The Panzer IV’s 7.5 cm short-barrel gun was primarily designed as a support weapon that was to destroy enemy fortified positions, while its 3.7 cm-armed Panzer III counterpart was to engage enemy armor. Despite this, the 7.5 cm gun still had enough firepower to be a serious threat to many early tank designs encountered in the invasions of Poland and the West. By 1941 standards, however, it was deemed insufficient by the Germans, who wanted a gun with increased armor penetration. It was for this reason that works on such a project was initiated, which ultimately led to the development of a single 5 cm L/60 armed Panzer IV based on the Ausf.D version.
A Brief History of the Panzer IV Ausf.D
The Panzer IV was a medium support tank, designed prior to the war with the intention of providing effective fire support. For this reason, it was armed with, what was at the time, a fairly large 7.5 cm caliber gun. Other Panzers were usually tasked with identifying and marking (usually with smoke shells or other means) targets, which were then to be engaged by the Panzer IV. This target was usually a fortified enemy position, an anti-tank or machine gun emplacement, etc.
Once it was introduced into service, the Germans made several modifications to the Panzer IV, which led to the development of numerous versions of it. The Ausf.D (Ausf. is short for Ausführung, which can be translated as version or model) was the fourth in line. The most visible change compared to previous models was the reintroduction of the protruding driver plate and the hull ball-mounted machine gun, which had been used on the Ausf.A, but not on the B and C versions. Production of the Panzer IV Ausf.D was carried out by Krupp-Grusonwerk from Magdeburg-Buckau. From October 1939 through to October 1940, of the 248 ordered Panzer IV Ausf.D tanks, only 232 were built. The remaining 16 chassis were instead used as Brückenleger IV bridge carriers.
Due to the underdeveloped German industrial capabilities in the early stages of the war, the number of Panzer IVs per Panzer Division was quite limited. Despite their low numbers in the early stages of the war, they saw extensive action. The Panzer IV, in general, proved to be a good design, performing its designated role successfully. While having relatively good anti-tank capabilities, heavy enemy tanks, such as the British Matilda, French B1 bis, Soviet T-34, and KVs proved too much for the short-barrel gun. This would force Germany to initiate a series of experimental projects with the aim of increasing the Panzer IV’s anti-tank firepower. One such project would be the Panzerkampfwagen IV Ausf.D mit 5 cm KwK 39 L/60.
Panzerkampfwagen IV Ausf.D mit 5 cm KwK 39 L/60
Unfortunately, due to its experimental nature, this vehicle is quite poorly documented in the literature. The research challenges are further exacerbated by the conflicting information present in the sources. Based on the available information, during 1941, German Army officials approached Krupp with a request to investigate whether it was possible to install a 5 cm L/60 gun into a Panzer IV Ausf.D turret. According to B. Perrett (Panzerkampfwagen IV Medium Tank), prior to this request, the Germans had plans to test the installation of the same caliber but shorter L/42 barrel into a Panzer IV. Given the weaker performance of this weapon against newer enemy armor, the decision was made to use the long gun instead. Other sources, such as H. Doyle and T. Jentz (Panzerkampfwagen IV Ausf.G, H, and J) state that Adolf Hitler personally issued an order that the longer 5 cm gun be installed in both the Panzer III and IV. The work adopting the Panzer IV turret to house this gun was given to Krupp. Prior to this, in March 1941, Krupp began developing a more compact version of the 5 cm PaK 38 anti-tank gun that could be installed in the Panzer III and IV turrets. The prototype (based on Fgst. Nr. 80668) was presented to Adolf Hitler during his birthday, on 20th April 1942. The prototype was transported to St. Johann in Austria during the winter of 1942, where it was used together with a number of other experimental vehicles for various trials.
The sources do not mention any changes to its overall design, aside from the obvious change of the main armament, and visually, it appears to be the same as a standard Panzer IV Ausf.D tank. Sadly, there is no available information about changes to the interior, which would have had to take place due to the installation of the new gun. In addition, the prototype was built on the Ausf.D version, it is possible that had the tank been produced in large numbers, later versions of the Panzer IV would have also been used for this modification too.
