Brand new Autoprotetto S.37 bearing registration number ‘RE 132468’. Source: Italie35-45.com
Original prototype of the A.S.37 showing the alternative position for carrying a spare tyre.
The A.S.37 started life in January 1941 with the acknowledgement by General Roatta (Deputy Chief of Staff for the Italian Army) of the need for an armored personnel carrier/light armored car for the Italian Army. A single-vehicle of the turreted armored car version of the Autoprotetto S.37 (A.S.37), also known as the Autoblindo T.L.37, was made. It was sent to North Africa for trials and the focus was switched to the evaluation of an armored personnel carrier variant of the vehicle instead.
Based on the T.L. 37 artillery tractor made by FIAT-SPA, this vehicle is also sometimes referred to as the T.L.37 Protetto. In a memo dated 24th May 1941, 200 examples of the ‘trattore L.37’ based armored cars were ordered, as it showed more promise than other designs which were considered at the time to be too big. These other contemporary designs were studies on the same T.L.37 chassis, the Dovunque 33 and 35 trucks, half-tracked armored personnel carriers, and two fully tracked ones, contemplated to be along the lines of the British Universal Carrier.
Italian Trattore Leggero 37 (TL.37) with large pneumatic tyres used as a tractor for hauling field guns.
Blueprint outline of the A.S.37 showing original means of lowering the rear spare tyre.
Unlike many other Italian projects, the development was very quick and went through relatively minor modifications. The blueprints from 2nd April 1941 provide some insight into the development process showing the rear door as a 2 piece design with the bottom half folding down. The spare tire position was attached to this rear lower door half, but it is noted to weigh 145 kg, which is presumably the reason why it was moved, as the door would be impossible to close from the inside. Closer analysis shows the fuel tanks were in front of the rear wheels under the top of the benches. These would later be moved, as would the radio mounting points.
Overall development of the A.S.37 was rapid and a prototype was ready in just 4 months and delivered to the Centro Studi Motorizzazione (CSM) in May 1941. The rapid development, however, met with very slow acceptance and the design was not standardized for production until 4th of February 1942. Despite this, the vehicle had actually been good enough to have received orders for 200 vehicles in the summer of 1941- early in its evaluation – although, by that acceptance time, production had only managed to produce 6 complete vehicles. Eleven more vehicles would be delivered by the end of February 1942 bringing the total to 16, plus the original prototype.
Original prototype A.S.37 with the spare tire mounted on the side by the driver. An additional spare tire can be carried in the triangular mount of the small front roof section or the mounts could be used interchangeably.
Vehicles accepted by the Italian Army received registration numbers ‘RE132452’ to ‘RE 132602’ (RE – Regio Esercito – Royal Army) which confusingly is only 150 vehicles, suggesting a modification to the 1941 order of 200 examples. Further confusing the numbers is the fact that each of the two armored divisions in the army were originally supposed to receive 90 vehicles each (for a total of 180 vehicles).
A.S.37 as standardized, showing the very distinctive oversized sand-tires and mounting a single Breda Mod. 1937 machine-gun
Layout and details
The overall design was simple because the vehicle on which it was based on required very little modification. The engine was at the front, allowing for a large boxy armored superstructure over the back with an open-top to provide protection for troops being carried. A very unusual split two-piece rear door provided access with the top half overlapping the lip of the bottom half of the door.
Rear view of A.S.37 registration ‘RE 132489’ showing the unusual split back door.
Power was provided by a modified version of the engine used in the TL37 tractor. Instead of a 52 hp (at 2000rpm) petrol engine, the FIAT-SPA 18VT version 3 petrol engine had been modified with a new compression ratio (4.9 to 5.5) and now delivered 67 hp (at 2500rpm). The driver’s position had not changed from the tractor and he sat on the front right, approximately centrally between the wheels. Vision for the driver was provided by a single rectangular hatch with a protective visor that could be raised or lowered depending on the tactical position. No other seats were provided in the vehicle, as the front left space next to the driver was empty and the rear seating was accomplished by means of long flat horizontal benches fitted with full length cushioned seats running above the top of the wheel arches to the rear. In this way, the maximum staff and utility of the vehicle were maintained allowing it to be used not only for troops but also for stores and so forth. Up to eight soldiers could be accommodated on those two rear benches and the spare space under the rear of the benches held two (one per side) 100 liter petrol tanks with an additional 90 liter fuel tank under the floor at the back for a total of 290 liters which provided an exceptional range of operation of up to 725 km.
