One of the distinguishing characteristics of German tank building in WWII was an aim to use up obsolete vehicles, including those which used to be the backbone of the German tank force. If a German tank became obsolete, that didn't mean that it would be scrapped. Some tanks were sent to training units, other were modernized. Obsolete tanks, especially light ones, were often converted to SPGs or engineering vehicles. This was the fate that awaited the PzI, Germany's first mass produced tank, which was already obsolete at the start of WWII.
Minor mechanization of infantry artillery
German infantry units were armed with a wide variety of artillery by the end of the 1930s. Aside from anti-tank guns and mortars, the infantry had howitzers and so called «infantry guns» (Infanteriegeschütz). The parameters of these cannons (barrel length, high elevation angles) made them closer to howitzers, but, formally, they were listed as regimental artillery.
German infantry used two types of infantry guns: the light 7.5 cm leIG 18 and heavy 15 cm sIG 33. The heavy gun was the most interesting, as nothing of the sort was used by any other military. Some of its characteristics were similar to those of a mortar, which was not surprising. The main objective of the sIG 33 was combat with enemy fortifications. Initially, the gun was towed with horses, but later a version that could be towed by artillery tractors appeared. It is easy to distinguish between the two: the motorized version has rubber rims on its wheels, which increased its top speed.
The sIG 33 was very good at its job. Its biggest drawback was a very large weight for an infantry gun: 1786 kg. This was partially compensated by use of tractors, including halftracks, but it was unlikely that the enemy would let a tractor drive around the battlefield unimpeded. The seven man crew could barely push around the gun on their own. In addition, heavy infantry guns sometimes had to fire at point blank range. Such experience was gained in Poland in the fall of 1939.
The logical solution of mechanizing the sIG 33 appeared by early 1940. To be fair, this was not the first attempt of making this gun self propelled. The sIG 33 was built under license in the USSR under the name NM. The USSR was the first to come up with the idea of using the gun in an SPG. The oscillating part of the NM was installed in the SU-5, an SPG built using T-26 components. The resulting vehicle was indexed SU-5-3. For a number of reasons, it was not mass produced.
In Germany, the same story took a different turn.
In early 1940, Alkett (Altmärkische Kettenfabrik) from Spandau received an order to develop an SPG on the PzI Ausf. B chassis. The choice of factory was not a coincidence: Alkett was as subsidiary of the Rheinmetall-Borsig AG conglomerate, the developer and producer of the sIG 33.
It was also logical to use the PzI Ausf. B as a chassis. After the campaign in Poland, there was a large number of these tanks in need of repairs. In the same campaign, it became clear that a tank with only machineguns for armament is unsuitable for modern war. The more powerful engine and longer contact surface than on the PzI Ausf. A allowed the PzI Ausf. B to serve as a chassis for an SPG. As for the PzI Ausf. A, they were converted into munitions carriers (51 units were built). In addition, 24 PzI Ausf. A tanks were converted into SPAAGs called 2 cm Flak 38 auf Pz.Kpfw.I Ausf.A. These SPAAGs, built at the Stöwer in Szczecin, had very questionable fighting ability.
The Alkett SPG, with the memorable name 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B (15 cm motorized sIG 33 gun on the PzI Ausf. B chassis) also had a very questionable design. It is often called Sturmpanzer I or Bison, but neither of these names has any connection with reality.
The unusual task given to Alkett resulted in an extraordinary vehicle. The turret platform was removed from the tank, and the modifications of the chassis ended with that. Installation of the oscillating part of the gun would be logical, but the requirements insisted on retaining the original design. The gun was simply rolled up onto the PzI Ausf. B chassis and fixed in place. The sIG 33 wheelbase was so wide that it had to be rolled up onto the fenders. Since they were not expected to hold up such a heavy mass, the gun's wheels were attached to special reinforcement brackets.
To protect from rifle fire, the front and the sides (partially) were protected with shields. The height of the SPG was 2.7 meters, and its weight was 8 tons. At the moment of its creation, it was the Wehrmacht's tallest tracked vehicle. Its crew consisted of seven men, three of which followed in an Sd.Kfz. 10 halftrack, which also served as a munitions carrier. The SPG itself only carried a handful of rounds (2-3). It also had no radio. The issue was solved using portable radios.
