The Semovente M40 da 75/18 was the first Italian self-propelled howitzer, developed by the firm of Ansaldo on the chassis of the Italian Carro Armato M13/40 medium tank of the IIIª Serie.
It was initially developed as a support vehicle for the infantry assault units of the Italian Regio Esercito (English: Royal Army). Nonetheless, due to the obsolescence of the Italian medium tanks, such as the Carro Armato M13/40, from mid-1942 until the end of the North African Campaign, in May 1943, it was deployed by Italian armored units as a tank destroyer and medium tank. In this unorthodox role, it compared positively to the other Italian tracked vehicles.
The Italian Medium Tanks
When the Regno d’Italia (English: Kingdom of Italy) joined the Germans in the Second World War, on 10th June 1940, in terms of tanks, its army was poorly equipped with tanks. The most numerous portion of its armored force was made up of the CV3 series of light tanks and only a hundred of Carri Armati M11/39 medium tanks. Production of the Carri Armati M13/40 was only just winding up and did not start until the month after the Italian declaration of war.
The Carro Armato M11/39 was a tank developed to fight in the mountainous terrains of the northern Italian peninsula. It was armed with a Cannone Vickers-Terni da 37/40 (37 mm L/40) gun placed on the right side of the superstructure and a one-man turret armed with two medium machine guns on the left side of the tank.
The Carro Armato M13/40 was a good tank by the standards of the 1930s, but, already in 1941, it had old-fashioned features which would render it quickly obsolete. This new tank had the same chassis as the Carro Armato M11/39, with some modifications, such as a more powerful engine and a new transmission cover. Its superstructure was raised and two machine guns were mounted in a casemate on the right side of the superstructure. A new horseshoe-shaped two-man turret was placed on top, armed with a Cannone da 47/32 Modello 1935.
The armor of the vehicle was light: 30 mm on the front of the hull, 42 mm on the front of the turret, and the sides were only 25 mm. As if that were not enough, the armor produced was of a poor quality, leaving it weaker than it should have been and with a tendency to spall.
There were faults with the guns too. The 37 mm and 47 mm guns had good anti-tank capabilities by 1930s standards, but, once more, by the 1940s, they were increasingly outdated and unable to keep pace with the growth and improvement in tank protection. On top of all of this, the optics were poor compared to contemporary British optics and their practical range was less than a kilometer.
History of the Project
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 howitzers.
The firm of Ansaldo claimed that, in the early stages of the Second World War, Italian war correspondents that followed the German Wehrmacht in France were impressed by the characteristics of the German Gepanzerten Selbstfahrlafette fur Sturmgeschütz 75 mm Kanone (English: Armored self-propelled gun carriage for assault gun 75 mm cannon) self-propelled assault guns, or more simply Sturmgeschütz III, based on the Panzerkampfwagen III chassis, the main German tank in that period.
Some Italian generals that had visited the European battlefields before the Italian declaration of war or that had been invited to witness German training had reported a positive impression of the German Sturmgeschütz III.
Other sources claim that the development of a self-propelled howitzer on the chassis of the Carro Armato M13/40 equipped with a Obice da 75/18 was conceived by Colonel Sergio Berlese of the Servizio Tecnico di Artiglieria (English: Artillery Technical Service) in collaboration with the Servizio Tecnico Automobilistico (English: Automobile Technical Service).
Col. Berlese had visited a German factory in Kiel in 1940, where gun-armed half-tracks were assembled. According to the plans of Col. Berlese, the Kingdom of Italy would produce an armored and armed half-track. However, at that time, the Italian industry was not producing half-tracks of any kind.
Despite the lack of a suitable half-track, Col. Berlese did not quit and would continue to advocate for his idea, finally culminating in 1943 with a paper project called Autocannone da 90/53 su Autocarro Semicingolato Breda 61. In the absence of a suitable half-tracked platform and to put his idea into practice, a fully tracked chassis was needed instead. The choice fell on the best medium tank chassis in Italy at that time, the Carro Armato M13/40.
The first mention of the Semoventi was in January 1941, when the Regio Esercito’s High Command created three proposals for self-propelled guns and howitzers. One of these was the Pezzo Semovente da 75/18 (English: 75/18 Self-Propelled Artillery Piece) on the hull of the M13/40 medium tank. It would have armor of 40 to 50 mm on the front and 25 mm on the other sides.
Each reggimento d’artiglieria (English: artillery regiment) of each divisione corazzata (English: armored division) would have a group of these self-propelled howitzers.
An important note is that these vehicles were developed as long range self-propelled howitzers, similar to the US M7 Priest, the British Ordnance QF 25-pdr on a Valentine known as the ‘Bishop’, or the German Leichte Feldhaubitze 18/2 Auf Fahrgestell Panzer II Wespe. However, during their service history, the Italian vehicles were mainly used as short range support vehicles or as tank destroyers.
On 28th May 1941, General Mario Roatta, Chief of Staff of the Regio Esercito, wrote to the Ispettorato Superiore dei Servizi Tecnici (English: Higher Inspectorate of Technical Services) to develop new designs of such vehicles on tracked or half-tracked chassis to support the armored divisions.
