The Wehrmacht's Unplanned Workhorse

How the Pz.Kpfw.IV became Germany's most numerous and longest serving tank.

There are many cases in worldwide tank building where not everything went according to plan. Even the legendary T-34 was supposed to leave the stage in 1941 in favour of the T-34M. Only the start of the war saved it from replacement. A similar thing happened to the Medium Tank M4. It was supposed to be replaced in 1943, but the replacements didn't turn out well. This happened to every long-serving tank, and the Germans were no exception.

The Pz.Kpfw.IV Ausf.C was the most common German medium tank at the start of the war.

Usually when one imagines a German tank, they think of a Tiger or a Panther. In reality, the typical German tank was a very different vehicle. The Pz.Kpfw.IV tank was initially developed as a fire support tank. It occupied a secondary role in the German armament system, but it was the most numerous German medium tank at the start of the war. It became the most numerous again in 1943 and kept the lead until the end of the war. How did this happen and why did the Panzer IV remain in production for so long?

Sword of Damocles

The situation where two medium tanks were in production at the same time was no accident. The Germans created a problem for themselves that they could not solve until the end of the war. Initially, there was only one medium tank: the Grosstraktor. Created as a German take on the British Medium Tank Mk.D concept, the Grosstraktor likewise had a lot of issues. The German army, including the 6th Department of the Ordnance Directorate, had a creative approach to tank building. This applied to both their requirements and their solutions. In the meantime, Germany had everything they needed in the late 1920s to build a good tank.

Grosstraktor, the first German medium tank.

To compare, the USSR took many ideas from the Grosstraktor to build the T-28. For some reason, the USSR got a working medium tank and the Germans didn't. They managed to fail at this a second time with the Neubaufahrzeug, which partially repeated the fate of the Soviet tank. Instead of 15 tons, it weighed 23. While the T-28's growth was caused by rising requirements (expanding the turret to 3 men, strengthening the armour, etc), the Nb.Fz. didn't grow any more powerful. Even its multiturreted layout was especially ineffective.

The Nb.Fz. weighed 23 tons instead of 15.

The arduous process of creating a medium tank was similar to what was happening with the light tank. The Leichttraktor weighed over 8 tons instead of the requisite 6, and that was just the beginning. The military didn't know where to stop. The programs to develop larger and larger light tanks led to the Z.W. medium tank. The Germans were not alone in this. For example, the French Char D family grew out of the Renault NC tank. The T-46-1 was also a 15 ton tank replacing the 10 ton T-26. The Pz.Kpfw.III Ausf.A weighed the same. Meanwhile, the T-46-3 with extra armour could have weighed all of 18-19 tons, not to mention the T-46-5 that would have weighed more than 30 tons.

B.W. (Kp), the tank born from a turret.

Events in Germany progressed differently. The Z.W. was a clear favourite and the Nb.Fz.'s successor was relegated to the role of a support tank. The Germans weren't alone here either. The British also built support tanks starting in the 1920s. However, only the Germans built a whole new tank for it. Other nations just replaced the gun or built a new turret at most. Initially, the B.W. (Begleitwagen, support vehicle) was built by Rheinmetall-Borsig and the turret was supplied by Krupp. However, Krupp managed to get permission to build a whole tank of their own. The B.W. (Kp) turned out to be better than the Rheinmetall-Borsig project. Krupp even managed to meet the weight requirement. This was a  rare scenario in German tank building.

Pz.Kpfw.III Ausf.A and Pz.Kpfw.IV Ausf.A. The former was no more than a proof of concept, while the latter was the first in a long series of production tanks.

The rest of the story is no less interesting. The 6th Department of the Ordnance Directorate began to suspect something after the B.W. was accepted into production as the Pz.Kpfw.IV. They realized that two very similar tanks were now in production and the more they evolved, the more similar their characteristics grew. The solution was logical: keep only one tank. However, the 6th Department had the wrong tank in mind. While the Z.W. was still going through significant growing pains, the B.W. was a quite successful vehicle from the very beginning. However, Kniepkamp continued to develop the Z.W. (Pz.Kpfw.III) while trying to cancel the B.W. (Pz.Kpfw.IV). Only the turret was to remain of the latter tank. Only the terrible state of the Z.W. program allowed the B.W. to remain.

The Pz.Kpfw.IV proved itself as the better medium tank during the 1939-40 campaigns.

The end result was predictable. The Z.W.38 (Pz.Kpfw.III Ausf.E) was a very unrefined tank. Its top speed of 70 kph was only achievable for a short time, as the running gear could not sustain it. After long attempts to beat the Maybach Variorex 10-speed semiautomatic gearbox into shape, the designers brought back the 6-speed ZF SSG 76. This meant that the mobility of the Pz.Kpfw.III and Pz.Kpfw.IV was essentially the same. The experience in 1939 and 1940 also gave food for thought. The army considered the Pz.Kpfw.IV a better tank. The penetration of the 75 mm KwK L/24 may have been close to the 3.7 cm KwK, but the effectiveness of the HE shell was incomparable. The 37 mm shell carried only 26 grams of explosive while the 75 mm shell had 680. The difference on the battlefield was obvioius.

The Germans had a long 75 mm gun on the 7,5 cm Kanone auf Selbstfahrlafette back in 1938. The decision to put something similar into a tank was only made in 1941, and even then with Hitler's personal involvement.

