Monday 26 April 2021

In the Panther's Shadow

The theory that Germany should have kept producing the Pz.Kpfw.IV instead of the Panther is common among amateur historians. However, the peak of Pz.Kpfw.IV production coincided with Panther production. Nobody was going to reduce production volumes, at least in 1943. The Pz.Kpfw.IV Ausf.H and Ausf.J became the most numerous German tanks of the second half of WWII, and the Pz.Kpfw.IV Ausf.J became its most numerous tank overall. It was outnumbered only by the StuG 40 Ausf.G, 8500 of which were built. Late production Pz.Kpfw.IV tanks were a litmus test for what was wrong with German tank production in the last years of WWII.

Aim to increase production

Development of the Pz.Kpfw.III hit a dead end, which forced the Germans to drop the idea of using the Pz.Kpfw.IV as a support tank. It turned out that even the long barreled 50 mm gun was not enough to combat Soviet tanks, especially the KV-1. A decision was made to install a long barreled 75 mm gun derived from the 75 mm Pak 40 on a tank. This gun, called the 7.5 cm KwK 40 L/43, easily fit in the turret of the Pz.Kpfw.IV, but attempts to create the Pz.Kpfw.III Ausf.K with this weapon failed. This was the beginning of the end for the Pz.Kpfw.III and revenge for the Pz.Kpfw.IV. The first long-barreled tank indexed Pz.Kpfw.IV Ausf.F2 was delivered in March of 1942. This index did not last for long. The name Pz.Kpfw.IV Ausf.G appeared on June 5th, 1942, and was finalized on July 1st, 1942.

In November of 1942 monthly production of the Ausf.G surpassed 100 units and 200 units in March of 1943. The tank was constantly evolving. In addition to modernization of various aspects of the design, the front of the hull and superstructure was thickened by 30 mm. However, the front of the turret was still 50 mm thick since the chassis was reaching its weight limit.

One of the first Pz.Kpfw.IV Ausf.H produced by VOMAG in May of 1943. The front hull applique armour is bolted on and there are still two headlights. The only giveaway that this is an Ausf.H is the new drive sprockets.

The high rate of production meant that these tanks were produced in large numbers by German measures, 1927 units over the course of just over a year. Discussion of the 9th series of the B.W. began already in the summer of 1942. This coincided with Krupp's repeated attempts to stick in the turret of the B.W.40 tank, which never made it off paper. It was similar to the Pz.Kpfw.IV turret, but had a narrower front and a hydraulic traverse instead of electric. This turret was rejected in July of 1942, but a Pz.Kpfw.IV Ausf.H project with a sloped upper front plate turned up in December of that year. The turret platform sides would also be sloped.

Work on this topic hit a dead end as the mass of the tank grew to 28.2 tons. This would radically increase load on the chassis, especially the front road wheels. This Pz.Kpfw.IV Ausf.H was rejected in February of 1943, and rightly so. The Panzer IV/70 (A) weighed 28 tons and showed only too well what an overloaded chassis led to.

Another VOMAG tank, this time June 1943 production. This tank has only one headlight, the driver's combat driving sight is gone, but the turret platform and hull still have applique armour attached with bolts.

In practice, 9.Serie/B.W. was a direct descendant of the Pz.Kpfw.IV Ausf.G. No radical changes were introduced in order to avoid slowing down production. The discussion of replacing the front applique armour with monolithic 80 mm thick plates began in February of 1943. Factories could not transition to new armour right away, since they had a backlog of old armour.

The issue of removing the side observation ports for the driver and radio operator came up in March of 1943. The issue was that the tank now had side skirts, which were not see through. When installed, they rendered the observation ports useless. The turret roof was thickened to 16-20 mm since Soviet sturmoviks inflicted a lot of losses on German tanks. Changes were also made to the transmission and drive sprockets. The mass reached 25 tons, which required changes to the final drive. The top speed dropped to 38 kph. The final drive covers were strengthened, primarily due to weakness against Soviet anti-tank rifles. Finally, the design of the drive sprockets changed.

Another transitional Pz.Kpfw.IV Ausf.H. The superstructure front is already monolithic, but not the front of the hull. The side observation ports are still present.

Three factories would build the 9th series. Grusonwerk received a contract for 500 tanks with chassis serial numbers 84401-84900. 450 more tanks with serial numbers 84901-85350 would be built by VOMAG, and 400 tanks with serial numbers 85351-85750 would be built at Nibelungenwerk. The first Pz.Kpfw.IV Ausf.H tanks were built in May of 1943, but they were practically identical to the Pz.Kpfw.IV Ausf.G. The only difference was a thicker roof and a new transmission. The first 30 tanks built at VOMAG still had the old transmission anyway.

