Saturday 19 August 2017

Marder II: Light Tank Destroyer

By the end of 1941, the Germans began to understand that the time of light tanks was over. This also applied to the PzII tank. By that time, it's main enemy was medium tanks with shellproof armour, against which the 20 mm autocannon was useless. Production of light tanks ended in Germany in the summer of 1942, but that doesn't mean that the PzII chassis was done for. Work on light SPGs on its chassis began in the spring. One of them was a tank destroyer that is best known as the Marder II.

Carrier for a captured gun

The creation of a tank destroyer on the PzII chassis was, in part, a consequence of the large amount of trophies captured by the Wehrmacht in the first few months of their campaign on the Eastern Front. About a thousand 76 mm F-22 guns were among the Red Army equipment was fell into their hands. The Germans used them under the index FK.296(r), the index FK 36(r) was also used. The most attractive thing about the weapon for its new owners was its anti-tank capability. At the time, this was Germany's most powerful anti-tank gun, and it could successfully deal with any tank.

The other side of the coin was the heavy mass of the F-22. It weighed 1620 kg in combat position, and dragging this weight around off-road was not easy. Not surprisingly, the first proposals to put the FK 36(r) on a self propelled chassis appeared in August of 1941. The Sd.Kfz.5 halftrack was chosen as the platform.

76 mm F-22 divisional guns, captured in the summer of 1941. Most of them were used as anti-tank guns almost immediately after being captured.

The Germans returned to the issue of mechanization of the FK 36(r) in the end of 1941. Another problem was added to the need to increase mobility. German light tanks became almost useless as Soviet tank units became saturated with T-34 and KV-1 tanks. This was especially true for PzII (F) flamethrower tanks. Meanwhile, production of a second batch of the tank, indexed PzII (F) Ausf. B, began in August of 1941. News from the Eastern Front raised questions about the further use of these tanks by early December.

As a result, the PzII (F) Ausf. B was the first tank from the PzII family for whom the road to the Eastern Front was closed. Production of the tank continued in 1942, but the Inspection of Motorized Forces (In 6) ordered a "self propelled mount" that used the La.S.138 chassis and the captured Soviet FK 36(r) gun on December 20th, 1941. Alkett, a leading SPG developer, was chosen as the contractor. 

One of the first 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.), spring 1942.

The first prototype, indexed 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.), was ready by April 1st, 1942. The gun, which was going to be installed on a PzII Ausf. D2 chassis, underwent many changes. A study of the captured gun revealed that it could be converted to use more powerful ammunition. The result was the so called 7.62 cm Pak 36(r). The first such gun was ready in late 1941. The chamber was bored out to accept a larger 716 mm long casing, identical to the one used on the 75 mm Pak 40 (but not compatible with it). The increase in propellant necessitated the use of a double baffle muzzle brake, although not all guns received it. The aiming mechanisms of the converted gun were both on the left side, which made aiming easier. A telescopic sight was added. The mount and gun shield were also changed. As a result, Germany's army received its most powerful anti-tank gun.

To simplify production, the gun shield of the Pak 36(r) was used on the 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.). It was somewhat trimmed on the sides, and additional plates were added to protect the crew from the flanks.

The downside of the densely packed fighting compartment was that a crane was needed to perform medium repairs.

Lots of work had to be done on the PzII Ausf. D2 chassis. The biggest problem was its layout. It was good for a tank, but caused difficulties when designing an SPG. It was impossible to move the gun forward, which resulted in an unusual design. The gun was moved as far back as possible instead, and the engine compartment roof became the floor of the fighting compartment. Not surprisingly, the ammunition capacity of the vehicle was only 30 rounds.

The placement of the gun in the rear raised the height of the 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.) to 2.6 meters. To protect the crew from bullets and shrapnel, a tall casemate, open from the rear and from the top, was added. The commander was moved to the radio operator's position. Despite all of these changes and an increased size, the mass of the vehicle decreased to 11.8 tons.

The small fightig compartment forced the addition of these stowage containers. They are encountered fairly often.