Cutaway of the S.37 showing the positions of the engine, driver and fuel tanks. Source: Italie 35-45.com
Armor was simply arranged and consisted of armored steel plates, flat and cut to size, bolted to a steel frame. Plate thickness ranged from 6 mm to 8.5 mm thick providing protection from small arms fire and shell splinters, although the lack of a roof left the soldiers vulnerable to shrapnel or fire from above. On the other hand, the lack of a roof provided a significant amount of cooling for the cabin, which otherwise, under desert conditions, would have become unbearable.
Protection only extended to the front, sides and rear. There was no mine protection, but the floor of the vehicle could be removed for maintenance purposes. The mounted infantry were not equipped with portholes from which they could fire, meaning they would either have to dismount to fight or stand above the protection of the side armor.
A.S.37 fitted with RF3M radio and with the antenna in the stowed position.
Despite being equipped and designed for use in hot desert conditions to support the war in North Africa, the A.S.37 was not deployed there, but instead found use in Yugoslavia, fighting partisans and for convoy escort duties. Vehicles were issued to the 31st Regiment (Siena), the 955th Sezione Autoprotetti with the 1118th Autosezione of the Macaerta Division, the 259th Autoreparto Autoprotetti of the 5th Autogrippo (Trento), the 1034th Sezione Autoprotetti of the 71st (LXXI) Battalion Motociclisti (6th Regiment Bersaglieri) and the 1034th Sezione Autoprotetti of the 11th Autoreparto Pesante (Albania).
Operations in Yugoslavia took their toll on the A.S.37’s with numerous losses but, by the end of April 1943, there were still 102 vehicles operational there with Italian forces. By the time of the Armistice in September 1943, this number was lower and many vehicles were used by Yugoslavian partisan forces as well as by the Germans, who recovered 37 vehicles. These vehicles in German hands kept doing the same job they had done for the Italians: internal security in an increasingly dangerous Yugoslavia.
In German service, the A.S.37 was renamed Gepanzerte Manntransportwagen S.37 250(i) (i = Italian) (Abbrev. gp.M.Trsp.Wg.S.37 250(i)) and saw service, not just against partisan forces, but also against the Soviets and Bulgarians at the end of the war. The A.S.37 was operated by the 7th SS-Freiwilligen-Gebirgs Division ‘Prinz-Eugen’ and also some Wehrmacht units.
Three A.S.37’s seen together in Yugoslavia belonging to the 259th Autoreparto Autoprotetti in 1943 fitted with roof shields and at least one machine-gun. Source: Pignato.
Italian A.S.37 with additional protective shields added on the sides of the open compartment.
A standard A.S.37 with the machine-gun facing forward.Illustrations by David Bocquelet, with some modifications by Bernard ‘Escodrion’ Baker.
Fighting partisans, who liked to ambush and conduct hit and run combat in a mountainous country like Yugoslavia, meant that the troops carried by the A.S.37 were vulnerable from the lack of roof, and additionally vulnerable when having to fire from the back of the vehicle, exposing themselves to enemy fire. As a result, at least two types of up-armored modifications of which we have knowledge of were developed.
Extra cramped A.S.37 in Italian use Yugoslavia in 1943. The unit logo is that of a jumping Ibex. The circular motif is a manufacturer’s badge. Source: WarWheels.net
Another shielded A.S.37 in Italian use in Yugoslavia. The 9 men are well-armed, with at least two Breda Model 1930 machine-guns. Source: Italie 35-45.com
One solution to the lack of crew protection when fighting from the A.S.37 was the expedient of mounting four rectangular armored loophole plates on the back by bolting them to the superstructure, creating the look of castle wall battlements. These plates provided shelter for the soldier to hide behind whilst shooting and featured a shuttered hole through which they could fire through too. The exact position and number of shields mounted vary from vehicle to vehicle, however, as some may have been added by field workshops and other lost through damage.
