History of the Project

The first Italian medium tanks of the M series, namely the Carro Armato M11/39 and the Carro Armato M13/40, were developed before the start of the Second World War. A hundred of the first were produced and were deployed until the total destruction of the batch in the first stages of the war, while the latter became the backbone of the Italian tank divisions in North Africa for the first years of war. Although the M13/40 was not heavily modified during its production life, it was criticized for its light armor, light main gun, and mobility problems after its early engagements with Allied tanks. The problems encountered with the Italian medium tanks in North Africa were only part of the motivations that led the Italian High Command to decide to adopt self-propelled guns.

The plan was to convert part of the Italian medium tank production lines to mount a more powerful armament on a modified turretless chassis, in order to maintain spare parts and maintenance commonality. The main armament was chosen to be the Obice da 75/18 Modello 1934 (Eng. 75 mm L/18 Howitzer Model 1934) installed in a spherical support.

The project of the semovente, designed by Colonel Sergio Berlese of the Servizio Tecnico di Artiglieria (Eng. Artillery Technical Service), was developed at Ansaldo-Fossati. On 10th January 1941, Ansaldo produced a wooden model of the self-propelled howitzer. The Regio Esercito officials were clearly impressed with the design compared to the Italian medium tanks. On 11th February 1941, the prototype, quickly assembled, was tested in Cornigliano, with great results.

The vehicle, called Semovente M40 da 75/18, was assembled modifying a Carro Armato M13/40. A total of 60 were then ordered, together with 30 command tanks. On 5th December 1941, the semoventi order was increased to 200 vehicles, but, at the time, the Carro Armato M13/40 was being substituted on the production lines by the Carro Armato M14/41 and the self-propelled guns changed chassis too.

A total of 162 of the new Semovente M41 da 75/18 were produced until November 1942. Like the medium tank from which it was derived, the only differences compared to the previous model Semovente M40 da 75/18 were a powerful model of engine, which slightly improved the driving performances, and longer mudguards that now covered the entire length of the tracks. In November 1942, the Carro Armato M15/42 entered production, substituting the Carro Armato M14/41. A month later, the Semovente M42 da 75/18 substituted the Semovente M41 da 75/18 on the production lines.

The Carro Armato M15/42 introduced a series of upgrades, such as a longer barreled gun (47 mm L/40 instead of the previous L/32), new more powerful petrol engine which necessitated elongating the engine compartment, and the entrance hatch moved to the right side instead of the left one, as on the other tanks of the series.

Design

Armor

The armor of the Semovente M42 da 75/18’s hull was the same as that of the Carro Armato M15/42. The two armored vehicles had 30 mm of armor on the transmission cover plate, which was rounded. The upper glacis plate was 25 mm thick and angled at 80°. The superstructure’s armor was 50 mm thick and angled at 5°. The previous semoventi had two 25 mm plates bolted together, but these were substituted by a single 50 mm plate. The angled plate that connected the upper glacis plate of the transmission cover and the front plate was 30 mm at 65°.

The sides were 25 mm thick for the hull and casemate, with the only difference that the hull sides were vertical and the casemate sides were angled at 8°. The rear of the casemate was protected by a 25 mm thick armored plate. The rear of the engine compartment was 27 mm thick and angled at 20°. The roof was composed of 15 mm armored plates, horizontal in the first section and then angled to 85°. On the sides of the roof, other 15 mm plates were angled at 65° on the right and 70° on the left side.

The engine compartment roof was composed of 10 mm armored plates angled at 74°. The inspection hatches of the engine compartment also had the same thickness. The brake inspection hatches were 25 mm thick, while the driver port on the front armored plate was 50 mm thick.

The armor was bolted to an internal frame, allowing for rapid construction of the vehicle, as well as easier replacement of damaged armor plates than on models with welded or cast armor. The price for this construction method was that it was not as light as a welded vehicle and that it generally made the armor less effective than it could have been.

A test was done by British technicians of the School of Tank Technology at Chobham regarding the armor thickness and resistance on the Carro Armato M14/41 and Semovente M40 da 75/18. The most resistant armor plate was the rounded front plate that covered the transmission of the Semovente. It had a Brinel hardness of 270 BHN, while the M14/41 had 210 BHN on the turret frontal plate and 245 BHN on the rounded transmission cover plate. These Brinell results showed this Italian armor to be slightly ‘softer’ than US armor, which had a hardness of 280-320 BHN, and far softer than the 413-460 BHN encountered on Soviet steel.

The abbreviation BHN – Brinell Hardness Number (unit of measurement kg/mm²) is a figure used to determine the hardness of a material from a hardness test. The harder a steel is, then generally the better it will be at resisting shell impacts, but also more vulnerable to shattering.

Hull and Casemate

On the left front mudguard, there was a support for the jack. On the sides of the superstructure, there were two headlights for night operations. The engine deck had two large-size inspection hatches which could be opened by 45°. Compared to the previous carri armati M and semoventi, the Carri Armati M15/42 and Semoventi M42 da 75/18 have ventilation grilles on the hatches to better cool the engine compartment.

Between the two inspection hatches were the sapper tools, including a shovel, a pickaxe, a crowbar, and a track removal system.

The rear of the vehicle had the horizontal radiator cooling grills and, in the center, the fuel cap. The rear had a towing ring in the center and two hooks on the sides, two spare wheels (which were later reduced to just one placed on the right), and a license plate on the left side, with a brake light. A smoke grenade box was placed on the rear armored plate instead of the left spare wheel during the production run.

