Beute Sturmgeschütz M42 mit 7,5cm KwK L/18 850(i), specifically a vehicle from 2nd Company of Panzerjäger Abteilung 278, captured by the Allies — in this case Polish forces — in July 1944 near the town of Ancona, source: Worldwarphotos.info with the permission of the site operator, edited

An Italian self-propelled gun

Under the designation Beute Sturmgeschütz M41 mit 7,5 cm KwK L/18 850 (i), the Germans incorporated into their own inventory the originally Italian self-propelled guns Semovente M41 da 75/18, seized after the Italians concluded a separate armistice with the Anglo-American Allies in September 1943. To tell the story of these fighting vehicles properly, we must begin not in Germany but in Italy, at the turn of 1940 and 1941. At that time the Italian army was looking for ways to improve the combat value of its medium tank, the M13/40. Besides fitting a more powerful engine, the Italians were primarily concerned with strengthening the armament so that their tank could stand up to capable British opponents such as the Matilda. It was, however, perfectly clear that the construction of the M13/40 tank made it utterly impossible to install any significantly more powerful weapon than the existing 47 mm gun. An entirely different solution had therefore to be found, and so the Italians turned for inspiration to their allies of the time — the Germans.

The specific object of their interest was the German conversion of the Panzer III chassis into the assault gun Sturmgeschütz III. The turretless assault gun design allowed a much more powerful weapon to be installed on an otherwise identical chassis than the original tank had carried — and that was precisely what the Italians needed. It is therefore no surprise that they decided to proceed in the same way. As early as 10 January 1941, the firm of Ansaldo prepared a full-size wooden mock-up of a turretless self-propelled gun on the chassis of the aforementioned M13/40 medium tank, and on 11 February the first functional prototype was completed. The new self-propelled gun with its fixed fighting compartment accommodated a 75 mm gun without difficulty — the same calibre carried by the German Sturmgeschütz III. The briefest driving and firing trials were sufficient for Italian army representatives to declare themselves entirely satisfied, and on 16 February 1941 an order was placed for the first 30 series vehicles. The new fighting vehicle received the official designation Semovente M40 da 75/18 — semovente meaning self-propelled.

Design description

The chassis and hull of the self-propelled gun were taken directly from the M13/40 tank. The vehicle therefore had eight small-diameter road wheels on each side, fitted with rubber tyres for a smoother ride. Each wheel consisted of two discs, allowing the track guide teeth to pass through the gap between them. The road wheels were paired on shared bogies, and two adjacent bogies were suspended from a shared swing arm sprung by a large leaf spring. With eight road wheels this meant four bogies and two swing arms with springs. In addition to these, the running gear also included a front drive sprocket, a rear idler wheel and three return rollers supporting the upper run of the track.

a German paratrooper guards a marshalling yard of captured Italian equipment near the town of Tivoli; at least three Semovente da 75/18 self-propelled guns are visible in the background, source: Flickr.com with the permission of the publishing user, edited

Along with the chassis and hull, various other elements were carried over from the original tank, including the FIAT-SPA 8T diesel engine developing 125 horsepower, fuel tanks with a combined capacity of 180 litres, and the gearbox with four forward speeds and one reverse. The layout of the engine and gearbox naturally remained the same as in the original tank — engine at the rear, gearbox at the front of the hull. Instead of the original rotating turret, the new armoured vehicle received a fixed box-type fighting compartment whose front wall was 50 mm thick (two 25 mm plates), with the sides and rear at 25 mm. The construction of the new compartment matched the rest of the hull, using riveted armour plates on a frame welded from steel angle sections. The front wall of the fighting compartment was almost vertical — a slope of only 5° — which of course did nothing to improve its resistance to penetration. The roof of the compartment was not flat as it might appear at first glance, but sloped gradually downward towards the rear.

The Obice da 75/18 howitzer

Inside the compartment was housed the weapon that was the whole reason for converting the original tank — the new Obice da 75/18 Modello 1934. Formally speaking this was not a gun but a howitzer (obice = howitzer), of 75 mm calibre with a barrel length of 18 calibres. For installation in an armoured vehicle, the weapon was fitted with a new muzzle brake of a very distinctive design featuring numerous small holes, and a new recoil mechanism which, according to some sources, was taken from a 105 mm Schneider gun. Where the barrel passed through the front wall of the compartment it was protected by a spherical mantlet allowing vertical elevation from –12° to +22°. The maximum horizontal traverse was 20° to the left and 18° to the right — though some authors cite only 16° to the right. The unequal traverse was related to the fact that the weapon was not mounted exactly on the vehicle's longitudinal centreline but slightly to the right of it. The reason for this eccentric gun position was the location of the gearbox selector lever beneath the gun — had the gun been mounted exactly on the centreline, it would have sat directly above the gearbox and the driver would most likely have been unable to change gear at all (the position of the gear lever is clearly visible in the photograph HERE).

