Crusader III, AA Mk III turret with twin 20 mm Polsten AA guns.
- Cromwell I
- Exactly the same as the Centaur I, but using the Meteor engine. Only 357 produced due to the switch from the 6 pounder (57 mm) to the 75 mm gun.
- Cromwell II
- Increased track width and removal of the hull machine gun to increase stowage. None produced.
- Cromwell III
- Centaur I upgraded with Meteor V12 engine. Only ~ 200 produced due to scarcity of Centaur I's.
- Cromwell IV
- Centaur I or III upgraded with Meteor engine, or built as such. The most numerous variant with over 1,935 units produced.
- Cromwell IVw
- Meteor engine, and all welded hull.
- Cromwell Vw
- Cromwell built from the start with the 75 mm gun and a welded instead of riveted hull.
- Cromwell VI
- Cromwell armed with 95 mm howitzer. 341 produced.
- Cromwell VII
- Cromwell IV and V upgraded with additional armour (101 mm to front), wider (15.5 inch) tracks, and additional gearbox. These were introduced very late in the war and did not see much in the way of combat. ~ 1,500 produced.
- Cromwell VIIw
- Cromwell Vw reworked to Cromwell VII standard, or built as new to that standard
- Cromwell VIII
- Cromwell VI reworked with same upgrades as VII.
Vehicles based on chassis
- Tank, Cruiser, Challenger (A30)
- The design combined a lengthened Cromwell chassis with widened superstructure to mount the 17-pounder gun in a new turret.
- SP 17pdr, A30 (Avenger)
- A version of the Challenger using a lighter open-topped turret.
- Centaur Dozer
- A Centaur with the turret removed and given a simple dozer blade operated by a winch. Since the winch passed over the top of the hull it was not possible to retain the turret. One of "Hobart's Funnies". 250 produced.
- Centaur Observation Post (OP)
- A Centaur with a dummy main gun, and extra radio communications.
- Centaur Kangaroo
- A Centaur with turret removed to make space for passengers. (Few produced)
- Centaur Armoured Recovery Vehicle (ARV)
- A Centaur with turret removed, and replaced with winch fitted instead, and an optional A-frame.
- Cromwell Command
- The main gun was removed and it carried one No. 19 (Low Power) and one No. 19 (High Power) Wireless sets. These were used by brigade and divisional headquarters.
- Cromwell Observation Post
- Cromwell IV, Cromwell VI, or Cromwell VIII fitted with extra radio equipment; 2 x No. 19 and 2 x No. 38 (portable) radios. The main gun was retained.
- Cromwell Control
- Two No. 19 Low Power radio. Main armament kept. Used by regimental headquarters
- Excelsior tank
- experimental design with elements of Infantry tank as a possible replacement for Churchill tank
- FV 4101 Charioteer
- Cromwell hull with a QF 20 pounder gun in a tall turret, designed in the 1950s to give more fire support. 200 produced.
Around 40 Centaur and Cromwell tanks survive, ranging from scrapyard wrecks to fully restored museum vehicles. At least two, one owned by the Czech Republic Army Technical Museum at Lešany and one owned by the Cobbaton Combat Collection in the United Kingdom, are in running condition.
Other examples include:
- Bovington Tank Museum, Dorset, England. Cromwell IV displayed in interior location accessible to public on payment of entry fee to museum. and a Centaur dozer 
- Thetford Forest, Norfolk, England. Cromwell IV in outside location freely accessible to public. This tank is located on the A1065 two miles north of Mundford. Between January and May 1944 the area was occupied by armoured regiments of the 7th Armoured Division (Desert Rats) prior to their embarking for Normandy. The tank forms part of a 1998 memorial to the Division. It is in good display condition having been refurbished and painted as a replica of the tank Little Audrey of 1st Royal Tank Regiment.
- The Royal Australian Armoured Corps Army Tank Museum, Puckapunyal, Victoria. Cromwell MkI shipped to Australia to assist with the up gunning of the Australian Cruiser tanks but did not arrive before that programme had been terminated. Repainted with the markings it arrived in Australia with, it is now under cover on display at the museum.
- The Israeli Armoured Corps Museum in Latrun. Cromwell IV tank, that was used by the IDF in War of Independence (1948–1949).
- The Liberty Park in Overloon, The Netherlands. Cromwell IV tank, that remained on the battlefield after Operation Aintree during the Battle for Overloon in October 1944 in which the 11th Armoured Division was involved. This tank is on display in the museum, accessible to the public on payment of entry fee to museum.
- The Tank Museum, Greek Army Armored Training Center, Avlona, near Athens, Greece. Centaur I (A27L) tank. The Greek Army received 52 Centaur I tanks from the British in 1946.
- Centaur tanks have been discovered in a good state of preservation in the Solent, but are unlikely to be recovered.
- A Cromwell tank sits as a memorial by the A12 road leading into Antwerp Belgium. This was unveiled in September 2014 for the 70th anniversary of the Liberation of the city in 1944.
- There are two surviving Centaur IV CS in Normandy, at Benouville near Pegasus Bridge and at La Brèche d’Hermanville
- There are two Portuguese Army's Cromwell tanks in Academia Militar (Portuguese Military Academy).
- Centaur I at Polish Muzeum Broni Pancernej Centrum Szkolenia Wojsk Lądowych in Poznań - being restored to running condition (as of March 2015).
Tanks of comparable role, performance, and era
- The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively.
- It is unclear if it was granted it's own number or also referred to as the A24.
||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (March 2009)|
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- "The Chieftain's Hatch: Exercise Dracula". world of tanks. 05/07/2014. Check date values in:
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- Bingham p. 28
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- Bingham p. 30
- Cromwell Tank p.xiii
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|Wikimedia Commons has media related to Cromwell tank.|
- OnWar specifications: Cromwell I, Cromwell IV
- Henk of Holland
- "Crusier tank A27M Cromwell". Photo Gallery of WW2 (in Danish).
- "The A27M Cromwell tank". Shermanic Firefly.