At the same time, Gen. Roatta asked the Inspectorate to develop an adequate observation/command tank and an armored ammunition carrier that would follow the self-propelled howitzers.
On 3rd June 1941, the Ispettorato Superiore dei Servizi Tecnici replied to the General, assuring him that a self-propelled howitzer with the following characteristics was being studied:
- Crew: 4
- Main Gun: a Obice da 75/18 or a Cannone da 75/34
- Ammunition: at least 50 rounds
- Ground pressure: 0.60-0.65 kg/cm3
- Power to weight ratio: at least 15 hp per tonne
- Maximum velocity: about 60 km/h
- Maximum height: 1.8 meters
The reply also mentioned that a trailer meant to be towed by the SPG on flat ground was also being designed, with a capacity for 50 to 70 rounds. It also mentioned that it was planned to move the powerpack to the front, mounting the main gun on a pedestal on the chassis’s rear.
The reply also specified that the Ispettorato dell’Arma dell’Artiglieria (English: Artillery Army Inspectorate) preferred the adoption of the Obice da 75/18 due to its specific support role (the Cannone da 75/34 was an anti-tank gun).
This solution was not adopted on the Semovente M40 da 75/18, but was later incorporated for the more powerful Semovente M41M da 90/53 tank destroyer with a Cannone da 90/53 Modello 1939 90 mm L.53 cannon.
The Ispettorato della Fanteria (English: Infantry Inspectorate), in a letter on 5th June 1941, wrote that they would avoid the production of a self-propelled howitzer on Carro Armato M13/40, because it was too expensive to produce. The Ispettorato della Fanteria suggested the production of a light self-propelled gun on the Carro Armato L6/40 chassis armed with a 47 mm gun for infantry support.
On 21st June 1941, the Chief of the Services Office of the General Staff of the Regio Esercito, General Aldo Rossi, wrote a document in which he listed the decisions made by the Army General Staff regarding the new self-propelled howitzers and guns.
The Regio Esercito awaited the new self-propelled gun armed with a Cannone da 75/34. They also wanted an observation tank and a command tank to accompany it. For the ammunition carriers, the army could rely on Carri Armati L3s or captured Renault UEs towing an ammunition trailer.
History of the Prototype
The project of the Semovente designed by Col. Berlese 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 and promptly ordered 30 vehicles on 16th January 1941.
On 11th February 1941, the prototype, quickly assembled, was tested in Cornigliano, with great results. Production began shortly after, and the Regio Esercito increased the order of self-propelled howitzers on the Carro Armato M13/40 chassis, after a decrease to 15 vehicles had been requested for unknown reasons on 10th March 1941.
On 25th May 1941, the order was increased to 60 vehicles. On 5th December 1941, it was increased to 144 vehicles and, in the end, it was increased to 200 vehicles on 17th May 1942, when the M40 was no longer in production. In fact, after 60 vehicles were produced, Ansaldo changed the chassis of the medium tank from the M13/40 to the slightly more powerful Carro Armato M14/41.
|Semoventi M40 Production|
|Order’s data||Number of Vehicles Ordered||Vehicle Type|
|16th February 1941||30||Semoventi M40 da 75/18|
|15th March 1941||151||Semoventi M40 da 75/18|
|25th May 1941||30||Semoventi M40 da 75/18|
|5th December 1941||144||Semoventi M41 da 75/18|
|Note||1 Ansaldo claimed to have received the request of just 15 semoventi officially.
On an unknown data before May 1941, the Regio Esercito corrected the misunderstanding with Ansaldo and the original order for 30 vehicles was restored
The prototype was then tested at Nettunia with members of the Servizio Tecnico Armi e Munizioni (English: Weapons and Munitions Technical Service), Ispettorato Superiore dei Servizi Tecnici, and Servizio Tecnico di Artiglieria in attendance. As General Umberto Farulli of the Servizio Tecnico di Artiglieria later wrote, the frontal armor on the prototype was not thick enough to withstand British 40 mm (2-pdr) armor piercing rounds.
For this reason, the vehicles in production were modified, slowing down the production rates. The frontal armor was substituted with new armor plates with higher percentages of nickel and chromium, which increased their strength.
The first vehicles were delivered to the Regio Esercito training schools in May 1941.
Production and Deliveries
In 1941, a total of 60 Semoventi M40 da 75/18 were produced. Many Italian companies participated in the production of the M40 da 75/18.
|Companies that participated in the M13/40’s production|
|Fabbrica Italiana Automobili di Torino (FIAT)||Turin||Fuel injector pump|
|Società Piemontese Automobili (SPA)||Turin||Engines|
|Società Italiana Ernesto Breda per Costruzioni Meccaniche||Brescia||Machine guns|
|Magneti Marelli||Corbetta and Sestri Ponente||Engine starter, radio systems, and batteries|
|San Giorgio||Sestri Ponente||Optics devices|
|Società Italiana Acciaierie Cornigliano (SIAC)||Cornigliano||Armor plates|
|Alemanno||Turin||Pressure gauges and tools|
|SA ALIT||Turin||Oil Filters|
|Pirelli & Company||Milan||Rubber parts of the return rollers and wheels|
|Ansaldo||Sestri Ponente||Guns and assembly|
All the produced parts arrived at the Ansaldo-Fossati plant in Sestri-Ponente, where they were assembled. Ansaldo produced the cannons, while Duco of Milan produced the paints with which the M40s were camouflaged in the Sestri Ponente plant.