Such an odd design did not stop the German command. With a clear list of drawbacks, it had one advantage: the increased mobility of the sIG 33 on the battlefield. In February of 1940, a batch of 38 SPGs was built. However, the word «built» is misleading, since, according to correspondence, Alkett played no part in the process. Most likely, these were conversions at army workshops.
A special type of unit was created for this vehicle: battery of motorized heavy infantry guns (s.IG.Kp(Mot.S)). According to the TO&E, each battery included 6 SPGs. The battery consisted of three platoons of 2 SPGs and 4 Sd.Kfz. 10 halftracks each. Six batteries were formed in the spring of 1940, distributed in the following way:
- s.IG.Kp(Mot.S) 701 – 9th Tank Division
- s.IG.Kp(Mot.S) 702 – 1st Tank Division
- s.IG.Kp(Mot.S) 703 – 2nd Tank Division
- s.IG.Kp(Mot.S) 704 – 5th Tank Division
- s.IG.Kp(Mot.S) 705 – 7th Tank Division
- s.IG.Kp(Mot.S) 706 – 10th Tank Division
All six batteries were ready for battle by the time the French campaign began. The results of use in combat were contradictory. On one hand, the firepower of the gun was impressive. One hit could destroy a house. On the other hand, the vehicle had plenty of drawbacks. Its large size made the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B a tempting target. Only the brief length of the campaign saved the new SPGs from significant losses.
The overloading of the PzI Ausf. B chassis was no smaller fault. Breakdowns on the march were a common occurrence. Strangely enough, the odd design of the vehicle helped here. It was possible to take off the heavy gun and hook it up behind the chassis. It's possible that the idea of the Waffentrager was born here: a self propelled chassis with the possibility of installing a towed gun.
Three batteries were used during the invasion of Yugoslavia: 701st, 703rd, and 704th. A month later, all SPGs were used during the invasion of the Soviet Union. Here, the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B were frequently used as tank destroyers. They were clearly not meant for that role, but their crews achieved some measure of success. For example, the 705th battery claimed two tanks, and the 702nd battery also claimed a few. As in France, the sIG 33 guns spent most of their time being towed behind the SPGs instead of on them.
Even though the war in the Soviet Union was not the same as the war in France, the losses in the batteries were not as high as one would have thought. The 706th battery took the hardest hit, and was disbanded by early 1942. Other batteries fought for much longer. The 702nd battery was disbanded in December of 1942, others in July of 1943. By the end of that month, the 5th Tank Division still had one 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B.
A long list of drawbacks of this SPG did not scare off the German military. On the contrary, for a nearly improvised design, the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B was rather decent, which is illustrated by its relatively long career. At the same time, experience showed that the PzI is not suitable for this kind of task. The chassis was much better suited for a different SPG.
A mix of Rhein and Bohemia
The idea of a light tank destroyer SPG was conceived in Germany in the mid-1920s. The result was the appearance of the Rheinmetall Leichttraktor Selbstfahrlafette and leichte Selbstfahrkanone. An insufficient design and other reasons caused the idea to be abandoned. Attempts to build a tank destroyer on a halftrack chassis followed. Experimental prototypes were built, but work did not move very far.
The idea of a light tank destroyer on a fully tracked chassis surfaced again in early 1940. The cause was simple: the military suddenly found out that their anti-tank arsenal is insufficient to fight the Char B1 bis. The German 3.7 cm Pak had insufficient penetration, and the 88 mm Flak 18 AA gun had poor mobility on the battlefield. 47 mm Skoda PUV vz. 36 guns obtained by the Germans after the occupation of Czechia were quite a fortunate acquisition.
The PUV vz. 36 could penetrate 55 mm of armour at 60 degrees from a kilometer away. This was enough to fight the Char B1 bis at medium distances. The gun had its drawbacks: greater mass than the 3.7 cm Pak, and wooden wheels, which limited the speed of transport. The gun was accepted into service with the Wehrmacht under the index 4.7 cm Pak 36(t). Production continued, and Skoda delivered 200 guns to its new customer in 1939. These guns, as well as later models produced for the Czechoslovakian army, were equipped with new wheels, with steel rims and pneumatic tires.