As already noted, the Obice da 75/18 Modello 1934 was formally classified as a howitzer. Despite this, the ammunition available for the weapon was dominated by armour-piercing rounds. There were two types of armour-piercing shell (granata perforante) — a standard steel type and one with a harder (presumably tungsten) core — and two types of shaped-charge round (granata anticarro effetto pronto and effetto pronto speciale). The standard armour-piercing shell left the barrel at 425 m/s and could penetrate 39 mm of armour at 500 metres. The tungsten-core variant achieved 476 m/s and 44 mm of penetration. The effetto pronto shaped-charge round, meanwhile, could defeat up to 100 mm of armour, and the improved effetto pronto speciale variant up to 120 mm. The Semovente M40 was apparently loaded with all of the above ammunition types — anti-personnel, armour-piercing and shaped-charge — in a total of 43 rounds, though figures of 44 and even 50 are also cited.

another photograph of vehicle No. 232 from 2nd Company of Panzerjäger Abteilung 278, captured by Polish soldiers; the four large sprocket teeth added to the front drive sprocket by the Germans are clearly visible here, source: Flickr.com with the permission of the publishing user, edited

The gun was not mounted on a pedestal — because the gearbox mentioned above occupied that space — but was fixed directly to the front wall of the compartment using 12 heavy bolts. The gunner, who also served as commander, sat to the right of the gun. For aiming the weapon he used a periscopic sight that extended through an opening in the compartment roof. The maximum range of the howitzer was around 9.5 km — applicable to its standard towed version with elevation up to 45°. Once installed in the self-propelled gun with its limited positive elevation, this figure dropped to around 7 to 7.5 km.

The Semovente M40 had no built-in secondary armament. The crew did, however, have the standard light machine gun Breda Modello 1930 of 6.5 mm calibre at their disposal. The machine gun could be used either freely — simply placed on its bipod on the compartment roof — or attached to a special mount on the roof, which allowed aimed fire against approaching enemy aircraft. When not in use, the machine gun was stowed along the right side of the compartment. It must be said that this was not a particularly happy choice of secondary weapon. The Breda Modello 1930 was underpowered, unreliable and fed not by a belt but by 20-round clips. Thirty loaded clips were carried on board — 600 rounds in total.

To the left of the gun was the driver's position, where the driver operated the vehicle using two conventional steering brake levers. Directly in front of him was his main vision port, fitted with a closeable armoured shutter. The port was not filled with any glass — so when open, it was truly open. In combat areas the driver was therefore advised in his own interest to keep the port closed and rely on the periscope that opened onto the compartment roof. Besides the gunner's sight and the driver's periscope, the roof also featured a pair of large entry hatches, in front of which was the already-mentioned machine gun mount, an antenna mount for the radio set on the left, and a rotating periscope for the commander on the right. In the centre of the rear wall of the compartment was a covered air intake for the engine's cooling system, with two small circular closeable firing ports for small arms on either side of it.

Indian soldiers from the British Army inspect a knocked-out Beute Sturmgeschütz M42 mit 7.5 cm KwK L/18 850(i), source: Worldwarphotos.info, Public Domain, edited

Behind the fighting compartment was the engine section, which was practically unchanged from the original M13/40 tank. Its roof featured two large access hatches for servicing the engine and two louvred vents expelling hot air from the radiator — incidentally, cooling air was drawn into the engine compartment through the fighting compartment itself, which was intended to ensure airflow and cool the interior, since the Italians anticipated deployment in the hot African climate. Between the two hot-air vents was a raised filler neck for the fuel tanks. Further rearward still, a spare road wheel, a jack, track removal and fitting tools and a steel towing cable were stowed. Exhaust pipes with their silencers ran along both sides of the engine compartment, lying above the tracks.

The Semovente M40 da 75/18 weighed 13.1 tonnes, measured 492 cm in length, 220 cm in width and 185 cm in height. Its maximum road speed was 31.8 km/h. Thanks to the diesel engine, the vehicle could cover up to 210 km on road from a single fill of its relatively modest 180-litre fuel supply. The crew consisted of three men: the driver, who sat to the left of the gun; the commander, who also served as gunner and sat to the right of the gun; and the loader, who also operated the radio set and was stationed behind the driver. Of the three men on board, only the loader lacked a proper seat — he sat on an ammunition stowage box.

