The Axis invasion (codenamed Directive 25) of the Kingdom of Yugoslavia started on the 6th of April 1941 (also known as the ‘April War’). The Yugoslav Army was completely surprised by the speed and size of the Axis forces. The war ended on the 17th of April 1941 with the capitulation, occupation, and division of Yugoslav territory by the Axis forces.
However, very soon after the Axis occupation, the first resistance groups started a rebellion against the occupiers in the second half of 1941. There were two resistance fighters groups, the royalist Chetniks (Четници) and the communist Partisans (Партизани). The Chetniks were led by General Draža Mihailović (Дража Михаиловић) and the communist Partisans movement was led by Josif Broz Tito (Јосиф Броз Тито). The term ‘Partisan’ describes both groups by definition, but today the name Partisans has become a synonym for the communist resistance movement in Yugoslavia.
Although in 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.
The modified M3A3 with the quad flak 38. Photo: SOURCE
By the end of 1943 and early 1944, because of the lack of Chetnik actions against the Germans, the Allies decided to send large amounts of military aid to the Partisan movement (weapons, tanks, aircraft etc.). According to the agreement between the Partisans and the Allies, it was planned to form one tank brigade equipped with Allied vehicles (armored cars and tanks).
This unit, named the first tank brigade, was formed on the 16th of July 1944. The British provided all the equipment needed to equip this brigade. In its inventory, there were some 56 x M3A1/A3 Stuart Light Tanks tanks, 24 x AEC Mk.II armored cars, and two M3A1 armored reconnaissance cars.
The caliber (37mm) of the main gun on the Stuart M3A1/A3 tanks was inadequate for anti-tank duties in 1944/45, but Stuarts were still used, since most German tanks on this front were older (mostly Italian and French models). There was also nothing better available at that time, and because there were not enough Soviet-supplied tanks to equip all units. The Partisans were forced to use the AEC Mk.II armored car (due to its better firepower, 57mm Anti-Tank Gun) for engaging better and stronger enemy tanks. But this tactic of using both vehicles types for fighting enemy armor led to a lack of any reconnaissance (vehicle or infantry) element of the brigade. The inability to determine exact information about the enemy forces, in particular, unit strength and exact positions, led to great losses.
By the end of the War, more than 60 Stuart tanks were destroyed or damaged (of around 100 supplied by the Allies during the war). On several of these damaged tanks, the turrets were removed and Partisan engineers decided to try to mount some captured German weapons, to be used as improvised self-propelled guns with increased firepower. Two confirmed modifications are known; one armed with a German 75mm PaK 40 anti-tank gun and the second armed with the 20mm Flak 38 Flakvierling anti-aircraft gun. These modifications were quickly built and without proper testing, but even so, the 20mm Flak 38 Flakvierling version remained in service long after the war.
There is also no information about the exact names for these vehicles and whether the Partisans even assigned an official name for them.
The tank’s turret was removed and in its place, a German 20mm Flak 38 Flakvierling anti-aircraft gun was installed. The only armor protection for the gun operators was the front gun shield, with no side or rear armor. It had five crew members: commander, driver, gunner, and two loaders. Three crew members were needed to effectively operate the main gun, but the area behind the gun was very limited. There is no information about the amount of ammunition for the main weapon that could be carried on and in the vehicle and by looking at contemporary photographs of these vehicles, the ammunition was probably kept in the vehicle itself. The secondary weapon was the single machine gun in the tank hull. By installing the new gun platform, and in order for the driver and the hull machine gunner reach their positions in the tank, it was necessary to do some modifications on the two roof hatch doors so that they could be opened forwards.
The M3 with full crew. Photo: SOURCE
Other characteristics are similar to the original M3A3 vehicle, with the exception of height and weight. The dimensions of this vehicle are similar to the original tank configuration, if not a bit higher, but the exact figures are unknown. The weight of this vehicle is probably around some 15 to 17 tons.
This vehicle was mainly used in the role of fire support for ground troops (German planes at that time and on this front, were a rare sight). They would use the immense rate of fire of their Flakvierling armament to suppress enemy infantry, unarmored vehicles, and Anti-Tank positions. However, it should be noted that the Flakvierling was not very effective against enemy tanks, except maybe damaging optics.
