Category: WW2 German Assault Guns

German Reich (1942)
Infantry Assault Gun – 24 Converted

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The concept of mounting a heavy infantry gun on a tank chassis was born out of a need to provide effective destructive firepower against enemy-fortified positions. While during World War Two the Germans already used the well-known StuG III series that fit this role effectively, something with an even greater punch was desirable. The need for a well-protected vehicle armed with a 15 cm gun arose in late 1942. At that time, the Germans were bogged down attempting to take the city of Stalingrad. Due to the urgent demand for such a weapon system, a small series of improvised vehicles armed with a 15 cm gun placed inside an armored superstructure would be created on a StuG III chassis, creating the Sturminfanteriegeschütz 33.

Early Attempts to Provide Close Fire Support Vehicles

Based on experience gained during the First World War, some people within the German Army, such as Erich von Manstein, argued for the introduction of well-armed and protected assault guns. Eventually, these would be the Sturmgeschütze (or StuG IIIs for short). These were to act as highly mobile artillery vehicles that were intended to provide close-up infantry support by destroying enemy fortified positions.

Whilst the concept was initially opposed by some elements within the German Army, the project was greenlit when it was approved by Oberbefehlshaber des Heeres (English: German Commander in Chief of the Army) Generaloberst von Fritsch in 1935. Due to many factors, but mostly related to the rather undeveloped state of the German industry and bureaucratic problems, the start of the StuG III’s production was delayed for years. The first production vehicles reached the troops at the start of the Western campaign in May 1940. Despite the small number of vehicles used, they quickly showed that a mobile, protected, and well-armed assault gun was capable of providing adequate infantry support.

Over the following years, the number of StuG IIIs would constantly increase. While its short barrel 7.5 cm gun was effective in its original role, due to urgent demand for mobile anti-tank vehicles, the StuG IIIs would be rearmed with long guns. After 1942, to further increase the effectiveness against enemy-fortified positions, the 7.5 cm guns were replaced by larger 10.5 cm guns.

While the StuG IIIs were well suited to their designated infantry support roles, there were never enough of them. As a result, the main artillery firepower for infantry formations came in the form of two different types of towed support guns: the lightweight 7.5 cm leIG 18 and the much heavier, larger caliber 15 cm sIG 33. Both of these proved to be excellent designs, serving the German infantry up to the end of the war. In the case of the larger 15 cm sIG 33 gun, it had sufficient firepower to destroy all but the most fortified enemy positions. It only needed a few rounds to completely demolish smaller buildings with ease. While the 15 cm sIG 33 offered great firepower to the German infantry, its weight severely limited its mobility. Infantry units of the German Army were in general not very mobile formations given the general lack of towing vehicles, mostly relying on horses to pull their equipment. Despite this, moving a heavy gun was tiresome and took some time to set up properly. Moreover, during retreats, the guns were often abandoned, as they could not be moved fast enough. These shortcomings became obvious after the Polish campaign in 1939. Shortly after that, WaPrüf 6 (English: German Army’s design office for armored vehicles and motorized equipment) issued orders to develop a self-propelled version armed with such a gun. Although initially it was intended to build a completely new design, this idea had to be abandoned due to a lack of production capacity.

Given that designing a brand-new chassis would take time, the Germans went for the simplest possible solution. They simply reused what they had available, in the form of the obsolete Panzer I Ausf. B chassis. A 15 sIG 33 gun was placed on this chassis, protected by a three-sided armored superstructure. This led to the creation of a rather awkward vehicle, that on the one hand solved the problems with the mobility of the 15 cm gun, but was plagued with other issues. Namely, the chassis proved to be too weak and prone to malfunction due to the extra added weight. The crew was poorly protected and only a few rounds could be carried inside. Despite all the problems, a small production run of 38 vehicles was made, which was completed by March 1940. This vehicle is known as 15 cm sIG 33 auf Panzerkampfwagen I ohne Aufbau Ausf.B and was intended to be used as mobile artillery, although it was occasionally used in a direct fire role. While its gun was effective at close ranges, other factors, such as its high silhouette, poor armor, and weak chassis, made using it in such a way highly dangerous. Any kind of enemy anti-tank weaponry could easily take out this vehicle. In addition, since it was open-topped, the crew was completely exposed to enemy fire from above, something that was likely to occur in urban fighting.

Experience in Stalingrad

In the summer of 1942, the Germans and their allies launched a new offensive with the aim of capturing the resource-rich Caucasus, but also the strategic and politically important city of Stalingrad. The fighting around and for the city of Stalingrad was notoriously vicious. The Soviets desperately tried to defend it, as the loss of the city named after their leader would be a huge morale boost for the enemy. The Germans had to fight for every street and building. As the Soviets were well entrenched, the Germans had great difficulty dislodging them.

This issue was discussed at a meeting on 20th September 1942 between Army officials and Adolf Hitler. During the meeting, it was agreed that a new vehicle capable of leveling entire houses with a few rounds was desperately needed. It was to engage targets at close range, so it had to be well protected. Given the urgency of the project, a small series of 12 vehicles were to be built within a two-week period. This meant that this vehicle had to be built using existing tools and equipment. The armament chosen was the 15 cm SiG 33 heavy gun. For the chassis, the Panzer III and IV were to be tested to establish if this gun could be installed inside their turrets. As this proved impossible to achieve, as a temporary solution, the StuG III chassis was to be used instead. Given that the company Alkett was responsible for the construction of the StuG III, it was tasked with developing this new vehicle. In theory, the cheapest way to produce this modification would be to mount the 15 cm gun inside the StuG III. In reality, though, this was not possible due to the large size of the gun, so a completely new superstructure had to be designed from scratch. The frontal armor protection of this vehicle was to be 80 mm thick, which was one of the mightiest in the German arsenal at that time, excluding the heavy Tiger tanks, which were slowly entering service. Due to the urgency of the project, any available StuG III chassis were to be reused for the construction of this new vehicle. In essence, this meant reusing older chassis which were either used for training or were from damaged vehicles which were returned to Germany for repairs. StuG III chassis used ranged from the Ausf.A to Ausf.F.

Name

This vehicle was simply designated as Sturminfanteriegeschütz 33. This name could be translated to infantry support assault gun. The number 33 refers to the main armament, the 15 cm sIG 33 (schwere Infanteriegeschutz – Heavy infantry gun). In the sources, it is sometimes also designated as 33B. The capital ‘B’ referred to the second version of this gun introduced in 1938. The sources occasionally shorten the name to StuIG 33. For the sake of simplicity, this article will use this shortened designation.

Production

Given the urgency and rather simple conversion process for the StuIG 33, the first 6 vehicles were completed by 7th October 1942, and the remaining six three days later. On 13th October, all 12 were reported ready for service. The remaining 12 from the second series were reported ready by mid-November 1942. Given the vehicle’s improvised nature, and the fact that its design arose from the fighting at Stalingrad, no further vehicles were ordered.

What is interesting is that in older sources, such as P. Chamberlain and H. Doyle’s Encyclopedia of German Tanks of World War Two, the first vehicle was stated as having been completed in December 1941. In a more recent publication, H. Doyle does not mention this date, which may suggest the older information has since been disproved with the appearance of more reliable information.

Design

Even though the StuIG was built using any available StuG III chassis, there were some differences in the vehicles’ overall design. As these were more of an improvisation than a dedicated designed vehicle, this should not come as a surprise.

Hull

The StuIG 33’s hull can be divided into three major sections. These were the forward-mounted transmission, central crew compartment, and rear engine compartment. The front hull was where the transmission and steering systems were placed and it was protected by an angled armor plate. The two square-shaped, two-part hatch brake inspection doors were located on the front hull. The front glacis had two small round-shaped covers. Their purpose is unclear, but on the original Panzer III, starting from Ausf. E/F, enclosed air intake ports were placed in the exact position of these round-shaped covers. What is unusual is that the StuG IIIs were not provided with such an air intake port except for the Ausf.A/B hybrid which was built in small numbers. A more probable explanation may be found in the fact that after the conclusion of the Western campaign in June 1940, the German Army initiated a huge program intended to improve Panzer III’s overall performance. This included adding extra armor plates to the front and rear. The armor plates that were added to the front were usually bolted down. As these Panzer IIIs were provided with the front air intake ports, it would be necessary to add holes to the frontal armor plates. The Germans would have likely reused these plates, and the round holes were filled with round-shaped metal plates.