The Panzer IV Ausf.D superstructure has the earlier mentioned reintroduction of the protruding driver plate and the ball-mounted machine gun. On the front of this plate, a protective Fahrersehklappe 30 sliding driver visor port was placed, which was provided with thick armored glass for protection from bullets and fragments.
Externally, the turret design of the 5 cm armed Panzer IV Ausf.D appears to be unchanged from the original. While most Panzer IV Ausf.Ds were equipped with a larger rear turret-mounted stowage box after early 1941, this prototype did not have one. It is possible that, if this version was to enter production, it would have had one attached.
Suspension and Running Gear
The suspension on this vehicle was unchanged and consisted of eight small road wheels suspended in pairs on bogies. In addition, the front-drive sprocket, rear idler, and four return rollers were also unchanged.
The Engine and Transmission
The Ausf.D was powered by the Maybach HL 120 TRM engine, giving out 265 hp@2,600 rpm. With this engine, the tank could reach a maximum speed of 42 km/h, with 25 km/h cross-country. The operational range was 210 km on road and 130 km cross-country. The addition of the new gun and the ammunition would likely not have changed the overall driving performance of the Panzer IV.
The Armor Protection
The Panzer IV Ausf.D was relatively lightly armored, with the front face-hardened armor being some 30 mm thick. The last 68 produced vehicles had armor increased to 50 mm of protection on the lower plate. The 5 cm armed Panzer IV Ausf.D was built based on one such vehicle with increased armor protection. The side armor ranged from 20 to 40 mm. The rear armor was 20 mm thick, but the lower bottom area was only 14.5 mm, and the bottom was 10 mm thick. The external gun mantlet was 35 mm thick.
From July 1940 onward, many Panzer IV Ausf.Ds received additional 30 mm appliqué armor plates bolted or welded to the front hull and superstructure armor. The side armor was also increased with 20 mm additional armored plates.
The 5 cm armed Panzer IV Ausf.D would have had a crew of five, which included the commander, gunner, and loader, who were positioned in the turret, and the driver and radio operator in the hull.
The original 7.5 cm KwK 37 L/24 was replaced with the newer 5 cm KwK 39 (sometimes even designated as KwK 38) L/60 gun. Unfortunately, there is no information in the sources about how difficult the installation of this gun was to perform or if there were any problems with it. Given the Panzer IV’s larger turret and turret ring, it can be said with some certainty that it would provide more working space for the turret crew. The external gun mantled of the original 7.5 cm gun appears to be unchanged. The gun recoil cylinders that were outside of the turret were covered with a steel jacket and a deflector guard. In addition, the ‘Y’ shaped metal rod antenna guide placed under the gun was also retained.
The 7.5 cm gun could defeat around 40 mm of armor (the number may differ between sources) at ranges of some 500 m. While this was enough to deal with most pre-war era tanks, newer tank designs proved to be too much for it. The longer 5 cm gun offered somewhat better armor penetration capabilities, as it could penetrate 59 to 61 mm (depending on the source) of 30° angled armor at the same distance. The muzzle velocity, when using the anti-tank round, was 835 m/s. The elevation would probably be unchanged, at -10° to +20°. The 5 cm tank gun, while more or less a copy of the infantry truck-towed PaK 38 anti-tank gun, still had some differences. The most obvious change was the use of a vertical breech block. With this breech block, the rate of fire was between 10 to 15 rounds per minute.
Originally, the ammunition load of the Panzer IV Ausf.A consisted of 122 rounds of 7.5 cm ammunition. Given the extra weight and higher chance of accidentally causing an explosion when hit or when on fire, the Germans simply reduce the load to 80 rounds on later models. The Panzer IIIs that were equipped with this 5 cm gun, such as the Ausf.J, were equipped with 84 rounds of ammunition. Given the smaller caliber of the 5 cm rounds and the larger size of the Panzer IV, the total ammunition count could have exceeded this number by a lot. Sadly, the precise number is unknown, as none of the sources even give a rough estimation.
