Friday 24 November 2023

African Pz.Kpfw.III

The heavy Panthers and Tigers are the best known of Germany's tanks. The lion's share of discussions of armoured vehicles in the Second World War is dedicated to them, even though lighter tanks carried the Panzerwaffe through the majority of the war. The Pz.Kpfw.III tank proved itself to be a worthy opponent in the first half of the war. At the same time, it remained a mystery for the British for a number of years until the first trophies began arriving from North Africa in 1941-42. This is what the British learned from these studies.

Third time's the charm

The Pz.Kpfw.III medium tank was posed as Germany's main tank from the early days of the Nazis' reign, but development was slow. Only 120 tanks were in the field by the start of the Second World War and 381 by the beginning of the Battle of France. Serious losses among them prove that they were actively used and the British Expeditionary Force couldn't have avoided meeting them on the battlefield. However, even if a tank of this type was captured there was no opportunity to study it or send it back to Britain. The speed of the German offensive forced the British to abandon even their own tanks on the continent.

A column of Pz.Kpfw.III tanks in France prepares to move out. The British did not gather any detailed information on these vehicles in 1940.

There was some basic information available. The British knew that the tank weighed 18 tons and was armed with a 37 mm gun. Its armour was 30 mm thick, but there were no details about its layout. The British guessed that this armour was the same all-around. It was also know that early Pz.Kpfw.III tanks had different types of suspensions. There was enough information to at least draw posters of the "Medium-light Pz.Kw.III tank and command tank" for the School of Tank Technology.

The British met the Pz.Kpfw.III tank again in Greece in 1941. The situation in France repeated itself. Little information was obtained about the Pz.Kpfw.III. There was some news of a 21 ton tank armed with the Czech 47 mm gun. The British considered it a further development of the "Type III 18-ton tank". Perhaps this was distorted information about the Pz.Kpfw.III Ausf.G tank that indeed had a more powerful gun and began to approach 21 tons in weight. The real caliber of this gun, 50 mm, was discovered later. The British also learned that the German began to up-armour their tanks with 32 mm thick plates. 

The start of fighting in North Africa resulted in a torrent of new information. The first Pz.Kpfw.III tanks arrived there in March of 1941. These were 80 tanks from the 5th Light Division, mostly Pz.Kpfw.III Ausf.G. The new German tanks clashed with the 2nd Armoured Division on March 31st. The German advance was very successful at first, but stalled at Tobruk. The British were pushed back even further, but these were battles, rather than a one-sided rout. In these conditions it was much easier to obtain information.

A report on the performance of the Pz.Kpfw.III tank in Africa written in the 5th Tank Regiment was soon captured, translated, and studied. The British found out that German tanks were ill-suited for long marches in the desert. The tanks had to drive at night at a speed of 18 kph in order to avoid overheating the running gear. The large swings in temperature had a negative impact on the lifespan of the rubber rims, which broke up after 400 km of driving. The engines also performed badly in the desert. Out of the regiment's 65 Pz.Kpfw.III, 44 experienced engine trouble during marches. Their air filters were helpless against fine desert dust. Sand also made its way into tanks and ruined their mechanisms.

British soldiers examine a captured Pz.Kpfw.III tank in North Africa. May 2nd, 1941.

A Pz.Kpfw.III tank knocked out as a result of a 2-pounder hit to the engine compartment was captured and studied by May 9th. As a result of a fire, its clearance sank from the nominal 305 mm to 229 mm. A dent from a Boys rifle bullet was found in the 30 mm thick armour. This tank was one of the latest models with a 50 mm main gun, "7.91 mm Spandau" machine gun, and 30 mm applique armour plates. The British found a lot of common with the Pz.Kpfw.IV: the engine, gearbox, turret traverse mechanism, and final drives. Only four crewmen were counted. The British expected the commander to perform the duties of the gunner.

The side hatch and its hinges were extracted for a penetration trial held on July 11th. The hatch door was 31.5 mm thick. The armour was homogenous, 363 BHN on the outside and 352 BHN on the inside. The hatch door was shot up after being examined in a lab. The Boys anti-tank rifle was ineffective. Four hits only left dents with bulges on the opposite side, even though one of the bullets hit an area weakened by a weld seam.

Diagram of the hatch door used in the penetration trials. Bullets #5 and #9 managed to damage the bolts, but could not knock off the hinges.

Firing the 13.2 mm Hotchkiss gun brought some success. The last of three hits achieved a complete penetration. The British deemed the quality of German armour to be lower their own. The hinges and bulletproof bolts that held them were fired upon separately. The bolts managed to withstand hits from armour piercing rifle bullets. A Boys rifle bullet smashed one bolt, but the hinge did not come off. The Hotchkiss gun also destroyed a bolt, but did not break off the hinge.

