British tank building developed rapidly in the 1920s, but started slipping in the first half of the 1930s. At the time, the British army was only buying light tanks, and even then miserly amounts of them. The situation with medium tanks was a fiasco. The replacement for the Medium Tank Mk.II never made it into production. By the time a worthy heir turned up, British policy regarding the use of tanks changed entirely. The result of this change was the Tank, Cruiser, A9, also known as the Cruiser Tank Mk.I.
Loser from Woolwich
Work on the A6 tank, also known as the Vickers 16-tonner, began in May of 1926. The new medium tank was significantly different from its predecessor, the Medium Tank Mk.II, which is not strange. This design was based on another tank, which was designed for foreign buyers, the Medium Tank Mk.C. The new tank had a classical layout with the engine and transmission located in the rear.
A characteristic feature of the A6 and its descendants was two machinegun turrets in the front. The machinegun turrets would be used to combat enemy infantry, and the main turret would take on enemy tanks. The main turret also had a coaxial machinegun for dealing with infantry. Because of this, the tank carried no HE shells for its 3-pounder (47 mm) gun. The British started this tradition in the early 1920s.
Three experimental A6 tanks were built by Vickers-Armstrongs in 1927-1928. In May of 1929, ROF Woolwich built two more improved tanks, indexed Medium Tank Mk.III. A third variant with an altered suspension was built in February of 1931 by Vickers-Armstrongs. The tanks were faster than their predecessors, had superior firepower, and better mobility of fire. The biggest problem was in the suspension. No matter how much it was modified, it remained too weak for this kind of chassis.
Issues with the A6's suspension became evident during the trials stage. The British solved the problem in two ways: evolutionary and revolutionary. The Medium Tank Mk.III was the result of the evolutionary path.
As for the revolutionary path, it would result in a whole new tank. It was designed at ROF Woolwich. The vehicle, indexed A7, was built as an alternative to the Vickers tank. With similar armour and armament, the vehicle was limited to 14 tons in weight. The machinegun turrets had to be sacrificed to achieve this. Instead, a hull gunner with a Vickers machinegun was placed next to the driver. The crew was reduced to 5 men, 3 of which were housed in the turret. The turret was also simpler and roomier.
As for the suspension, Woolwich did not try to reinvent the wheel, and further developed the solutions used in the Birch Gun. A more powerful 120 hp air cooled Armstrong Siddeley engine had to be used because of the increased mass.
Experimental A7E1 and A7E2 tanks were ready in May of 1929. Externally, the tanks differed in the height of the skirt armour. In addition, the rear was slightly different. The A7E1 used a 4-speed Armstrong Siddeley gearbox, the same one as on the first two Medium Tanks Mk.III. The A7E2 received a Wilson hydraulic planetary gearbox.
For their time, the tanks were advanced, if not plain revolutionary. The A7 was slightly longer than the Medium Tank Mk.III, but was a lot more modern. The turret turned out really well: the commander received a very comfortable commander's cupola, and the gun mount was well designed. However, the bow gunner's hatch in the front armour received some criticism.
More questions were raised at the Mechanical Warfare Experimental Establishment proving grounds, where the A7E1 and A7E2 entered trials in 1931. The A7E1 received the WD number T.816, registration number MT9639, and proving grounds number MEE383. The A7E2, in turn, was numbered T.817, MT9640, and MEE493, respectively. Trials showed that the designers were very optimistic with their calculations. The theoretical top speed was 40 kph, but the tanks did not reach a speed of over 24 kph during trials. In addition to the weak engine and high mass (the A7E2 weighed 16.8 tons), the suspension was a limiting factor. The leaf springs on the A7E1 worked very poorly, and trials were brief. The A7E2 had a new suspension with vertical coil sprints. It performed better, but frequent breakdowns were noted.