Secondary armament would consist of two 7.92 mm MG 34 machine guns for use against infantry. One machine gun was placed in a coaxial configuration with the main gun and was fired by the gunner. Another machine gun was positioned on the right side of the superstructure and was operated by the radio operator. On the Ausf.D, the Kugelblende 30 type ball mount, was used. The ammunition load for the two MG 34s was 2,700 rounds.
End of the Project and its Final Fate
Production of the first batch of some 80 vehicles was to be undertaken by Nibelungenwerk, which, at that time, was slowly becoming involved in Panzer IV production. It was estimated that these could be completed by spring 1942. Ultimately, nothing would come from this project. There were basically two reasons for its cancelation. Firstly, the 5 cm gun could be easily placed in the smaller Panzer III tank, with some modification. This was implemented in the production of the later Panzer III Ausf.J and L versions. While this gun had relatively good penetration capabilities for 1942, it would be quickly outclassed by superior enemy designs. This ultimately led to the cancelation of the 5 cm armed Panzer III production in 1943. Ironically, it was the Panzer III that would be refitted with the Panzer IV’s short-barrelled gun in the end, instead of the other way around.
The second reason for the cancelation of the 5 cm armed Panzer IV project was that the Germans simply deemed it a waste of resources to install such a small-caliber gun in the Panzer IV, which clearly could have been armed with stronger weapons. Roughly parallel with its development, the Germans began working on installing the longer version of the 7.5 cm gun. This eventually led to the introduction of the L/43 and then L/48 long 7.5 cm gun, which offered superior overall firepower than the 5 cm gun. Ironically, some of the damaged Panzer IV Ausf.Ds that were returned from the frontline were instead equipped with the longer 7.5 cm guns. While these vehicles were mostly used for crew training, some may have been also reused as replacement vehicles for active units.
Sadly, the final fate of this vehicle is not listed in the sources. Due to its experimental nature, it is unlikely that it ever saw any frontline service. It is likely that it was either rearmed with its original gun or reused for other experimental projects. It could have also been issued for crew training or any other auxiliary role on that matter.
The Panzer IV Ausf.D armed with the 5 cm gun was one of several different attempts to rearm the Panzer IV series with a gun that had better anti-tank capabilities. While the whole installation was feasible and offered the crews a somewhat larger working space (in contrast to the Panzer III), likely with an increased ammunition load, it was rejected. Given that the same gun could be installed in the Panzer III, the Germans simply saw the whole project as a waste of time and resources. The Panzer IV could instead be rearmed with a much stronger gun. This was what they actually did, introducing the 7.5 L/43 and later L/48 tank guns to their Panzer IVs, creating excellent anti-tank vehicles that remained in use until the war ended.
Panzerkampfwagen IV Ausführung D mit 5 cm KwK 39 L/60
|Dimensions (L-W-H)||5.92 x 2.83 x 2.68 m|
|Total weight, battle-ready||20 tonnes|
|Crew||5 (Commander, Gunner, Loader, Driver and Radio operator)|
|Propulsion||Maybach HL 120 TR(M) 265 HP @ 2600 rpm|
|Speed (road/off-road)||42 km/h, 25 km/h|
|Range (road/off-road)-fuel||210 km, 130 km|
|Primary Armament||5 cm KwK 39 L/60|
|Secondary Armament||Two 7.92 mm M.G.34 machine guns|
|Elevation||-10° to +20°|
|Armor||10 – 50 mm|
- K. Hjermstad (2000), Panzer IV Squadron/Signal Publication.
- T.L. Jentz and H.L. Doyle (1997) Panzer Tracts No.4 Panzerkampfwagen IV
- D. Nešić, (2008), Naoružanje Drugog Svetsko Rata-Nemačka, Beograd
- B. Perrett (2007) Panzerkampfwagen IV Medium Tank 1936-45, Osprey Publishing
- P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
- Walter J. Spielberger (1993). Panzer IV and its Variants, Schiffer Publishing Ltd.
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- H. Doyle and T. Jentz Panzerkampfwagen IV Ausf.G, H, and J, Osprey Publishing