As different StuG III chassis were used for the StuIG 33’s construction, there were some minor differences between them. For example, the StuG III Ausf.E used smaller cast hinges for the two glacis hatches.

Suspension

The suspension was the standard StuG III type which consisted of six road wheels on each side. These were suspended using a combination of individual swing axles together with torsion bars which were placed in the bottom of the hull. The upper movement of each wheel’s swingarm was limited by bump stops covered in rubber. Additionally, the first and the last wheels were equipped with a hydraulic shock absorber.

Once again, due to its somewhat accelerated development, any StuG III chassis that was available at hand were reused for this project. This is visually most noticeable when observing the suspension, which often had mixed components from the older and newer StuG III versions. The use of different types of front drive sprockets and rear idlers was common on the StuIG 33. As these were intended to be used on the Eastern Front during the winter of 1942/43, wider Winterketten (English: Winter track) were often used. The added weight of the gun and the superstructure to the front of the vehicle caused huge problems with the front road wheels and the transmission, which were prone to breakdowns. This issue would occur later on in other German designs as well, such as the Jagdpanzer IV series. Whilst the Germans did some improvements, such as the use of internal suspended metal wheels, the StuIG 33 did not receive any such modifications. Basically, the driver would have to pay great attention during driving so as to not overstress the front transmission.

Engine

The StuIG 33 was powered by the standard StuG III twelve-cylinder, water-cooled Maybach HL 120 TRM engine giving 265 [email protected],600 rpm. With this power unit, the StuIG 33’s maximum speed was only 20 km/h. The reason for this drop in maximum speed is not quite clear. Given the vehicle’s weight at 21 tonnes, it was not much different from the later 23.9 tonnes StuG III Ausf.G. This StuG III version with the same engine could achieve a maximum speed of nearly 40 km/h.

The fuel load of 310 liters was stored in two fuel tanks placed below the radiators in the engine compartment. With this fuel load, the StuIG 33 operational range was 110 km on roads and 85 km cross-country. To avoid any accidental fires, these fuel tanks were protected by firewalls.

The engine compartment was protected by an enclosed superstructure. On top of this compartment, two two-part hatches were added for access to the engine. Further back, two smaller doors were added to provide the crew access to the fan drives. The air intakes were repositioned to the engine compartment sides and were protected with armor plates. One major change was the addition of a large storage box above the engine compartment.

Superstructure

The superstructure had a simple box-shaped design. On the front part, there was the main opening for the gun mount, and to the left of it, the driver’s visor port was located. Right off the main gun, the machine gun ball mount was placed. The StuIG 33 had quite a limited field of view as no side or rear vision ports were provided. On the right side of the superstructure, a small pistol port was added.

To the rear, there were two hatches placed opposite of each other. Each of them had small pistol ports. On top, there was one hatch located in the bottom left corner. In addition, there was an opening for the gunner’s periscope. To avoid dust, rain, or, worse still, enemy grenades falling inside, a small protective roof was added on top of it. Lastly, there was a round opening for the ventilation port. Given that no such ventilation unit was fitted on any of the 24 StuIG 33 vehicles, it was simply covered by a round armor plate.

Armament

The main armament of this vehicle was a 15 cm sIG 33. Rheinmetall began its development in 1927 and it entered service in 1933. With a total weight of approximately 1,700 kg, it was one of the heaviest guns to be ever used for infantry support. It was a reliable and robust gun that was easy to build and required very little maintenance.

In terms of construction, it was quite a conventional design. It had a two-wheeled carriage and the older type of box trail equipped with a hydropneumatic recoil system placed under the gun barrel. The gun possessed a high elevation and used a horizontal sliding-block breech mechanism. To help counteract the muzzle weight, two balancing springs (one on each side) were installed. The 15 cm sIG was considered a satisfactory weapon by the Germans, but the greatest issue was its weight. It would remain in use throughout the whole of World War II in both its original form and as the main weapon of many German self-propelled guns.

The 15 cm sIG 33 fired a 38 kg heavy high-explosive round at a maximum range of 4.7 km. This high-explosive round, during the explosion, created a lethal area of around 100-120 m wide and 12-15 m deep. While the 15 cm sIG used several different ammunition types, in the sIG 33 auf Pz. I configuration, only the high-explosive rounds were used.

The main gun elevation was -4° to +75, while the traverse was 5.5° to either side. These figures differ depending on the source consulted. The rate of fire was low, at only 2 to 3 rounds per minute. This was due to the heavy weight of the shells and the use of separate two-part ammunition (shell and charges). The 15 cm sIG 33 used the Zeiss Rblf 36 gun sight.

During the construction of the Panzer I modification, the whole gun with its trailing leg and wheels was simply placed on top of the Panzer I hull. While this made the replacement of damaged parts or even the removal of the gun itself easier, it added unnecessary weight and height. Given that the StuIG 33 was to have an enclosed superstructure, using a whole gun assembly was impossible. Luckily for the Germans, Škoda was developing a modified version of this gun, known as the 15 cm sIG 33/1. This version was intended to be used on Škoda’s own self-propelled gun project that was in the works but delayed due to the great need for anti-tank vehicles based on the Panzer 38(t)’s chassis. In this modified version, the 15 cm sIG 33/1 had its wheels and trail removed. As a result, the gun could easily be installed in any fighting vehicle capable of carrying its weight.

The 15 cm sIG 33/1 gun was positioned slightly offset from the center to the right. The reason for this is not mentioned in the sources, but was possibly influenced by the driver’s position. The gun’s vertical rectangular opening was covered by a simple flat and sliding armor plate which moved with the gun when elevating. There were two parallel guiding rail plates bolted to the front armor, placed on opposite sides of the gun’s opening. The central opening for the gun was not fully protected, as there was some room between it and the gun barrel.

When the gun was highly elevated, there was an opening at its lower opening on the superstructure. To avoid potentially creating a death trap, the German engineers added a small sliding armor plate. When the gun mantlet plate was fully raised, it fell down and covered the small opening. This was a far from a perfect solution, but due to the urgency of the project, it was the best thing that the German engineers could think of.

The StuIG 33’s gun mount offered only a limited traverse of -3° to +3°, or -10° to +10°, depending on the source. Elevation ranged from -3° to +25°. Despite having a larger size than the smaller Panzer I, due to the 15 cm sIG 33’s large ammunition, only 30 rounds were carried inside the StuIG 33. When in movement, the gun was held in place by a forward-mounted travel lock.

The secondary armament consisted of one 7.92 mm MG 34 machine gun. It was placed on a Kugelblende 30 on the right side of the vehicle’s superstructure. The numbers 30 indicate the armor thickness of this ball mount. This ball mount consisted of two parts. The movable armored ball to which the machine gun was attached and the external and fixed armored cover. It offered a 15º traverse to either side. It could be elevated to 20° and depressed to -15°. For spotting targets, a telescopic sight with a field of view of 18° and 1.8 x magnification was provided. Only 600 rounds of spare ammunition were carried inside. Lastly, the crew was also provided with two 9 mm MP 40 submachine guns.

Armor Protection

Given the specialized role that the StuIG 33 was to perform, it had to be well protected. Because the Germans had not yet fully introduced 80 mm thick plates, as a temporary solution, bolted armor was used. While it slightly complicated the overall production, the Germans never noted any major issue with bolted armor plates, which were commonly used on the StuG III series and other vehicles up to the war’s end.

The original StuG III’s chassis had frontal armor formed of two plates with a thickness of 50 mm and placed at 21° and 52° angles respectively. For the StuIG 33, the Germans added an additional 30 mm of frontal armor. The smaller lower hull plate, placed at 75°, remained 30 mm thick, while the sides and rear were 30 mm thick.

The front superstructure’s armor consisted of one 50 and one 30 mm thick armor plate, placed at an 81° angle. The side plates were 50 mm thick and placed at a 75° angle. The rear armor was flat and only 30 mm thick. The top was only 20 mm thick. The top engine compartment was lightly protected by 16 mm of armor.

Adding all kinds of spare equipment was often used as improvised armor. The most common way was to mount one or more spare wheels to the front of the superstructure. In addition, some crews added track holders, which were installed on the superstructure’s sides.

Crew

The crew of the StuIG 33 consisted of five: a commander, two loaders, a driver, and a gunner. The driver was positioned on the left side of the vehicle. Behind him was the gunner and after him the commander. While not specified in the sources, due to the radio’s 2 m antenna being positioned on the left, we can assume that the commander was also the radio operator.