The backlog continued to have an impact on the way the tanks looked over the coming months. Even though the Pz.Kpfw.IV Ausf.H was supposed to have monolithic front hull and superstructure armour, some tanks produced in June, July, and even August had applique armour held on with bolts. There were also combinations where the superstructure had a monolithic plate and the hull had applique armour or vice versa. A similar situation took place with the side observation devices. The situation where the front hull was already monolithic but the observation devices were still in place was not uncommon. The observation devices only finally vanished in September of 1943. Rear pistol ports on the turret also lagged behind the name change and were only removed starting with August of 1943.

Krupp-built Pz.Kpfw.IV Ausf.H, October 1943. The tank had the second type of skirt armour and forged drive wheel hubcaps.

Like the Pz.Kpfw.IV Ausf.G the 9th series tanks slowly changed their look. Installation of smoke grenade launchers on the side of the turret ceased in June of 1943. Tow hook linking attachments known as C-hooks due to their shape were introduced at the same time. Two of these hooks were carried near the left headlight. The right headlight was removed somewhere in June-July of 1943 as the Germans started to cut corners. Another simplification took place in September of 1943 when welded travel stops were introduced instead of cast ones. Cast hubcaps were replaced with forged ones at the same time.

Zimmerit was not applied like this for long. Application to the side skirts quickly stopped.

Another element was introduced in September of 1943, which causes arguments to this day. The 6th Department of the Ordnance Directorate launched a project in March of 1943 to develop a special paste that protected against enemy magnetic mines. This was a preventive measure, as only the Germans used such mines. The winner of the tender was Chemische Werke Zimmer & Co, which gave the name to the paste: Zimmerit. Zimmerit was applied in two layers. First the base layer, then the upper layer, designed to make the surface uneven and make the mine's contact surface smaller.

Zimmerit was tested in the 7th and 4th Tank Divisions in June of 1943. The idea to just send Zimmerit to front line troops proved poor, as they did not know how to apply it properly. For this reason, Zimmerit was applied at the factory starting with late September 1943. Initially it was applied both to the main armour and the spaced armour, but this idea was soon dropped. Not only was it pointless, but the extra Zimmerit weighed down the chassis even more. Factories applied it as they saw fit at first, but soon the characteristic striped design emerged.

The same tank from above. Pz.Kpfw.IV Ausf.H tanks looked like this until the end of 1943.

Simplifications continued in October of 1943. Rubber production was in crisis, and it had to be saved wherever possible. On the Pz.Kpfw.IV the return rollers became steel rimmed. This was supposed to be only a temporary replacement, but as we all know there is nothing more permanent than the temporary. Simplified cast idlers also appeared in October of 1943. They never fully replaced the old idlers and both remained in use until the end of production. Another introduction made in October of 1943 was the second type of skirt armour. Experience showed that the mountings need changing, and these changes were introduced in October. A month later the bottom of the front skirt armour section was trimmed.

Cast idlers were introduced in October of 1943. They never fully replaced their predecessors.

As with the Pz.Kpfw.IV Ausf.G, production moved fast. Nibelungenwerk led the pack. This factory was the first to cross the 100 tank mark in May of 1943, becoming the main producer of Pz.Kpfw.IV tanks. Nibelungenwerk would retain the lead in Pz.Kpfw.IV production as numbers only rose. Total production of the Pz.Kpfw.IV Ausf.H surpassed 300 units in October and remained there until the end of the year. In December Nibelungenwerk delivered a record 210 tanks, giving a total of 1381 tanks in 1943. There were 2982 Pz.Kpfw.IV tanks produced in total between the three factories that year. No other German tank was built in such numbers. Towards the end of 1943 the front and sides of the superstructure were reinforced. Tanks built at Nibelungenwerk also received a characteristic holder for three spare track links on the rear of the hull.

Starting with November of 1943 the bottom of the front section of the skirt armour was trimmed.

The increase in production made additional contracts necessary. Since Grusonwerk was not in a hurry, contracts with VOMAG and Nibelungenwerk were renegotiated. Grusonwerk also initially received another contract for 400 tanks with serial numbers 85751-86150. Another contract called for 500 tanks with serial numbers 88101-88600. The factory ended up using neither of these serial number pools, nor did they ever fully expend their first allocation.

