Cold War, United Kingdom

Conqueror – Britain’s Answer to Soviet Heavies

The Conqueror was a British heavy tank designed specifically as a counter to the IS-3 first seen by the Allies at the end of WWII. Weighing 70 tons and carrying a massively powerful 120 mm gun in a 20 ton turret, this monster was one of the most formidable tanks of its day.

The FV214 Conqueror was near the top of the food chain and an armored icon of the 1950s, but its development dated back to WWII.

It was part of a solution to Britain’s realisation during WWII that they were outgunned and out-armored by foreign designs.

But by the time it arrived, the Conqueror, and the wider idea of heavy tanks was already becoming a thing of the past. Still, Britain had asked for an IS-3 killing tank, and an IS-3 killing tank is what they received.



Britain did not have much luck with its tanks for the majority of WWII. Hampered by bureaucracy, unreliability, weak guns and convoluted doctrines, Britain struggled to field good, well rounded tanks until the very end of the war.

However after its experiences against thick German armor and anti-tank guns, Britain finally scored a win with not one, but two late war designs, Comet and Centurion.

An A34 Comet
The Comet carried a slightly de-powered version of the 17 pdr, and is considered a genuinely excellent design.

Centurion was the result of Britain’s ‘Universal Tank’ idea, something that we today call the main battle tank, or MBT. The Centurion arrived with the powerful 17 pdr, but Britain understood that this would not be enough to deal with heavy Soviet armor already on the scene.

They needed a bigger gun.

At the time there was no way of putting a IS-3 killing gun on any serving tank, so they had to resort to the previously cancelled Universal Tank.

Universal Tank

At the end of World War Two, Parliament forced the British military to reorganize and reduce the number of armored vehicles it employed. After all, if one vehicle could perform multiple roles, the cost savings from parts, maintenance, and training would be astronomical.

To accomplish this ambitious project, the British set about designing the FV200 Universal Tank. British designers envisioned this series of tanks to answer all of their armor needs. The only problem was the design did not consider the existing logistical capabilities of their own forces along with rapidly advancing Soviet technologies.

FV201 Prototype 1 with a Centurion Mk.II turret.

When Parliament reviewed the program in 1949, they found that the existing bridge clearing and DD model tanks would not have the vertical clearance needed to be launched from existing LST ships. Additionally, the tank design as it stood did not have enough room to accommodate the accessory gearbox required to operate the mine flailing attachment.

Combining these failures with the fact that Parliament and the Ministry of Defence concluded that by the time the FV200 series tanks could be operational they would be obsolete, meant its death sentence.

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However even though Parliament cancelled an allegedly defunct program, saving British taxpayers untold millions of pounds; it did not change the fact that the Soviet IS-3 was still the dominant heavy tank on the battlefield with no weapon available to challenge it.

IS-3 on display.
The IS-3 had a huge impact on post-WWII tank design. Image by Alan Wilson CC BY-SA 2.0.

They simply did not have time to develop a completely new model from scratch, and they needed a weapon system that could be fielded quickly and at minimal cost to match the IS-3.

As it happened, the FV200 project was hefty enough to carry the large gun necessary to counter Soviet tanks.

The FV200 chassis received a massive turret and an equally large gun, creating the Tank, Heavy No. 1, 120 mm Gun, Conqueror. For you and I, that is Conqueror.

FV214 Conqueror

Though the basic design remained the same, the designers did tweak the engines a bit. The engineering team kept the existing Meteor engine configuration the same but changed the fuel injection system. Now the engine was configured to spray pressurized, atomized fuel just before the inlet valves opened.

They also designed it so that no matter the gradient the vehicle was operating on; it would create an even flow. The result was that the Meteor engine would now have increased efficiency on each of its 12 cylinders, increasing from 750 hp to 810 hp.

A Mk III Meteor V12 engine.
The Conqueror used one of the last Meteor variants, the M120. This Meteor pictured is a Mark III. Image taken at The Tank Museum.

The Conqueror also employed a series of redundant generators to supply power to the hulking beast. For normal operations, the Conqueror used a 150-amp generator. But when in combat, with higher expected energy needs, the Conqueror used a separate 350-amp generator powered by an independent 29 hp motor. Because of this multiple, redundant system of power, the tank was able to withstand greater damage and stay in the fight longer without fear of the going dark.

Despite making few changes to the hull and engine, the British made drastic changes to the tank’s turret and main armament; a massive 120mm gun. The British army needed the huge caliber to engage and destroy the heavier IS-3 tank beyond the effective ranges of the Centurion tank.