The StuIG 33 was not provided with a command cupola, which limited the commander’s ability to scout the battlefield. Furthermore, the initial 12 produced vehicles were at first not even provided with scissors periscopes. Lastly, the two loaders would be placed opposite the previously mentioned crew members. One of them operated the machine gun.

Combat Use

Immediately after completion, the first 12 vehicles were sent to the Eastern Front. They arrived at the River Chir, near the Don River, on 28th October 1942. Half of them were given to the Sturmgeschutz-Abteilung 117 (English: Assault Gun Battalion) and the remaining half to the 244th. Unfortunately, there is no surviving combat record of these 12 vehicles that saw service at Stalingrad. Given the heavy fighting, they likely saw extensive combat action.

The second group was initially attached to the 17th Lehr Abteilung, a training unit. Given the deteriorating situation at Stalingrad, especially after the Soviet encirclement of the 6th Army, these vehicles were part of the German relief force, which failed to break the enemy line. During this fighting, 5 vehicles were lost. The remaining 7 vehicles were allocated to the Gruppe Burgstaller (English: Burgstaller Group), essentially an ad hoc military unit, something that would become quite common for the Germans to do in later years. In April 1943, the Gruppe Burgstaller and its vehicles were integrated into the 23rd Panzer Division. The division itself was in the process of rearmament and reorganization, so any armor elements were welcome additions. As part of the 23rd Panzer Division, the StuIG 33s saw at least some combat action. At the end of May, this unit sent a combat report about the overall performance of the StuIG 33.

“ We advise close co-operation with tanks, since the self-propelled gun can destroy antitank guns and artillery positions at ranges up to 3,500m. Enemy tank assembly positions were effectively obliterated. We note that it is very effective against buildings, also infantry and anti-tank rifle positions. The gun did not achieve direct armor penetration when used against tanks. Mechanical maintenance is guaranteed only when used in conjunction with a tank regiment.

During the assault by our tank forces against concealed positions all were overrun and occupied. An advance in stages was carried out only under the cover of accompanying armored infantry. …. The mounting bolts on the [gun] cradle’s armor plate are too weak. The commander’s cupola is too small to provide good observation. The hatch impedes vision to the right. The vehicle is front-heavy. The second running wheels are overloaded. The engine is underpowered and the clutch is too weak, also the brakes wear out too quickly. “

On 11th May 1943, three vehicles were reported to be fully operational, while the remaining four were under repair. The last vehicle was reported lost in October 1943. Some sources also mentioned that at some point the 22nd Panzer Division briefly operated these vehicles.

Surviving Vehicle

Surprisingly, despite the limited number of the vehicles built, one StuIG 33 actually survived the war. It was captured at some point during the fighting for Stalingrad, and can now be seen at the Russian Kubinka Tank Museum.

Conclusion

While there is little to no information about the StuIG 33’s overall combat performance, we can assume that thanks to the 15 cm gun, it was quite effective in taking out designated targets. But given its rather improvised and rushed design, many flaws were noted. The vehicle was handicapped by low mobility and prone to breakdowns of the suspension and the drive unit. The gun, while effective, had limited traverse and a small ammunition load. The crew had poor vision of their surroundings, especially the commander. Despite all these flaws, the StuIG 33 showed that such a vehicle was needed, and further development would lead to the introduction of an assault gun known as Sturmpanzer IV, which saw service in greater numbers.

Sources

D. Nešić (2008) Naoružanje Drugog Svetskog rata-Nemačka, Beograd
T.L. Jentz and H.L. Doyle (1999) Panzer Tracts No.8 Sturmgeschütz
T.L. Jentz and H.L. Doyle Panzer Tracts No.9 Sturmpanzer
P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
H. Doyle (2005). German military Vehicles, Krause Publications
Ian V. Hogg (1975) German Artillery of World War Two, Purnell Book Services Ltd.
T. L. Jentz and H. L. Doyle (1998) Panzer Tracts No.10 Artillerie Selbsfahrlafetten
J. Engelmann, Bison und andere 15 cm-Geschutze auf Selbstfahrlafetten, Podzun-Pallas-Verlag GmbH
Tank Power Vol.XXIV 15 cm sIG 33(Sf) auf PzKpfw I/II/III, Wydawnictwo Militaria
Walter J. Spielberger (1993) Sturmgeschütz and its Variants, Schiffer Publishing Ltd
T. Anderson (2016) Sturmartillerie Spearhead Of the Infantry, Osprey Publishing
W. J. Spielberger (2007) Panzer III and its Variants, Schiffer Publishing Ltd.
B. Carruthers (2012) Sturmgeschütze Armored Assault Guns, pen and Sword

German Reich (1943-1945)
Light Self-Propelled Gun – 194 Captured and Produced

The Semovente L40 da 47/32 was an Italian light Self-Propelled Gun (SPG) developed as an infantry support vehicle. It entered service in 1942, immediately proving to be obsolete. The Regio Esercito (Eng: Italian Royal Army) used it until September 1943, when the Cassibile Armistice was signed, the Italian Royal Army was disbanded and the Italian peninsula not yet under Allied hands was occupied by the German troops.

After the armistice, from 1943 to 1945, all the surviving Semoventi (Italian world for self-propelled guns, Semovente singular) that were deployed, not only in Italy, but also in the Balkans, were captured by the armies or militias in the area.

The Semovente L40 da 47/32

The development of a new light infantry support gun that could support the assault of the Bersaglieri units (Eng: Italian Light Assault Troops) started in the late 1930s, but the first two prototypes were not accepted into service.

Another prototype development started in January 1941. On May 10th, it was presented to the Royal Army. After the tests, the Italian Royal Army High Command requested some changes to the prototype. It was renamed Semovente Leggero Modello 1940 da 47/32 or Semovente L40 da 47/32 (Eng: Lightweight Self-Propelled Gun Model 1942 armed with 47/32).

A total of 402 vehicles were produced under Italian and German control based on the hull of the L6/40 light reconnaissance tank.

German Operation Achse

After the arrest of Benito Mussolini, the leader of the Partito Nazionale Fascista Italiano (Eng. Italian National Fascist Party), on July 25th 1943, the Germans had foreseen the Italian surrender. They planned Fall Achse (Eng: Operation Axis), which they launched on September 8th when the signing of the Armistice of Cassibile (which had been secretly signed on September 5th by the Italian Royal Army and Allied Forces) was made public. In 12 days, the German troops managed to occupy all the Italian command centers and divisions in Italy and in the other occupied territories.

The Germans captured all the Italian factories that produced armaments or military equipment. They also captured 977 Italian armored fighting vehicles, of which about 400 were tanks and self-propelled guns, 16,631 trucks, over 5,500 artillery pieces, 2,754 anti-tank or anti-aircraft guns, over 8,000 mortars, 1,285,000 rifles, 39,000 machine guns, and 13,000 submachine guns. They imprisoned 1,006,730 Italian soldiers stationed in Italy, the Balkans, Greece, and France.

By October 1st, 1943, Wehrmacht documentation stated that German units had captured 78 L40 da 47/32s in all occupied territories (including the 20 L40s produced before the Armistice and not delivered). In German service, this vehicle was known as the Sturmgeschütz L6 mit 47/32 770(i). For this reason, some sources wrongly call it Semovente L6 or StuG L6.

In addition, many former Italian factories, such as FIAT, Lancia, Breda, and Ansaldo-Fossati, were also under German control. With this and with the acquisition of many spare parts and materials, it was possible to restart the production of nearly all Italian vehicles. This was the case with the Semovente L40 da 47/32, with the Germans producing 74 new Sturmgeschütz L6 mit 47/32 770(i).

Under German control, another 46 Command and Radio Center vehicles on the L40 hull were produced, which brings the total number of L40 produced by the Germans to 120 units.

Operational service in Italy

While the Semovente L40 da 47/32s were available in some numbers, their use in Italy by the Germans was limited. The units that had this vehicle in Italy were the 305. and 356. Infanterie Divisionen, Schwere Panzerjäger Abteilung 590, 114. Jäger Division and the 20. Luftwaffe-Field-Division.

The 305. Infanterie Division fought between September 8th and 10th to occupy the port of La Spezia. It was transferred in the following weeks to near Rome, where it was supplied with some Italian vehicles, among which were some L40 from 47/32s.

The 305. Division then defended the Gothic Line and the Gustav Line before surrendering, together with most of the German divisions that remained after the Battle of Bologna, on the Po River.