On the left side of the engine deck, on the rear fenders, there was a storage box and the muffler covered by a steel shield to protect it from impacts. On the right side was an identical muffler but with a Motogeneratore Garelli Tipo Carro Armato (Eng. Garelli Tank Type Generator) which was an auxiliary power unit to charge the batteries of the tank while the main engine was stopped.

A total of six racks for 20-liter cans were placed on the sides of the vehicle, two on the right side, three on the left side, and one on the rear. In fact, from 1942 onward, the racks were factory fitted on all vehicles, as most would have gone to operate in North Africa, where the cans would have increased the range of the vehicle. It should be noted, however, that on the Semoventi M42, the cans were rarely transported by the crews, because they were never sent to North Africa, and it was not necessary to transport a great amount of fuel during operations in Italy, where the vehicles were deployed.

The mudguards were reinforced compared to the previous ones mounted on other medium tanks and self-propelled guns (except some late production Carri Armati M14/41 and self-propelled howitzers on their chassis). The mudguards received “x” ribbings and a new front support. On the left side was also a jack to lift the vehicle and substitute part of the suspension or remove the tracks.

On the roof there were two large diameter hatches, a hyposcope for the driver placed on the front left and a periscope for the commander/gunner on the right. Both devices were produced by San Giorgio in Genoa. There was also a small hatch on the front right for the main gun’s optic and the antenna radio support on the rear left side.

Interior

On the inside, at the front of the vehicle, was the transmission connected to the braking system, which had two armored inspection hatches. These could be opened from outside by means of two handles, or from the inside by means of a knob located on the right side of the vehicle, which could be used by the gunner. On the left was the driver’s seat equipped with a fold-down back for easy access. In front, it had two steering tillers, a driving port that could be closed with a lever, and a hyposcope used when the port was closed. The hyposcope had 19 x 36 cm dimensions and a vertical field of view of 30°. On the left was the dashboard and, on the right, the gun breech.

Behind the driver was the seat for the loader. The loader had, on the left, the radio apparatus and, above him, one of two armored hatches. In case of an attack from the air, the loader would also have to use the anti-aircraft machine gun. On the right side of the fighting compartment was the gunner’s seat without a backrest. In front of his seat, the gunner had the elevation and traverse handwheels.

On the gunner’s right was the support for the anti-aircraft machine gun when not in use, a maintenance kit, and a fire extinguisher. Behind the support was a wooden rack for ammunition for the secondary armament. In order to prevent the magazines from falling on rough terrain, the rack had a closable curtain. Behind the gunner/commander were the ammunition racks for the main gun. On the rear bulkhead were air and petrol filters, an engine cooling water tank, and, on the floor, the Magneti Marelli batteries. On the rear side of the superstructure were two pistol ports which could be closed by revolving shutters from the inside. These were used for self-defense and to check the rear side of the vehicle, in order to avoid the crew having to expose themselves outside of the vehicle. The transmission shaft ran through the entire fighting compartment, dividing it in half.

Radio Equipment

The radio apparatus of the Semovente M42 da 75/18 was an Apparato Ricetrasmittente Radio Fonica 1 per Carro Armato or Apparato Ricevente RF1CA (Eng. Tank Audio Radio Receiver Apparatus 1) produced by Magneti Marelli in Sesto San Giovanni. It was a radiotelephone and radiotelegraph station with a power of 10 Watts in both voice and telegraphy modes. It fitted inside a 350 x 200 x 246 mm sized-box and had a weight of about 18 kg. It was placed on the left side of the superstructure, behind the driver’s dashboard.

Operating frequency range was between 27 to 33.4 MHz. It had a range of 12 km in telegraph mode and 8 km in voice mode. These figures were reduced when the self-propelled guns were on the move.

The radio was powered by an AL-1 Dynamotor supplying 9-10 Watts. The batteries consisted of four Magneti Marelli NF-12-1-24, each with a voltage of 6 Volts, connected in series.

After 1942, a new antenna support was mounted on Italian vehicles. The first model equipped with this new antenna was the Semovente M41M da 90/53, and it was introduced in the Semovente M42 da 75/18 later. The new antenna had a 360° lowerable support, meaning that it could be folded down in any direction. Usually, a hook on the left side of the front of the casemate held it down during long drives to avoid it hitting electrical cables or interfering with driving in narrow areas.

Engine

The Semovente M42’s engine was inherited from the Carro Armato M15/42. In addition to the increase in displacement, which increased the overall performance of the vehicle, the novelty was that the new engine worked on gasoline instead of diesel fuel, which had been used by the engines on the Carro Armato M11/39, Carro Armato M13/40, Carro Armato M14/41, and the SPGs based on their hulls. The change from diesel to gasoline was due to the fact that the Italian diesel reserves were almost completely exhausted in mid-1942.