A.S.37 fitted with fully superstructure additional armor on route to service in Yugoslavia
The second variant featured a much more cohesive superstructure lacking any ‘battlements’. Instead, this version used four large armored panels bolted completely around the top of the A.S.37 providing full coverage for the troops from both sides to above head height, whilst at the same time, retaining the open top of the vehicle. Large rectangular shuttered loopholes were provided in this top, with one positioned centrally on each face and one in each corner providing all-round coverage.
Both versions of up-armored A.S.37’s seen in Yugoslavia. The unusual rear door is apparent in the vehicles nearest to the camera. (Registration ‘RE 132558’). Source: Bundesarchiv 1011-203-1660-07A
On the original prototype, a single Breda Model 1938 8mm machine-gun was mounted to the rear right-hand corner but this was later standardized to a mounting point partway forwards of that on the right-hand side.
Side view of the prototype A.S.37 (left) and standardized vehicle (right) showing the relative positions of the machine-gun.
A.S.37 showing off the flamethrower somewhere in Yugoslavia
Another armament variation is that of the flamethrower version. Again, for combatting partisan activity in Yugoslavia, an unknown number of A.S.37’s were converted to carry a single flamethrower in the back and made use of two small rectangular shields on the rear superstructure, which are distinctive by the very wide unshuttered loopholes.
A.S.37 in Yugoslavia showing three shields added to the top as used in the flamethrower carrying versions.
A final variant of the armament carried by the A.S.37 seen in use by German forces mounted a single Italian 47 mm L/32 anti-tank gun in the open-topped body. No further details are known.
A.S.37 in German hands with Italian 47mm L/32 anti-tank gun mounted. Unit and date not known.
Due to the large amount of space available inside the vehicle, the vehicle found itself being converted in small numbers to a command and control variant fitted with the RF3M radio. The radio itself was mounted on the left wall of the inside, sat on the front of the left bench with the large heavy batteries down in the front left of the vehicle, which was available as there was no seat there., A simple chair was bolted to the floor centrally in the front though for the radio operator to sit on. The large antenna for the RF3M could fold down on a rotating mount fitted to the front left-hand side of the superstructure. A further variant of this command vehicle had a second radio set fitted. This version was the Centro Radio variant and also carried a RF1C short-range set. With the RF3M mounted on the front left, the RF1C was mounted on the front right behind the driver and the batteries for it under the driver.
The RF3M, depending on the model and the antenna used, had a range of 100 km and was considered a short-to-intermediate-range set. The RF1C was a tactical set for short-range communications to a range of about 12 km under ideal conditions. The two radio variants can be distinguished by the addition of a second antenna mounted on the opposite side to the first one.
A.S.37 mounting the RF3M (left) and RF1C as well (right)
War Wheels.net A Century of Italian Armoured Cars, Nicola Pignato
Encyclopedia of Armoured Cars, Crow and Icks
Italian Tanks and Combat Vehicles of WW2, Ralph Riccio
Gli autoveicoli da Combattimento dell’Esercito Italiano, Nicola Pignato
Mezzi Corazatti Italiani 1939-1945, Nicole Pignato
FIAT S37 specifications
|4.95 x 1.92 x 1.8 m (without additional armored superstructure)
2.13 m high with additional shields
|4.78 tonnes to 5.3 tonnes, payload 770 kg at combat weight
|1 + 8
|4.053 liter 18VT version III 4 cylinder petrol engine producing 67 hp at 2500 rpm
|Maximum speed (on-road)
|52 km/h (road)
|725 km (450 mi)
|Single Breda Model 37 or 38 8 mm machine-gun
Or 47 mm L/32 anti-tank gun
|6-8.5 mm steel