The 356. Infanterie Division fought in anti-partisan actions between November 1943 and January 1944. It was transferred to Anzio and was provided with the self-propelled L40 vehicles along the way.

The unit fought fiercely for the defense of the region together with the Italian Republican National Army units until they were forced to retreat along the Gustav Line in March 1944. After the Gustav Line was broken through, the unit fought in Tuscany. retreating to the south of Florence in July 1944. In January 1945, it was transferred to Hungary but, according to the surviving documents, it was no longer equipped with Italian self-propelled vehicles.

The Schwere Panzerjäger Abteilung 590 was used from June 13th to September 14th, 1944 to secure central Italy. In order to perform this task, the unit was provided with some L40 self-propelled vehicles. From September 15th, 1944 to January 15th, 1945, the unit was involved in defensive combat in the Emilia-Romagna region.

Due to the scarcity of artillery towing vehicles and the obsolescence of the self-propelled L40 variants, many self-propelled vehicles were modified by removing the cannon to be used as artillery tractors.

From April 22nd to May 2nd, 1945, the unit was involved in the fighting retreat, desperately battling against the Allied forces.

The 114. Jäger Division was transferred to Italy from Yugoslavia in January 1944. It was supplied with material captured from the Italian Army, including some L40 self-propelled vehicles. After the Battle of Anzio, the unit was employed only in anti-partisan roles. It was responsible or co-responsible for three different massacres in the region of central Italy against innocent civilian victims. The unit was completely annihilated in April 1945 during fighting with Allied forces.

Panzer Ausbildung Abteilung Süd (a training tank battalion) was equipped with the Semoventi L40s, but these were used mainly for crew training. Organization Todt, which was present in Italy, operated an unknown number of L40 da 47/32s, but mostly as tractor vehicles without their guns.

In May 1944, the 20. Luftwaffe Field Division (20. LwFD), previously employed in Denmark, was sent to Italy, more precisely to Lazio. There, it was re-equipped with a number of Semoventi L40 da 47/32s and immediately participated in hard clashes with the U.S. Army units in the Terracina area. On June 1st, the unit assumed the designation of 20. Luftwaffen-Sturm-Division.

The division retreated to Tuscany and established defensive positions near Roccastrada. From there, at the end of June, it was again engaged in heavy clashes against U.S. forces.

After fighting house by house for the control of Siena against the units of the Corps Expéditionnaire Français en Italie (Eng: French Expeditionary Force in Italy), in July 1944, the division withdrew to the area of Volterra. It was then withdrawn from the front to be sent to the rear to guard the coast between Viareggio and La Spezia, where it absorbed the remains of the 19. LwFD. In mid-September, the division received orders to move to the coast of the Adriatic Sea, facing the Commonwealth forces between Rimini and Santarcangelo di Romagna and then south of Cesena.

After the killing of their commander in Bologna by the partisans and further heavy losses in the fighting between Cesena and Forlì, the division was disbanded on November 28th, 1944 and its survivors were reassigned to other German units.

Operational service in Balkans

In the Balkans, the L40 da 47/32s saw extensive use against Yugoslav resistance movements. Several German units were equipped with them. Some of these were the 117. and 118. Jäger Divisionen, 11. Luftwaffe-Field-Division, and the 181., 264. and 297. Infanterie Divisionen. Many police units of different sizes (such as the 13. Verstärkt Polizei Panzer Kompanie, 14. Panzer Kompanie, 4. SS Polizei Division) were also equipped with this vehicle. Some smaller units were also supplied, such as SS Panzer Abteilung 105. and Panzer Kompanie z.b.V 12.

In 1944, due to the availability of Italian armored vehicles, it was possible to resupply many German units which fought in Yugoslavia with them. The Germans did not form dedicated Panzer units with these vehicles. Instead, these vehicles were usually used to equip reconnaissance or anti-tank units (Aufkl. Abt and Pz.Jag. Abt.). By May 1944, German forces operating in Yugoslavia had at least 165 Semovente 47/32 vehicles.

By the end of 1943, Panzer Kompanie z.b.V 12 had in its inventory 12 operational Semoventi L40 da 47/32s and 4 in repair. In early 1944, it received an additional 14 Semoventi da 47/32, one L6 light tank, and 4 M13/40s. By February 1944, there were only 2 operational Semoventi da 47/32 and 2 in repair. On March 1st, 1944, some 10 were operational and 3 in repairs. These were allocated to the 2nd Company, which took action against partisan units around the city of Kraljevo. In July, the number of Semoventi da 47/32 was increased to 15 vehicles. The reason for the large monthly oscillations in available numbers is not clear. It could be either a mistake in sources or, because of the poor mechanical reliability, some vehicles were simply not listed. By September and October 1944, while this unit still had 16 such vehicles, they were replaced in order to increase the number of M15 tanks.

The 14th Panzer Kompanie was another example of a German unit using the Semovente L40 da 47/32. This unit, which was active in Slovenia in September 1944, was reinforced with two 8 vehicle strong platoons equipped with the Semovente L40 da 47/32. One smaller unit with four such vehicles was kept in reserve.

While fighting the Partisans in the Balkans, the L40 da 47/32s were usually dispersed and used in smaller groups. The usual tactical employment was that one vehicle would advance while the remaining vehicles provided cover.

By the end of 1944, on the Yugoslavian Front, the Germans and their allies had less than 80 Semoventi L40 da 47/32. Near the end of the war, in March 1945, the numbers were reduced to less than 40.

In German hands, the Semovente L40 da 47/32 was modified in order to improve its performance. As the L40 da 47/32 was initially only armed with the main gun, it was less effective against infantry attacks. For this reason, the Germans added machine gun mounts that were protected with an armored shield at the front. The machine gun models used included the Breda Mod. 37 and Breda Mod. 38, both 8 mm caliber, and, in some cases, MG34s or Fiat-Revelli Mod. 14/35. Additional armor plates were added to the side of the superstructure, and in some cases, even on the top. Additional spare part boxes were also sometimes added.

Also, as previously noted, a significant number of these vehicles were modified to be used as towing tractors or as training vehicles. For these modifications, the main gun was removed. In the case of the training vehicles, a wooden shield was simply added where the gun was.

The SS Polizei-Regiment 18 Gebirgsjäger was equipped with two Italian armored cars and at least five Semoventi 47/32s when it was relocated from Greece to the northern regions of Serbia in October 1944. It was engaged in a failed German attempt to stop the advancing Soviet Forces in Vojvodina and suffered heavy losses, probably losing all its vehicles.

In general, the German view of the L40 was very negative. It was small and narrow and the cannon was not able to face the most modern opponent vehicles. In anti-partisan actions in Italy and in the Balkans, it proved relatively effective, as its small shape and weight allowed it to climb very steep mountain roads, where only mules could pass. The cannon, even if almost useless against the armor of Soviet or American tanks, had a good High Explosive round that was effective against infantry.

The Germans, as well as the Italians, realized that the vehicle was very vulnerable to ambushes. Consequently, German tankers learned to wear the Stahlhelm helmet and carry MP40s and hand grenades inside the vehicle for close defense.

Camouflage

The Germans repainted the L40s that they captured from the Italians or that they received after November 9th with a three-tone camouflage, depending on the unit that used them.

For example, Schwere Panzerjäger Abteilung 590 repainted its L40 da 47/32s with dark green and dark brown stripes on a standard khaki base. SS Polizei-Regiment 18, stationed in Greece, repainted its vehicles in three-tone camouflage, dark green, and brown spots on standard khaki. The 20. Luftwaffen-Feld-Division, which used some L40s in anti-partisan duties in central-northern Italy, camouflaged its self-propelled guns vehicles with patches of green and dark brown.

Conclusion

The Semovente L40 da 47/32, while cheap and small in size, was by 1943 standards generally an obsolete vehicle. For the Germans who were at this stage of war becoming ever more desperate to find any additional armored vehicle, it was a welcome addition. The use of the Semovente L40 da 47/32 by the Germans in its original role against the Allied forces in Italy was limited. They did see service in other secondary roles for example crew training or as armored tractors. They were more deployed in combat against the Partisans especially in the Balkans where the enemy had limited anti-tank capabilities.