The new FIAT-SPA 15TB Modello 1942 (‘B’ for ‘Benzina’ – petrol), water-cooled 11,980 cm³ engine developed 190 hp at 2,400 rpm (some other sources claim a maximum output of 192 hp or even 195 hp). It was designed by FIAT using the FIAT-SPA 15T Modello 1941, 8-cylinder V-shaped, diesel engine, 11,980 cm³ producing 145 hp at 1,900 rpm as its base. Both engines were produced by FIAT’s subsidiary company, the Società Piemontese Automobili (SPA) (Eng. Piedmontese Automobile Company). On the Semoventi M42 and M42M, the engine system was slightly different from that of the Carro Armato M15/42. They had different starting and lighting systems, engine cooling system, and fuel circulation. In order to start the engine, a Magneti Marelli electric starter was used, but an inertial starter produced by the Onagro company of Turin was also available. The lever for the inertial starter could be inserted outside the vehicle, on the rear, or from the inside of the fighting compartment. Two crew members had to turn the crank, reaching about 60 rotations per minute. At that point, the driver could turn the engine button on the dashboard until the first strokes of the engine.

The FIAT-SPA 15TB Modello 1942 engine gave the vehicle a maximum speed of 38 km/h on-road and 20 km/h off-road. It had an on-road range of 200 km and an off-road range of 130 km, or 12 operational hours. On the Carro Armato M15/42 and Semovente M42M da 75/34, thanks to the increased space in the engine compartment, the tank’s fuel tanks were increased to 338 liters according to the book Carro M, Carri Medi M11/39, M13/40, M14/41, M15/42 Semoventi e altri Derivati and 327 liters according to Gli Autoveicoli da Combattimento dell’Esercito Italiano fino al 1943. This figure is also supported by Ralph Riccio in Italian Tanks and Combat Vehicles of World War II.

The engine was connected to a new transmission produced by FIAT, with five forward and one reverse gears, one gear more than the previous semoventi and medium tanks.

Suspension

The suspension was of the semi-elliptical leaf spring type. On each side, there were four bogies with eight doubled rubber road wheels paired on two suspension units in total. This suspension type was obsolete and did not allow the vehicle to reach a high top speed. In addition, it was very vulnerable to enemy fire or mines. Due to the lengthening of the hull, one of the two suspension units was mounted a few inches further back. The M42 chassis had 26 cm wide tracks with 86 track links per side, six more than the Carri Armati M13/40, M14/41, and Semoventi M40 and M41, due to the hull lengthening. The drive sprockets were at the front and the idlers with modified track tension adjusters at the back, with three rubber return rollers on each side. The small surface area of the tracks (14,200 cm²) caused a ground pressure to about 1 kg/cm², increasing the risk that the vehicle would bog down in mud, snow, or sand.

Main Armament

The main armament of the Semovente M42 da 75/18 was the Obice da 75/18 Modello 1934. It was a field howitzer developed after the Direzione Superiore del Servizio Tecnico Armi e Munizioni (Eng. Higher Directorate of Weapons and Munitions Technical Service) created a call in 1929 for the replacement of field guns that had been developed in the 19th century. Due to the experiences gained during the First World War, the gun had to be as light as possible to be easily deployable in mountainous areas.

In 1932, Ansaldo presented its project: the Obice da 75/17 with a single central trail, weighing 696 kg and capable of firing at a range of 9,300 m. The range was low compared to other 75 mm howitzers developed at the time, but the light weight was considered more important than maximum range.

After lengthy trials, the gun was slightly modified, reaching a total weight of 780 kg, and accepted into service in 1934.

On the Semovente M42 da 75/18, the Obice da 75/18 Modello 1934 was mounted slightly on the right, in order to give the driver more space. Its traverse was 20° to the left and 16° to the right. Elevation was from -12° to +22°.

The gun had modifications to the recoil mechanism to diminish the recoil inside the vehicle and the modified support came from the Cannone Schneider da 105/28 Modello 1916. The sight was a field one modified to be mounted inside the self-propelled gun and could be dismounted when not used. The sight had a small hatch on the roof that was opened when the sight was mounted.

In case of damage to the sight, the periscope mounted on the right could be aligned with the main gun and deployed as an auxiliary sight.

Due to the limited elevation and the general low range of the gun, the Semovente M42 da 75/18 was not the perfect solution for indirect fire support.

Secondary Armament

The secondary armament of the Semovente M42 da 75/18 consisted of a 8 mm Mitragliatrice Media Breda Modello 1938 (Eng. Breda Medium Machine Gun Model 1938). This gun was developed from the Mitragliatrice Media Breda Modello 1937 medium field machine gun according to the specifications issued by Ispettorato d’Artiglieria (Eng. Artillery Inspectorate) in May 1933. It was a vehicle-mounted variant and differed from the infantry’s Modello 1937 through a shortened and heavier barrel, pistol grip, and a new 24-round top-curved magazine instead of 20-round strip clips. These modifications were made to save up space and ease shooting with it in the cramped spaces inside armored vehicles.

The theoretical rate of fire was 600 rounds per minute, while the practical rate of fire was about 350 rounds per minute. The 8 x 59 mm RB cartridges were developed by Breda exclusively for these machine guns. The 8 mm Breda had a muzzle velocity between 790 m/s and 800 m/s, depending on the round.

On the Semovente, the machine gun was mounted on an anti-aircraft support on the vehicle’s roof. When not deployed in an anti-aircraft role, the machine gun was stored on a support on the right sponson of the fighting compartment. Together with the support, in the right sponson, there was a maintenance kit for the machine gun.

