Yugoslavian Partisans (1944/45)
Improvised Self-Propelled Anti-Tank Gun – 1 To 5 Converted
During the war, the Yugoslavian communist Partisans were often faced with shortages of war materiel, especially in regard to anti-tank weapons and tanks. Luckily for them, after 1943, the Western Allies decided to send large quantities of all kinds of war material, including M3A1/A3 light tanks. While these tanks were a welcome addition in the Partisan’s fight for the liberation of occupied Yugoslavia, their guns were not up to the date and lacked serious firepower. By the end of 1944, the Partisans simply decided to resolve this issue by mounting a captured German 7.5 cm PaK 40 anti-tank gun on a few M3A3 tanks. While not perfect, these at least gave them a much needed increase in firepower, effectively being a weapon that could destroy any vehicle on this front.
The M3 light tanks in the Balkans
Following the quick conquest of the Kingdom of Yugoslavia during the April War (that lasted from 6th to 18th April 1941), its territories were divided between the victorious Axis forces. Due to the harsh and brutal occupation by the Axis troops stationed in Yugoslavia, by the second half of 1941, two resistance groups started a rebellion against the occupiers. These were the Royalist Chetniks and Communist Partisans. Although, at the beginning these two groups worked together in the fight against the occupying Axis forces, a conflict between these two forces in late 1941 would break out into an open civil war. This lasted until the end of the war and the victory of the Partisans.
By the end of 1943 and start of 1944, the Communist Partisans movements were heavily involved in organising a number of attacks on German and their allies vital communication and supply lines, military bases and airfields, and other targets , inflicting increasing losses in men and materials. While, initially, the Western Allies mainly supported the Chetnik movement, due to various reasons (including a lack of major military action against the Germans or even open cooperation with them), this attitude changed drastically from 1943 onwards. The Allies instead focus on supporting the ever increasing Partisan movement by supplying them with ammunition and equipment but also special personnel to help train the Partisan ground forces.
Beside these, Allied High Command made an agreement with the leader of the Partisans, Josip Broz Tito, to form a tank brigade that was to be equipped with Allied tanks and armored cars. The unit, named First Tank Brigade, would be formed on 16th July 1944. The British supplied some 56 M3A1/A3 tanks, 24 AEC Mk.II armored cars and two M3A1 scout cars. The Partisan crews were previously sent to Italy in order to be trained in operating these vehicles. They also managed to salvage a few more damaged tanks from Allies repair facilities.
The First Tank Brigade would see extensive action against the Germans and their allies until the end of the war in May 1945. Due to a high attrition rate, a great number of M3A1/A3 tanks were either lost or heavily damaged. Given the general lack of replacements, these had to be repaired in order to keep the whole unit operational. Some damaged vehicles had their turrets removed and replaced with captured weapons. One such modification included installing a captured 7.5 cm PaK 40 on top of an M3A3 tank, creating a bizarre vehicle somewhat similar to the German Marder tank hunter series.
The M3 Light Tank
The M3 Light Tank was designed in 1940 to replace the older and outdated M2 tanks that were in service with the American armored forces. The M3 had many improvements over the M2, including thicker armor, stronger (due to the increase in weight) vertical volute spring suspension (VVSS) with a bigger rear idler wheel, increased speed, and improved firepower consisting of four 7.62 mm machine guns and a 3.7 cm cannon. The first series was powered by the gasoline-fueled (petrol) Continental seven-cylinder four-cycle radial aircraft engine. After 1942, a new four-stroke diesel radial Guiberson A-1020 engine was used. It had a crew of four (driver, driver assistant, gunner, and commander). From March 1941 to August 1942, some 5,811 Stuarts with petrol engines and 1,285 with diesel engines were built. The much improved M3A1 version was produced from April 1942 onwards. The first batches of M3A1 tanks were built by using riveted armor, but later models had welded armor. The changes that were made were an improved turret design (the small commander cupola was removed) with two hatch doors, reducing the number of machine guns to three on later built vehicles, and the addition of a turret basket.
Soon after the M3A1, a new model, the M3A3, was made as a result of the poorly designed frontal armor and small fuel capacity of the first versions. The front and side armor of the Stuart M3A3 were angled and the front hatches for the driver and his assistant were replaced by new overhead ones. Due to extra space that the Stuart M3A3 now had, it was possible to increase the fuel capacity. This version was produced until August 1943, with a total of some 3,427 vehicles being built.
The Stuart series saw extensive operational service throughout the war on many different fronts. The USA supplied the Stuart series to other nations through Lend-Lease, including the British Empire, USSR, Brazil, China, France, the Netherlands, and many other Latin American nations. Britain would subsequently give some of their Stuarts to the Yugoslav Partisans. By 1943, however, the M3 was already outdated, due to its weak gun and feeble armor.