The radio set was mounted at the rear along the left wall of the compartment, which is why the antenna was located on the left side of the roof. The set was of the type Magneti Marelli Radio Fonica 1 per Carro Armato (RF1CA) — a combined transmitter and receiver (described in the manual as "Apparato trasmittente ricevente"). According to some sources it had a transmission range of up to 8 km in voice mode and up to 12 km in Morse, which seems rather optimistic. Other sources give figures of only 2 km for voice and 4 km for Morse.

the 7th SS Volunteer Mountain Division "Prinz Eugen" also received Beute Sturmgeschütz vehicles with the 75/18 gun and deployed them in anti-partisan operations in Yugoslavia, source: Flickr.com with the permission of the publishing user, edited

Second generation

As already noted, in February 1941 the army ordered the production of 30 of the new self-propelled guns. Their manufacture — or more precisely their assembly — took place at the Gio. Fossati & C. factory in Sestri Ponente (now part of Genoa), a subsidiary plant of Ansaldo. The first of these vehicles were handed over to the troops in May 1941. That same month, a second order was placed for a further 30 vehicles. All 60 ordered examples were delivered by the end of 1941. In December 1941 a third order followed, this time for 144 vehicles at once. By that point, however, the M13/40 tank itself had been replaced in production by the modernised M14/41, and the self-propelled gun had to adapt accordingly. Fortunately this entailed no fundamental design change, as the tank's modernisation consisted essentially "only" of the adoption of a more powerful FIAT-SPA 15T engine developing 145 horsepower.

The second generation of the self-propelled gun, based on the M14/41 chassis, received the designation Semovente M41 da 75/18. It was produced from late 1941 until November 1942, with a total of 162 examples built. The more powerful engine was the main but certainly not the only difference distinguishing the Semovente M41 from its predecessor the M40. In photographs the two vehicles can be told apart by, among other things, the track mudguards — on the M41 these ran the full length of the sides, whereas on the M40 they were present only at the front. The design of the hot-air exhaust vents from the engine compartment also changed: on the M40 the louvres ran lengthwise, while on the M41 they ran across.

The second generation Semovente also received improved secondary armament. The earlier Breda Modello 1930 of 6.5 mm calibre was replaced by the more powerful and reliable Breda Modello 1938 of 8 mm calibre, fed by 24-round clips. Forty-six such clips were carried on board, giving a total supply of 1,104 rounds. The weight of the Semovente M41 increased by around 400 kg to 13.5 tonnes, but thanks to the more powerful engine the vehicle's maximum speed also increased modestly, to 33.3 km/h. Range remained at approximately 210 km on road. Late-production vehicles, however, were fitted with brackets on the sides of the fighting compartment for 20-litre jerry cans. With six such cans full of diesel, the vehicle's range could be extended to as much as 350 km on road.

a destroyed Beute Sturmgeschütz M42 mit 7.5 cm KwK L/18 850(i), source: Worldwarphotos.info with the permission of the site operator, edited

Third generation

In December 1942 a further modernised version of the Ansaldo medium tank entered series production. Following the first-generation M13/40 and the second-generation M14/41, the third generation arrived under the designation M15/42. The self-propelled gun naturally had to adapt once again to the design of the tank on whose chassis it was based. Production of the Semovente M41 therefore ended in November 1942, and in December the Fossati factory began producing the third generation of the self-propelled gun, designated Semovente M42 da 75/18.

With the new chassis version, the Semovente received a new engine — the petrol-powered FIAT-SPA 15TB Modello 1942 with a displacement of 11.98 litres and an output of 190 horsepower at 2,400 rpm. A petrol engine was naturally thirstier than the preceding diesel units, so the designers had to increase the fuel tank capacity, raising it to 338 litres — though a slightly different figure is also cited. These changes necessitated certain modifications to the engine section layout. Its rear portion had to be redesigned and lengthened, which also increased the vehicle's overall length by around 14 to 15 cm. The hot-air exhaust from the engine was redesigned, and the service access panels in the engine deck received entirely new ventilation cutouts. The exhaust system was also of new design. Alongside the engine came a new FIAT gearbox with five forward speeds and one reverse. Thanks to the more powerful engine and the additional gear ratio, the vehicle's maximum speed rose to 38 km/h — despite its total weight increasing to exactly 15 tonnes.