Study of Pz.Kpfw.III armour continued until December of 1941. The quality was generally similar to that of British I.T.80 steel, but some samples were considerably worse. For instance, the 15 mm BESA could not score complete penetrations against one 31.5 mm thick hatch door at even 100 yards (91 m) but incomplete penetrations were scored from as far as 430 yards (393 m). Three other 31.2 mm thick plates could be penetrated fully at 150 yards (137 m). The 16 mm thick engine compartment roof could be penetrated at an angle of 35 degrees with a rifle bullet from 35 yards (32 m) and a Boys rifle from 100 yards.

The armour could not withstand trials against more serious weapons. Two hits from 2-pounder AP shot at a velocity corresponding to a range of 1100 yards shattered a 31.2 mm thick plate installed at an angle of 20 degrees in two pieces. The larger piece was reinstalled and fired at with APC shot at the same velocity. The first shot penetrated the plate, the second shattered it again. The upper portion was placed at a 30 degree angle, but another APC shot shattered it into four pieces. There was no point in firing any longer and the shards were passed off to scientists. They confirmed what was already obvious: German armour was too brittle. The quality of welding was also poor. Weld seams cracked under fire and components that were welded on broke off.

Armour of Pz.Kpfw.III tanks first encountered in North Africa (left) and types discovered later (right).

One tank was shipped to the UK for trials. It was examined by a commission from the AEC (Associated Equipment Company) in June of 1942. The tank's top speed was established to be 25 mph (40 kph). 

The tank suffered some damage either during the mobility trials or before that. When the tank was given to the chemists in October, it was missing the inspection hatch door in the engine compartment bulkhead, machine gun along with the ball mount, and the turret ventilation fan. All of these components had to be replaced in order to test chemical weapons on the specimen. This was quite important, since no German tank was made available for chemical weapons trials previously. A ventilation fan was taken from a Churchill tank, a new door was made, and the machine gun mount was simply welded shut. Trials showed that the Pz.Kpfw.III was very poorly protected from anti-tank chemical weapons. Lethal amounts of poisonous substances entered the tank during an attack and lingered there even with the engine and ventilation fan running.

Thicker armour

The impressive results against tanks with 30 mm thick armour weren't relevant for long, as the Germans had an upgrade ready. Some Pz.Kpfw.III tanks began arriving with applique armour nominally 30 mm thick welded to the front. The plate was surface hardened with an outer hardness of 740 BHN and inner hardness of just 460. 2-pounder shot could penetrate this armour when they hit it, but could not penetrate the main armour behind it. There was only one saving grace: after one or two shots the applique armour fell into pieces or broke off. 

The Pz.Kpfw.III changed its looks quickly as various improvements were introduced.

New 6-pounder guns could penetrate this armour at a range of 500-600 yards (457-549 m). American 37 mm guns could do it from 200-300 yards (183-274 m). American 75 mm semi-AP shells could penetrate the armour from 400-500 yards (366-457 m). A hit from such a large shell could also burst the main seams of the tank. M61 capped armour piercing shells could penetrate the armour at a range of over 1000 yards (914 m). The sides remained vulnerable at longer ranges.

There were also tanks with much softer applique armour, just 540 BHN. The British theorized that this was not an official measure, but a field modification performed in local workshops. The quality of these upgrades was very inconsistent.

Pz.Kpfw.III Ausf.J tanks with 50 mm thick front armour were spotted in January of 1942. The British called these "Mark III New Type". Laboratory analysis of captured vehicles showed that this armour was also surface hardened, but not as much as before. The hardness of the outer side was 530 BHN and the inner side was 375. This armour no longer shattered when hit with 2-pounder shot. On the contrary, British shot fell apart into pieces when hitting it, leaving just a small dent. Penetration could only be achieved at close range. Regular AP shot penetrated the front from 100 yards (91 m), shattering in the process. Improved shot with a higher muzzle velocity penetrated from 300 yards (274 m) leaving a jagged hole 45 mm in diameter.

A Pz.Kpfw.III Ausf.J tank captured by Australians at Tel el Eisa near El Alamein, summer 1942. This tank has even more additional armour.

Laboratory analysis showed that if the shot could penetrate the shallow hard outer layer then it could effortlessly go through the rest of the plate, which was much softer. Testers estimated that penetration with ordinary shot could be reached from 200 yards (183 meters) and from 400 yards (366 m) with improved shot. Higher quality American 37 mm shot could penetrate from 600 yards (549 m). 6-pounder shot penetrated this armour from 800-900 yards (732-823 m), shattering in the process. The American 75 mm gun managed to penetrate the front at a range of up to 700 yards (640 m) with semi-AP and 1700 yards (1554 m) with proper AP. The performance of the armour was considered to be high when it came to defeating uncapped shot, but worse than British I.T.80 armour against APC shot.