The armor of the Semovente M40 da 75/18 hull was the same as that of the Carro Armato M13/40. 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 consisted of two 25 mm welded armored plates with a combined thickness of 50 mm angled at 5°. 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 for the hull and casemate, with the only difference that 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.
During a test 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
The hull was the same as that of the Carro Armato M13/40 IIIª Serie. At the front, the tank had a cast rounded transmission cover. The rounded plate had two hooks on the sides and a towing ring in the center. There were also two inspection hatches above the brakes to improve the flow of air around the transmission, especially to help cool the clutch on long drives. In combat, these hatches were meant to be closed. The two hatches could be opened or closed from the inside of the vehicle even while driving by means of a lever located on the right side of the chassis, operated by the gunner.
On the frontal armored plate, there was a round hole for the main gun’ spherical support. On the left side, there was a slot for the driver, who also had a hyposcope placed above for use when the slot was closed. The hyposcope had a size of 19 x 36 and a vertical field of view of 30°, from +52° to +82°.
For night driving, there were two adjustable headlights on the sides of the superstructure.
On the roof, there were two big hatches, which opened backwards and permitted the crew to easily access or exit the vehicle and to load the ammunition.
There was a panoramic monocular periscope produced by San Giorgio placed on the left side of the hatch for the loader/radio operator on the roof. For the commander/gunner, there was a sight mounted on the right side of the gun. The roof had a small hatch that could be closed when the sight was not mounted.
On the rear side of the superstructure, there were two pistol ports closed by revolving shutters from the inside and an air intake. The pistol ports were added after the negative experiences of Italian crew members during the Second Italo-Abyssinian War (1935-1936), where they could not defend themselves from Ethiopian warriors attacking the sides or rear. The air intake sucked air from the outside into the crew compartment and then into the engine compartment. This gave a sort of comfort to crews operating in North Africa, where, inside the tanks, the temperature could reach 60°C, but could create problems during winters in the Italian peninsula or Balkans.
On the mudguards, on each side behind the superstructure, were tool boxes and the mufflers behind. The engine deck had two large-size inspection hatches which could be opened at 45°. Between the two inspection hatches were the sapper tools, including a shovel, a pickaxe, and a crowbar.
The rear top 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, one spare wheel on the right, a jack on the left, a track removal system on the center, a license plate on the left side with a brake light.
For tooling, the crew could transport a shovel, a pickaxe, a crowbar, and a sledgehammer on the engine deck, between the two inspection hatches. A jack, a spare wheel, a track connecting tool, a tow rope, and a towing shackle were on the rear, plus two tool boxes on the sides, in front of the mufflers, used to store wrenches and small spare parts.
The suspension of the Semovente M40 da 75/18 was of the laminated semi-elliptical leaf spring type. On each side, there were four bogies with eight doubled rubber-covered road wheels paired on two suspension units. 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.
The drive sprockets were at the front and the idlers, with modified track tension adjusters, were at the back, with three rubber return rollers on each side.
The tank had 26 cm wide tracks with 84 track links per side. The small surface area of the tracks (about 13,750 cm²) gave a ground pressure of about 0.95 kg/cm², increasing the risk that the vehicle would bog down in mud, snow, or sand.
Engine and Transmission
The Semovente M40 da 75/18 was powered by a V-shaped, 8-cylinder, liquid-cooled FIAT-SPA 8T diesel engine with a maximum power output of 125 hp at 1,800 rpm. It was mounted on the rear part of the vehicle, separated from the crew compartment by a bulkhead. The engine compartment had two large inspection hatches, through which it was easy to check and maintain the engine, something positively highlighted in British reports on the Italian tanks and self-propelled guns. The hatches had two butterfly screws on the lower side and were attached to pins on the upper side, opening upwards at 45° and blocked in an open position by a rod, like a car’s engine deck. Usually, in North Africa, during driving on asphalted roads where not much dust was raised, the crew kept the hatches open to ventilate the engine.
The associated 5-speed gearbox had 4 forward and one reverse gears. In addition, thanks to the built-in reducer, another 4 forward and a reverse gear were available. However, to switch between standard and reduced gears, the vehicle had to come to a stop. Unfortunately, the model of the transmission is not mentioned in any source, but it was a FIAT model, probably produced by Società Piemontese Automobili, its subsidiary. It was coupled with a FERCAT oil radiator and Modello 80 oil filters.
The engine was the same as the one on the Carro Armato M13/40, one of the tank’s major handicaps. It was not very powerful and also not very reliable. This engine was developed for vehicles weighing around 8 tonnes and had already created problems on the Carro Armato M11/39, a tank more than 2 tonnes lighter than the M13/40 and the M40 da 75/18.
In the first series of M13/40s, the lack of sand filters was a serious problem, resolved to some degree in the 3rd series (from which the M40 da 75/18 was derived) with the Bosch Fa 11 S1 anti-sand filters.