Grusonwerk delivered its last Pz.Kpfw.IV Ausf.H tanks in January of 1944. It built 391 tanks of this type before fully transitioning to the StuG IV. Unlike Grusonwerk, VOMAG fully used up the pool of serial numbers allocated in the first contract. The factory then began working on another contract for 450 tanks with serial numbers 86151-86600. An additional contract was signed for tanks with serial numbers 88601-89100. A contract for 500 tanks numbered 86601-87100 was signed with Nibelungenwerk. Their third contract was the largest: 1500 tanks with serial numbers 89101-90600.

A typical late production NIbelungenwerk Pz.Kpfw.IV Ausf.H. Spare track links were carried on the rear and the return rollers had metal rims.

2414 Pz.Kpfw.IV tanks were produced in total, plus Nibelungenwerk delivered 90 chassis (30 for StuG IVs and 60 for Sturmpanzer IVs). 693 of these tanks were built at VOMAG. The factory managed to cross the 100 tanks produced monthly mark in January of 1944, but that was the last month of production, as the factory moved on to making Jagdpanzer IV tank destroyers. A breech-loaded mortar was supposed to be introduced in the roof of the turret in January of 1944, but implementation of this feature was behind schedule. The additional air filter that looked like two cylinders on the right side of the hull was removed starting in February of 1944. These filters were installed starting in the fall of 1943, but the troops often removed them, sealing the resulting holes with sheet metal. The lack of filters was nothing compared to what awaited the Pz.Kpfw.IV in February of 1944. A new version of the tank was introduced that promised to become the most numerous German tank of the war.

Lonely at the top

The reasons for simplifying the Pz.Kpfw.IV further are unknown. It is likely that components became more and more scarce. The desire to equip the tank with a hydraulic turret traverse was no accident. The problem was that the auxiliary DKW motor was needed to power the electric turret traverse. The 6th Department of the Ordnance Directorate took the obvious route and only left the hand traverse. They considered that the turret could be traversed a little bit by hand and that wide turns were not common. The exhaust system for the auxiliary motor and turret traverse motor were removed. An extra 210 L fuel tank was installed in order to fill up the newly freed up space. Many tanks had nothing installed there since the fuel tanks were not ready when the decision to remove the powered turret traverse was made.

Missing auxiliary motor muffler, the first sign that this is a Pz.Kpfw.IV Ausf.J.

Such drastic changes led to a new designation: the 10.Serie/B.W. or Pz.Kpfw.IV Ausf.J. This time the serial numbers weren't changed and VOMAG and Nibelungenwerk simply moved on to the new series. The first Pz.Kpfw.IV Ausf.J built at VOMAG had serial number 86394 and the first one build at Nibelungenwerk had the serial number 89531.

The changes stopped for a little bit and production volumes rose. Production numbers fell to 252 in February of 1944 when VOMAG began producing the Jagdpanzer IV, but went back up to 310 in March. This happened thanks to an increase of production at Nibelungenwerk. VOMAG already knew that they would soon stop producing tanks. This factory delivered 180 Pz.Kpfw.IV Ausf.J from February to May of 1944 before Nibelungenwerk was left as the sole producer of this tank. Their output was growing: 200 tanks in February, 250 in March, 259 in April, 274 in May, and 300 monthly from June to August of 1944. No other German factory could build tanks at this rate.

This tank was built in 1944 at VOMAG. This factory built its last Pz.Kpfw.IV in May of 1944, fully transitioning to Jagdpanzer IV production.

This increase resulted in the need to sign more contracts. The next contract with Nibelungenwerk requested 1950 tanks with serial numbers 91300-93250, in 1945 another contract was signed for 415 tanks with serial numbers 110010-110415. Nibelungenwerk also delivered 230 chassis for other vehicles in 1944. This factory also produced the Jagdtiger.

A typical Pz.Kpfw.IV Ausf.J produced at Nibelungenwerk in the spring-summer of 1944.

Improvements to the Pz.Kpfw.IV finished in 1943, after that the tank was only simplified. This can be easily seen in changes made to the Pz.Kpfw.IV Ausf.J. The decision to remove observation devices and pistol ports in the turret side doors was made in mid-April of 1944. This decision was put into practice starting in May, but that didn't mean that they suddenly vanished. Production of hatch flaps with openings for observation devices and pistol ports continued. The engine deck was also simplified in May. The road wheel design slightly changed in June and attachments for a 2-ton crane were added to the turret. An additional fuel tank was installed in June, but it quickly vanished due to frequent leaks. The fuel tank returned in September of 1944. A breech-loaded mortar was added to the roof of the turret in June, and the ventilation system was changed as a result.