Not waiting for the completion of the first prototype, the military signed a contract with Alkett for production of 150 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.). 62 existing PzII (F) Ausf. B were sent to be converted into tank destroyers. According to initial plans, Alkett would deliver 45 SPGs in April of 1942, 75 in May, and the remaining 30 in June. In practice, Spandau worked faster than anticipated, and all 150 vehicles were ready by May 12th, 1942.

By that point, they were called Pz.Sfl.I f. 7,62 cm Pak 36. The new SPG was renamed 4 times in 1942, and 10 times in total.

In this case, the fighting compartment is covered with a metal sheet from the back instead of a mesh.

The second batch of Pz.Sfl.I f. 7,62 cm Pak 36 is worth a special mention. Not all PzII (F) were lost, and about 60 of them ended up in repairs. A logical idea came up to convert them into tank destroyers as well. Wegmann from Kassel was chosen as the contractor. A contract was signed to produce 60 casemates and convert 60 PzII (F), or PzII Ausf. D1, tanks.

Unlike Alkett, Wegmann worked slowly. The first 13 vehicles were converted in June of 1942, 9 in July, 15 in September, and 7 in October. Another 4 were converted in May of 1943, and 4 in June. 52 tank destroyers were built on the PzII Ausf. D1 chassis, and the overall production of tank destroyers on the La.S.138 chassis was 202 units.

The Battle of Stalingrad resulted in a rich harvest of trophies, including the Pz.Sfl.I f. 7,62 cm Pak 36.

In mid-February, a TO&E was approved for a motorized tank destroyer battery, which included 9 SPGs. In practice, the composition of these units was somewhat different. On March 9th, the Supreme Command of the Land Forces (OKH) composed a plan for deliveries of the 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.). Grossdeutschland and the 1st SS Division received 18 vehicles each (two batteries of 9 vehicles) and the 10th, 16th, 29th, and 60th motorized divisions, as well as SS division Wiking, received a battery of 12 vehicles each. As of June 28th, the military had 133 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.) in use. Of those, 33 ended up in the 559th, 611th, and 670th Tank Destroyer Battalions (11, 12, and 10 respectively). Another 12 were later added to the 525th Tank Destroyer Battalion.

Captured tank destroyer on the NIBT proving grounds, Kubinka, summer of 1943.

The chassis was the cause of mixed reports regarding the Pz.Sfl.I f. 7,62 cm Pak 36. The first battles showed that the idea of using the Pak 36(r) on a motorized chassis was correct. According to reports, even KV-1 tanks could be knocked out at a range of 1200-1400 meters. However, there were complaints regarding breakdowns of the weapons. As for the chassis, the situation was somewhat different. The SPG was too tall, which made it a tempting target. In addition, a number of units considered the 4-man crew insufficient. According to photographs and reports, some units split up the radio operator and commander. There was not a lot of space for the third man in the fighting compartment, and there was nowhere for him to sit.

The same, from the left.

The small fighting compartment forced personnel of some units, for example the 611th Tank Destroyer Battalion, to add external containers for personal belongings. Issues with unreliable chassis arose fairly often. Servicing the vehicle was a headache. The gun had to be removed to access the engine, and half of the vehicle had to be taken apart to remove the gearbox.

In Soviet documents, the vehicle is called "76 mm SPG on the M-1F flamethrower tank chassis".

Out of 194 Pz.Sfl.I f. 7,62 cm Pak 36 built in 1942, 16 remained by April 20th, 1943. Such staggering losses were, in part, due to the success of the Red Army in the winter of 1942-43. A large number of Pz.Sfl.I f. 7,62 cm Pak 36 were captured at Stalingrad. At least one ended up at the NIBT proving grounds in Kubinka.

Based on the number of vehicles in units, they were not used in battle often in 1943. By the end of the year, their number increased to 20 due to repairs. By that point, the SPGs received their more popular name, Marder II, first used on November 29th, 1943. By the end of December of 1944, there were 8 of these vehicles remaining. By March 15th there were only 6, 4 of them in the 58th Infantry Division.