Sources

Bojan B. Dumitrijević and Dragan Savić (2011) Oklopne jedinice na Jugoslovenskom ratištu,, Institut za savremenu istoriju, Beograd
T. L. Jentz (2008) Panzer Tracts No.19-2 Beute-Panzerkampfwagen
F. Cappellano and P. P. Battistelli (2012) Italian Light tanks 1919-45, New Vanguard
Nicola Pignato e Filippo Cappellano – Gli autoveicoli da combattimento dell’Esercito Italiano, Volume secondo (1940-1945).
Filippo Cappellano – Le artiglierie del Regio Esercito nella Seconda Guerra Mondiale
Nicola Pignato – Armi della fanteria Italiana Nella Seconda Guerra Mondiale
Olivio Gondim de Uzêda – Crônicas de Guerra

German Reich (1944)
Assault Gun – 18 Built

Of all of the heavy tank projects from Germany in WW2, one vehicle stands out as something very different from the others and drew significant curiosity from the Allies when they first encountered it. A vehicle combining the armor of a heavy tank with a weapon never fitted to an armored fighting vehicle before, a 38 cm mortar. This incredible vehicle was developed for a specific purpose, urban combat. In such a situation, a huge shell could demolish whole buildings and defensive structures. It could deliver a huge explosive shell at close quarters or be used for long range shelling of an enemy position. That vehicle was the German Sturmtiger.
The origins of the Sturmtiger, or, more correctly, the ‘38cm RW61 auf Sturmmörser Tiger’, started with a call from the German Army (Heer) for a heavy howitzer specifically to help in urban combat, where a well-defended building could hold up an attack or otherwise be resilient against even ‘normal’ caliber artillery fire. What was needed was a gun capable of firing a large explosive shell both directly and indirectly and to have it mounted on a heavily protected chassis. This call was put into reality by Hitler on 5th August 1943, following the failure of other ideas for high-angle guns mounted on tank chassis.

Prototype to production

Despite Hitler’s order to develop a vehicle being issued in August 1943, only one prototype was initially ordered, possibly indicating how much confidence there actually was for such a weapon. Nonetheless, a vehicle was put together based on the chassis of a Tiger tank by the firm of Alkett in Spandau, using an armored superstructure built and assembled by the Brandenburg Iron Works (Brandenburger Eisenwerke) at Kirchmöser. The vehicle was ready and was shown to Hitler at the Ayrs Training Camp in East Prussia on 20th October 1943, an impressive turn-around time of under 3 months.
Despite the impressively rapid construction of a prototype, mass production was severely hampered by the slow rate of manufacturing of Tiger I tanks and was not due to start until mid-1944. Any production of Sturmtigers alongside the Tiger I would have impeded Tiger I production. Since priority was clearly given to the Tiger I tank, the Sturmtiger had to wait. In the meantime, the prototype was undergoing testing and trials.

Prototype Sturmtiger with rubber-tired road wheels. Note: this vehicle is in the possession of the Russian collection at Kubinka with steel-rimmed wheels and the steel counterbalance on the muzzle of the mortar – two later modifications, although it retains the uparmored lower front hull. Source Spielberger. The top image has been colorized by Jaycee ‘Amazing Ace’ Davis.
By May 1944, the Sturmtiger prototype had been kept busy with trials and firing tests for the development of range tables, but production had still not started and the concept was likely to be scrapped. Rather than ditch the idea though, Hitler ordered that, instead of interrupting the production of the Tiger I, the Sturmtigers would be built on the chassis of Tiger I tanks which had already been in action and suffered serious damage. These were being sent back to the factory for rebuilding rather than just for repair. Twelve Sturmtiger units were to be prepared. A Tiger I cost RM250,800 (Reichsmarks) each to build, but as these Sturmtigers were made from rebuilds, it is not possible to calculate the cost of the rebuilding of each hull as each vehicle used had suffered a different amount of the damage. Even so, the cost of building a Sturmtiger was estimated at RM53,000, which, if added to the RM250,000, means that each one constituted an investment of over RM300,000 (approximately US$4,255,264 in 2015 values). This was an enormous sum of money considering it cost just RM117,100 (approximately US$1,660,971 in 2015 values) for a Panther tank.*
*RM to US$ exchange values conducted using Historical Statistics
Twelve Sturmtigers were built which, with the prototype, makes thirteen Sturmtigers finished by the end of September 1944. Five more were ordered by Hitler on 23rd September 1944. Those additional five vehicles were all finished by the end of December 1944, followed by orders for more, although these were never produced. In total, 18 Sturmtigers were built.

Running gear

The running gear for the Sturmtiger was identical to that of the Tiger I with the exception that only the prototype had the rubber-tired wheels. The production Sturmtigers were supposed to be fitted with the rubber-tired road wheels to help manage the additional 8-tonne load of the Sturmtiger over that of the Tiger I, but they all are seen with the steel-rimmed wheels common to late Tigers. The rubber-tired wheels are one of the identification features of the original prototype Sturmtiger, even though even these were later changed to the steel-rimmed wheels. The engine remained the same as on the Tiger I, a Maybach HL 230 TRM P45 and, with the additional weight, the Sturmtiger was markedly slower and less maneuverable than the Tiger I. If a later production damaged Tiger I tank was used to build a Sturmtiger it would be powered by the more powerful Maybach HL 230 TRM P45 V-12 700 hp petrol engine.

Armor and Optics

The lower hull of the Sturmtiger was that of the Tiger I and remained unchanged. Nominally, the armor on the Tiger I consisted of a lower front hull plate 100 mm thick, a short glacis 60 mm thick and a reclined driver’s plate 100 mm thick. The sides were a uniform 80 mm thick and vertical on both lower and upper section, and 80 mm thick on the back. Due to manufacturing tolerance allowance of 0 to +5%, many of these plates ended up being recorded as slightly thicker i.e. 102 mm instead of 100 mm.

For the Sturmtiger, the turret was removed, as was the roof of the hull over the fighting compartment. Further, the driver’s plate was mostly gone, with the top half of it cut-off across the full width. Replacing all of this was a large flat-sided box containing all the crew and the main gun. The front of this box was made from a single slab of armor plate 150 mm thick angled back at 45 degrees which extended down to a point about halfway along the length of the glacis. It was held to the front of the hull by two substantial armor plates bolted over the joint. In the front of the plate was a large, armored ball-mount 69 mm thick for the 38 cm mortar and a small ball-mount for the forward-firing M.G.34 machine gun. The gun and mount were also protected by a 150 mm thick mantlet. On the left of the gun was a rectangular opening which took the aiming telescope and, below this, a pair of small visors under a small cowl were placed for the driver. The sides and rear were made from slabs of armor 80 mm thick but angled inwards towards the roof, which was 40 mm thick. On the prototype, an additional 50 mm thick slab of armor was bolted to the lower front hull of the Sturmtiger, but this feature was dropped from production vehicles, presumably to save weight.

Armor scheme for the Sturmtiger which omits the remnants of the bottom half of the driver’s plate and top part of the glacis which would lie just behind the bottom edge of the 150 mm thick front plate on the Sturmtiger. This scheme also omits the armored mantlet around the gun barrel. Source: Wikipedia

View of the driver’s station at the front-left of the Sturmtiger clearly shows both his vision optics but also that the original glacis was left intact and the original driver’s plate was simply cut off lengthwise for the new front plate. Source: Schneider

Seen from the outside, it is clear that the new front plate significantly overlaps the old armor on the front of the Tiger. The thick block of armor on the corner is there to cover the overlap between the new casemate and the hull. The bolts on the side indicate a reinforcing plate added on the inside joining the two sections together. Source: Schneider
Sighting for the mortar was by means of a Kugeloptik ZF3 x8 sight using the aperture to the left of the main gun and a KgZF2 sight. Other features included the pistol ports on both sides, perhaps more useful for aiding vision than the original intention for them.