This tank was built in September of 1944. A breech-loaded mortar and a new air intake can be seen on the roof.

Tank production changed as a result of Allied bombing raids. Some tanks were built without surface-hardened armour in the summer of 1944. Some design changes had to be cancelled completely, for instance C-shaped hooks were supposed to be replaced with S-shaped ones, but this never happened. The commander's cupola was also supposed to be replaced with the same one used on late Tiger and Panther tanks, but this also never happened. The reason was that the Pz.Kpfw.IV was going to be ousted either by the Panzer IV/70 or the Pz.Kpfw.III/IV, but neither replacement ever took place. The tank changed its look again in August. Straight exhaust pipes were installed instead of a muffler. The commander's cupola did end up changing after all, but later.

A new hatch flap was designed in August of 1944. It lifted up and rotated to the side, like the Panther's did. It was introduced somewhere in November of 1944. Hand guards were also added in August, as commanders often injured their hands when the gun fired.

Straight exhaust pipes introduced in August of 1944.

Production at Nibelungenwerk dropped in the fall of 1944 partially due to bombings that took place on October 17th. 180 tanks were delivered in September, 187 in October, 200 in November, 195 in December. In total 2815 tanks were built here in 1944 (a third less than the total number of Panthers, which was built by three different factories).

Simplifications and changes continued. Application of Zimmerit was cancelled in September of 1944, as it did not meet expectations. The superstructure roof was thickened to 16 mm in October. This change was planned in the summer, but only went into production in the fall. Many more changes were made in November. The last observation port was removed from the turret, the one located in the front. A new commander's cupola hatch was put into use. Heating for batteries was introduced. Racks for the breech-loaded mortar rounds were added. The track pin splints were also changed. More changes were made in December of 1944. The most visible changes were the new tow hooks and reduction of number of return rollers to three per side.

Another novelty added in the fall of 1944: mesh skirt armour. This design was almost identical in effectiveness to the 5 mm thick sheet metal, but weighed less.

The skirt armour deserves a separate mention. The cutout in the front section was cancelled in March of 1944. The skirt armour remained the same until the fall of 1944 when it was changed radically. The skirt plates were fairly heavy, and work on a lighter design started in the summer of 1944. It turned out that a mesh was not much less effective than sheet metal. It's worth it to restate that the spaced armour was designed to protect the tank from Soviet anti-tank rifles, not HEAT ammunition. Protection from the latter was just a nice side effect. Despite good performance in trials, the mesh skirt armour was introduced only in September of 1944. According to German tradition, the introduction of the new mesh didn't mean that the old plates would suddenly vanish, and these were installed on tanks well into 1945. Improvements were made to the mesh armour during production, for instance sections were added to protect the superstructure from above.

The final variant of the Pz.Kpfw.IV used in the last months of production. The number of return rollers was reduced to 3, a new commander's cupola hatch was installed.

The Germans planned to continue production of the Pz.Kpfw.IV Ausf.J until May of 1945. 650 tanks would be delivered from February to May, 100 of which were due in May. Nibelungenwerk would then transition to Panther Ausf.F production. Only the Panzer IV/70 (V) would remain out of all the vehicles on the Pz.Kpfw.IV chassis. As production would cease, there were nearly no changes made to the design of the tank, only the maintenance hatches for the brakes were removed in February of 1945.

The wishes of German high command did not always correspond to reality. Plans changed, often due to Allied bombings. Nibelungenwerk delivered 170 tanks in January of 1945, 160 in February. This was the last month when production remained this high. A rain of bombs fell on February 14th, heavily damaging the factory. Chassis production ceased and Nibelungenwerk delivered only 55 tanks in March. April was the last month of production, during which 50 tanks were delivered.

The end of production at Nibelungenwerk. The factory's equipment was taken in the summer of 1945 as reparations. The same fate awaited VOMAG.

Even though Nibelungenwerk produced the Pz.Kpfw.IV Ausf.J alone for most of its production run, it managed to set a record. The factory put out 3240 Pz.Kpfw.IV Ausf.J tanks and 260 chassis. 3420 tanks of this type were built in total, a record for Germany, even if it does pale in comparison to Soviet or American production numbers. This number includes the Pz.Bef.Wg.IV commander's tank. 17 tanks of this type were built in August-September of 1944. More commonly the Pz.Bef.Wg.IV would be built our of refurbished Pz.Kpfw.IV tanks. 88 tanks were converted between March and July of 1944.