Comparative trials alongside the A6E3 showed that this tank was faster than the A7E2, but it had its own problems. The A6E3 could only hold a speed of 40 kph for a short time. The tank was used as a testbed for the Vickers-Horstmann suspension. There were plans to install it on the A7E2, but they were eventually cancelled. Trials of the second prototype continued until 1936, but it was clear that the tank was a failure.
Requirements for a modernized A7 were composed in January of 1934. The design of the hull and turret was largely satisfactory, and the main efforts of the designers were aimed at resolving issues with the engine, transmission, and suspension. Tired of fighting with air-cooled Armstrong-Siddeley engines, designers from ROF Woolwich turned to the Associated Equipment Company (AEC), one of the leading manufacturers of buses. The 6-cylinder 7.74 L 126 hp engine used in AEC Regent double decker buses was chosen. Interestingly enough, these buses also used Wilson planetary gearboxes. One of these engines was not powerful enough, and so a doubled up 252 hp engine was built.
The suspension was radically redone. Each road wheel received an individual vertical coil spring. At the same time, the hull was altered: the biggest difference was a wider turret platform and new machinegunner's hatch. The turret was also radically changed, and now housed the new 2-pounder (40 mm) gun. The installation of a 3 inch (76 mm) howitzer was also worked on. The coaxial machinegun mount that shared the gun mantlet was also improved. Observation devices were also changed.
According to documents, the A7E3 was built in May of 1934, but only entered trials in 1936. Like the previous prototypes, it was built from mild steel. Upon arrival at Farnborough, the tank received the WD number T.1340, registration number BMM 117, and proving grounds number MEE961. At this point the same 2-pounder gun was installed into the A7E2, but it was clear that this tank became secondary.
The first trials of the A7E3 revealed that the tank obvious surpassed its predecessors. Even though its mass increased to 18.2 tons, the more powerful engine allowed it to reach a speed of 39 kph on roads and 26 kph off-road. Trials showed that the working conditions of the crew were acceptable. Optimistically, the testers stated that the top speed of the tank could reach 48 kph with some improvements. This claim looks like science fiction, especially since after a number of improvements to the tank's fuel system the top speed decreased. The biggest problem was due to breakdowns. After 122 km of trials the brakes broke for the first time, and broke 6 more times during the rest of the trials. After 274 km of trials the suspension broke down.
The idea of installing the Vickers-Horstmann suspension tested on the A6E3 was raised. However, it had to be discarded, since the suspension turned out to be too bulky and heavy. In December of 1936, Colonel Martel, one of the ideologues of the cruiser tank concept, proposed the installation of the Liberty L-12 engine and transmission from the Christie tank. Trials of the Christie M1931 (also known as Cruiser Tank A13E1) showed that it had high mobility. Martel estimated that the top speed of the new tank would increase to 61 kph with the A13E1's engine and transmission. However, detailed calculations showed that Martel's estimate was too high. Even with all possible changes, the top speed of the tank would be 56 kph. As with the American Medium Tank T2, the installation of a more powerful engine did not resolve the limitations imposed by the suspension. It's not surprising that work on the A7E3 ceased in 1937.
However, the A7E3 program was hardly a failure. The idea with a doubled up engine migrated to the A12 infantry tank, better known as the Matilda. The suspension was also put into production on the A22 infantry tank, better known as the Churchill. The turret also did not vanish, as it was slightly changed and used on the Cruiser Tank Mk.III and Mk.IV.
Another vehicle deserves a mention, as it was conceptually close to the A7E3 and even used some components from A7 tanks. This is the Tank, Medium, A8, developed by Vickers-Armstrongs since 1933. Little is known about this vehicle, only that it was also developed using the experience gained from the A7E1 and A7E2. Its mass of 17.5 tons was compensated by the installation of two Rolls Royce Phantom II engines that worked with a Wilson gearbox. The tank used the turret from the A7E2 with a 2-pounder gun.