Overhead view of a Sturmtiger showing the large rectangular roof hatch used for reloading. Source: The Tank Museum, Bovington

The gun

Originally, the request from the Army called for a 210 mm howitzer but, with no suitable options, they turned to Rheinmetall-Borsig for their Raketenwerfer 61 L/5.4 (Gerat 562 – Sturmmörserwagen 606/4). The gun itself existed in two iterations at the time. One, the R.aG 43 (Raketenabschussgerät 43), was a ship-mounted anti-aircraft weapon used for firing a cable-spooled parachute-anchor creating a hazard for aircraft. The second, the RTG38 (Raketen Tauch Geschoss 38), was a land-based system. Both systems had been made by Rheinmetall-Borsig, in Dusseldorf, but had been designed by MOHRA Gerätebau Aktiengesellschaft Bautsch of Ostsudeten. It was the RTG38 which formed the basis of the weapon in the Sturmtiger. With a range of 3,000 m, it had originally been planned for use in coastal installations by the Kriegsmarine firing depth-charges against submarines. For use in a vehicle, it was to find use as a demolition gun and had to be modified for that role. This modification work was carried out by Rheinmetall at their Sommerda works.
In its coastal defense role against submarines, it was not an effective weapon, and only 12 were made, of which 3 were tested in 4th April 1944 at Trondheimsfjord, Norway. The result was that problems were identified with the fuzing and the rounds failed to achieve the ranges (up to 3,000 m) desired. A second test firing, held on 20th April 1944, revealed an 18% failure rate, likely due to problems encountered when the shell hit the water. Instead, the weapon was selected for use against surface targets and they were based in positions at Fanø Island, Denmark (1 weapon based on the Marine Küsten Batterie Gneisenau) and at batteries at Alta, Agdenes, and Trondheim in Norway (unknown numbers). Two of these weapons are preserved in museums in Copenhagen (Denmark), and Tromsø (Norway), respectively.

R.aG43 at the Tøjhusmuseet in Copenhagen, Denmark, marked ‘bwo 38cm R.ag.M43 Nr.10’ (left). Unconfirmed RTG38 (possibly a modified RaG43) at the Narvik War Museum (right), the example in Norway appears unmarked or illegible. Source: Massimo Foto on Landships (left) and Yetdark on Flickr (right) Further research on these guns is needed.

Believed to be a R.aG43 on a land mount for coastal defence in Denmark or Norway. Source: Axishistoryforum.com
Modified for use in a vehicle, the recoil from the modified rocket-mortar was enormous, about 40-tonnes, and this meant that only a heavy chassis could be used to mount the gun. The only suitable vehicle in Autumn 1943 was the Tiger I.
Some of the gun barrels were modified during production with a heavy steel ring around the muzzle as a counterweight to make elevation easier but, other than the mounting, the gun was effectively the same principle as before. The shells for the weapon were extremely heavy, far too heavy for a man to load manually, at 330 kg each. As a result, each of them had to be carried by means of a ceiling-mounted trolley from their rack to a roller-mounted tray at the breech. Once on the tray, four soldiers could then push it into the breech to load it. The whole process took 10 minutes per shot from loading, aiming, elevating to firing.

Breach of the RW61 with shell absent (left) and being loaded, providing a good view of the vents on the bottom of each shell (right). Source: Schneider (left), Navweaps (right)
The rounds were huge and only 12 rounds could be carried internally on the 6 racks provided, stacked three high and two deep on each side. No special resupply vehicle was provided to carry additional shells but additional shells could be carried in trucks by the unit, which would allow the Sturmtiger to be reloaded having withdrawn from combat. Reloading of these huge shells was carried out by means of a roof-mounted (temporary) crane which was erected on the back of the cab and lowered shells through a removable hatch in the roof of the casemate and down onto the stowage racks.


Reloading process for the Sturmtiger was laborious but straightforward. 1) Unpacking the shell after rolling it into place on a pair of wooden rails. 2) Attaching the clamp for the crane to lift the shell. 3) Hoisting the shell up with crew to keep it steady. 4) Lowering the shell through the roof hatch to be racked inside. Source: Schneider.
Rebuilt for the Wehrmacht, the mortar was named the 38cm Rocket Launcher RW61 (RW – Raketenwerfer) and fired two types of shell, an explosive shell (Raketen Sprenggranate 4581) for general use, and a hollow-charge shell (Raketen Hohlladungsgranate 4592) specifically for targeting reinforced concrete structures, as the warhead could penetrate up to 2.5 m of reinforced concrete. The range, however, was dependent on temperature ranging from a maximum range of 4,200m at -40 C to 5,900m at 50 C, and 6,650m at 15 C. This very large difference in shell performance was because it used a combustion process of propellant as the rocket was fired which was slower-burning in cold weather – the result were very lengthy range/temperature tables for the crew to use in order to accurately lay the gun. Not only was the range affected by temperature but so was shell flight and accuracy. To account for these discrepancies temperature measurement was important in the vehicle and the crew was provided with details range tables listing the elevation, range and temperature in order to maintain accuracy. The minimum range for firing from the tables was just 50 m.
Each shell came in two parts: a case about 550 mm long holding 40.1 kg of diglycol powder (rod form) as the propellant, and the H.E. shell itself carrying 122.5 kg of Amatol 50/50 high-explosive (with six P.E.T.N. pellets acting as the exploders), forming a complete 1,489 mm long (1,440 mm shell and case plus 49 mm fuze) long. Each shell used the same Treibsatz 4581 rocket motor and each case was thin-walled with 32 venturi holes in the bottom to vent out the propellant gases. The venturi holes were angled at 14 degrees to the axis of the rocket, and together with the splines which went into the rifling of the gun caused the shell to rotate clockwise in flight for stability.
Following examination of the records at the Sommerda factories in 1945, it was determined that there were two types of fuzes produced for the Sturmtiger shells. The first was the A.Z.KM 8m.r. (or K.N.9) direct action and delay fuze (percussion fuze with an optional delay of 0.12 seconds) for the High Explosive Shell (4581), and the A.Z.KM.10 hollow charge fuze (nose percussion with no delay) for the hollow charge shell (4592). The delay fuse was found to sometimes malfunction when striking a target at an angle of less than 14 degrees requiring multiple impacts before it would function. When striking a hard target at a steep angle, therefore, the round could actually break up without detonating so the delay on the fuze was not used when firing against hard targets or when the ground was very hard.

38cm Raketen-Sprenggranate 4581 (High Explosive) (left) and 38cm Raketen-Hohlladungsgranate 4592 (right). Source: War Office(UK) 1945 (left) and Navweaps (right)

The disassembled 38cm Raketen-Sprenggranate 4581 (High Explosive) shell with the HE containing section at the front. Source: US Army Catalog of Enemy Ordnance
Elevation was by means of a crank at the left of the mounting and could elevate the gun between 0 and 85 degrees with a traverse-crank over the barrel controlling side-to-side movement. This traverse movement allowed firing up to 10 degrees each way.
The barrel was radically different in design to other guns, with a cast outer body and a liner inside made from steel about 12 mm thick. Into this liner were cut nine rifling grooves into which splines on the rocket would sit and then rotate during firing. During firing, the gases produced were vented through the gap between the inner barrel and the outer barrel sheath. The two pieces of the barrel were held together at the breech and muzzle with steel rings and by drilling 32 holes the gases from combustion could be vented forwards keeping the gas out of the crew space and reducing the recoil of the gun.

Dunkelgelb-camouflaged Sturmtiger used during the Warsaw Uprising.

Sturmtiger in a late-war “ambush” camouflage, Reichswald, Germany, February-March 1945.

Illustration of a Sturmtiger receiving ammo. This was a tough job, in which the whole crew was involved due to the sheer weight of the shells.

Combat

Sixteen of the eighteen Sturmtigers were issued to Sturmmorser Companies 1000, 1001, and 1002 for the defense of the German homeland in 1944. These companies, known as Panzer Sturmmörser Kompanien (Pz.Stu.Mör.Kp.), were originally intended to be issued with 14 vehicles each but, in the end, unit 1000 received just 4 Sturmtigers and 1001 and 1002 received 6 each (16 vehicles). In unit organization, Sturmtigers were paired up, with two vehicles forming a Zug (Platoon).
Pz.Stu.Mör.Kp.1000 was formed from two Zugs for a total of 4 vehicles. It was officially formed on 13th August 1944 and the day after formation, the unit was ordered to form part of Heeresgruppe Mitte (Army Group Mitte) and a force of two vehicles (with personnel from Alkett) was sent (15th to 18th August) to quell the Warsaw Uprising. After this, there were plans to send them to Bratislava (Pressburg) to quell the September 1944 Slovak Uprising, but that rebellion petered out before the unit was sent.
The second Zug of two Sturmtigers was sent to France by the end of August 1944. The first Zug was then sent to Hungary, where it was attached to Panzer-Brigade 109 by the middle of September 1944. By the end of October, the second Zug was withdrawn back to Warsaw and then sent back to Sennelager in Germany for refitting. In December 1944, Pz.Stu.Mör.Kp.1000 had been attached to 15th Armee as part of 6th SS-Panzer-Armee but only had 3 operational vehicles in time for Operation Wacht Am Rhein (Watch on the Rhine) in the Ardennes. As a result of problems with transportation though, these vehicles never reached the starting points for the operation and took no part in the offensive. By the end of January 1945, this unit had been redesignated as an Artillery unit and the strength had been increased to 3 Zugs comprising 6 vehicles.
A record of the use of the Sturmtiger by this unit in combat comes from the unit history for the US 113th Cavalry Group, which recorded that, on 5th February 1945, they were shelled by ten ‘rocket-type’ projectiles which produced huge explosions, followed by two more rounds against the town of Pier. This is believed to be an attack by Pz.St.Mör.Kp.1000 and, when the 113th Cavalry captured the town of Bedburg, they found an abandoned Sturmtiger which is what they ascribed that shelling by rocket-projectiles too. The 737th US Tank Battalion, during actions around the town of Menden, also reported being attacked by a Sturmtiger thought to be from this unit.