The Conqueror's gun.
The Conqueror’s L1 120 mm rifled gun was based on the American M58 used in the M103 heavy tank. Image taken in The Tank Museum.

The only problem was that the British had no experience building such a massive tank gun. As a result, they turned to the Americans and their M103 Heavy Tank. They adapted the 120 mm from that tank to the Conqueror, giving it fearsome firepower.

Matching its gun, the Conqueror was covered in some seriously thick armor. Its upper glacis was protected by 130 mm of steel angled at 60 degrees.

Sources vary on its turret thickness, but this is likely to be around 250 mm on the front, with some estimates placing this at 300 mm.

The Conqueror's turret.
The exact thickness of the Conqueror’s turret has been quite the mystery, with estimates ranging from 150 mm to over 300 mm.

One of the Conqueror’s distinguishing features is its advanced fire control system.

The commander was located in a separate fire control turret that moved independently from the main turret and allowed him to seek and select targets while the gunner was engaging a previous target.

By looking through two eyepieces, the commander’s right eyepiece would first have to site the target squarely in the middle. Using a handwheel and traversing the turret, the commander can get the target into the center of the range finder in the left eyepiece.

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Once satisfied with the target, the commander then moves the turret in line with the sight. The gunner can also see the same target picture displayed on the commander’s eyepiece. The gunner could then make corrections, such as the lateral tilting of the tank.

Conqueror commander's cupola.
This is the Conqueror’s independently rotating commander’s cupola, an advanced feature for the time. Image taken in The Tank Museum.

The system then allowed the gunner to conduct the engagement while the commander was free to search for the next target. However, despite being a remarkable engineering feat, this complicated system often failed in practice, forcing the British army to adopt a somewhat less complex version in the Mk II models.

Another flaw in the gun design was its limited arc of elevation. With a maximum of 15 degrees to minus 7 degrees, the tank had limited capability of traversing its gun. In areas where the tank was to take up defensive positions on a hill shooting down, the Conqueror had limited utility.

As an added safety feature, the Conqueror’s fire control system had a characteristic that when it detected speeds of at least 1.5 mph, it would automatically unlock the gun from the elevation control to its stabilized mode. This protected the 2.9 ton gun from damaging its mounting, but at the same time prohibited the tank from firing on the move.

Conqueror gun
The Conqueror’s gun was so large and heavy that it automatically entered a free moving mode when on the move to stop it rattling its mounting apart. Image taken in The Tank Museum.

The Conqueror’s ammunition also pigeonholed it into a static defense role rather than an infantry support role. Its 120mm gun only had two types of ammo manufactured for it, the High Explosive Squash Head (HESH) and Armor Piercing Discarding Sabot (APDS). British designers meant for both of these rounds to be tank killers, and with only 35 rounds on board, each shot had to count.

Though the Conqueror did have two 7.62mm machine guns, these were purely meant for crew self-defense and not for offensive operations.

But even with all the advancements made, the Conqueror never once fired a round in combat.


The British army deployed them to bases in West Germany for an invasion that would never come. Though if it did come, the Soviets would have faced quite a difficult nut to crack since the British army testing proved that in a 214-round trial, they recorded just one miss!

Had the Soviets invaded West Germany, they would have encountered Conquerors in a limited, long-range fashion. British doctrine dictated that only up to nine would be issued to each armored regiment, and each Centurion squadron would get one at a minimum.

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The Centurions would take the lead in offensive operations, with the Conquerors rumbling behind to take long-range shots. In a defensive role, the squadron or regimental commander would place his Conquerors to defend the most likely enemy tank approaches to their position.

A Conqueror MK.II.
In battle, the Conqueror would have fired from long range over the heads of attacking Centurions. It was hoped that the Conqueror’s advanced gunnery system would help stop the mass Soviet tank attacks.

But alas, the Conqueror would never see the day for when they would get to test out these theories. After it was first introduced into service in 1956, the army produced only two models, and production was limited to just 180 units total. After a measly ten years in service, the army retired the tank from service.

Why they did so was for several factors. As evidenced in the report, the Conqueror served a limited purpose stop gap to combat the heavy IS-3 tank. When secret army testing proved that the final product had little benefit in actually accomplishing that task, British army planners opted to build a replacement tank as soon as possible.

While this tank was in development, the army started refitting Centurion tanks with the L7 105mm gun. Combining this with the fact that the replacement tank, the FV4201 Chieftain heavy tank, was in total production by the early 1960s, soon meant the end of the Conqueror.

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Once the British had produced enough of these tanks to outfit entire units, the British army retired them from service and relocated them to the history books.