Beginning in early 1943, Italian factories started to produce a licensed copy of the German Nebelkerzenabwurfvorrichtung (NKAV) (Eng. Smoke Grenade Dropping Device). It was a smoke grenade system that, through a wire connected to a camshaft, dropped a smoke grenade to the ground behind the vehicle. Total capacity was five Schnellnebelkerze 39 (Eng. Quick Smoke Grenade 39) smoke grenades. The commander had to pull the wire and the camshaft rotated dropping a smoke grenade. If the commander pulled the wire 5 times, all the 5 Schnellnebelkerze 39 would be released. This system was mounted on the rear of the vehicle, so the smoke screen was created behind the vehicle and not around it, on the frontal arc.

The Germans stopped using this system in 1942 in favor of smoke grenade launchers on the turret, because of the problem that grenades fell at the back and the tank had to reverse to hide behind the smoke. The Italians, on the other hand, apparently gave no thought to this problem and adopted it in 1943.

It seems that the Italians copied the protected variant called Nebelkerzenabwurfvorrichtung mit Schutzmantel (Eng. Smoke Grenades Dropping Device with Protective Sheath) with a rectangular protection, even if the Italian and German protections seem different. It is not known if the Italians also produced the Schnellnebelkerze 39 smoke grenades under license or if the Italian vehicles used grenades imported from Germany. This smoke system was quickly adopted on all the Italian armored tracked vehicles starting from the Carro Armato M15/42 and on all the semoventi on its chassis and, in a smaller version, even on the Autoblinde AB41 and AB43 medium reconnaissance armored cars. A cylindrical support for spare smoke grenades was also transported on the vehicle. It was fixed on the rear side of the armored superstructure, over the air intake armored plate, and could transport five more smoke grenades.

Ammunition

The Semovente M42 da 75/18 had two ammunition racks, carrying a total of 44 75 mm rounds in rows of four interspersed with rows of three. The racks were opentable from the top, which slowed down the reloading operations. The gun fired 75 x 232.5 mmR cartridges.

There were 1,104 (i.e. 46 magazines) machine gun rounds on the Semoventi M42 da 75/18. The machine gun magazines were transported in wooden racks mounted on the sides of the fighting compartment.

Organization

The organization of the semoventi da 75/18 sensibly changed during the production of these self-propelled guns from 1941 to 1943. The units were numbered with Roman numerals, such as DLVII, DLVIII, and so on.

Before the adoption of the Semoventi M42 da 75/18, the organization changed two times, but finally, from 1st October 1942, the gruppi semoventi da 75/18 (Eng. 75 mm L/18 self-propelled gun groups) were reorganized with three batterie (Eng. batteries) with six semoventi each, for a total of 18 semoventi and nine Carri Armati Comando Semoventi M42.

Delivery

The Regio Esercito received 194 semoventi M42 da 75/18 out of 205 produced by Ansaldo company between December 1942 and September 1943. The majority of the Semoventi M42 da 75/18 went to equip the 135^a Divisione Corazzata ‘Ariete II’ (Eng. 135th Armored Division). The division was formed in Ferrara on 1st April 1943 and named in honor of the 132^a Divisione Corazzata ‘Ariete’ which had fought and been totally destroyed during the North African Campaign.

The Raggruppamento Esplorante Corazzato ‘Lancieri di Montebello’ (Eng. Armored Exploration Group), the heavy reconnaissance unit of the ‘Ariete II’ had two gruppi squadroni (Eng. squadron groups) in its ranks. The first one had two medium tanks squadrons and a motorcycle squadron and the second one had 24 Semoventi M42 da 75/18 and two Carri Armati Comando Semoventi M42 divided into the 4° and 5° squadrone semoventi (Eng. 4th and 5th self-propelled gun squadrons).

The 10° Reggimento Corazzato ‘Lancieri di Vittorio Emanuele II’ (Eng. 10th Armored Regiment), also assigned to the ‘Ariete II’, had three gruppi squadroni in its ranks. All three groups were equipped with a Carri Armati M15/42 squadron and two Semoventi M42 da 75/18 squadrons, for a total of 70 Carri Armati M15/42, 12 Carri Armati M15/42 command tanks, 71 Semoventi M42 da 75/18, and seven Carri Armati Comando Semoventi M42.

Finally the 16° Reggimento Motorizzato ‘Cavalleggeri di Lucca’ (Eng. 16th Motorized Regiment) had a Squadrone Semoventi M42 in its ranks, with a total of 24 Semoventi M41 and M41 da 75/18.

This meant that the 135^a Divisione Corazzata ‘Ariete II’ alone had a total of 119 Semoventi da 75/18 (only very few were M41s) in its ranks before the Armistice.

The 12ª Divisione di Fanteria ‘Sassari’ (Eng. 12th Infantry Division), after participating in the invasion of Yugoslavia and the anti-partisan fighting in the Balkans, was transferred to Italy in July 1943. During reorganization, the division received the XII Battaglione Semoventi da 75/18, with a total of 12 Semoventi M42 da 75/18. Some sources, such as Italian Order of Battle: An organizational history of the Italian Army in World War II written by George F. Nafziger, wrongly reports the unit as being armed with Semoventi L40 da 47/32.