On a more common platform

The PzII Ausf. F remained in production for longer than any other variant, returning to the PzII Ausf. C concept. This vehicle, in may ways a last, and temporary, resort, managed to outlive several successors. Nevertheless, it was clear by the spring of 1942 that its combat effectiveness is approaching zero. On May 13th, 1942, the idea of building an SPG on its chassis was voiced at a meeting with Hitler.

This time, the 75 mm Pak 40 would be used. This gun, designed by Rheinmetall, had slightly lower penetration than the Pak 36(r), but was initially built as an anti-tank gun. The most important thing was that the gun was built from scratch, instead of converted from trophies, so there would be no issues with supplies. Later, the Pak 40 became Germany's most numerous anti-tank gun. However, it had the same drawbacks as the 7,62 cm Pak 36(r): a mass over 1.5 tons and a muzzle brake that kicked up a large cloud of dust when firing.

Pz.Kpfw.II als Sfl. Mit 7,5 cm Pak 40 prototype, Alkett factory courtyard.

On May 18th, OKH issued orders to develop a tank destroyer on the PzII Ausf. F chassis with a 75 mm Pak 40 gun. MAN was responsible for the chassis, Rheinmetall-Borsig for the gun, and Alkett for the casemate. Alkett was a subsidiary of Rheinmetall-Borsig. The time allotted for development was short: the deadline was on June 15th, 1942, or less than a month away. Alkett was slightly late, and factory trials began only on June 20th.

The same vehicle from the back.

The design of the prototype, named Pz.Kpfw.II als Sfl. Mit 7,5 cm Pak 40, differed from the 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.). Partially, this had to do with experience gathered during the design of the previous vehicle, but the effect of a better chassis was also obvious. The engine and gearbox on the right side allowed for a better layout of the fighting compartment. The oscillating part of the Pak 40 was shifted forward, leaving place for the gunner (also commander) and loader. The radio operator's duties were given to the driver. Of course, this combination of roles was not an ideal solution, but the size of the vehicle was significantly smaller than its predecessor. Its height was 2.2 meters, only 5 cm taller than the PzII Ausf. F.

Thanks to the improved layout and clever technical solutions, the ammunition capacity was increased to 37 rounds. They were stored in three racks to the rear, right above the engine compartment. Two of the three racks were installed on hinges, and could swing out to allow access to the engine or cooling system. This decision saved space and made loading easier.

The armour of the fighting compartment was also better laid out. The horizontal aiming arc was wider: 56 degrees, vs the 50 degrees of the 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F) (Sfl.). Overall, the tank destroyer could be called the best SPG converted from a tank.

Mass produced version of the 7.5 cm Pak 40/2 auf Sfl.II, seen from above. The difference in the fighting compartment layout is noticeable.

On June 4th, two weeks before work on the first prototype of the Pz.Kpfw.II als Sfl. Mit 7,5 cm Pak 40 was done, a decision was made to build half of all PzII Ausf. F tanks as tank destroyers. On June 29th, the amount of tanks was reduced to a quarter, and production of the PzII tank was cancelled completely on July 11th. In August, every PzII Ausf. F chassis was used to build SPGs.

It was assumed that FAMO and Ursus would build 463 SPGs between July 1942 and March 1943. As it often happens, reality was different from plans. Instead of 30 vehicles, only 18 were delivered in July of 1942, but production was increased to meet expectations in August. In addition, 83 vehicles were built in December of 1942, and 80 in January of 1943, higher than expected. However, only 45 were built in February, and no 7.5 cm Pak 40/2 auf Sfl.II, as they were called then, were built in March or April.

This was caused by the fact that Ursus and FAMO received an urgent order for 105 mm SPGs, better known as the Wespe. Production of the 7.5 cm Pak 40/2 auf Sfl.II continued in May of 1943, when 46 vehicles were built. The last 33 SPGs of this type were delivered in June of 1943. It was clear that the factories cannot make two kinds of SPGs at once, so production focused on the Wespe.