Repair Facilities at Šibenik
The Partisan First Tank Brigade, after some heavy fighting with the Germans, managed to push them out of the city of Šibenik (located on the Adriatic coast of modern Croatia), which was captured on 3rd November 1944. Prior to the war, Šibenik had been a large naval shipyard and possessed a number of workshops. Despite many of them being sabotaged by the retreating Germans, there was still sufficient working equipment and materials left to meet the needs of the Partisan mechanics, who were somewhat in great need of such tools. Namely, the fighting with the Germans had led to heavy tank losses. As there was no way to replenish lost tanks, the Partisans were forced to try to salvage and repair damaged vehicles. Even those that were damaged beyond repair were reused for spare parts. Enemy vehicles and equipment captured by that time were also transported to Šibenik in hope of repairing them or, if this was not possible, to be cannibalized for spare parts. Šibenik would remain the Partisans’ main base for repairs and maintenance until the end of the war. In addition, it also served as a vital training ground for new Partisan tank crews from November 1944 onwards. The Partisan repair work was actually supervised and assisted by British Major Peterson supported by an unnamed Sergeant.
Modification of the M3A3
While the Partisans were surely grateful to the Allies for the Stuart tanks, they were, to say the least, quite disappointed with their firepower. The Stuart was armed with a 37 mm gun which was quite inadequate for anti-tank duties in 1944/45. While the enemy tanks which operated in Yugoslavia were mostly obsolete French and Italian tanks, a number of them were more modern (Panzer III, Panzer IV, StuG III, or even captured T-34s), against which the 37 mm gun could do little. Another issue with the Stuart’s gun was that it was noted to be generally ineffective against well fortified enemy positions. The Partisans, to some extent, resolved these issues by utilizing the AEC Mk. II (due to its better firepower, the 6 pounder – 5.7 cm gun) as anti-tank vehicles. This, in turn, led to another problem. The armored cars, which were intended to perform reconnaissance, were instead reused for the anti-tank role. This forced the Partisans to use ordinary infantry for reconnaissance, which was not always effective or even reliable and often led to great losses.
Rearming the already existing tanks seemed one possible solution. One attempt was arming a Somua S35 with a 5.7 cm gun placed in a modified turret. This vehicle was lost on its first combat missions and appears to have been quite ineffective in design. Given the general improvised nature, this should not come as a big surprise
By the end of 1944, at ‘La Dalmatien’ workshop in Šibenik, a number of Stuarts with damaged turrets that were probably beyond repair were present. A decision was made by the Partisan authorities stationed in Šibenik to try and install a number of German captured weapons in hope of increasing their combat effectiveness. While a number of sources claim that four different such modifications were made, based on the information and evidence available, only two of these can actually be confirmed. At least one was armed with a German 7.5 cm PaK 40 anti-tank gun and a second vehicle was armed with the 20 mm Flak 38 Flakvierling anti-aircraft gun.
General information about these two vehicles are scarce and difficult to find, mainly as the Partisans kept a poor record of them. What is known is that these were likely hasty improvisations with little to no testing done prior to their completion. The work on these modifications began sometime at the end of 1944 and was completed by early 1945.
Sadly, there are no available sources that mention the precise names of these vehicles. It is also unknown if the Partisans ever actually bothered to give them any designation or even a nickname. Sometimes, it is simply referred to as the M3A3 with 7.5 cm PaK 40. This article will use the simple PaK Stuart designation for the sake of simplicity only. It is important to note that this is purely a modern designation.
For this modification, damaged Stuarts M3A3s were used (as they were present in greater numbers). Instead of the original tank turret, a simple three-sided shield and a 7.5 cm PaK 40 anti-tank gun were placed. This is where the sources effectively stop describing the overall PaK Stuart design. More information can be obtained based on analysis of available photographs and educated guesses.
The Gun Mount
The general decision to use the 7.5 cm PaK 40 anti-tank gun can be explained simply by the fact that it was the best anti-tank weapon in Yugoslavia. Also, the Partisans captured a number of these guns, so they used what they had.
Precisely how the Partisans mounted the 7.5 cm anti-tank gun is unknown. Given the general urgent need for a vehicle with increased firepower and in order to reduce the overall construction time needed, the Partisans would most likely have gone for the simplest working solution. One possible solution is that the Partisans first install a reinforced (likely using metal bars) base, on which they mounted the gun with its cradle mount. In order to save weight and space, the 7.5 cm PaK 40 wheels and trailing legs were removed. The gun would be placed on the previously mentioned base and held in place either by being welded in place or by bolts. Thus, the gun’s original elevation (-5° to +22°) and traverse (65°) would likely remain the same. While no front gun travel lock was installed, there is a photograph of such a vehicle being under construction with what appears to be a rear positioned travel lock. This had a simple design, using two bars in a reverse ‘V’-shape. On the other hand, given the lack of a better view of this position, the part believed to be a V-shaped travel lock could also be (at least in this case) a simple tool that was used during the mounting of the gun. Either way, the use of a travel lock on a long gun like the PaK 40 was quite essential. For example, driving over rough terrain without one could potentially damage the gun mount or even affect its overall precision.