The engine used three different types of oil, depending on the temperatures in which the vehicle operated. In Africa, where the outside temperature exceeded 30°, Ultra Denso (English: Ultra-Thick) oil was used. In Europe, where the temperature was between 10° and 30°, Denso (English: Thick) oil was used, while in winter, when the temperature fell below 10°, Semi Denso (English: Semi-Thick) oil was used.
Due to the poor Regio Esercito logistics, in some cases, the battalions had to use winter oil in North Africa, diminishing the effectiveness of oil lubrication.
In order to start the engine, there was a Magneti Marelli electric starter but also an inertial starter produced by Onagro. The lever for the inertia 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.
In order to start running, the crew members needed to check the amount of coolant, engine oil, and transmission and gearbox oil. Then, they had to be sure that there were no leaks from the various tanks and that the brakes and suspension were working properly. The sag of the tracks had to be 2 to 3 cm between the upper rollers, so that, in case of mud or sand between the track and the wheels, the track would not break.
The driver, with the levers released, the transmission in neutral, the handbrake set, had to turn on the instrument panel, via his key, and the dynamo bulb would turn red. After having opened the fuel tap on the main tank and brought the fuel pump to full power (its controls were located on the rear bulkhead), it was necessary to press the button on the dashboard that allowed the heating of the glow plugs.
Once the glow plugs had become incandescent, it was necessary to press the button that controlled the engagement of the two starter motors. If everything was in order, the start would be immediate. When the engine reached 450 revolutions per minute and the oil pressure between 6 to 7.5 kg/cm², the vehicle could move.
The two large fans, powered by the engine, sucked air through the fighting compartment. This allowed for the ventilation of air for the crew but also the cooling of the braking system and transmission due to the air drawn through the opened brake inspection hatches.
In order to stop the tank, the engine was turned off by the driver pushing the button for the fuel injection pump (essentially stopping the flow of fuel to the engine), located on the bulkhead on the rear of the fighting compartment. The fuel injection pump was a FIAT 6.70 2D18.
Before getting out the tank, it was necessary for the crew to clean the exterior of the tracks and suspension from mud, snow, and debris, and the interior of the tank by opening, if necessary, the holes in the bottom of the hull. The crew also needed to open a small inspection hole on the sprocket wheels to lubricate them.
The fuel tank capacity was about 145 liters plus 35 liters of reserve, for a total of 180 liters in three tanks, two of about 60 liters each and the third of 35 liters. The range was 210 km on road or about 10 hours off-road. In North Africa, it was common for the crews to transport 20 liter cans everywhere there was space inside and outside the self-propelled gun in order to increase the range. A total of 6 or more 20 liters cans (180 liters) were commonly transported on the Semoventi M40 da 75/18.
The self-propelled gun could reach a maximum speed of 30 km/h on the road and about 15 km/h on rough terrain. With a turning radius of about 4.50 m, it could cross 2 m wide trenches, ford water 1 m deep, and climb steps 0.80 m high. The vehicle was also equipped with a hand brake that locked the sprockets.
The transmission of the Semovente M40 da 75/18 was as epicyclic, as was the clutch. It was mounted frontally, connected to the front sprocket wheels. It was removable, together with the brakes, after removing the armored plate that protected it.
The main armament of the Semovente M40 da 75/18 was the Obice da 75/18 Modello 1934. It was a field howitzer developed after General Ettore Giuria created a call in 1929 for the replacement of outdated guns.
It had to be light to be quickly transported anywhere and had a caliber of 75 mm. This questionable decision was taken even if, during the First World War, the Regio Esercito had noted that a howitzer with a larger caliber was better to destroy enemy fortified positions. The reason why the Servizio Tecnico di Artiglieria chose the 75 mm caliber again was due to the presence of thousands of 75 mm rounds in the army depots and barracks.
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. It had 3° of traverse to either side and an elevation from -10° to +80°. The Obice da 75/18 Modello 1934 weighed 780 kg.
After lengthy trials, this design was abandoned in 1933 in favor of that of Lieutenant Colonel Berlese, at the time a member of the design bureau of the Direzione Superiore del Servizio Tecnico Armi e Munizioni (English: Higher Directorate of Weapons and Munitions Technical Service). This gun was accepted into service and was designated Obice da 75/18 Modello 1932.
On the Semovente M40 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°.
It had modifications on 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 secondary armament consisted of a Fucile Mitragliatore Breda Modello 1930 (English: Breda Light Machine Gun Model 1930) that could be used on the anti aircraft support or with a bipod in order to defend the crew when operating outside the self-propelled gun.
Even if, before the war, the Fascist propaganda considered it a well designed example of Italian technology, in reality, it proved to be a far from perfect weapon. It was chambered for the same 6.5 mm x 52 mm Mannlicher-Carcano cartridge used in Italian rifles. It was a light munition for a machine gun, but the Italian Army preferred this cartridge to ease its logistic lines.
Developed in 1929 from the Breda Modello 5GF light machine gun, it was adopted in 1930 after a series of modifications. It was fed by 20 round clips that were loaded in a swing chamber on the right side of the weapon.