The remaining 63 Semoventi M42 da 75/18 were assigned to training units across the peninsula. At least seven were assigned to the CCCCXXXIII Battaglione Complementi (Eng. 433rd Replacement Battalion) in Parma. Other semoventi were assigned in unknown numbers to the 1° Reggimento Fanteria Carrista (Eng. 1st Tank Crew Infantry Regiment) in Vercelli for training, to the 3° Reggimento Fanteria Carrista in Bologna, to the 4° Reggimento Fanteria Carrista in Rome, to the 31° Reggimento Fanteria Carrista in Siena, to the 32° Reggimento Fanteria Carrista in Verona, to the 33° Reggimento Fanteria Carrista in Parma, and to the depots of artillery units in Livorno, Rovereto, and Mantova.

The book Gli Autoveicoli da Combattimento dell’Esercito Italiano written by Nicola Pignato and Filippo Cappellano also refers to the presence of Semoventi M42 da 75/18 in the XVIII Battaglione Carri M14/41, a mixed battalion which was planned to be sent in Sardinia. Apart from that book, no other source claims the presence of self-propelled guns in that unit. They were probably planned to be allocated but never delivered.

In the book Carro M – Carri Medi M11/39, M13/40, M14/41, M15/42, Semoventi ed Altri Derivati written by Antonio Tallillo, Andrea Tallillo, and Daniele Guglielmi, it is reported that the XIX Battaglione Carri M42 was equipped with 18 Semoventi M42 da 75/18, but this seems incorrect. The XIX Battaglione Carri M42 was the only mixed battalion in the Regio Esercito which received Semoventi M42M da 75/34 with long-barreled guns instead of the short-barreled semoventi da 75/18.

Operational Use

The Semoventi M42 da 75/18 were deployed by the Regio Esercito units exclusively during the battles that erupted after the proclamation of the Armistice between the Kingdom of Italy and the Allied forces on 8th September 1943.

In July 1943, due to the very poor performance of the Kingdom of Italy in the war, the Italian king, Vittorio Emanuele III, had Benito Mussolini arrested. Despite the arrest of the Fascist leader, the Italian monarch assured the Germans that he would continue the war on their side. However, secretly, he arranged meetings with the Allies.

The Germans expected such a move and organized Fall Achse (Eng. Operation Axis), an operation aimed at disarming and capturing as many Italian troops as possible in case they changed sides.

On 8th September 1943, the Allied troops announced the Armistice, but very few generals in Italy were aware of the Armistice, and all soldiers and officers in all theaters of the war were taken by surprise by the news. That very night, the King, his family, and many politicians and army commanders fled south to join the Allied troops, leaving Italian soldiers without orders and at the mercy of the Germans.

The Germans, who, on the contrary, expected this situation, attacked the confused Italian troops in Europe and on the Italian peninsula, in most cases disarming and capturing them with hardly any fighting.

In Rome, the Italian capital, the situation was completely different. The 135^a Divisione Corazzata ‘Ariete II’, together with the 12ª Divisione di Fanteria ‘Sassari’ and another two infantry divisions without self-propelled guns, started to resist the German troops that tried to enter the city after the initial surprise.

The first clashes involving units of the 135^a Divisione Corazzata ‘Ariete II’ occurred in the morning of 9th September 1943 in the Monterosi and Manziana areas, north of Rome. In the Monterosi area, the 6° Squadrone Semoventi da 75/18 of the 10° Reggimento Corazzato ‘Lancieri di Vittorio Emanuele II’ and the Squadrone Semoventi M42 of the 6° Reggimento Motorizzato ‘Cavalleggeri di Lucca’ blocked the road to Rome. In the Manziana area, the 8° Squadrone Semoventi da 75/18 of the ‘Lancieri di Vittorio Emanuele II’ did the same.

Together with infantry, armored cars, and artillery units, these units clashed with Kampfgruppe “Grosser” (Eng. Battle Group) a two-battalion strong battle group of the 3. Panzergrenadier-Division (eng. 3rd Mechanized Infantry Division). The Italian units put up a strenuous resistance, forcing the Germans to break their advance and inflicting moderate losses.

Despite this, the Germans bypassed the Italian troops in the Monterosi area and, to avoid also being circumvented, the Italians at Manziana and Monterosi retreated to Tivoli. In the clashes, the 6° Reggimento Motorizzato ‘Cavalleggeri di Lucca’ lost seven self-propelled guns, while the ‘Lancieri di Vittorio Emanuele II’ lost 10 Semoventi M42 da 75/18 in total.

The Raggruppamento Esplorante Corazzato ‘Lancieri di Montebello’ was deployed on the same day in the south-west area of Rome, along the Via Ostiense (an old Roman road which connected Ostia to Rome). The attack from the south was launched by Kampfgruppe “Von der Heydte”, composed of paratroopers of the 2. Fallschirmjäger-Division (Eng. 2nd Paratrooper Division).

During 9th September, the Semoventi M42 da 75/18 supported the Italian soldiers of the 21ª Divisione di Fanteria ‘Granatieri di Sardegna’ (Eng. 21st Infantry Division) and other Italian units which slowly retreated inside the city, trying to inflict as many losses as possible on the German forces. During the afternoon, the Italian self-propelled guns and Autoblinde AB41 of the ‘Lancieri di Montebello’ launched a series of counter-attacks to slow down the Germans from reaching their objectives, but this came at the cost of severe losses.

After a quiet night, on the morning of 10th September, the fighting restarted. The Germans received reinforcements during the night and inflicted severe losses on the armored units of the 135^a Divisione Corazzata ‘Ariete II’, moving dangerously close to the city center.

