Wednesday 22 May 2024

Quick-Fix Tank Destroyer

British tank building was in crisis in the spring-summer of 1941. The latest Pz.Kpfw.III and Pz.Kpfw.IV tanks encountered in North Africa could only be defeated with the 2-pounder gun at short range. Intelligence reported on heavy and superheavy Pz.Kpfw.V, Pz.Kpfw.VI, and Pz.Kpfw.VII tanks that the 40 mm gun would be completely powerless against. The British were in urgent need of a vehicle with a more powerful gun.

Any color the customer wants

The British needed to find a suitable gun and a suitable chassis. There were promising weapons: the 57 mm 6-pounder and 76 mm 17-pounder. These guns could deal with the even the most modern tanks. There was, however, a small problem. Mass production was not scheduled to start until at least the end of the year. It was also necessary to develop new gun mounts and turrets to fit these guns. The issue of cost was also an important one, as the British had to replenish their tank fleet after abandoning a good part of it in Europe, and a 2-pounder gun was considerably cheaper than a 6-pounder, let alone a 17-pounder.

Penetration of the 3" gun using a new round with increased muzzle velocity. This gun could theoretically fight any German tank.

There was a more budget friendly variant. The QF 3-inch 20 cwt AA gun accepted into service back in 1914 was being pushed out of service by a more modern 3.7" gun. Old AA guns could still be found in storage, and they could make a powerful anti-tank weapon. 

Trials showed that the HE shell was useless against even light tank armour. However, 12.5 lb (5.67 kg) AP shot with a muzzle velocity of 2600 fps (792 m/s) could penetrate 75 mm of armour at 30 degrees from 400 yards (365 meters), 58 mm from 1000 yards (914 meters) and 37 mm from 2000 yards (1828 meters). An improved AP shot was also developed that was supposed to penetrate 100 mm from 100 yards (91 m) and 80 mm from 750 yards (686 meters). In trials, the shot penetrated 91 mm at 400 yards, 77 mm at 1000 yards, and 55 mm at 2000 yards. This weapon couldn't defeat phantoms like the Pz.Kpfw.VII, but it was good enough to fight any real German tank. There was also some discussion of developing an AP-HE shell that would be more effective than simple shot.

Carrier, Churchill, 3-inch Gun, Mk.I with a 3" 20 cwt gun. The WD number is still in a tank format.

The weapon had its share of drawbacks. As the name suggests, it weighed 20 cwt or about 1000 kg. It was not very compact either. The gun would not fit into any existing tank, but luck was on the side of the British that day. Work on the Infantry Tank Mk.IV or Churchill was just coming to an end. This tank was considerably larger than any existing tank and could fit the AA gun.

The War Cabinet approved this initiative by the end of April 1941. Use of 100 guns of various types was authorized, including the Mk.IA, Mk.IB, and Mk.IIIA. Vauxhall built a wooden model of the vehicle in early July.  The company didn't seek out any novel solutions and simply stuck the gun inside a ball mount in the front of a rectangular casemate. The gun was located quite low, shifted to the left from the center. The crew entered the vehicle through the commander's hatch in the roof or a large door in the back. The Churchill's evacuation hatches in the sides were retained. A second pair of pistol ports was put into the sides of the casemate.

The prototype as seen from the front.

The driver stayed in the same place as on the basic tank. The gunner sat behind him and the commander sat behind the gunner. The loader sat to the left of the gunner.

Since the Churchill tank was developed at Vauxhall, they also got the contract to build the tank destroyer. Contract T2787 for 100 "A.22 tanks special type" was signed on July 25th, 1941. Officially, the vehicle was designated Carrier, Churchill, 3-inch Gun, Mk.I.

Vauxhall ended up completing only the prototype. Assembly of the rest of the vehicle was passed on to Beyer, Peacock & Company of Manchester in contract T11614. Since the imminent threat of invasion had passed, the contract was cut to 24 units, but then later increased to 49. The "special tanks" were allocated WD numbers from S.31273 to S.31321. The letter S indicated that this was indeed a self propelled gun and not a tank. This decision was not made immediately and the prototype still carried the tank number T.31996.

The plan was to produce 24 tank destroyers in April of 1942 and the rest in May. Production was delayed and only started in May, ending on November 2nd.

The first production Churchill Gun Carrier.

Trials with a predictable result

The decision to built the improvised tank destroyer was easy, but building it was harder. A report on tank development dated August 22nd, 1941, stated that development had been going for a long time, but there were no concrete results.

Permission to conduct live fire trials at Lulworth was only given on May 14th, 1942. The tank destroyer was officially demonstrated on June 27th, 1942. Eight shots were fired at a moving target from 1200 yards (1100 meters). Six hit the target and another hit was considered likely. 

The casemate was large and poorly armoured.

The first production tank destroyer with WD number S.31273R arrived at Lulworth by August. The letter R meant that the vehicle had gone through the remanufacturing program. Trials were conducted in September.

32 shots were fired during trials. The vehicle rocked back and forth after firing, which made observation and fire correction difficult. The Gun Carrier also rocked when changing targets. This was noticed during trials of the prototype, but not to such an extent. The prototype calmed down after 1.5 seconds when changing targets and 1.4 seconds after firing, which allowed the gunner to observe the impact of the shell at a range of over 1000 yards. The production vehicle oscillated for 2.4 seconds at a higher amplitude after changing targets and 2.8 seconds after firing, which meant that the gunner could only observe a shell hit at over 1800 yards (1646 meters). The trials report noted that observing the impact of a shell with a muzzle velocity of 2800 fps (853 m/s) would be even harder.