After opening the swing chamber forward, the gunner had to load the clip with 20 rounds, remove the empty clip, close the swing chamber, reload the gun, and open fire. This was a time-consuming operation that decreased the rate of fire to 150 rounds per minute.
It proved an ineffective weapon for the infantry because of mechanical problems. In fact, it jammed often if not perfectly lubricated, a problem that was exacerbated in sandy North Africa.
As a secondary armament for a self-propelled gun, it proved even less effective. The short range and difficulty of reloading it made it even less effective with a further diminished rate of fire.
When not used, the Breda Modello 1930 was stored on the right side of the casemate, near a maintenance kit.
The Semovente M40 da 75/18 had two ammunition racks, for a total of 43 75 mm rounds in rows of 4 interspersed with rows of 3. The racks were opentable from the top, which slowed down the reloading operations.
|Semovente M40 da 75/18 common ammunition|
|Name||Type||Weight (kg)||Muzzle Velocity (m/s)||Penetration (mm) at|
|100 m||500 m||1,000 m|
|Granata Dirompente Modello 1932||HE||6.35||450||//||//||//|
|Granata Perforante da 75 mm||APCBC||6.42||425||44||39||33|
|Granata Perforante Modello 1932||APCBC||6.26||476||50||44||38|
|Effetto Pronto Speciale||HEAT||5.20||400||120||120||120|
Secondary ammunition also consisted of 600 machine gun rounds divided in 30 20-round clips. The clips were stored on the vehicle’s floor, near the gunner’s seat.
Starting from the front of the vehicle, there was the transmission connected to the braking system. On the left was the driver’s position, with the seat with a fold-down back for easy access. In front, it had the two steering tillers, an armored slot that could be closed with a lever, and a hyposcope for driving with the slot closed. On the left, he had the control panel from which the driver started the engine and, on the right, the gun breech.
Behind the driver, there was a box rack for the 75 mm gun ammunition. This also served as a seat for the loader. The loader had, on the left, the radio system and radio batteries and, above him, one of the 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/commander’s seat without a backrest. In front of his seat, the gunner had the elevation and traverse handwheels. On his left was the gun breech.
Interestingly, the lever for opening the breech was placed on the upper side of the breech. This meant that, after firing, the gunner had to rotate his torso by about 90° (a very uncomfortable action in the narrow space) and open the breech. On his right was the support for the anti-aircraft gun (when not in use), a maintenance kit, and a fire extinguisher.
Behind the gunner/commander was the last ammunition rack. On the rear wall of the fighting compartment, there were four cumbersome filters for air, oil, and two for the fuel. The engine fan, an engine cooling water tank, the batteries for engine ignition were also there, and the transmission shaft ran through the entire fighting compartment, dividing it in half.
The radio equipment of the Semovente M40 da 75/18 was a Magneti Marelli Apparato Ricetrasmittente Radio Fonica 1 per Carro Armato or Apparato Ricevente RF1CA (English: Tank Audio Radio Receiver Apparatus 1). This was a radiotelephone and radiotelegraph station with power of 10 Watts in both voice and telegraphy with a size of 35 x 20 x 24.6 cm and a weight of about 18 kg. The decision to equip each Semovente with a radio apparatus was taken on 28th May 1941 by Gen. Mario Roatta.
The operating frequency range was between 27 to 33.4 MHz. It was powered by an AL-1 Dynamotor supplying 9-10 Watts mounted on the hull’s right side. It had a range of 8 km in voice mode and 12 km in telegraphics mode. These two numbers reduced when tanks were on the move.
The radio had two ranges, Vicino (Eng: Near), with a maximum range of 5 km, and Lontano (Eng: Afar), with a maximum range of 12 km.
Crews were urged to use voice mode but with short messages and, if possible, in dialect. There are 20 regions in Italy, each with different dialects that in some cases vary significantly even within the same region. This was a great method because, even if enemy troops could listen to Italian communications, it was really difficult that one enemy soldier could understand all the different Italian dialects.
The crew was composed of three: the driver on the left, the commander/gunner on the right and, behind the driver, on the left, the loader/radio operator that also manned the anti-aircraft machine gun.
Due the small space inside the self-propelled gun, loading the gun was a laborious task. To make matters worse, the loader and the vehicle’s commander had to perform too many tasks. For example, the loader could not load the gun if using the radio, and to fire the anti-aircraft machine gun, he would have had to expose himself. Additional ammunition for the anti-aircraft machine gun would have to be passed to him by the gunner/commander, further slowing down the loading process and rendering it impossible for the vehicle to use the main gun at the same time.
Organization and Deployment
On 24th May 1941, General Mario Roatta, the new Capo di Stato Maggiore (English: Chief of Staff) of the Regio Esercito, wrote a document in which he specified that the first 60 Semoventi M40 da 75/18 and 20 Carri Armati Comando M40 were enough to create the first 5 gruppi (English: groups).
He also explained that the Semoventi M40 da 75/18 had to be deployed in long-range support and not, as they were deployed in North Africa, for assault support, following the Italian infantry.
He also required that a new support vehicle had to be developed to follow the infantry in the assault. He suggested a fast vehicle based on a half-track or fully tracked chassis.