Links, Resources & Further Reading
Artillery From WWI to the present day, Michael E. Haskew, Amber Books 2010.
Waffentechnik im Zweiten Weltkrieg, Alexander Ludeke.
Fighting men of WWII Axis Forces, David Miler, Chartwell Books.
German Artillery of World War Two, Ian V.Hogg
Vek Srpske Protivvazdušne odbrane , Bojan Dimitrijević, Odbrana Beograd 2015,
Oklopne jedinice na Jugoslovenskom ratištu, Bojan B. Dumitrijević i Dragan Savić, Institut za savremenu istoriju, Beograd 2011.
Modernizacija i intervencija, Jugoslovenske oklopne jedinice 1945-2006, Institut za savremenu istoriju, Beograd 2010.
Illustration of the M3A3 Flakvierling by Tank Encyclopedia’s own David Bocquelet
The Flak armed Stuarts were used in combat, mostly in the battle for Trieste 1945. For the flak version, there is reliable information that both vehicles survived the war. In June 1946, the first tank brigade handed these two vehicles over to the first tank division. These vehicles were in use until 1949, but because of the fact that Stuart tanks remained in use by Yugoslav People’s Army until 1960, it was possible that they were in use even after 1949.
On this picture we see the lack of adequate armor protection and limited working space for the tank and gun crew. Photo: SOURCE
The Flak 38
The Flak 38 proved to be a successful weapon during war, especially the four-barrel Flakvierling versions. It was designed to shoot down low-flying aircraft but it was also found to be very effective when used against unarmored ground targets.
The Flak 38 Flakvierling was designed by Mauser-Werke to replace the old Flak 20, and was introduced in May 1940. At first it was mostly used by the German Kriegsmarine (navy) to provide anti-air defense for battleships, destroyers and cruisers. During the war, this anti-air gun saw much wider use with the rest of the German army in various mounts. This gun was transported on the Sonderanhanger 52 platform and carriage which was the same as for the one gun Flak 38 original version but enlarged and strengthened. The Flak 38 Flakvierling was also used as a mobile mounted weapon on several German vehicles, like the half-tracks (Sd.Kfz 6/1 and Sk.Kfz 7/1), tanks, trucks, and even on armored trains. An interesting fact is that, on some later versions, radars were fitted, in which case a parabolic reflector was installed between the four gun barrels. During WWII, the Flak 38 Flakvierling proved to be a highly effective and successful weapon that remained in use throughout the war, with some 3850 being produced.
The Quad Flak 38 in German service. Photo: Bundesarchiv
The Flak 38 Flakvierling had 8 crew members. Its effective range was 2 km (6562 ft.) or 2.2km (7229 ft.), depending on the source, with the maximum horizontal range of 5782 m (5230 yds). The maximum rate of fire was 1680 to 1920 rpm, (700-800 rpm was a more appropriate operational rate of fire). The gun could traverse a full 360° and the elevation was –10° to +100°. The weight in action was some 1520 kg (3352 lbs.). The Flak 38 Flakvierling was first equipped with the Flakvisier 40, that was a modified version of the Flakvisier 38. But, during the later part of the war, this was replaced by more simple types.
For this gun there were several different types of ammunition available that were used in combat, some of them were:
– SprGr.Patr.L/Spur – HE (high explosive) shell with self-destroying tracer (velocity 900 mps./2953 fps.)
– 2cm Pzgr Patr 40 L/Spur – AP (armour piercing) shell with tungsten core, armor penetration at 100 m was 40 mm (1.57 in. at 109 yds.), probably rarely used because of a shortage of tungsten,
– 2cm Pzgr Patr L/pur m Zerlegung – AP/HE/incendiary shell with no fuse and with a heat relay self-destroying tracer. Velocity was 830 mps./2723 fps.
– 2cm Sprgr Patr L/Spur (Ub) – Empty practice shell.
It is believed that two Stuart tanks were converted. These two tanks survived the war and remained in use for a next few years after the war. It is not known what finally happened to them or when, or if, they were scrapped.
|Dimensions||4.33 x 2.47 x 2.29 m
|Total weight, battle ready||15-17 tons|
|Crew||5 (Gunner, two loaders, driver and commander).|
|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||2cm Flakvierling 38, and one machine gun|
|Armor||From 13 to 51 mm (0.52-2 in)|