Alkett also received the order for a tank destroyer on the PzI Ausf. B chassis. The experimental prototype, personally inspected by Hitler, was ready by February 10th, 1940. Alkett didn't reinvent the wheel: the turret platform had its roof and rear cut off, which were replaced with an open casemate. Unlike the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B, where the casemate was riveted, the tank destroyer had a welded casemate. The oscillating part of the PUV vz. 36 and a new gun shield were installed inside.
The tank's crew increased to 3 men, and the fighting compartment had enough room for a radio and 84 shells for the gun (74 of which were armour piercing). The mass did not increase much, only to 6.4 tons, which helped the SPG retain its mobility. Its index was no simpler than that of the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B: 4,7 cm Pak (t) (Sfl) auf Pz.Kpfw.I (Sd.Kfz.101) ohne Turm (47 mm self propelled anti-tank gun on the PzI Ausf. B chassis without a turret).
Before the first tank destroyer was ready, a battle broke out within the German military. On one hand, the tankers wanted these new vehicles, since the tank destroyer was built on a tank chassis. On the other hand, the infantry also wanted a highly mobile anti-tank gun. Initially, the tankers were winning: a day before the demonstration to Hitler, the infantry was scheduled to get only 10 vehicles out of 132. Everything changed on the next day: a decision was made that all SPGs would end up in units formed from infantry anti-tank battalions.
Understandably, these plans had their opponents. On February 20th, Guderian noted that infantry units would have issues with spare parts and repairs. It was logical, in his view, to give the tank destroyers to tank units, and leave towed anti-tank guns for infantry.
During these debates, the vehicle was called Panzerjäger or Panzerjäger Pz.IB. Later, this index transformed into Panzerjäger I, which became the official title.
Production of the Panzerjäger I was organized at Alkett. 40 conversions were planned for March of 1940, another 60 for April, and 30 in May. Krupp also took part in the process, as it was up to them to build 60 casemates. In Krupp's correspondence, the vehicles were indexed La.S.47. Another 72 casemates were built at Deutsche Edelstahlwerke AG (DEW) in Hanover. Skoda wasn't left out, and received a contract to produce guns for the tank destroyers.
According to plans of the Armament Directorate signed on March 20th, 1940, 132 Panzerjager I would be distributed in the following way. Wa.Pruf 1 and Wa.Pruf 4, responsible for ammunition and artillery respectively, received one vehicle each. By April 1st, 36 vehicles would be sent to equip six batteries to make two tank destroyer battalions. 54 SPGs would create three more battalions by May 1st, and 36 vehicles would be sent out by June 1st. 6 SPGs were left in reserve.
In reality, only the 521st Tank Destroyer Battalion received 6 SPGs in each battery. It was reformed by April 2nd, 1940, from a towed gun unit. Other battalions had a different structure. The 616th, 634th, and 670th battalions had three batteries with 9 SPGs each. By May 31st, another 18-vehicle battalion was being formed, with one SPG in reserve. In reality the last two vehicles remained at Alkett for a long time. Skoda traditionally failed to meet its quota. The second to last Panzerjager I was finished in September of 1940, and the last much later, in July of 1941.
Self propelled anti-tank battalions were formed in a hurry. This did not allow the crews to fully get used to their vehicles. Nevertheless, the Panzerjager I showed itself well in the May-June campaign in 1940. The vehicle was rather low, and breakdowns did not happen as often as with the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B. There were some issues with spare parts, but they were solved quickly. The Panzerjager I proved itself as an effective measure against French tanks and fortifications.
Of course, the SPG had its drawbacks. The crews complained about poor visibility and a cramped fighting compartment. The ammunition loadout was deemed poor, and the share of high explosive shells was increased to 50%. Despite all of its drawbacks, the Panzerjager I was evaluated as a more effective weapon than towed guns.
These results were sufficient to consider building an additional batch of SPGs. On September 19th, 1940, a contract for 70 casemates was signed with Krupp. Vehicles from the second series had a slightly different casemate, which also had additional side armour.