The added gun, armor plates and ammunition certainly raised the vehicle’s overall weight, but to what extent is unknown. It is also unknown how the whole modification affected the M3A3’s overall driving performance.
This vehicle was armed with the excellent 7.5cm PaK 40 anti-tank gun. It was more than well suited to successfully engage any tank in the Yugoslav theatre of operation until the end of the war. Beside installing this gun onto the Stuart tank, the Partisans would also face problems with where to store the relatively large PaK 40 ammunition. While the sources do not provide us with an explanation, there are quite few solutions to this issue. One possible solution is that the Partisan crews stored spare ammunition inside the vehicle. Given the small size of the vehicle, only a limited amount of ammunition could be stored this way. How these would be given to the gun crews is questionable. If the new gun mount installation left no opening for the ammunition to be taken from inside the tank, the driver or his assistant had to provide them. This would leave them open to enemy fire and this was, in general, quite an ineffective method.
Another solution was that spare ammunition was stored in the fighting compartment and in easy reach of the gun crews. Due to the small size of this fighting compartment, only a few spare rounds could be carried. The last solution may be that the vehicle was used to engage targets at greater ranges and the ammunition was instead carried by another vehicle (likely an ammunition supply truck). Given the general lack of information about such a vehicle, this seems unlikely but not impossible.
The secondary armament consisted of the original hull mounted Browning 7.62 mm machine gun. Interestingly, some vehicles appear to lack the hull positioned machine gun. The reason for this is unknown, but possibly done to make more room inside the vehicle, or they were simply removed for maintenance or ammunition reasons. On some photographs, a second Browning machine gun can be seen placed on top of the gun shield or behind it, but the photographs are not clear enough.
The armor protection of this vehicle (with the exception of the original Stuart hull) is unknown. The gun keeped its own twin layer gun shield (each plate was 4 mm thick with 25 mm of free space between them). On both sides of the vehicle’s new fighting compartment, there were simple angled armored plates. These were made from salvaged German vehicles that were too damaged to be repaired. Interestingly, on the rear bottom of the side armor plates, there are what appear to be small hatches that had no obvious reason to be there. One possible solution is that this was actually part of the original salvage metal plates that the Partisans did not bother to remove.
To fill the gap between the gun and the hull, an armored plate was added. The top and the back of this fighting compartment were completely open, exposing the crew to the elements and enemy fire. In principle, the armor of the upper modified gun platform at best offered only limited protection for its crew, mostly from small caliber bullets and shrapnel.
While the Stuart turret was removed, the rest of the vehicle appears to have been unchanged. On the Flak armed Stuart version, the two hull hatches were redesigned to be opened forwards. This was done to provide a better firing angle for the main weapon. On the PaK armed version, this was not the case. Given the fact that the gun itself was higher up, there was still plenty of room to use the hatches in their original configuration.
While there is no certain information, the crew of this vehicle likely consisted of four. These include a driver and an assistant, who was also the machine gun operator, which were located in the hull. The gun loader, who was probably the commander, and the gunner were positioned in the small open fighting compartment. While the hull crew were fully protected, the gun operators were completely exposed to weather and had only limited protection from enemy fire.
The number of PaK Stuarts built is unknown. It is generally believed that at least three vehicles were constructed. One such source is the book written by authors B. B. Dimitrijević and D. Savić (Oklopne jedinice na Jugoslovenskom ratištu 1941-1945). Various internet websites mention a number of 5, which seems to be unlikely. What is particularly strange is that this conversion always appears alone in contemporary photographs, so it is possible that only a single vehicle conversion was ever carried out.
Author D. Predoević (Armored Units and Vehicles in Croatia during WWII, Part I, Allied Armored Vehicles) also agrees that three vehicles were modified in this manner. He also gives an explanation about the production number mystery. He claims that, in Partisan documents regarding the 4th Army (dated from April 1945), they mentioned the use of four Stuart self-propelled guns. These, in fact, were Howitzer Motor Carriage M8s armed with the 75 mm howitzer developed and built by the Americans. Between 7 and 9 such vehicles were supplied to the Partisans during April 1945. These vehicles may be the main culprits for the overall confusion about the precise number of PaK Stuarts built. The same caliber being present on both vehicles may have led to some sources wrongly describing them as the anti-tank vehicles developed by the Partisans.