During the early morning, radio messages also arrived that were misinterpreted. The Raggruppamento Esplorante Corazzato ‘Lancieri di Montebello’ retreated toward the city center, only to be recalled to the front line at 10:30 AM by the 21ª Divisione di Fanteria ‘Granatieri di Sardegna’ headquarters. At that point, the clashes were fought in Porta San Paolo (one of the old Roman gates of Rome’s defensive wall).

In the fighting around Porta San Paolo, the ‘Lancieri di Montebello’ suffered the loss of nearly all its Semoventi M42 da 75/18 and also the Semoventi M43 da 105/25 of the DCI Gruppo Semoventi da 105/25 (assigned to another unit of the 135^a Divisione Corazzata ‘Ariete II’), but resisted until 5:00 PM, when the German forces crossed the old gate, entering the city center.

A desperate counter-attack was launched by a battery of Semoventi M42 da 75/18 of the XII Battaglione Semoventi da 75/18 12ª Divisione di Fanteria ‘Sassari’, the remaining self-propelled guns of the ‘Lancieri di Montebello’ and 11 tanks and self-propelled guns of the 4° Reggimento Fanteria Carrista. The latter ones, under the command of Second Lieutenant Vincenzo Fioritto, were sent from the 4° Reggimento Fanteria Carrista depot in Forte Tiburtino. The vehicles were quickly knocked out by the anti-tank guns placed by the Germans paratroopers in the streets. The self-propelled gun of Second Lt. Fiorito was hit and he was severely wounded in the arm. As he died, the officer continued to call on his men to fight.

Some Italian units fought until 11th September 1943, but the Germans took command of the city with generally negligible losses. All the Italian vehicles not destroyed or sabotaged were taken over by the Germans and placed in improvised depots outside the capital, awaiting their reassignment to German units.

The only unit that fought the German troops using the Semoventi M42 da 75/18 outside Rome in the days of the Armistice was the CCCCXXXIII Battaglione Complementi. Shortly before the Armistice, the unit had a total of one Carro Armato M15/42 and seven Semoventi M42 da 75/18 in Parma and Fidenza, where they were used as public duty garrisons.

The unit departed from Fidenza at the dawn of the 9th September with its eight armored vehicles and 14 trucks full of soldiers. Due to their police duty tasks, each Semovente M42 da 75/18 was equipped with only 5 rounds, while the remaining ones were target practice rounds.

The CCCCXXXIII Battaglione Complementi reached Parma at 6:00 AM, but the Germans of the 1. SS-Panzer-Division “Leibstandarte SS Adolf Hitler” (Eng. 1st SS Panzer Division) were already waiting for them with anti-tank guns and at least one Panzerjäger 38(t) für 7.5 cm PaK 40/3 (Sd.Kfz.138) Ausf.H tank-destroyer.

Without the Italian Semoventi M42 da 75/18 being able to offer resistance or score a hit against German targets, they were quickly knocked out one after another. The remaining three vehicles were sabotaged by the crews and abandoned at 8:30 AM.

A month after the Armistice, on 8th October 1943, the Germans reported 123 Semoventi M41 and M42 da 75/18 captured (including the 11 not yet delivered and still present at Ansaldo). Considering that the Semoventi M41 da 75/18 represented a negligible number (some sources says just 4 captured), this means that, of the 194 Semoventi M42 da 75/18 already delivered to the Regio Esercito, 78 were destroyed, sabotaged, or hidden by the Italian crews before being captured by the Germans.

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German Service

When Fall Achse was completed on 20th September 1943, along with the death of about 20,000 Italian soldiers and the capture of over a million others in the Italian peninsula, France and Balkans, the German troops also captured 16,631 motor vehicles (trucks, staff cars, motorcycles, etc.) and 977 armored vehicles.

A total of 123 Semoventi M41 e M42 da 75/18 were captured by the Germans, primarily in Rome, along with 11 Semoventi M42 da 75/18 that had not yet been delivered to the Italian units and were captured directly at the Ansaldo company.

The vehicle was renamed Beute Sturmgeschütz M42 mit 7.5 cm Kampfwagenkanone L/18 850 (italienisch) (Eng. Captured Assault Gun M42 with 7.5 cm Tank Cannon [Coded] 850 [Italian]), abbreviated to StuG M42 mit 75/18 850(i).

In October 1943, a German delegation visited various Italian production plants, evaluating the armored vehicles being produced. If the vehicles were judged favorably, or if there were enough raw materials to restart the production, the German signed a contract for production under their control.

A total of 55 StuG M42 mit 75/18 850(i) were ordered on 9th October 1943, all delivered by 1944. The Germans did not order more of them after that in order to give priority to higher-performance vehicles, such as the Beute Sturmgeschütz M42 mit 75/34 851(i) (Semovente M42M da 75/34), the Beute Sturmgeschütz M43 mit 75/46 852(i) (Semovente M43 da 75/46), and the Beute Sturmgeschütz M43 mit 105/25 853(i) (Semovente M43 da 105/25).

The Beute Sturmgeschütze would equip the Panzerjäger-Abteilungen (Eng. anti-tank battalions) of German divisions deployed in the Italian peninsula and in the Balkans.

Theoretically, each Panzerjäger-Abteilung was equipped with a Beute Sturmgeschütz Befehlswagen M42 772(i) (Carro Armato Comando Semoventi M42) for the Stab-Zug (Eng. Command Platoon). The 1. Batterie (Eng. 1st Battery) was equipped with 6 Sturmgeschütz M42 mit 75/18 850(i) and the 2. Batterie (Eng. 2nd Battery) with 8 Beute Sturmgeschütz M42 mit 75/34 851(i).