Initially, Alkett was supposed to convert the PzI Ausf. B into the Panzerjager I again, but plans changes on October 15th. Alkett was busy with building the StuG III Ausf. B. As a result, only 10 vehicles were converted in Spandau. Klöckner-Humboldt-Deutz was chosen as a backup. This company, which included the Magirus firm, was known for its trucks. Nevertheless, it was responsible for converting 60 tanks into Panzerjager Is between December 1940 and February 1941.
The new tank destroyers were sent to the 529th and 605th battalions, 27 vehicles apiece. The Leibstandart SS division was another unit to receive these vehicles, a battery of nine Panzerjager I. The remaining SPGs were sent to the 900th Training Brigade. It was a training unit only on paper, since the brigade was taking part in combat in the USSR in July of 1941.
All units armed with the Panzerjager I fought on the Eastern Front, with the exception of the 605th Tank Destroyer Battalion. The units were constantly given completely unsuitable tasks. For example, the 529th battalion was given objectives better suited for the StuG III. Without the armour of an assault gun, the tank destroyers were more vulnerable, which led to heavy losses. The Panzerjager I was also plagued with technical problems. This often applies to road wheels, which did not survive long marches.
The 47 mm gun was sufficient to fight Soviet T-34 tanks. In addition, production of subcaliber Pz.Gr.40 shells began in 1941, which let these tank destroyers fight the KV as well. Nevertheless, 140 Panzerjager I were lost in 1941. The remaining SPGs kept fighting until early 1943. The vehicles in the 521st Tank Destroyer Battalion served the longest, eventually sharing the fate of the 6th Army at Stalingrad.
The 605th Tank Destroyer Battalion deserves a separate mention. In March of 1941, it was sent to Lybia, where it was included in the 5th Light Division. In 1941, the battalion lost 13 vehicles. Most of the losses happened during November, when the British launched Operation Crusader. One of the enemies of the tank destroyer was the British Matilda tank. At 600-800 meters, the armour piercing shells could not penetrate this tank, but spalling could injure the crew. The Matilda could only be penetrated with subcaliber shells. German crews complained that there was shortage of them.
Including reinforcements, the 605th Tank Destroyer Battalion had 11 Panzerjager I by October of 1942 and the start of the Battle of El-Alamein. The British captured three SPGs during this battle. One of them, a vehicle with tactical number 32, was handed over to the Americans. This vehicle spent a long time at Aberdeen. In the early 1980s, it was returned to Germany, where it was restored. Presently, it is the only surviving Panzerjager I in the world.
Unlike the 15 cm sIG 33 (mot S) auf Pz.Kpfw.I Ausf.B, the first German mass produced tank destroyer was a very good vehicle. Despite many drawbacks, mostly connected with the chassis, the Panzerjager I met its expectations. While criticizing the PzI as a chassis, one must remember that it was far from the worst, recalling the 4.7 cm Pak(t) (Sfl) auf Fgst.Pz.Kpfw.35 R 731(f), whose combat career lasted for less than two weeks in the summer of 1941.
In the end, let us mention one more SPG that was built from the Panzerjager I. During the Battle of Berlin in April of 194, the Germans used a vehicle which carried a 75 mm StuK 40 L/48 gun. It is not known who built this SPG. It is only known that the Germans used it in Berlin and abandoned it.
Translated by Peter Samsonov. Read more interesting tank articles on his blog Tank Archives.
- Central Archives of the Russian Ministry of Defence
- Panzer Tracts 7–1 Panzerjaeger 3.7cm Tak to Pz.Sfl.Ic development and employment from 1927 to 1941, Thomas L. Jentz, Hilary Louis Doyle, 2004, ISBN 0–9744862–3-X
- Panzer Tracts No.10 Artillerie Selbstfahrlafetten, Thomas L. Jentz, Hilary L. Doyle, 2002, ISBN 0–9708407–5–6
- NUTS & BOLTS 07 Panzerjäger I 4,7 cm Pak(T) Auf Pz.I Ausf.B (Sd.Kfz. 101), Heiner F Duske, Tony Greenland, Frank Schulz, NUTS & BOLTS GrB, 1997
- NUTS & BOLTS 19 15cm sIG33 (Sf) auf PzKpfw 1 Ausf B & 15cm sIG33 towed, Jürgen Wilhelm, NUTS & BOLTS GrB, 2005
- Author's photo archive