Work on the A8 resulted in a wooden model and constantly reworked blueprints. The A8E1 would receive the WD number T.1341 and registration number BMM118, but the tank was never built in metal. Work on the A8 stopped in 1937. Later, the idea of a medium (later, heavy cruiser) tank evolvd into the A14 and A16 tanks, which turned out to be even heavier. Another tank that was being designed by Vickers-Armstrongs was a lot more promising.
Cruiser by circumstance
In 1934, the same year work on the A7E3 began, the British War Ministry had the idea of creating another alternative medium tank. The A7E1 and A8 were already heavier than the Medium Tank Mk.III. The initial idea was to make these vehicles lighter. The increased mass meant not only an overloaded chassis, but additional cost. Increased mass meant the tank would be more expensive. There was even a formula to estimate the price of a tank: 1000 pounds Sterling per ton. As a result, the idea of an alternative medium tank was raised. This tank would be close to the Medium Tank Mk.III in capabilities but smaller and weighing in at 12 tons.
The 12 ton medium tank received the index A9. Vickers-Armstrongs received the contract for its development. Initially the work was headed by John Carden, but after his death in December of 1935 the leadership was passed to Leslie Little. The task was not simple. The thickness of armour and the armament had to be the same as on the Medium Tank Mk.III, but with a 2-pounder gun instead of a 3-pounder. The turret was of the A7E3 type. The top speed of the tank had to be 40 kph. All of this had to be achieved within the weight limit of 12 tons. It was clear that any existing suspension would not do, as they all worked poorly at high speeds.
The Vickers-Horstmann suspension had the best characteristics of those available, but it was far from ideal. Vickers engineers designed a suspension that was similar to the one used on Vickers light tanks. The suspension elements, road wheels, and return rollers were all a part of the same assembly which could be easily replaced in the field.
Each bogey had two road wheels 459 mm in diameter and one 610 mm in diameter. The larger road wheels were first and last on each side. The idlers had the same diameter as the large road wheels. The resulting design effectively spread out the pressure along the ground.
Air-cooled Armstrong Siddeley engines have been completely discredited by this point, plus they were far to large. Instead, the 120 hp Rolls Royce Phantom II engine was used, the same one that would go into the A8. The power to weight ratio of this tank would be 10 hp/ton, an acceptable amount for a medium tank of the time. The gearbox was a 5-speed Meadows No.22. The transmission layout was very interesting. Its elements were compact, as the final drives took up a lot of room inside the drive sprockets. The result was rather unusual, but worked reliably.
Thanks to the compact placement of the engine and transmission elements, the length of the hull was reduced. The A9's hull was 5791 mm long, while the A6 was 6550 mm long and the A7 was 6833 mm long. The tank was also 25-30 cm lower than its predecessors. This had an effect on the mass. The designers did not meet the 12 ton requirement, but the tank turned out to weigh only half a ton over the limit. Like the A6, the tank had three turrets: one with a cannon and two with machineguns. One notable feature was a hydraulic turret traverse drive, a first in British tank building.
The A9 project was finally approved in late 1935, and in April of 1936 a prototype called A9E1 was built. A distinctive feature of this model was the conical roof of the machinegun turrets. The gun turret also differed, having a slope in the rear. In June of 1936 the tank arrived in Farnborough, where it received the registration number BMM 133. Trials were completed successfully, but the engine turned out to be weak. By that point, a more powerful 9.6 L AEC bus engine was available. The tank version of this engine was named A179 and put out up to 150 hp. With this engine the power to weight ratio of the A9 was a little lower than that of the A7E3, but the tank didn't need to have two engines.
Leslie Little insisted on using a diesel engine. AEC could offer such an engine, but the War Ministry chose otherwise. As the not so distant future showed, this was a mistake.
In 1936, the tank was named Tank, Experimental, Medium, A9E1. In 1937, after Martel familiarized himself with Soviet BT tanks, the idea of building cruiser tanks instead of mediums came to him. These tanks would distinguish themselves with high speed. The only tank that was even remotely close to meeting this requirement was the A9E1.
