Tracklink Article - A43 Black Prince – The Last Infantry Tank

This was originally published in Issue 109 (Summer 2021) of Tracklink, the magazine of the Tank Museum.  However, the photos which accompanied it are owned by the tank Museum, so I have replaced them with another photo from the public domain

For much of the Second World War, British thinking divided tanks into three categories. Light tanks were for scouting, but in practice this role was increasingly taken over by armoured cars. Cruiser tanks were originally intended to operate in an independent “cavalry” role, but were increasingly used almost interchangeably with US Mediums supplied under Lend-lease. Finally, Infantry tanks were slow but heavily armoured vehicles for infantry support.

By 1943, the standard Infantry tank was the A22 Churchill. This had overcome its initial problems with reliability to become a well regarded design, and the latest Churchill Mk VII had been up-armoured to 150mm, significantly more than the 100mm carried by the German Tiger.

Although the Churchill had been successfully up-gunned to carry the 75mm gun, it was obvious that neither the 75mm nor the 6 pdr retained on a proportion of Churchills in Europe because of its better armour piercing performance would be able to take on the more heavily armoured German tanks such as the Panther, which were being met in increasing numbers

Fitting a more powerful gun was the obvious answer, but this was difficult because the Churchill's high track run meant its turret ring sat between the tracks rather than above them. This restricted the turret ring to only 54 inches (1,350mm) and meant the Churchill could not be upgraded to carry the powerful 17pdr, while the Sherman - a smaller vehicle overall, but with a turret ring above its tracks instead of between them – could de developed into the 17pdr Firefly.

The obvious solution was General Staff Specification “Tank, Infantry, A43 Black Prince”, issued in 1943, which essentially set out a requirement for a 17 pdr armed “Super Churchill”. The lead producer was Vauxhall Motors, who produced the Churchill. Unsurprisingly, the new tank had bore a strong resemblance to its predecessor.

The hull was effectively an enlarged version of the Churchill, widened by 10in to accommodate the larger turret ring for the 17 pdr turret. It retained the side escape hatches of the Churchill, though the engine intake louvres were re-located to the rear deck rather than protruding from the sides, which partly offset the increase in vehicle width.

More importantly, and to the disappointment of the Department of Tank Design, it retained the stepped front plate for a hull Besa MG fired by the co-driver, rather than a more modern sloped glacis. The latter would either have increased the effective thickness of the front armour from its already impressive 152mm, or allowed it to be thinned down to reduce weight while keeping the same effective thickness.

The suspension was a reinforced version of that fitted to the Churchill, consisting of 12 separately sprung wheels with a front idler and drive sprocket at the rear. The tracks were widened by 10 inches to carry the extra weight, so ground pressure was reasonably good.

The front idler was slightly lowered and the Driver’s position moved slightly forwards, improving the driver's visibility past the track ‘horns’, which had been an issue on the original Churchill.

The larger gun required a new and larger pentagonal turret, with the same 152mm front face armour as the hull and containing the standard three man crew of gunner, loader and commander. It did not copy the recessed internal mantlet used on the Churchill, which created an obvious shot trap, but used a conventional curved mantlet similar to that used on the contemporary A34 Comet cruiser tank.

Like the Comet, a canvas cover was fitted over the mantlet. This prevented dirt and small stones getting into the gap between mantlet and turret and stopping it from moving up and down, which had been a problem during trials.

The main armament was the 76mm Ordnance QF 17-Pounder Mk. VI, an upgrade of the 17 Pounder anti-tank gun which first appeared in 1943. The Mk VI was a modification of the Mk IV used on the Sherman Firefly, which had the breech modified to open sideways rather than downwards as the towed anti-tank gun did and thus took up less more room inside the turret.

The 17 pdr was a well regarded weapon capable of dealing with any contemporary German tank. The primary ammunition against enemy armour was either APCBC (Armour-Piercing, Capped, Ballistic-Capped) which could penetrate 163 mm of armour at 500 meters and 150mm at 1,000m or APDS (Armour-Piercing Discarding Sabot). The latter could penetrate 256 mm of armour at 500m and 233mm at 1,000m. However, while the APDS round had superior penetration, it had accuracy issues at ranges over 500m, and did not completely supplant APCBC.