During the war, just a few units received the theoretical number of Italian self-propelled guns needed to equip an entire Panzerjäger-Abteilung. Many German units did not receive even half of the planned vehicles, while others incorporated even a 3. Batterie with Beute Sturmgeschütz M43 mit 105/25 853(i).

Repubblica Sociale Italiana and Italian Partisans

After the Armistice of 8th September 1943, Benito Mussolini returned to power in the territories of the Italian peninsula not yet liberated by Allied forces. On 23rd September 1943, he created the Repubblica Sociale Italiana (Eng. Italian Social Republic), which was, de facto, a German puppet state.

The Repubblica Sociale Italiana’s armed forces were composed of Italian soldiers who were still loyal to Mussolini’s Fascism. The Germans captured nearly all the armored vehicles and controlled the production plants and generally did not deliver any vehicles to the new Italian units. The Italian soldiers scoured every military depot, barracks, and training school to acquire any equipment they could find.

During the 18 months from September 1943 to April 1945, the Repubblica Sociale Italiana armed forces had a total of four semoventi da 75/18, one on the M41 chassis, and three on M42 chassis.

A total of three of these vehicles (one on the M41 and two on the M42 chassis) were deployed by the Gruppo Squadroni Corazzati ‘San Giusto’ (Eng. Armored Squadrons Group) which operated on the north-eastern border against Yugoslavian partisans.

These vehicles were assigned to the Sezione Semoventi (Eng. Self-Propelled Gun Section) of the Squadrone Carri M (Eng. Medium Tank Squadron) together with a Semovente M42M da 75/34 and two Semoventi L40 da 47/32.

However, the Semoventi da 75/18 had poor mechanical reliability and were rarely deployed, remaining in the workshop or in storage most of the time.

The Semoventi M42 da 75/18 were involved in some clashes with Yugoslavian Partisans in the Ruppa area (now Croatia), along with other vehicles, between the 18th and 27th April 1945. Due to air strikes and land mines, however, many of the vehicles were damaged or immobilized, and on 27th April, when the unit returned to Mariano del Friuli (the group’s headquarters), it discovered that the depot had already been liberated by partisans. At that point, the tank crews abandoned the last available vehicles and moved to safety.

The last Semovente M42 da 75/18 of the Repubblica Sociale Italiana was deployed by the Raggruppamento Anti Partigiani (Eng. Anti-Partisan Grouping), which operated from Turin in the whole Piedmont region. In January 1945, the German forces delivered various damaged vehicles to the Italian unit, including two semoventi da 75/18. Some of the vehicles were repaired but nothing is known about the semoventi. When the Great Partisan Insurrection broke out on 25th April 1945 (in Turin, the insurrection started on 26th April), the Italian Partisan’s VII Divisione Autonoma ‘Monferrato’ (Eng. 7th Autonomous Division) occupied the Raggruppamento Anti Partigiani’s headquarters. An Italian Partisan veteran claimed that a Semovente M42 da 75/18 was captured in the headquarters. That was probably one of the two delivered by the Germans in January, while the second one had been cannibalized for spare parts.

The vehicle was covered with markings such as ‘W la Monferrato’, ‘W Stalin’, and ‘Torino’ to prevent friendly fire and ‘Ali’, the nickname of Gagliardone Sereno, a partisan of the 3rd Brigade of the Division, who captured the self-propelled gun. The Semovente M42 da 75/18 was redeployed by the Partisans in the clashes in Turin, specifically against the Fascist forces which defended Turin’s prefecture and main square.

In the days after the liberation of the city, the Semovente M42 da 75/18 was cleaned of the majority of the markings except for ‘W la Monferrato’ and deployed in the Great Partisan Parade of 6th May 1945 through the streets of Turin. It was then probably delivered to the Arsenale di Torino (Eng. Turin’s Arsenal) for a complete overhaul.

Italian Republic

After the Second World War, the Italian population voted to become a republic and, on 2nd June 1947, the Kingdom of Italy became the Repubblica Italiana (Eng. Italian Republic). The new army was renamed Esercito Italiano (Eng. Italian Army) and was nearly entirely equipped with US and British materiel. Nevertheless, some training units and infantry support units received some of the few Italian armored vehicles which had survived the war.

Some semoventi da 75/18 returned to service between 1948 and 1950, and the last ones were not retired from service until 1956. Unfortunately, of the few dozen of semoventi da 75/18 returned to service, it appears that a very small number were semoventi on the M42 chassis. At least one was delivered to the Arsenale di Torino immediately after the war (probably the Partisan vehicle from Turin). It was left in the depot until the late 1940s, when the Turin Arsenal received the greenlight by the Esercito Italiano high command to overhaul it and deliver it to the armored forces, but its fate is unknown.