Of course, the Cruiser Tank A13 was a superior specimen, but the first prototype of the A13E2 was only built by October of 1937. The War Ministry decided not to tempt fate and accept at least some kind of tank into service. In June of 1936, the A9E1 was accepted as the Tank, Cruiser, A9 Mk.I. The experimental A9E1 continued serving as a test lab. Underwater driving equipment was tested on it. However, this turned out poorly. The tank was built with rivets and was not particularly watertight. During trials the tank quickly took on water.
First time is not the charm
The acceptance of the tank into service did not mean that it would remain identical to the first prototype. A lengthy list of required changes was composed, and the production tank underwent a serious metamorphosis. The hull and turrets were altered. Significant attention was paid to increasing visibility. It turned out that the existing cupola did not serve that purpose well. Instead, a two-piece hatch was installed, with a Vickers Mk.IV Gundlach periscope in one of the pieces. The turret bustle was straightened. The tank received a No.9 Wireless Set. Observation slits were added to the machinegun turrets, which also improved visibility. The shape of the front of the hull was changed, and the muffler moved from the left fender to the rear.
The first contract with Vickers for 50 tanks was signed in 1938. The tanks were built at the Elswick Works factory near Newcastle-under-Lyme. Organizational issues resulted in the first tank only being ready in January of 1939. The first A13 Mk.I was also built in January of 1939.
The situation with British tank production goes a long way to explain Neville Chamberlain's policy of appeasement. As of the fall of 1938, the situation with tanks in Britain was catastrophic. New tanks were either only being accepted or production was just starting up. The situation with medium tanks was even worse: Britain had no new medium tanks at all, and the Medium Tank Mk.I and Mk.II were being removed from service as hopelessly obsolete. Even Czechoslovakia and Poland were in a better place in regard to tank production. As a result, Chamberlain had to continue to appease Hitler. The year that was won thanks to this policy allowed Britain to launch tank production.
The last Tank, Cruiser, A9 Mk.I were delivered by Elswick Works in February of 1940. The tanks received WD numbers from T.3493 to T.35.42 and registration numbers HMH848-HMH897.
Even during preparations for production it became clear that Vickers alone cannot meet the army's demand for new tanks. This is how the shipbuilding branch of Harland & Wolff from Belfast was dragged into building tanks. A contract for 75 tanks was signed with this company. Around the same time, the decision to build howitzer tanks, named A9 CS Mk.I, was made. They were armed with a 3.7» (94 mm) howitzer, and were equipped with HE and smoke shells. 36 tanks of this type were ordered at Harland & Wolff.
The first A9 Mk.I produced by Harland & Wolff was ready in June of 1939. The last A9 CS Mk.I was delivered in July of 1940. Assembly of the Infantry Tank Mk.II* began in Belfast in March of 1940. By this point, the designations of the tanks changed: the A9 Mk.I was now called Cruiser Tank Mk.I and the howitzer variant was called Cruiser Tank Mk.I CS. The tanks produced by Harland & Wolff received WD numbers T.7196-T.7270. Initially, the tanks were to receive registration numbers PMV552-PMV626, but as of PMV572 registration numbers were no longer used.
The A9 filled the same slot as the A13 in the tank forces. British military plans accounted for 1500 light cruiser tanks: 488 in reserve, 210 for forces in Egypt, and 855 for the main forces. 4 tank divisions would be formed. Each of these units would number 349 tanks, 108 of which would be light tanks, 159 light cruiser, 24 howitzer cruiser, and 58 heavy cruiser. The only heavy cruiser tank at the time was the A10: a version of the A9 without machinegun turrets, but with reinforced armour.
The A9 was a temporary member of this hierarchy. It had neither the mobility of the A13 nor the armour of the A10. The only role it could fill was the close support role. Because of this, the last 36 tanks built at Harland & Wolff were of the A9 CS Mk.I type.
The only tank unit that was more or less fully equipped before active fighting on the Western Front was the 1st Armoured Division. The division had 24 A9 tanks, 18 of them A9 CS Mk.I, by May 20th. The British sent everything they had at the time, but it turned out to not be enough to stop the German offensive.