Each gruppo (English: group) was composed of 2 batteries with 4 Semoventi M40 da 75/18 and 2 Carri Armati Comando M40, for a total of 8 Semoventi 40 da 75/18 and 4 Carri Armati Comando M40, plus 2 more Semoventi M40 da 75/18 and 1 Carro Armato Comando M40 in reserve. Each gruppo consisted of a comando (English: Command), two batterie (English: batteries) with four Semoventi M40 da 75/18, and a reparto munizioni e viveri (English: Ammunition and Supplies Unit). Each battery was divided in two squadra (English: Squad) with 2 Semoventi M40 da 75/18 commanded by a Carro Armato Comando M40. The command section was composed of a staff car, 2 Carri Armati Comando M40, 2 SPA CL39 light lorries, 2 one-seat motorcycles, 3 two-seat motorcycles, and one motor tricycle.
For logistic and reconnaissance roles, each battery was equipped with a staff car, 7 SPA CL39 light lorries, 2 one-seat motorcycles, 2 two-seat motorcycles, one motor tricycle, and other 6 light trucks were deployed to transport various types of equipment and supplies.
The reparto munizioni e viveri (English: Supply and Ammunition Department) assigned to each group was equipped with 1 staff car, 20 light trucks, 1 one-seat motorcycle, 1 mobile workshop, and a water tanker truck.
From 2nd July to November 1942, the batteries were modified, adding 4 semoventi and bringing the total number of Semoventi M40 da 75/18 to 12. This came with the decrease of Carri Comando M40 to 4 in total, 2 for the command and 1 for each battery. The composition of these groups was 19 officers, 21 NCOs, 206 tank crew members and soldiers, 81 drivers and 20 tank drivers, 4 staff cars, 16 SPA CL39 light lorries, 31 light trucks (FIAT-SPA 38R or FIAT SPA AS37), 2 heavy trucks, 2 towing trucks, 1 mobile workshop, 2 prime movers, 7 one-seat motorcycles, 9 two-seat motorcycles, 3 motor tricycles, 3 medium machine guns, 4 radio stations, 2 trailers, 12 semoventi, and 4 command tanks.
From 1st October 1942, the groups were reorganized with 3 batteries with 6 Semoventi each, for a total of 18 semoventi and 9 command tanks. Only the DLIII Gruppo Semoventi M40 da 75/18 (English: 553rd M40 Self-Propelled Gun Group), the DLVII Gruppo Semoventi M40 da 75/18 (English: 557th M40 Self-Propelled Gun Group), and the DLIX Gruppo Semoventi M40 da 75/18 (English: 559th M40 Self-Propelled Gun Group) were created with the later organic formation of 3 batteries group.
Two army circulars summarize the deployment of the Semoventi M40 da 75/18 on the African front. One is Notizie Circa l’Impiego dei Carri e Autoblindo in A.S. [Africa Settentrionale] (English: News About the Use of Tanks and Armored Cars in North Africa) written by Colonel Mario Bizzi. The second is Nuovi Ordinamenti Organici per le Artiglierie delle Divisioni Corazzate in A.S. (English: New Organic Orders for the Artillery of Armored Divisions in North Africa) of 8th July 1942 from the Ordering Office of the General Staff of the Regio Esercito. These two texts stated that the Semoventi M40 da 75/18 had participated in action by flanking enemy tanks, where the enemy armor was lighter and this had surprised the British themselves. However, shortcomings were also listed, such as a limited range of the cannon, poor accuracy at long ranges, and a small field of fire. All this meant that the Semoventi M40 da 75/18 were used for tank support actions and not as self-propelled guns.
The first Semoventi M40 da 75/18 were allocated to IV Gruppo M40 da 75/18 and VI Gruppo M40 da 75/18 (English: 4th and 6th M40 Group), usually simply called IV and VI Gruppo by the sources. These 2 groups were assigned to the 133° Reggimento Artiglieria Corazzata ‘Littorio’ (English: 133rd Armored Artillery Regiment) of the 133a Divisione Corazzata ‘Littorio’ (English: 133th Armored Division).
The IV Gruppo, commanded by Major Pasqualini, and VI Gruppo, commanded by Captain Viglieri, were sent to the Nettunia training center, where the crews trained on the new vehicles and where Benito Mussolini inspected the Semoventi in September 1941. In early January 1942, the two groups were sent to North Africa, where they were then assigned to the 132° Reggimento Artiglieria Corazzata ‘Ariete’ (English: 132nd Armored Artillery Regiment) of the 132a Divisione Corazzata ‘Ariete’ (English: 132th Armored Division). The 2 groups reached the 132° Reggimento Artiglieria Corazzata ‘Ariete’ in El Agheila on 18th January 1942.
After the victorious Axis offensives in North Africa in summer 1942, the Comando Supremo (English: Supreme Command) stated that the number of Semoventi M40 da 75/18 in the armored divisions was inadequate, and an increase of 60% was demanded, decreasing the number of now obsolete Carri Armati M14/41.
From August, the Ispettorato dell’Arma d’Artiglieria (English: Artillery Army Inspectorate) decided to create mixed battalions with M tanks and Semoventi M40 da 75/18.