Versions

Semovente M42M da 75/34

Around the same time when the first Semoventi M42 da 75/18 were produced, the Cannone da 75/34 Modello SF [Sfera] (Eng. 75 mm L/34 Gun Model [on] Spherical [Support]) successfully passed firing tests. This new gun was developed for the Carro Armato P40 (Eng. P40 Tank), but due to delays relating to the production of this heavy tank, the gun was also mounted on self-propelled guns. The only difference between the Semovente M42 da 75/18 and the Semovente M42M da 75/34 was the length of the armored superstructure. On the Semovente M42M da 75/34, it was lengthened by 110 mm due to the longer breech and recoil of the new gun. The vehicle received an ‘M’ in the name, which stood for Modificato (Eng. Modified). From March 1943 to April 1945, 145 Semoventi M42M da 75/34 were produced, of which 94 were assembled before the Armistice of 8th September 1943. The remaining vehicles were produced under German control and deployed by German units in the Italian peninsula and Balkans. Only a single example was deployed by the Gruppo Squadroni Corazzati ‘San Giusto’ of the Repubblica Sociale Italiana after the Armistice.

Semovente M43

In late 1942, the design of a self-propelled gun armed with a 105 mm howitzer on the Carro Armato P40 chassis was started. Due to delays with the P40’s development, the decision was made to continue the development of the semovente on the Carro Armato M15/42 chassis.

To accommodate such a large gun, the chassis of the Semovente M42 was lengthened, reaching 5.100 m (compared to the previous 5.069 m) and enlarged to 2.450 m (compared to previous 2.280 m). It was also lowered by 11 cm, reaching a total height of 1.740 m (compared to 1.850 m). This new chassis, first called M42L for Lungo (Eng: Long), was then renamed M43.

The new chassis received some upgrades, for example, the transmission cover was welded and composed of two angled plates instead of the older rounded one. The front armor plate was thickened from 50 mm to 70 mm and the sides from 25 mm to 45 mm.

In the first model, called Semovente M43 da 105/25, the vehicle was armed with a Cannone da 105/25 Modello SF (Eng. 105 mm L/25 Gun Model [on] Spherical [Support]) and a reserve of 48 rounds. The Semovente M43 da 105/25’s total weight was 15.7 tonnes and its maximum speed on road was 38 km/h. A total of 121 Semoventi M43 da 105/25 were produced until April 1945, of which only 30 were delivered to the Regio Esercito, while the remaining were produced for the Germans.

The M43 chassis was also employed for the production of two Italo-German projects, the Semovente M43 da 75/46 and the Semovente M43 da 75/34. These were two self-propelled guns on a M43 chassis equipped with 25 mm spaced armor plates on the front and sides to increase protection. The armament was composed of a Cannone da 75/46 Contraerei Modello 1934 (English: 75 mm L/46 Anti-Aircraft Cannon Model 1934) and the Cannone da 75/34 Modello SF.

The self-propelled guns weighed 15.6 tonnes for the first and 15.5 tonnes for the latter, both with a top speed of 38 km/h. Both semoventi are also known as M43T, where the ‘T’ meant Tedesco (Eng. German).

A total of 18 Semoventi M43 da 75/46 and 29 Semoventi M43 da 75/34 were produced exclusively for the Germans from mid-1944 to April 1945.

Conclusion

The Semovente M42 da 75/18 was the last self-propelled howitzer produced by the Kingdom of Italy in the Second World War. It was a simple upgrade of the previous self-propelled howitzer that was based on the Carro Armato M14/41. Its powerful petrol engine improved the mobility and maximum speed but, except for these two improvements, the vehicle remained almost identical to the previous versions.

Despite it being produced in sensibly more numbers compared with the semoventi M40 and M41 with the same 75 mm howitzer, its service was shortened due to the Armistice of 8th September 1943, which did not permit a useful deployment of this vehicle. The only time in which the Semoventi M42 da 75/18 were deployed by Regio Esercito units was during the Defense of Rome. For the rest of the war, the vehicles were deployed by German forces and Italian Fascist forces in small numbers.

Sources

Pignato N., Cappellano F., Gli Autoveicoli da Combattimento dell’Esercito Italiano, Volume Secondo (1940-1945), Ufficio Storico dello Stato Maggiore dell’Esercito, Roma, 2002

Pignato N., Cappellano F., Gli Autoveicoli da Combattimento dell’Esercito Italiano, Volume Terzo (1945-1955), Ufficio Storico dello Stato Maggiore dell’Esercito, Roma, 2002

Tallillo Antonio, Tallillo Andrea, Guglielmi D., Carro M – Carri Medi M11/39, M13/40, M14/41, M15/42, Semoventi ed Altri Derivati Volume Secondo, Gruppo Modellistico Trentino di Studio e Ricerca Storica, Trento, 2012

Pignato N., Cappellano F., Andare Contro i Carri Armati, L’Evoluzione della Difesa Controcarro nell’Esercito Italiano dal 1918 al 1945, Gaspari Editore, Udine, 2007

Crippa P., I Reparti Corazzati del Regio Esercito e l’Armistizio, Volume 1, Soldiershop Publishing, 2021

Crippa P., I Reparti Corazzati del Regio Esercito e l’Armistizio, Volume 2, Soldiershop Publishing, 2021

Crippa P., Storia dei Reparti Corazzati della Repubblica Sociale Italiana 1943-1945, Milano, Marvia Edizioni, 2022

Pignato N., Semovente da 75/18 Tecnica e Storia del Primo Semovente Italiano, Albertelli Edizioni Speciali (Storia Militare), Parma, 2010

Nava M., Corbatti S., … Come il Diamante. I Carristi Italiani 1943-45, Laran Editions, January 2008

Preliminary Report N° 18, Italian Tank M13/40, School of Tank Technology, October 1943