The tank was also shot up from the air with 20 mm AP Mk.III shells from the Hispano aircraft gun. Three shots out of 16 that hit penetrated the side in the first pass, 9 out of 26 in the second, and 14 out of 28 in the fourth. On the third pass the pilot attacked the tank from the front, but didn't score any hits. The shells that penetrated dealt a lot of damage. The turret side hatch was jammed, the shells that penetrated the roof destroyed the ammunition bins, and the fuel tank was penetrated, which could have caused a fire.

Hull of the Pz.Kpfw.III tank after being hit by the 20 mm Hispano autocannon. This was the main weapon of British ground attack planes.

Analysis carried out at the American lab at the Watertown arsenal gave similar results to what the British found. The armour studied by the Americans was a bit softer: 331-388 BHN on the inner side and about 600 BHN on the outside. Like the British, the Americans judge the depth of the hardening to be insufficient. 37 mm M80 shot penetrated it easily, let alone M51 capped shot. The armour itself and its weld seams cracked easily.

The same was true for the 16 mm thick homogeneous roof when tested against 20 mm shells. This unsatisfactory performance under fire was a surprise, as the steel was rich in alloys and could have performed a lot better. The quality of the armour was worse than that of American armour of the same thickness. This was not just the fault of one bad batch. Judging by the paint on the armour, the samples were not only taken from different tanks, but also from different theaters of war.

A Stuart tank passes a burning Pz.Kpfw.III. Even the American 37 mm gun could penetrate the tank's armour.

This brittleness showed itself on the battlefield. Cracks, shattering, and ragged penetrations were common when disabled German vehicles were inspected. On one tank, the gun mantlet was shattered completed by a hit from a 6-pounder or 75 mm shell. The face of the turret also cracked.

Close encounter

The British finally captured a more or less intact Pz.Kpfw.III tank in February of 1942. Unfortunately, it was unsuitable for mobility trials, as after 1600 km of driving the engine was very worn. The tank's top speed was measured at just 26 kph. The British didn't blame just the sand for the tank's condition. By their calculations, the Pz.Kpfw.III had two tons of modernization reserve when they first encountered it. The upgrade to a 50 mm gun and thicker armour ate it all up and then some. The German tradition of loading their vehicles with sandbags and spare track links for protection didn't help.

Study of the tank showed many cracks all over its hull. It seemed that the tank was previously knocked out, evacuated, and repaired. A penetration in the side was welded up, causing more cracks.

A demolished Pz.Kpfw.III. In the open desert, it was often easier to demolish an enemy tank than try to recover it for study.

The British counted 89 rounds in the ammunition racks. The shells themselves were interesting, as the 50 mm shell carried 16 grams of HE. The British considered that this was done to make the shell burst after penetration. Brittle British shot that shattered in the process of passing through armour didn't need any help. Further study showed that the red-hot splinters could ignite ammunition if they struck an ammo rack. As a result of this study, the British started to protect their ammo racks.

The subcailber armour piercing shot was more interesting. The British previously encountered it only squeezerbore weapons. Without a squeeze bore, the British considered the shot's ballistics to be "hopelessly poor" and did not consider it to be superior to an ordinary shot.

The quality of the telescopic sight was judged to be high, but it could not be used at the same time as a gun shoulder stock, a popular solution on British tanks for elevation. The German gun had geared elevation with a spring mechanism for balance.

The ammunition racks did not impress the British. The sliding lids easily gathered sand and jammed. It was also difficult to retrieve the rounds from their slots. Some tanks were found with a great deal of ammunition outside of their racks stored loose on the floor. In this case, a single tank could carry up to 178 rounds of ammunition, mostly armour piercing. The British estimated that the 5 cm KwK penetrated 56 mm of armour at 500 yards (457 m) at 30 degrees and 68 mm at normal, with 47 and 58 mm respectively at 1000 yards (914 m). 

There was no shortage of captured Pz.Kpfw.III after victory at El Alamein, but by then the British were more interested in other German tanks.

The Pz.Kpfw.III's cupola was also not very interesting. It was considered to be a big target, but its exit hatch was too small. The periscopes were too slow to switch between and the field of vision of 70 degrees was insufficient.

In general, the study of British documents reveals that the "light-medium" tank had its share of drawbacks. At the same time, it should not be underestimated. The Pz.Kpfw.III was a dangerous opponent with a weapon that could defeat nearly every contemporary British AFV at long range, and it was only with the arrival of American medium tanks with long 75 mm guns that British tankers could fight the Pz.Kpfw.III with relative impunity. However, the war was far from over, and the German tank continued to evolve.

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