Once the PaK Stuarts were ready, during early 1945, they were initially used for training the crews in order to effectively operate these modified vehicles. During late March, these vehicles were dispatched to the front line and saw action against the Germans until the end of war.
There is little information on the usage in action and losses of the Partisan Stuart PaK version. What is known from contemporary photographic evidence is that they were used in combat. There are only a few documented actions in which these tanks were used. The modified PaK Stuart vehicle (or vehicles) were used in battles near cities like Mostar, Bihać, and Drenovača during February/March 1945. Besides a few photographs, their precise usage during these battles is unknown.
At the end of April, they were engaged in heavy fighting with the Germans near Ilirska Bistrica. On 28th April 1945, the Germans, supported by captured T-34s and vehicles described as ‘Panthers’ managed to push back the Partisans. While the precise vehicle types used are unknown (as no real Panther were used in Yugoslavia during the war), it is possible that these were in fact StuG IIIs. The Partisans made a counter-attack and pushed the Germans back. During this offensive, during a short engagement, a modified Stuart managed to destroy a German T-34 tank. While its general performance is unknown due to a lack of information, what is known is that the gun recoil during firing would cause the whole vehicle to be pushed back several meters. Firing of the gun probably also put enormous stress on the M3A3 chassis. The modified Stuarts (the PaK and Flak versions) participated in the liberation of Trieste near the end of the war, in May 1945.
While the modified Flak Stuart did survive the war and was in service for some time after that, the precise fate of the PaK Stuarts is unclear. Authors B. B. Dimitrijević and D. Savić (Oklopne jedinice na Jugoslovenskom ratištu 1941-1945) gives some clues, as they mention that the PaK Stuart survived the war but do not go into detail about its potential usage or even its final fate. If these survived the war, they were not preserved in any museum and were likely scrapped.
The M3A3 armed with the 7.5 cm anti-tank gun was a Partisan attempt to quickly build a vehicle capable of effectively destroying any enemy target. While in this they succeeded, the overall performance of the vehicle was most likely quite disappointing. While its new gun gave it huge firepower, it was also its Achilles’ heel. The gun’s tremendous recoil during firing was simply too much for the small Stuart. The small and poorly protected fighting compartment was also a huge issue. The small ammunition load would also limit its effectiveness in prolonged combat missions. While the Partisans managed to destroy a number of enemy tanks with it, this modified M3A3 was simply a hastily improvisation using any available resources at hand. Despite its somewhat poor design, it certainly served as a reminder of the harsh battles fought in Yugoslavia and the ingenuity of the Partisans fighting there.
|Crew||4 (Gunner/ commander, loader, driver and driver assistance)|
|Propulsion||Continental 7 cylinder petrol
250 hp – air cooled
|Speed||58 km/h (36 mph) road
29 km/h (18 mph) off-road
|Range||120 km at medium speed (74.5 mi)|
|Armament||7.5 cm PaK 40 Anti-Tank Gun|
|Armor||From 13 to 51 mm (0.52-2 in)|
- B. B. Dimitrijević, (2011) Borna kola Jugoslovenske vojske 1918-1941, Institut za savremenu istoriju.
- B. B. Dimitrijević and D. Savić (2011) Oklopne jedinice na Jugoslovenskom ratištu 1941-1945, Institut za savremenu istoriju, Beograd.
- D. Predoević (2008) Oklopna vozila i oklopne postrojbe u drugom svjetskom ratu u Hrvatskoj, Digital Point Tiskara
- B. Perrett (1980) The Stuart light tank series, Osprey Publishing
- M. Babić (1986) oklopne Jedinice u NOR-u 1941-1945, Vojnoizdavački i Novinarski Centar
- I. V.Hogg (1997) German Artillery of World War Two,
- D. Predoević (2002) Armored units and vehicles in Croatia during WW II, part I, Allied armored vehicles, Digital Point Rijeka
5 replies on “Light Tank M3A3 with the 7.5 cm PaK 40”
I found some info about M3A3 conversions, in my grandfathers dairy ( he worked in staff of 1st tank brigade like clerk in supply department)
He mentioned 4 M3A3 conversions, 1 with flak 38 20/4, 2 with Pak 40 75mm and one with Pak 38 50mm ( first idea was to put one italian 75mm gun- 75/32 modello 37 but was to complicated to go in turret, so one english NCO recommended pak38 because he sow one conversion in African desert in 1942), Conversion with pak 38 was lost in fight near Bihac by direct hit of 100mm howitzer ( probably M14/19) handled by ustasha forces.
Could you please send us a copy of the page that mentioned these vehicles? It would help greatly for our future research.
Could you please send us a scan of the whole thing?
How were the Stuarts delivered to the Partisans?
We have an article related to M3 vehicles in the Yugoslav service https://tanks-encyclopedia.com/light-tank-m3a1-a3-in-yugoslav-service/