Autocannone da 20/70 su ALFA Romeo 430RE

Italian Social Republic (1944-1945)
Self-Propelled Anti-Aircraft Gun – At Least 2 Converted

The Autocannone da 20/70 su ALFA Romeo 430RE was an Italian Second World War improvised Self-Propelled Anti-Aircraft Gun (SPAAG) mounting a 20 mm automatic cannon on the ALFA Romeo 430RE chassis. It was used by the Legione Autonoma Mobile ‘Ettore Muti’ (English: Mobile Autonomous Legion) of the Guardia Nazionale Repubblicana (English: Republican National Guard) in Lombardia and Piemonte near the end of the war.

Its primary task was to escort fascist military convoys between Milan and Turin, defending them from Allied air attacks, and also protecting the convoys from partisan ambushes at a time when they were becoming increasingly frequent.

The Situation of the Repubblica Sociale Italiana after the Armistice

After the Italian Armistice was signed on 8th September 1943, the Italian Regio Esercito (English: Royal Army) was disbanded. The Italian soldiers in the Italian Peninsula independently decided their own fate. Some joined the Esercito Cobelligerante Italiano (English: Co-belligerent Army) under Allied control, others created and joined the first Italian partisan units, while others swore allegiance to the Germans. The soldiers who opposed the German troops in Italy or in the rest of the territories under Italian and German control were killed or captured. Between 8th and 23rd September 1943, about 20,000 Italian troops were killed and over a million Italian soldiers were captured by the Germans.

A coup organized by the Italian king Vittorio Emanuele III di Savoia and some generals loyal to the king had deposed Il Duce Benito Mussolini on 25th June 1943. Mussolini had spent the period of time between his arrest and the Armistice in an Italian prison. On 12th September 1943, he was freed in a daring mission by a group of German Fallschirmjäger commanded by SS-Obersturmbannführer Otto Skorzeny.

Benito Mussolini was then taken to Germany, where he met Adolf Hitler in order to decide the destiny of the rest of Italy and also to recover from his prison experience. Returning to Italy on 23rd September 1943, he created the Repubblica Sociale Italiana or RSI (English: Italian Social Republic) in northern and central Italy, regions that were controlled by the Germans at that moment.

Of the thousands of Italian vehicles captured by the Germans (tanks, armored cars, supply vehicles, artillery pieces, etc), only a few were returned to the new Italian units loyal to Mussolini. This meant that the units needed to equip themselves with vehicles abandoned by the Regio Esercito after the Armistice, with vehicles damaged before the Armistice and abandoned in the military depots after 8th September, or with civilian trucks requisitioned for military necessities.

The Esercito Nazionale Repubblicano, the heir of the Regio Esercito, received the majority of these vehicles, but there were not enough. The Army seems to have received or retrieved less than the 20% of the vehicles it needed.

The Guardia Nazionale Repubblicana, or GNR, was used as a Military Police and to counter partisan actions, with most of its units assigned to the rearguard. It was equipped with an even lower amount of vehicles, although some units were able to equip themselves with many armored fighting vehicles and trucks, such as the Gruppo Corazzato ‘Leonessa’ (English: Armored Group), which managed to acquire around 60 tanks of multiple types, around 20 armored cars and more than a hundred of trucks, cars, and motorcycles.

The Corpo Ausiliario delle Squadre d’Azione delle Camicie Nere (English: Auxiliary Corps of the Action Squads of the Black Shirts), an auxiliary corps used mostly to counter partisan actions, was barely equipped at all. Of the 56 Black Brigades created, only two received armored vehicles, while the other brigades had only civilian or military trucks which the Black Brigades had to armor in an improvised way in civilian workshops.

The majority of the Repubblica Sociale Italiana’s units were only equipped with military or civil trucks that they used as transport vehicles or that they armored themselves or in civilian workshops.

The RSI faced the problem of the Italian partisan units that were present throughout the territory under Nazi-Fascist control and that almost daily struck military convoys or isolated Italian or German garrisons. The RSI also had to face another major threat, the fighters and ground attack aircraft of the U.S. Army Air Force and the British Royal Air Force. These acted almost undisturbed, attacking Italian convoys and other military and civilian targets.

Design

The ALFA Romeo 430 truck

The company now known as Alfa Romeo was founded under the name A.L.F.A. (Anonima Lombarda Fabbrica Automobili, English: Anonymous Lombardy Automobile Factory) in Milan on 24th June 1910 . In 1918, it changed its name to ‘ALFA Romeo’ following the acquisition of the company by Engineer Nicola Romeo. The first and largest plant of ALFA Romeo was in Milan, in the ‘Portello’ district, from which it took its name.