A High Explosive (HE) round was also used against infantry positions, an important task for an infantry support vehicle. However, an inevitable compromise of the higher muzzle velocity that made the the 17 pdr an excellent anti-tank weapon was that its HE round actually had a smaller bursting charge than the older 75mm HE rounds used by the Sherman and Churchill, and was correspondingly less effective.

Secondary armament consisted of two 7.92mm Besa machine guns, one mounted coaxially next to the main armament and the other in the front hull. 89 rounds of 17 pdr ammunition were carried, plus 8,125 rds of 7.92mm for the Besas and 600rds of .303 for the AA Bren.

There was brief discussion of the Black Price mounting the 94mm (32 pdr) gun which began development in late 1942 as a successor to the 17 pdr, with an estimated 25% improvement in armour piercing performance. However, this would have required an even larger vehicle, and since the appearance of the improved APDS rounds for the 17 pdr reduced the need for the new gun, the project did not go ahead and the 94mm gun was only ever used in a fixed casemate on the six A39 Tortoise prototypes.

The A43 prototypes passed acceptance tests reasonably well, with one completing 1,500 miles, although there was grumbling over the awkward ammunition stowage for the long 17 pdr rounds. However, there were concerns over speed and power-to-weight ratios.

Infantry Tanks were not expected to be fast, given they were limited to the pace of the infantry they supported in action anyway. The 40 ton Churchill Mk VII, heaviest of the family, managed 12.5 mph on roads and 8 mph cross country with a 350 HP Bedford horizontally opposed twin-six petrol engine.

However, the 50 ton Black Prince used the same engine in a vehicle ten tons heavier. The result was predictably underpowered, achieving at best 10.5 mph on roads and 7.5 mph cross country, though the latter was on frozen ground and would probably have been rather worse under normal conditions.

The problem was made worse by a tricky five-speed gearbox, compared to the four speed box on the Churchill. The gears were too close together,and gear shifts had to be fast and certain to avoid stalling the underpowered vehicle, especially when changing upward where retaining momentum was vital

The obvious solution of using the much more powerful 600 HP Rolls-Royce Meteor engine was considered. This would have improved the power-to-weight ratio from 7.5:1 to 12.5:1 and it was estimated that this would have give a very respectable top speed of around 22 mph. The Meteor was too tall to fit within the existing engine bay, and would have needed to be installed at an angle. Although the proposal seems to have been regarded as viable from an engineering point of view, it did not go ahead.

One reason why the Army appear to have rather lost interest in the Black Prince was that by the time the Black Prince prototypes appeared in May 1945, the need for them no longer really existed. The Sherman Firefly and the Cromwell-derived A30 Challenger had both appeared mounting 17 pdr guns the previous summer, though both were only flawed interim solutions.

The A34 Comet appeared in December 1944, mounting a 77mm gun that was almost equivalent to a 17 pdr, and more importantly the first prototypes of the A41 Centurion also appeared in May 1945. This had the same armament as the Black Prince, equivalent armour if one allowed for the better sloping and much better mobility.

There was discussion of using the Centurion Mk I turret on the Black Prince chassis, since it carried the same 17 pdr gun, had the same 152mm armour standard and would fit the same turret ring. While standardising turrets was logical and would have had cost and logistic benefits, it did rather raise the question of whether two separate tanks with the same turret were actually required. In any event, the idea was not taken forward

British doctrine had also moved away from separate lines of Infantry Tanks and Cruisers. Montgomery had been vocal well before D-day about his preference for ending Infantry Tank production (including the Churchill) in favour of a “capital” or “universal” tank capable of performing both functions, and had insisted throughout the NW European campaign on all armoured units under his command being interchangeable and able to work in any role, whatever tanks they might have.

This line of thought was doubly attractive with the war against Germany almost over, as Britain was heavily in debt and clearly needed to concentrate on a smaller number of armoured vehicle types to minimise the strain on limited postwar development budgets

The ultimate result was that the Black Prince was cancelled, and Britain standardised on the Centurion as its first postwar “Main Battle Tank”.

Only six Black Prince prototypes were built. One went to FVEE for acceptance trials, two went to Vauxhall for development, one went for offensive firing trials, one went for “firing at” trials and the last for wading trials. The fourth prototype survives in running condition at the Tank Museum, while the hull of another was recovered from Salisbury Plain in the 1980s and is held in a private collection.