Still from a video of the Sturmtiger in combat 1944. Source: Spielberger
Pz.St.Mör.Kp.1001 did not fare much better. Officially formed on 23rd September 1944, the first Zug was not ready until the end of September, followed in the first week of October by the second Zug, but was not combat ready until the end of the month. On 10th November 1944, both Zugs were sent to Oberbefehlshaber West. Just like Pz.St.Mör.Kp.1000, this unit was also deployed for Operation Wacht Am Rhein (Watch on the Rhine) and was also assigned to 15th Armee as a part of the 6th SS-Panzer Armee, again with just 3 vehicles. Unlike Pz.St.Mör.Kp.1000 which did not reach its starting point for the operation, the 3 vehicles of Pz.St.Mör.Kp.1001 did get to the start point. The Operation had called for (amongst other things), the capture of the Belgian city of Liege in the Northern sector of operations. It was for this task that both Pz.St.Mör.Kp.1000 and 1001 were originally intended. As it was, the German forces never got close to Liege and only Pz.St.Mör.Kp.1001 even got to the theatre. Pz.St.Mör.Kp.1000 did not see action during the operation, but Pz.St.Mör.Kp.1001 did, albeit not for its original target of Liege.
Instead, Pz.St.Mör.Kp.1001 saw action around Duren and Euskirchen just before the New Year, covering the retreat of German forces. Just like Pz.St.Mör.Kp.1000, Pz.St.Mör.Kp.1001 was reassigned and, by the end of January, along with Pz.St.Mör.Kp.1000, was redesignated as an Artillery unit with a strength set to be 3 Zugs (6 vehicles).
During action at Duren on 26th February 1945, one Sturmtiger was knocked out when the driver got the vehicle stuck in a ditch along the roadside during the withdrawal from the town. Immobilised, it was shot at least three times in the rear by a Sherman tank of C Company, 743rd Tank Battalion, which was supporting the attack by the 117th Infantry, part of the US 30th Division. With the 80 mm thick rear armor penetrated and the vehicle stuck, the crew bailed out, all had survived these multiple strikes but one crew member was shot and killed by the infantry as they fled. This vehicle was recovered in March 1945 by the 464th Ordnance Evacuation Company and shipped to Great Britain for evaluation. The vehicle was later scrapped but the gun remains on display at the Tank Museum, Bovington.

This Sturmtiger of Pz.St.Mör.Kp.1001, immobilized in a ditch, was hit repeatedly by a Sherman of 743rd Tank Battalion causing the crew to evacuate. Source: Zaloga
The final action of Pz.St.Mör.Kp.1001 took place in the defense of Drohlshagen to the East of Bonn in Spring 1945. Shortly after, with just 3 Sturmtigers left and with serious problems with maintenance, the vehicles were destroyed by the crews prior to capture.
The final company, Pz.St.Mör.Kp.1002, was formed in October 1944 and was sent, in December 1944, to be a part of Oberbefehlshaber West. Just like Pz.St.Mör.Kp.1000 and 1001, it was redesignated as an Artillery unit at the end of January 1945 and was supposed to be increased to a strength of 3 Zugs (6 vehicles). Its combat history started at the battle of the Reichswald followed, in March 1945, by action at Kirschellen. Further actions followed at Polsum, Marl, and Datteln. By the middle of March 1945, the unit had exhausted its supplies and the last two vehicles were blown up by their crews.

Sturmtiger firing one of its 38cm rockets. Source: Spielberger

Conclusion

The Sturmtiger was, in one way, a very clever way of reusing a damaged Tiger-tank hull. The hulls were expensive to make and anything that kept the investment of the Reich in service against the Allies was a good move resource-wise. The logic of the weapon system though is less clear, as by the time they were built they effectively had no role. These might have found in a role in a battle for a city such as at Stalingrad, but that was over well before the first Sturmtiger ever saw service.
The combination of a unique weapons system with very limited utility, on a heavily armored platform was not really what Germany was needing at the time. Better use might have been to consider simply mounting an effective anti-tank gun into that casemate instead, as vehicles like the StuG III had proven their utility as cheap and effective tank destroyers. Even a short-barrelled howitzer of some description might have found a role for infantry support and both ideas would surely have been a better use of those valuable hulls. As a vehicle for assaulting a heavily urban area, when by this time the urban fighting was defensive, it simply had little use. This is proven out by the actual combat history of the Sturmtiger, where it simply failed to find a clear role in the later war, an interesting but essentially useless weapon considering the resources poured into it.

Surviving Vehicles and Guns

Chassis Number 250174 – Deutsches Panzermuseum in Munster (German Tank Museum)
Chassis Number 250043 – Patriot Park, Kubinka, Russia
Sturmtiger 380mm Mortar (no vehicle) – The Tank Museum, Bovington, UK
R.aG43 – Tøjhusmuseet, Copenhagen, Denmark
Unconfirmed RTG38 (possibly a modified RaG43) – Narvik War Museum, Norway

Surviving Sturmtiger at the Deutsches Panzermuseum. Photo: wikimedia

Sturmtiger specifications
Dimensions	6.28 x 3.57 x 2.85 m
Total weight, battle ready	65 tonnes
Crew	5 (Commander, Driver, Gunner, 2 Loaders)
Propulsion	Maybach HL 210 TRM P45 21-litre V-12 petrol engine producing 650 hp at 3000 rpm or Maybach HL 230 TRM P45 V-12 700 hp petrol engine (later production vehicles)
Speed (road)	40 km/h
Armament	38cm RW61 L/5.4 (12 rounds) MG 34 machine-gun
Armor	Casemate front: 150mm @ 47 deg. Sides and rear: 82mm @ 20 deg. Roof 40mm @ 0 deg. Prototype had additional 50mm plate on the lower front of the hull
For information about abbreviations check the Lexical Index

Sources

Chamberlain, P., Doyle, H., Jentz, T. (Ed.). (1993). Encyclopedia of German Tank of World War Two. Arms and Armour Press, London, England.
Culler, B. (1989). Tiger in Action. Squadron/Signal Publications, TX, USA
Datenblätter für Heeres Waffen Fahrzeuge Gerät W127. (1976).
Schneider, W. (1986). Elefant, Jagdtiger, Sturmtiger. Schiffer Publishing, PA, USA
US Chief of Ordnance. (1945). Catalog of Enemy Ordnance. US Army.
Willey, D., Hayton,M., Vase, S. (2015). Tiger Tank: Owners’ Workshop Manual. Haynes Publishing Group, UK
Zaloga, S. (2012). Armored Victory 1945. Stackpole Books, PA, USA
War Office. (4th April 1945). Technical Intelligence Summary No.171.

Video of the Sturmtiger featuring footage of it firing

Tanks Encyclopedia Magazine, #2

The second issue of the Tank Encyclopedia magazine covers the fascinating history of armored fighting vehicles from their beginnings before the First World War up to this day! This issue covers vehicles such as the awe-inspiring rocket-firing German Sturmtiger, the Soviet SMK Heavy Tank, the construction of a replica Italian Fiat 2000 heavy tank and many more. It also contains a modeling section and a feature article from our friends at Plane Encyclopedia cover the Arado Ar 233 amphibious transport plane! All the articles are well researched by our excellent team of writers and are accompanied by beautiful illustrations and period photos. If you love tanks, this is the magazine for you!
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German Reich (1943)
Heavy Assault Gun – 303-316 Built

Development of the Sd.Kfz.166

In 1942, Albert Speer placed an order for a howitzer mounted on a tank chassis to keep up with the Panzer Divisions. Alkett received the order to design the new vehicle, which would be known as the Sd.Kfz.166, Sturmpanzer, or Sturmpanzer 43. Although commonly referred to as the Brummbär, this was the nickname given to the Sturmpanzer 43 by Allied intelligence, not by the Germans. They referred to it casually as the Stupa 43.