British tankers had to fight not only with the Germans, but with their own tanks. Out of 11 lost A9s, 4 were the victim of technical issues. However, this was the smallest proportion among all cruiser tanks. The AEC A179 engine was the tankers' greatest headache. The narrow tracks were another sore spot, as they did not have any grousers and were very complicated. The 24 A9s remained in France, becoming German trophies. The tanks were indexed Kreuzer Panzerkampfwagen Mk I 741(e), but they were not useful even as training tanks. A number of them were sent to exhibitions and one to the Kummersdorf proving grounds.
The fiasco in France did not mean that the career of the tank, now called Cruiser Tank Mk.I, was over. Other British cruiser tanks were not much better, and the war was still on. On June 10th, after some deliberations, Italy joined the war, threatening British possessions in Africa. Understanding that the situation was dire, the British began reinforcing their units in Egypt back in the fall of 1939. The Cruiser Tank Mk.I was going to be the best tank in use in the Egypt tank division. 68 tanks of this type would be sent to Africa. The tanks would received a set of tropical gear, which included sand shields from the left side.
In practice, the 7th Armoured Division that formed in February of 1940 had only a small amount of Cruiser Tanks Mk.I. A number of its tanks were armed with machineguns only, and the cannons arrived later. Nevertheless, the 7th Armoured made its combat debut on June 14th. 6 of its tanks took part in the attack on Fort Capuzzo. In the summer of 1940 neither of the belligerents had enough forces for active fighting. In September, one Cruiser Tank Mk.I was captured by the Italians.
Gradually, the 1st Royal Tank Regiment began receiving new tanks. By September 20th, it contained 17 Cruiser Tanks Mk.I, and 20 by November 30th. By that point forces in Egypt began to receive other types of cruiser tanks.
British cruiser tanks were plagued by mechanical problems in North Africa as well. The suspension and clutch resulted in the most problems. As of April 1st, 1941, 66 Cruiser Tanks Mk.I and 6 Cruiser Tanks Mk.I CS were present in the theatre. Despite all of their issues, they were used in combat actively. It was soon clear that the machinegun turrets were a bad idea, and they were often removed, with the openings covered by sandbags. The turrets were repurposed as AA defenses.
By September 7th the British Army still had 48 Cruiser Tanks Mk.I, 38 of which were runners and 6 of which were in training units. By this point the British naming system for tanks had changed. This change was also going to affect the Cruiser Tank Mk.I, which would be called Krait I. Since the tanks were hopelessly obsolete by the fall of 1941, this did not happen. A number of British tanks did not receive new names for the same reason.
The saturation of British forces with Crusader, Matilda, Valentine, and Stuart tanks meant that they could entirely replace old vehicles on the front lines. The Cruiser Tank Mk.I was reclassified as a training tank by November of 1941. This didn't mean that they entirely vanished from active combat. For instance, 6 tanks were still present in Tobruk. Service on islands continued even longer. For instance, 4 Cruiser Tanks Mk.I were still in service on Malta as of the summer of 1941.
Two Cruiser Tanks Mk.I survive to this day. One of them, with WD number T.7230, was built by Harland & Wolff in February of 1940. It was one of the last tanks to be built with a 2-pounder, as Belfast began producing howitzer tanks exclusively soon after.
Despite a number of drawbacks, the Cruiser Tank Mk.I was a notable tank in British tank building. However, the concept was already obsolete by the time it was put into production. Nevertheless, the tank designed by Vickers-Armstrongs proved viable in WWII.
Translated by Peter Samsonov. Read more interesting tank articles on his blog Tank Archives.
- Medium Marks I-III, N.W. Duncan, Profile AFV 12, Profile Publications Limited;
- British Cruiser Tanks A9 & A10, Peter Brown, Model Centrum Progres, 2017, ISBN 978–83–60672–28–0;
- Author's photo archive.