In November 1942, the Second Battle of El Alamein was fought between the Axis and Commonwealth forces. The Italians deployed in that battle all the Semoventi M40 da 75/18 present in their batteries. The IV Gruppo and the VI Gruppo were now renamed DLI Gruppo and DLII Gruppo (English: 551st and 552nd Groups).
The new DLIII Gruppo (English: 553rd Group) was assigned to the 1a Divisione di Fanteria ‘Superga’ (English: 1st Infantry Division) but was lost at sea during transport. The DLIV and DLVI Gruppi (English: 554th and 556th Groups) in the 133a Divisione Corazzata ‘Littorio’ (English: 133rd Armored Division) were also lost during the Second Battle of El Alamein, apart from 2 reserve semoventi of the DLIV Gruppo that were sent to Yugoslavia before the departure of the group to the North African theater of operations.
An unknown number of Semoventi M40 and M41 da 75/18 of DLIV Gruppo and DLVI Gruppo fought admirably at the Second Battle of El Alamein. During the battle, they were all loaded with as many 75 mm rounds as possible stored everywhere in the fighting compartment. They fought near Quota 33 and Quota 34 (equivalent to US Hill), but only 2 Semoventi M40 da 75/18 survived.
Twelve Semoventi M40 da 75/18 of the DLI Gruppo and DLII Gruppo fought during the night between 4th and 5th November 1942 together with the entire 132a Divisione Corazzata ‘Ariete’, which had a total of 27 tanks. The Division had until then remained in the rear. It now covered the retreat of the entire Italian-German Army, not far from Bir El Abd, in an attempt to stem the Commonwealth armored brigades which were now on the attack. The ‘Ariete’s’ tanks claimed to have destroyed about 30 enemy tanks, including M4 Shermans, M3 Grants, and Crusaders.
The last radio message of the 132a Divisione Corazzata ‘Ariete’ was transmitted at 15:30 on November 5th by commander Francesco Arena:
“Carri nemici fatta irruzione sud Divisione Ariete. Con ciò Ariete accerchiata. Trovasi circa 5 chilometri nordovest Bir el Abd. Carri Ariete combattono”.
“Enemy tanks broke through south of the Ariete Division. Because of that Ariete is surrounded, located five kilometers north-west of Bir-el-Abd. Ariete tanks are still fighting”.
Some sources speak of 3 Semoventi M40 da 75/18 still in action on the Fuka Road on 6th November and of the last radio message claiming “3 self-propelled guns remain, we strike back”. However, most sources speak of the total destruction of the 132a Divisione Corazzata ‘Ariete’ in the night between 4th and 5th November. The 2 surviving self-propelled guns of DLVI Gruppo were lost during the defense of Ridotta Capuzzo fort on November 9th against Australian forces.
The last Semoventi M40 da 75/18 unit was the DLVII Gruppo (English: 557th Group) that was formed with crew members of the 133a Divisione Corazzata ‘Littorio’. It arrived in Africa and was assigned to the 131a Divisione Corazzata ‘Centauro’ together with the DLVIII Gruppo (English: 558th Group) equipped with the more powerful Semoventi M41 da 75/18 on Carro Armato M14/41 chassis. These 2 groups were destroyed during the Tunisian campaign in April 1943.
After the end of the North African campaign, the Semovente M40 da 75/18 did not participate in any military operations.
Carro Armato Comando M40
The Carri Comando Per Semoventi M13/40 (English: Command Tanks for Self-Propelled Guns) or Carro Armato Comando M40 were Carri Armati M13/40 3a Serie without the turret. Instead of the turret ring, a 4-door hatch with an anti-aircraft support was mounted.
The two Breda medium machine guns in the hull were left for self-defense, while a Breda Modello 1930 light machine gun was stored inside for anti-aircraft duties. The crew consisted of four: driver, commander, machine gunner, and radio operator.
It was equipped with the Apparato Ricetrasmittente RF1CA and the Apparato Ricetrasmittente RF2CA from Magneti Marelli, mounted on the right side of the fighting compartment. Its stereoscopic rangefinder was placed inside the fighting compartment and mounted on the tank’s roof when used. The vehicle was produced exclusively to command the self-propelled gun units.
Semovente M40 da 75/32
The Semovente M40 da 75/32 was an Italian prototype of self-propelled gun developed to equip the Italian units with a more powerful gun with better anti-tank characteristics than the shorter-barrel Obice da 75/18. The project was appreciated, but the Cannone a Lunga Gittata da 75/32 Modello 1937 (English: Long Range 75 mm L/32 Cannon Model 1937) was a field gun and did not have adequate characteristics to be installed on armored vehicles. It was substituted by the Cannone da 75/34 Modello S.F. (English: 75 mm L/34 Cannon Model Spherical) on the Semoventi M42M da 75/34, of which about 170 were produced.
Differences Between Semoventi da 75/18 Models
The Semovente M40 da 75/18 was derived from the Carro Armato M13/40. The more powerful Semovente M41 da 75/18 model, derived from the Carro Armato M14/41, was externally identical to the previous model apart from new, longer mudguards that in the latter model, covered the entire length of the hull.