The German generals didn't understand the situation themselves. They considered it sufficient to give the Pz.Kpfw.III a 50 mm gun. Even the 5 cm KwK was a half-measure. Only a shortened version was put into production because of size concerns, so the penetration did not grow that much. The 75 mm gun remained at the length of 24 calibers. A long 75 mm gun was created back in the late 1930s, but was never installed on a tank. The 5 cm KwK 39 L/60 and 7.5 cm KwK 40 L/43 were only introduced as a result of one man's insistence, and this was a man that German generals usually blamed for their own failures.

The Pz.Kpfw.IV turned out to be the only tank in mass production that could take a long 75 mm gun. This was only considered a temporary solution.

Attempts were made to stick the long 75 mm gun into the Pz.Kpfw.III, but in early 1942 it became clear that the Z.W. chassis exhausted its reserves. Meanwhile, the Pz.Kpfw.IV could easily accept this gun. This made it a very dangerous enemy for T-34 and KV-1 tanks at medium distances. It seemed like the perfect time to scale up production, but the Pz.Kpfw.IV only surpassed the 100 tanks per month mark in November of 1942 and 200 tanks per month in March of 1943. The tank was still considered a temporary solution. The Germans bet on the Panther tank that evolved from the VK 20.01 program. However, the 20 ton tank grew into a 35 ton one, and then to 45 tons. This was a medium tank that weighed as much as a heavy.

Everything became clear only in 1943.

The Pz.Kpfw.IV tank became the most numerous German tank. This wasn't because of its exceptional characteristics. The potential of the chassis was exhausted by late 1942. The problem was that the Panther, the replacement for the long-suffering Pz.Kpfw.III, took about a year to bring up to to a satisfactory state and had nowhere to grow from the very beginning. The only way to get the required number of tanks was to expand production of the Pz.Kpfw.IV to factories not involved in production of the Panther. The Nibelungenwerk factory was the star of this expansion. This Austrian factory became the main producer of Pz.Kpfw.IV tanks starting in the second half of 1943. 4800 units were produced here.

Production of the Pz.Kpfw.IV reached its peak despite multiple attempts to remove it from production entirely.

Several attempts were made to remove the Pz.Kpfw.IV from production, but none were successful. Even after the war, the Panther quickly retired from the scene, but service of the Pz.Kpfw.IV continued for another three decades.

Shocking myopia

The Pz.Kpfw.IV was not well regarded in many nations. The Pz.Kpfw.III was considered to be more advanced. Only the United States gave it due respect. The tank was named Germany's best tank in 1940 and was responsible for the use of a 75 mm gun on the Medium Tank M3. The Medium Tank M4 was also created as an analogue to the German tank, but a universal vehicle rather than a support one. 

The NIBT Proving Grounds had a Pz.Kpfw.IV tank by the fall of 1941. Trials were not conducted since it was not considered very interesting.

Was the Pz.Kpfw.IV an exceptional tank? If one studies it carefully, it becomes clear why it was overlooked abroad. Krupp's engineers made a good tank with an adequately laid out driver's compartment with decent hatches (unlike the Pz.Kpfw.III's side flaps), good overall concept, high ammunition capacity, but no "special features". It was a good all around tank without any exceptionally progressive solutions, which is why designers from abroad did not consider it interesting.

The Pz.Kpfw.IV was not an exceptional vehicle, but it was a reliable workhorse like the Medium Tank M4.

One way or another, the tank ended up as the Wehrmacht's workhorse, just as the Sherman settled in the American army. The chassis of both tanks were settled by the end of the 1930s. While the Americans saw the potential of their design, the Germans seemed to be more motivated to get rid of theirs. The Pz.Kpfw.IV was far from hopeless. One only needs to recall the Pz.Sfl.IVc that evolved out of the Pz.Kpfw.IV. New running gear and a powerful engine gave it a top speed of 60 kph. The vehicle weighed 26 tons, which was already out of reach for the stock Pz.Kpfw.IV chassis.

The Pz.Sfl.IVc showed that the Pz.Kpfw.IV chassis could have been modernized if the Germans wanted to do so.

Could the Germans have modernized the Pz.Kpfw.IV? Experience with the Pz.Sfl.IVc suggests that they could have. Just like with the Medium Tank M4, the external suspension allowed the modernization of the tank without significant changes to the hull. The Americans wanted to do this, but the Germans didn't, hoping to get rid of the Pz.Kpfw.IV instead. 

B.W.40, an attempt to modernize the Pz.Kpfw.IV. This improvement was cancelled, which backfired on the Germans.

There was a possibility to upgrade the Pz.Kpfw.IV chassis to a better one with the B.W.40 back in 1940. However, Kniepkamp found it easier to crush Krupp's project. The 9.Serie/B.W. with a new hull and modernized running gear was also crushed. The even more simplified Pz.Kpfw.III/IV project was stillborn. By early 1944 the time to replace the Pz.Kpfw.IV had run out. The Pz.Kpfw.III/IV paled in comparison to the T-34-85 and Medium Tank M4(76). The fatal mistake was made back in 1942 and there was no hope of correcting it by 1944. Even then, the Germans only made attempts to modernized the chassis. The armament remained the same.

T-40/75 N, the post-war Czechoslovakian modernization of the tank.

One could say the mistake was made even earlier. The Germans should have faced reality in 1938 and disposed of the Z.W. in favour of the Pz.Kpfw.IV. However, no one was about to do that with their own favourite project. The result was predictable. Our enemy created unnecessary problems for themselves, which we can only commend them for. If the Germans produced as many long-barrelled Pz.Kpfw.IV tanks in 1942 as they did the Pz.Kpfw.III, there would have been a lot more problems on the front lines.

Original article by Yuri Pasholok.