The ALFA Romeo 430 (factory designation T.430) was a cab-forward 3.5 tonnes medium-duty truck originally developed for the military. In order to speed up development and save money, it was derived from the Alfa Romeo 800 heavy truck. Its development was approved by the Italian War Ministry on 23rd September 1941.

In early 1942, ALFA Romeo presented the prototype of the T. 430RE (RE for Regio Esercito) to the Centro Studi della Motorizzazione or CSM (English: Center of Motorization Studies). However, it was powered by a 4-cylinder diesel engine developed to be connected to an electrical generator, while the military wanted a gasoline engine.

The first Regio Esercito order was for 400 units, which increased to 600 by the end of 1942. The Italian Regio Esercito insisted on the adoption of a gasoline engine, so the company manager, engineer Ugo Gobbato, ordered the development of a petrol version of the truck which never entered production.

After the armistice of September 1943, the Portello plant stopped the production for some days and the petrol engine version was abandoned. The Regio Esercito order was initially reconfirmed by the Germans. In early November 1943, Germans officers and specialists evaluated the truck and canceled the request.

Thanks to the tenacity of engineer Ugo Gobbato, ex-manager of the FIAT Lingotto plant, furious at this decision, production resumed. He sent a letter to the Reich Ministry of Armaments and Production to defend his project and, for an unknown reason, the Germans reversed their decision and the Portello plant restarted production, building a total of 99 ALFA Romeo 430RE with diesel engines between 1944 and 1945.

After the war, the ALFA Romeo 430 was also produced as a civilian version, with medium trucks, buses, and tractor variants. Production resumed in 1945 and continued for another five years, until 1950.

After the war, the military version was redesignated as ALFA Romeo CM50 (Carro Medio Modello 1950 – Medium Truck Model 1950). The engine was upgraded, increasing the power by about 10% and enlarging the cab, allowing the addition of a berth behind the seats. There was also an increase in the empty weight to 3.7 tonnes. The military version remained in production until 1952. A military all-wheel-drive version was also developed but did not meet with success and the project was abandoned.

Engine and Suspension

The engine of the Alfa Romeo 430 was the Tipo 430. This was a direct injection, 4-cylinder, 5,816 cm³ diesel engine providing 80 hp at 2,000 rpm. The maximum on-road speed of the truck was 65 km/h, while the range was 390 km thanks to the 75 liters tank fixed on the right side of the chassis. The water-cooling system was connected to a 26-liter water tank, while the oil tank capacity was 11 liters.

Fuel consumption was 19 liters for 100 km, remarkably low for the time, thanks to the FB company direct injection system and the use of a Spica PC4C80 T29/0 variable injection pump. The good qualities of the engine, however, hid flaws. The Tipo 430 was derived from a static engine used as a generator. On the truck, it proved inadequate to the rigors imposed by its new role.

The gearbox, with an intermediate reductor, had four forward gears plus the reverse gear.

The front suspension was independent. The main innovation was the adoption of double coil spring suspension and hydraulic shock absorbers. The T430 was the first truck to be equipped with this suspension system. The rear suspension consisted of easy-to-produce leaf springs. The tire dimensions were 7.5 x 20” (19 x 50.8 cm). Photographic evidence shows that the most frequently used on the T430 were the Pirelli Tipo ‘Raiflex’.

The big advantage of the Alfa Romeo 430RE was that it retained the bigger ALFA Romeo 800’s silhouette and they had a high logistic commonality, sharing many spare parts. The two vehicles were distinguishable primarily by the bumpers. The T430 had two-part ones, with the central section cut for the radiator grille, while the T800 had a one piece bumper.

Structure

Like the bigger ALFA Romeo 800 from which it was derived, the ALFA Romeo 430 was a medium truck with a forward cab and right-hand drive.

The RE version differed from the civilian one by the addition of acetylene headlights, a bulb horn, and lacking the triangular placard on the roof of the cab used in the civilian models to indicate the presence of a towing trailer.

The wooden loading bay was 4 m long, 2 m wide, and 0.65 m tall. Only the rear side was foldable and the chassis had a step to facilitate the climb. The T430, with an empty weight of 3.55 tonnes, was homologated to load a cargo of 3.15 tonnes. For the RE variant, it was not rare to see trucks with a load of more than 4 tonnes of cargo. Thanks to the tow hook, the truck could also tow a load not exceeding 6.5 tonnes.