Even though the Churchill Carrier's casemate was large, it was not roomy.

There was also an issue with aiming. The flywheels were not easy or intuitive to operate, which meant that the gunner took a long time to get on target. It was difficult to turn the traverse flywheel due to its short handle and the elevation flywheel had no handle at all. There was a considerable backlash on both flywheels. The gun had to be locked at maximum elevation during travel.

The No.30 telescopic sight was not installed on the vehicle that arrived for trials. The proving grounds attempted to install one themselves, but the opening was too narrow. The mount made it almost impossible to fix the sight in place, and it wobbled so much that calibrating it would have been pointless.

The large gun sight opening was protected by a shutter so thin that it could be penetrated by a rifle bullet.

The testers also did not like the casemate. The front armour was 87 mm thick and the front of the sides was 53 mm. The rear portion of the sides that protected the ammunition was as thin as the roof: 20 mm. There were even more vulnerable parts of the vehicle. The gun sight opening was protected with a shutter just 16 mm thick. A 7.7 mm bullet could penetrate it from 50 yards (45 m). The report noted that a German armour piercing bullet could penetrate 19 mm from 100 yards (91 meters). There was no splash protection for the gun mount.

Fighting compartment, looking to the rear. Most of the ammunition was located here, protected by just 20 mm thick armour. The rear hatch that was supposed to be left open can be seen.

The gun only had 5 degrees of traverse to each side. Three vanes were welded to the roof in order to help the commander visualize the range of his gun. The gun could only be fired with the engine running, and not just because the whole vehicle needed to turn in order to aim. The engine also sucked out the fumes from the fighting compartment. Even so, official instructions recommended keeping the rear hatch open while firing. 

There were other complaints, such as inconvenient location of instruments. The overall evaluation was not kind. The vehicle was too large and poorly protected to be a tank destroyer. Poor mobility and a narrow traverse range of the gun gave it few chances of survival at short distances. The Churchill Gun Carrier could also not fire on the move. The report flat out stated that the Churchill Gun Carrier was unsuitable for front line service.

Churchill Carrier on a landing ship. Unlike other tanks and SPGs of the time, the Carrier did not take part in large scale landing exercises.

Work on the Churchill Gun Carrier didn't end here. The first production vehicle was used to test different gun sights until the end of 1942. A decision was made to use the No.33 sight. The final sight markings were only approved by the end of February 1943. There was also work done on the issue of splash protection. Deflectors were developed in March and tested in late April. They were approved after some improvements, but that was the last mention of the Churchill Gun Carrier in Lulworth's reports.

Service without glory

Despite many drawbacks, the tank destroyer still entered service. The 1st Canadian Tank Brigade was notified on April 8th, 1942, that as a temporary measure "against enemy superheavy tanks" they are being issued nine such vehicles. No additional crews were sent. Official instructions recommended one platoon of three vehicles per battalion, but the Canadians decided to gather their tank destroyers into one heavy support company.

One of the four Churchill Gun Carriers found in Kent in 1999. Photo from Chris Shillito. 

The company TO&E was developed by May 22nd and approved on June 24th, 1942. The company had three platoons of three tank destroyers and its own staff. There were 97 men in the company in total: 28 in the staff and 23 per platoon. Personnel from the brigade's regiments were reassigned to form the company.

On June 27th, 1942, the company staff settled in Ovingdean, East Sussex. Training began in August even though the vehicles themselves only arrived in September. Just five were available by September 19th, all converted from Churchill III tanks. By October 10th they had 8 vehicles and 10 by November 7th, one over authorized strength. The extra tank destroyer was passed on to another unit on January 23rd, 1943. The rest of the vehicles did not last for much longer. The company was disbanded on February 15th and the Gun Carriers were sent into storage.

At time of writing, the last surviving Churchill Gun Carrier can be seen in a storage yard behind the Tank Museum in Bovington.

The career of other Churchill Gun Carriers followed more or less the same path. It was clear in 1943 that the Germans would be unable to invade the Home Islands. The British themselves were preparing for a landing in Europe. Germans superheavy tanks never appeared, and the 17-pounder was enough to combat the Tiger. There was simply no need to send the hurriedly slapped together tank destroyer into battle. The Churchill Gun Carrier never found a purpose. It came too late to defend Britain from an invasion in 1941 and there was nothing else it could be used for. The history of this awkward vehicle was brief and unremarkable.

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  1. The "quick fix" was authorized in April 1941 and resulted in 10 crappy useless vehicles by November 1942 - about 18 months. Is it just me or is this another example of the poor performance of the WW2 British AFV industry? How does this compare to German and Soviet efforts to produce new vehicles in response to urgent requirements?

    1. Very badly. A comparable situation happened in the USSR with the ZIS-30. Discussion began on June 9th, 1941. The German invasion expedited things a little, so a prototype was ready by July 20th, deliveries of the production vehicle began in September and a batch of 100 was fully shipped in October. The line ended there as the chassis was no longer in production, but it shows that a vehicle can be put together from existing parts very very quickly.

      I think with the Germans the equivalent would be the Marder II or rather 7,62 cm Pak 36(R) auf Fgst. Pz.Kpfw.II(F) (Sfl.). The order to combine captured guns and the failed Pz.Kpfw.II Ausf.D chassis was made in December of 1941, a prototype was ready by April, 150 vehicles were built by May 12th, 1942.