Old workhorse

The Pz.Kpfw.IV Ausf.H was put into production in the summer of 1943. German tanks enjoyed an advantage over their Soviet counterparts in those days, although the Panther was quite raw when it debuted at the Battle of Kursk, and so the replacement of the Wehrmacht's workhorse was delayed. The Pz.Kpfw.IV picked up the slack, which can be seen from production volumes. 2982 Pz.Kpfw.IV and 1777 Panthers were built in 1943. The difference in 1944 was less: 3125 Pz.Kpfw.IV and 3783 Panthers. Recall that Nibelungenwerk produced nearly all Pz.Kpfw.IV tanks in 1944 on its own while the Panther was being built at three different factories.

In 1943 the Pz.Kpfw.IV surpassed its analogues in armament, but fell behind in mobility.

The chassis no longer had any resources left for improvement with the launch of the Pz.Kpfw.IV Ausf.H. A modernized chassis was never put into production for a number of reasons, partially because the Germans had high hopes for the Panther as the main tank of the future. This was a mistake. The Panther was too heavy and too large from the start. There was no hope of modernization and far too many issues, some of which would plague the tank until the end of its production. There was still a demand for a tank with the size and weight of the Pz.Kpfw.IV. The Germans essentially ended up with two medium tanks: a small one and a big one.

The flip side of improved protection: visibility was radically reduced.

The increase in mass reflected on the Pz.Kpfw.IV's mobility. The tank also started to experience issues with another characteristic: visibility. The introduction of side skirts and gradual elimination of observation ports meant that only the commander could see normally. The driver, radio operator, gunner, and loader could all see only forward. There were no observation periscopes. As a result, the crew could not see the battlefield and only relied on the commander's directions. Another significant issue was that the front of the hull and superstructure were thickened to 80 mm, but not the turret. There was no possibility of improving the armour any more, as the chassis' weight limits were exceeded.

The Pz.Kpfw.IV's cannon was inferior to those used by the T-34-85 or M4A1(76)W by 1944, but it could still defeat most medium tanks, and even heavy tanks at close range.

The Pz.Kpfw.IV Ausf.H and Ausf.J remained dangerous opponents and could still defeat any Allied tank fielded in 1943. However, the Allies didn't sit still either. The Red Army accepted the IS heavy tank into service in the fall of 1943 and the T-34-85 entered production in 1944. The US began building the M4A1(76)W in February of 1944. Both the USA and the USSR had a large number of modernized medium tanks that were built by the thousand monthly. The new tanks surpassed the German Pz.Kpfw.IV in many aspects, including visibility. As for the Pz.Kpfw.IV, attempts to install an L/70 gun failed, as did Guderian's efforts to create a successor.

Surrender of the German troops in Courland, May 1945. This was not the Pz.Kpfw.IV's last war.

Unlike the Panther, the Pz.Kpfw.IV was a hardy and reliable tank. This can be seen from their usage in other armies. These tanks served for decades after the end of WWII, showing that Krupp's design was a good one. Even though the Panther and Tiger are often called the best German tank, this honour falls of the humble Pz.Kpfw.IV tank as the only German tank that remained in production and use from the first day of WWII to the last. The tank had a large modernization reserve and turned out to be well suited for production and long term use. Luckily for us, German high command never understood that the optimal medium tank has a weight of somewhere around 25-30 tons. The Germans had every chance to create a worthy successor to the Pz.Kpfw.IV, but they missed it.


  1. The last paragraph summarized it all. The Germans should have made something akin to the proposed uparmored T-34/85M variants, or better yet, the T-44 (using the 88 mm Kwk36, a good compromise gun between AT and HE capability). That was clearly doable by 1940s technology. That would have been far better tank to build than the one-trick pony Panther tank (great for fighting defensively at long range against other armor, not so great at doing anything else).

    You wonder how much of the Germans' tangents off to create overweight, unreliable, "unkillable" beasts was due to playing to Hitler's preferences (Hitler once opined disapprovingly that the only advantage for a tank having greater speed was for it to "be able to run away").

  2. How fast in °/sec was the handtraverse of the J? I have seen one source saying in 36 sec it could turn 360 degree so 10°/sec.