Armament

The main armament of the autocannone was the Cannone-Mitragliera Scotti-Isotta-Fraschini 20/70 Modello 1939 20 mm L/70 anti-aircraft automatic cannon. It was mounted on a Complesso di Puntamento Libero (English: Independent Aiming Support) produced by Elettro Meccanica Societa Anonima or CEMSA (English: Caproni Electro Mechanical Limited Company) and better known as the Complesso di Puntamento Libero Scotti – CEMSA.

Developed in the late 1920s by Engineer Alfredo Scotti as an aeronautical gun, it was never used for this. In 1932, Scotti sold the patent, which was bought by the Swiss company Oerlikon. Scotti’s design was probably studied by engineer Marc Birkigt before developing the 20 mm Hispano-Suiza H.S. 404.

In 1935, the Regio Esercito made a request for a new multipurpose automatic cannon capable of engaging flying targets. At the same time, it had to be able to deal with light armored vehicles. Scotti and the Società Italiana Ernesto Breda per Costruzioni Meccaniche responded to the request with the Cannone Scotti da 20/70 and the Cannone Breda da 20/65 Mod. 1935. After tests, the Breda gun was chosen, while the Royal Army gave a negative review of Scotti’s gun.

In 1938, the Isotta-Fraschini company in Milan bought the patent of the gun and started to update the project. This was presented a year later as the Scotti-Isotta-Fraschini 20/70 Modello 1939. The new gun was bought by the Italian Regia Aeronautica (English: Royal Air Force) and Italian Regia Marina (English: Royal Navy), with a fixed mounting for airfield defense and as an anti-aircraft gun on some Italian warships.

When the war started, the Regio Esercito showed interest in the gun, mainly because Breda could not satisfy the army’s requests and because the Scotti-Isotta-Fraschini gun was less expensive and faster to produce. For the Regio Esercito, the Scotti-Isotta-Fraschini 20/70 Modello 1941 was produced with a wheeled carriage. It was also produced under license by the Officine Meccaniche company or OM (English: Mechanical Workshops), which was known as the Scotti-OM 20/70 Mod. 1941.

The gun was gas-operated and had a theoretical rate of fire of about 500 rounds per minute. However, this dropped to 250 rounds per minute in practice. Its maximum firing range was 5,500 meters against ground targets and 2,000 m against flying targets.

The gun fired the 20 x 138 mm B ‘Long Solothurn’ cartridge. This was the most common 20 mm round, used on 20 mm guns of the Axis forces in Europe, such as the German FlaK 38, Finnish Lahti L-39 anti-tank rifle, and Italian automatic cannons.

The gun was fed by eight 20 mm round feed strips or twelve 20 mm round feed strips loaded by a loader. A more practical 41-round drum magazine also existed. The Scotti-Isotta-Fraschini 20/70 on the CEMSA support was free to rotate 360°, with a maximum elevation of +90°.

Operational Use

The Legione Autonoma Mobile ‘Ettore Muti’ was created on 18th September 1943 as an action squad for anti-partisan duties. On 18th March 1944, it became a legion and was placed under the authority of the Italian Social Republic Ministry of the Interior. It was designated as an Armed Police Force. Questore Francesco Colombo, a fascist infamous for his extremist ideas, was put in charge of the unit.

The legion had in its ranks the 1º battaglione ‘Aldo Resega’ (English: 1st Battalion), 2º battaglione ‘Piero De Angeli’ (English: 2nd Battalion) and the Battaglione di riserva ‘Luigi Russo’ (English: Reserve Battalion). The names given to the battalions were the names of fascist militants killed by the partisans. Another important unit of the legion was the Compagnia Mezzi Pesanti ‘Pietro Del Buffa’ (English: Heavy Vehicles Company) created on 2nd July 1944. Pietro Del Buffa was a Sergeant of the 601ª Compagnia of the Guardia Nazionale Repubblicana killed on 28th December 1943 in Turin.

The unit assimilated the Compagnia Motorizzata (English: Motorized Company) and the Plotone Mezzi Pesanti (English: Heavy Vehicles Platoon) and was commanded by Lieutenant Bonacina.