Design

The chassis was the one of the reliable, mass-produced Panzer IV. Above it, Alkett fitted a massive 15 cm (5.9 in) Sturmhaubitze (StuH) 43 L/12 developed by Škoda, which had common ammunition with the standard siG 33 howitzer in German service. 38 rounds with their separate propellant cartridges were carried, stored in the casemate and the hull. However, these massive rounds had a combined weight of 46 kg (38 kg/84 lb for the High Explosive shell itself and 8 kg/18 lb for its propellant cartridge), which made manual loading especially arduous on some elevations. The gunner set up the trajectory and aimed the gun using a Sfl.Zf. 1a sight.
The howitzer was protected by a casemate with sloped sides and thick armor plates. Indeed, this thickness was 100 mm (3.93 in) at a 40° angle on the front, 40 mm/12° (1.57 in) for the front hull, 50 mm/15° (1.97 in) for the side superstructure, 30 mm (1.18 in) for the side of the hull and 30 mm /25°/0° (1.18 in) for the rear of the casemate and 20 mm /10° (0.79 in) for the back of the hull. The top and bottom were protected by 10 mm (0.39 in) of armor at 90°. Outside the main howitzer, a single MG 34 machine gun could be fastened to the open gunner’s hatch, in the same way as for the Sturmgeschütz III Ausf.G. In addition, early vehicles carried a MP 40 sub-machine gun intended to be fired through the two firing ports on each side of the superstructure.
The driver was located forward, slightly in front of the casemate, and was given the Tiger I Fahrersehklappe 80 sight. Ventilation of the casemate’s fumes and heat was provided by natural convection, exiting through two armored covers at the back of the roof. By the time these vehicles were ready, spaced armor became the norm and Schürzen plates were factory-fitted. The first production vehicles proved their superstructure was way too heavy for the chassis, and experienced breakdowns of suspension elements or the transmission. The second series corrected this issue with a newly shaped, lighter casemate. The decision was taken in October 1943 and after the redesign, 800 kg (1,800 lb) of steel were spared, including from the gun mount itself on the third series. This new series was named StuH 43/1. Also, the Zimmerit anti-magnetic coating was factory-applied until September 1944.

Production & variants

Sources conflict as to how many were built, either 306 or 313. There were four series built as follows, all using variants of the Panzer IV chassis.
– Series 1: April 1943 60 built by Vienna Arsenal, with 52 using Panzer IV Ausf.G and 8 using rebuilt Ausf.E chassis.
– Series 2: December 1943-March 1944 60 built at the Vienna Arsenal using Ausf.J chassis.
– Series 3: March-June 1944 Built at Vienna Arsenal.
– Series 4: June 1944-March 1945 Built at the Deutsche Eisenwerke on Ausf.J chassis.
Because of the weight of the gun, there were problems with the suspension of the Brummbär. With Series 4 a new, lighter gun eased the problem considerably; in addition, a MG 34 was mounted for close defense. Previous models had a MG 34 mounted on the commander’s cupola.
The only variant of the Brummbär was a command vehicle, Befehlsturmpanzer IV. It had extra radio capacity. Krupp also built one prototype of a proposed Jagdpanzer IV with a 8.8 cm Pak 43 L/71.

The Sturmpanzer IV in action

The Brummbär primarily saw service in 4 battalions, Sturmpanzer-Abteilungen 216, 217, 218, and 219.
Sturmpanzer-Abteilung 216 first saw action at Kursk, when it formed the 4th battalion of Panzerjaeger 656, where it got as far as Ponyri. Afterwards, it withdrew to defensive positions to repel the Soviet offensive around Orel. As an independent battalion, it next saw service at Anzio in Italy, and from then to the end of the war it withdrew north until the battalion was forced to destroy its remaining vehicles and surrender in the Po valley.
Sturmpanzer-Abteilung 218, raised in August 1944, fought against the Warsaw Uprising, then remained on the Eastern Front until destroyed in East Prussia, in April 1945.
Sturmpanzer-Abteilung 219 fought against the Soviets in the Budapest area. At least two companies of Brummbär-equipped units are known: Sturmpanzer -Kompanie z.d.V. 218 took part in crushing the Warsaw uprising, then incorporated into the Sturmpanzer Abteilungen noted above. Sturmpanzer-kompanie Z.B.V. 2.-/218 was transferred to the Paris area on August 20th 1944, nothing more is known of this unit.
During the battle of Normandy in the summer of 1944, short barrelled 15 cm Sturmpanzer IV ‘Brummbärs’ (Sd.Kfz.166) were deployed to assist in street fighting in the villages and deal with enemy units in fortified locations. They were part of the 217.Sturmpanzer-Abteilung (assault tank battalion). It was formed of three companies of fourteen Sturmpanzer IVs and three additional vehicles used by the command company.
On 24 June 1944 it was ordered to move from Grafenwöhr in Germany to Normandy. On 18 July 1944 the battalion reported that it had reached the area of Condé-sur-Noireau/Le Bény-Bocage and Vire in Normandy. Not all of the Sturmpanzer IVs had completed the journey. Some had suffered mechanical problems.
On 23 July 1944 the 2nd Company was attached to the 21.Panzer-Division. It reported it had eleven working vehicles with two being repaired. On 29 July 1944 it was transferred to the II.SS-Panzer-Division LAH and the next day reported that it now only had nine working vehicles with two in repair.
The 3rd Company had been attached to the II.SS-Panzer Korps. On 30 July 1944, the 3rd Company was transferred to the LXXIV Korps.
On 6 August 1944, Thirteen Sturmpanzer IVs from the 217.Sturmpanzer-Abteilung were reported to be supporting the 89.Infantry-Division. Things changed because on 9 August 1944 ten of these Sturmpanzer IVs were in action with the SS-Panzer-Divison Hitlerjugend on only one was left with the 89.Infanterie-Division.
Some wrecked Sturmpanzer IVs locations were noted following Operation Totalize 8/9th August around the Normandy village of Cintheaux on the Caen-Falaise main road. One was found 1.5 km north west of Cintheaux in the field south east of the junction of the D23 with the road, now track, called La Maisonnette by the cross roads. Two were found near each about 750 m south west of Cintheaux along a track that runs south west from the town limits sign on the D183. A fourth was reported in a field to the west of the D167 about 1 km south south west of Cintheaux.
On 10 August 1944, only five of the ten vehicles were reported in a working condition. The situation was the same the next day. On 11 August 1944 the 1st Company, 217.Sturmpanzer-Abteilung was reported attached to the 271.Infanterie-Division.
On 16 August 1944 the 217.Sturmpanzer-Abteilung reported that between 1 to 15 August 1944 the battalion had lost ten men killed, twelve were missing and thirty-five were wounded. Only seventeen Sturmpanzer IVs were combat ready. Fourteen were under repair and predicted to be ready in less than three weeks.
The Battalion’s remaining Sturmpanzer IVs continued to see action supporting the SS-Panzer-Divison Hitlerjugend and the 89.Infanterie-Division. Both units fought on the same front in Normandy.
Those that escaped the Falase pocket were reformed and saw action during the battle of the bulge, Ardennes offensive. It reached St. Vith, but got no further. The unit was finally captured in the Rhur pocket in April 1945.

Sources

Objective Falaise by Georges Bernage
Sturmpanzer-abteilung 216 by Attilios on Panzer-central, World War II German Army Research, Historyofwar.org, Achtung Panzer
The Sd.Kfz.166 Brummbär on Wikipedia
Sturmpanzer IV article

Early Brummbär from the Sturmpanzer Abteilung 217, Caen area, Normandy, France, July 1944.

Early Sd.Kfz.166 from the St.Pz.Abt.218 in Warsaw, August 1944.

Sturmpanzer Abteilung 216, Italy, fall 1944.

Late production Sd.Kfz.166 Brummbär with Zimmerit paste and metallic rim roadwheels, now preserved at the Saumur Museum.

Late production Brummbär with the “ambush” type camouflage, Eastern Germany, 1945.

Gallery

Late type Brummbär at the Saumur tank museum, covered with Zimmerit.

Video about the Brummbär

Germans Tanks of ww2