The small ammunition capacity forced crews to carry additional ammunition in regular crates on the engine deck. This was dangerous, but there was no other choice.

Production didn't end with 553 units. Knowing that the PzII's value in combat was close to zero, MAN and Skoda began converting earlier PzII Ausf. c-C and Ausf. F tanks. These vehicles are easy to distinguish thanks to their chassis. Even if the PzII Ausf. F was used, it can be distinguished by the false observation device (tank destroyers built from scratch didn't have it), as well as a different design of several elements of the casemate. Later, FAMO joined in to the conversion efforts. In total, about 130 tanks were converted. The last conversions were delivered in January of 1944.

7.5 cm Pak 40/2 auf Sfl.II converted from the PzII Ausf. F. The false observation device gives it away.

In addition to factories, units converted tanks themselves. The most interesting conversion was done by the 559th Tank Destroyer Battalion in the summer of 1943. The battalion received 10 PzII tanks from the 12th Tank Division. There was not enough guns for each tank, resulting in an interesting hybrid, known as 5 cm Pak 38 auf Fg.St. Pz.Kpfw.II (Sf). The Pak 38 anti-tank gun was mounted on a PzII Ausf. F chassis, and not just the oscillating part, but the entire mount, although without the trails or wheels. The resulting design was armoured from the front and the sides. Ammunition was carried in crates on the engine deck. Overall, the vehicle was awkward, but better than just a light tank and a gun on their own.

Later, the 559th Tank Destroyer Battalion was renamed to the 128th Tank Destroyer Battalion, and it was included into the 23rd Tank Division. This unique SPG also ended up there.

5 cm Pak 38 auf Fg.St. Pz.Kpfw.II (Sf), built in the 559th Tank Destroyer Battalion.

The first 9 Pz.Kpfw.II als Sfl. mit 7,5 cm Pak 40 were sent to the 3rd Tank Division. This happened in August of 1942. 9 more vehicles were sent to the 24th Tank Division. These tank destroyers were largely sent to tank divisions, as they were mobile and reliable enough. The distribution was uneven: the 5th Tank Division only received 4 vehicles, the 17th: 6, the 20th: 13, and the 4th set a record, receiving 27 vehicles. The last case was an attempt to plug a hole: the 4th Tank Division had no PzIV tanks with long KwK 40 guns. Tank destroyers were also sent to SS units, infantry divisions, and tank destroyer battalions.

Captured 7.5 cm Pak 40/2 auf Sfl.II, NIBT proving grounds, summer of 1943.

Reviews of this tank destroyer were more favourable than the 7,62 cm Pak 36(R ) auf Fgst. Pz.Kpfw.II(F). An increase in mass played its part, however. The overall performance matched that of the tank, but an increased load on the front road wheels demanded more careful driving. Some units reported a decrease in reliability. The ammunition capacity of 37 rounds was still too small. The comments on the stability of the Pz.Kpfw.II als Sfl. mit 7,5 cm Pak 40 during firing were unanimous. For a tank destroyer, that is one of the most important requirements. Thanks to its powerful anti-tank gun, the SPG was a dangerous enemy for any Soviet tank of that period.

In documents, the tank destroyer was called "75 mm SPG on the T-IIb chassis"

Starting with late 1942, these tank destroyers were largely used by the Germans on the Eastern Front. Despite active use, 363 7.5 cm Pak 40/2 auf Sfl.II remained in use on June 30th, 1943. This was the most numerous tank destroyer at the time. Even half a year later, there was still a large number of them left in service: 249.

The same vehicle from behind.

Overall, the La.S.100 turned out to be suitable for building SPGs. The roomy fighting compartment and weight reserve of the suspension allowed the installation of a powerful gun, providing respectable mobility and stability. A rather simple change in the layout could have resulted in a more suitable platform for an SPG. It appeared in the summer of 1942 and was produced until June of 1944, but that's a topic for another article.