As the M14/41 medium tank, it had a FIAT-SPA 15T Modello 1941, 8-cylinder V-shaped, diesel engine, producing 145 hp at 1,900 rpm, increasing maximum speed to 33.3 km. The superstructure’s armor consisted of a single armored plate with a thickness of 50 mm instead of two 25 mm thick plates bolted together. The ammunition racks were the same as on the M40.
The original 6.5 mm Fucile Mitragliatore Breda Modello 1930 was replaced in the Semoventi M41 series by a more powerful 8 x 59 mm Mitragliatrice Media Breda Modello 1938 with a total of 864 rounds (36 magazines) in 2 wooden racks, one with 16 magazines on the left side and one with 20 on the right side, above the radio inverter.
On 8th May 1943, the Semovente M42 da 75/18, derived from the Carro Armato M15/42 hull, was delivered to units. A new base for the Italian self-propelled guns, it weighed 13.25 tonnes with improved protection of 35 mm of armor on the hull and sides and 20 mm on the rear.
The Semovente M42 da 75/18 was a little longer (5.06 m compared to the 4.92 m of the Semovente M40 and M41) because the new engine compartment needed to accommodate the new more powerful petrol engine, the modified FIAT-SPA 15TB (‘B’ stands for Benzina – Petrol) Modello 1942 with 190 hp and its accompanying fuel tanks with a increased capacity of 307 liters (including 40 liters of the reserve). It also had improved fire fighting equipment due to the increased flammability of the petrol fuel. It had a consumption of 1.5 l/km, the maximum road speed was 38.4 km/h and the range was decreased to 150 km.
The number of rounds carried was 44 in the usual 3 racks and 1,104 rounds (46 magazines) for the Mitragliatrice Media Breda Modello 1938 machine gun. The antenna support was modified and three 20 liter can supports were added on each side plus two on the rear side of the casemate. The new engine compartment had new cooling grilles on the inspection hatches and new rear plate and shields to protect the mufflers from impacts.
Apart from a first production of 60 Semoventi M40 da 75/18, a total of 162 vehicles were produced on Semovente M41 da 75/18 until 1942 when the chassis was again changed. Before the Italian Armistice in September 1943, another 66 Semoventi M42 da 75/18 were built. This meant that a total of 288 semoventi da 75/18 were produced on the 3 chassis models.
Only 2 Semoventi M40 da 75/18 have survived to this day out of 60 built. One was recovered after the war from the El Alamein scrapyard, and, without repairs, was transported, probably by Italian volunteers, to the El Alamein War Memorial in December 1967, when the museum was officially created.
A second vehicle is exhibited at the Musée des Blindés of Samur, in France. This vehicle is in great condition, even if its camouflage seems to be totally wrong. In fact, the 3-tone camouflage was painted on vehicles after the loss of the North African campaign, while the Semoventi M40 da 75/18 were all lost after the El Alamein or in fighting occurred shortly after the battle.
The Semovente M40 da 75/18 was the first Italian self-propelled gun of the Second World War, which led to the development of a whole range of Italian self-propelled guns until 1945.
Its series was one of the most produced Italian SPGs during the war. With its short-barreled howitzer, it could support the infantry and fire against enemy tanks thanks to shaped charge rounds.
Its thin armor, weak engine, and cramped interior affected its operational use. These problems decreased the efficiency of the semoventi, while their powerful main gun offered the Italian divisions adequate anti-tank firepower that the medium tanks had failed to deliver early in the war.
Luckily, the M40 da 75/18 was quickly replaced by the Semovente M41 da 75/18, which shared the majority of its parts with the previous model, but had a more powerful engine and new anti-aircraft machine gun.
Semovente M40 da 75/18 Specification
|Size (L-W-H)||4.915 x 2.200 x 1.850 m|
|Weight, battle ready||13.1 tonnes|
|Crew||3 (Driver, gunner/commander, loader/radio operator)|
|Engine||FIAT-SPA 8T Modello 1940 diesel, 8-cylinder, 11,140 cm³ 125 hp at 1,800 rpm|
|Armament||Obice da 75/18 Modello 1934 with 44 rounds and a Breda Modello 1930 light machine gun with 600 rounds|
|Armor||25 mm to 50 mm|
Guida alle Artiglierie Italiane nella 2a Guerra Mondiale. 1940-1945. Regio Esercito Italiano, Repubblica Sociale Italiana ed Esercito Cobelligerante – Enrico Finazzer – Italia Storica – Genova 2020
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Andare contro i carri armati. L’evoluzione della difesa controcarro nell’esercito italiano dal 1918 al 1945 – Nicola Pignato e Filippo Cappellano – Udine 2008
Semovente da 75/18, Tecnica del Primo Semovente Italiano – Nicola Pignato – Storia Militare – Parma 2010
Italian Medium Tanks 1939-45; New Vanguard Book 195 – Filippo Cappellani and Pier Paolo Battistelli – Osprey Publishing, 20th December 2012
Carro M – Carri Medi M11/39, M13/40, M14/41, M15/42, Semoventi ed Altri Derivati Volume Primo and Secondo – Antonio Tallillo, Andrea Tallillo and Daniele Guglielmi – Gruppo Modellistico Trentino di Studio e Ricerca Storica, 2012