The Compagnia Mezzi Pesanti ‘Pietro Del Buffa’ was composed of:

• At least two Autocannoni da 20/70 su ALFA Romeo 430RE
• An ALFA Romeo 430RE with a Cannone da 75/13 Modello 1915 on its loading bay
• A SPA 38R towing a Cannone da 75/27 Mod. 1911

There were also three other companies created in February 1945 and subordinated to the ‘Pietro Del Buffa’, the Compagnia Mortai da 81 mm ‘Enrico Maggi’ (English: 81 mm Mortar Company), the Compagnia Mitragliatrici da 20 mm ‘Attilio Da Broi’ (English: 20 mm machine gun Company), and the Compagnia Artiglieria ‘Giuseppe Lucchesi’ (English: Artillery Company).

The Autocannoni da 20/70 su ALFA Romeo 430RE’s crew of seven consisted of a driver, sitting on the right side of the cabin, a vehicle/gun commander sitting on the left side, a gunner, two loaders, and two more soldiers.

In the loading bay, some ammunition wooden crates were placed behind the cab, immediately behind a wooden bench fixed to the floor, where two soldiers were seated. In the middle of the cargo bay was the CEMSA support for the Scotti-Isotta-Fraschini cannon, while on the rear was another wooden bench and more ammunition crates.

The company never operated independently, but in support of the infantry units of the ‘Muti’ Legion or of other Italian units operating in the region. On 14th August, part of the company’s armed vehicles was sent to Varzi, near Pavia in Lombardia, where they had to fight the local partisans together with the Compagnia Speciale ‘Baragiotta-Salines’, another Legione ‘Muti’ unit.

On that occasion, the fascist column was ambushed and immobilized by the partisans in the neighborhood of Pietra Gavina. Unable to continue the operation, the two companies returned back to Varzi. On that occasion, the ALFA trucks armed with 20 mm guns were probably used by the unit.

Another important task that the Compagnia Mezzi Pesanti ‘Pietro Del Buffa’ had to complete was escorting convoys that went from Milan to Turin, two of the most important cities for the Italian fascist faction, or vice versa via the A4 Highway, which was a very busy road. These were not only lorries full of soldiers, ammunition or fuel that passed through it every day, but also trucks loaded with spare parts and other material that kept both the war and civilian industries going.

These were also very easy targets for the fast Allied fighters and ground attack planes, which often machine-gunned convoys on the highway without even encountering anti-aircraft fire.

Vehicles, such as the ALFA Romeo 430RE, armed with high-elevation automatic cannons, were meant to provide effective defense against Allied air attacks. Unfortunately, the fate of these interesting anti-aircraft vehicles is unknown. They were probably destroyed or captured by the partisans during the insurrection in Milan in late April 1945.

The license plates of the vehicles are unknown and it is not known if they had the unit’s coat of arms painted, since the frames of a video of the Istituto Luce showing their appearance during a parade in Milan on 17th December 1944 are of very poor quality.

From what is visible, it is possible to deduce that the two ALFA Romeo 430RE were in the typical monochrome camouflage of the Regio Esercito, the Saharan Kaki. Another interesting detail is the triangular placard on the roof of the cab, which was mounted only on medium and heavy civilian trucks and not on military ones. The vehicles also lack acetylene headlights, so it seems logical to assume that the vehicles were ALFA Romeo 430 trucks produced during the war for the civil market and requisitioned by the fascist troops after the Armistice, given the shortage of vehicles at their disposal.

Conclusion

Although very little is known about these vehicles, it can be assumed that their use to support the troops of the Italian Social Republic against partisan units was effective. Until early 1945, the partisans were too disorganized and poorly armed to respond adequately. Nothing is known about their use as self-propelled anti-aircraft vehicles, but they were definitely far preferable to the nothing the Italian units were usually equipped with.

Dimensions (L-W-H)	5.955 x 2.13 x ~ 2.5 m
Total weight, battle ready	3.8 tonnes
Crew	7 (vehicle commander, driver, gunner and 4 loaders)
Propulsion	ALFA Romeo Tipo 430, Diesel, 4-cylinder, 5,816 cm³, 80 hp at 2,000 rpm
Speed	65 km/h
Range	390 km
Armament	One Cannone-Mitragliera Scotti-Isotta-Fraschini 20/70 Modello 1939
Armor	//
Total production	at least two ALFA Romeo 430RE modified

Sources

Italia 43-45. I blindati di circostanza della guerra civile – Paolo Crippa
Ruote in Divisa, Un Secolo di Veicoli Militari Italiani – Brizio Pignacca