Certain changes also took place in other parts of the vehicle. For instance, the front armour of the fighting compartment on the Semovente M42 consisted of a single 50 mm steel plate, as opposed to the two superimposed 25 mm plates used on the older M40 and M41. During production — specifically sometime in early 1943 — one further novelty was introduced. A bracket for five smoke dischargers began to be fitted to the rear wall of the hull. This was a licensed copy of the German device known as the Nebelkerzenabwurfvorrichtung, commonly seen on the rear of German tanks. The bracket allowed a smoke grenade to be ignited and released remotely from inside the fighting compartment whenever the vehicle found itself in difficulty and needed a smokescreen to prevent the enemy from taking accurate aim. From December 1942 until the Italian separate armistice with the Allies in September 1943, the army accepted 194 Semovente M42 da 75/18 self-propelled guns.

the Nebelkerzenabwurfvorrichtung smoke discharger bracket is clearly visible on the rear of this Beute Sturmgeschütz M42, source: Flickr.com with the permission of the publishing user, edited

Into German hands

With the mention of the Italian armistice of September 1943 we finally approach the moment when the German army enters the story and the Semovente da 75/18 self-propelled guns become its booty. But first, a little more historical context. On 10 July 1943 British and American forces landed in the south of Sicily. Over the following weeks the Allies steadily pushed the Italian and German defenders north-westward towards the port of Messina. Any clear-sighted observer must have seen that Sicily would soon fall, and with it the Allies would gain an ideal springboard for an invasion of the Italian mainland. Italy's political leadership therefore began to consider whether the time had perhaps come to open negotiations with the Allies. This would, however, first require removing Mussolini from power, which was of course easier said than done. All it took was the first American air raid on Rome — which occurred on 19 July — and events began to move.

At a session of the government — the Grand Council of Fascism — on 24 and 25 July 1943, Mussolini was removed from the office of Prime Minister and subsequently arrested outright. The newly appointed Italian Prime Minister Pietro Badoglio assured Hitler that Italy remained firmly by his side, but the Germans had no doubt as to what the Italians were planning and began thorough military preparations for their betrayal. On 3 September 1943 — the day the British landed on the Italian mainland — the Italians signed an armistice agreement with them. When this fact was officially made public (which did not happen until 8 September), the Germans were not the least bit surprised and without hesitation launched the retaliatory operation codenamed Achse (Axis).

Among the main objectives of this operation were the occupation of as large a portion of Italian territory as possible and the disarming of the Italian army. In the course of this disarmament, the Germans confiscated from their now former ally an enormous quantity of weapons, including nearly a thousand armoured fighting vehicles of all types. Among these were 123 examples of the Semovente M41 da 75/18 and Semovente M42 da 75/18 — the oldest version, the Semovente M40, was no longer among the captured equipment, as all examples had long since been lost in combat in North Africa. The Germans incorporated these vehicles into their own inventory under the designations Beute Sturmgeschütz M41 mit 7,5 cm KwK L/18 850 (i) and Beute Sturmgeschütz M42 mit 7,5 cm KwK L/18 850 (i) respectively.

a Beute Sturmgeschütz da 75/18 abandoned by its crew somewhere on the Gustav Line; the badge of the German 71st Infantry Division is clearly visible on the front armour, source: Worldwarphotos.info, Public Domain, edited

The German assessment of the captured self-propelled guns was far from glowing. In brief it could be summarised as follows: weak gun, weak armour, weak engine — the last particularly true of the M41 version — plus limited observation and a cramped interior. The Germans in no way considered these vehicles comparable to their own assault guns StuG III, and rated their combat value as negligible. The only advantages they recognised in these vehicles were their low silhouette, light weight and overall compact dimensions, which allowed them to move with relative ease both in mountainous terrain and through the narrow streets of Italian villages and small towns. Despite this critical assessment, the Germans nevertheless decided to keep the production of the 75/18 self-propelled guns running. For alongside the finished vehicles, the Fossati parent factory had also fallen into their hands, with parts already prepared for a further 55 Semovente M42 da 75/18 waiting inside. The necessary contract with the Italian manufacturer was signed on 5 October 1943 and included a requirement for certain minor design modifications.

The assault guns produced to the German order received four new large teeth on the front drive sprockets, intended to prevent the tracks from slipping off under heavy load — for example in muddy terrain. The hatch of the right-hand entry hatch was divided into two smaller sections, brackets for hanging steel helmets were added to the sides of the fighting compartment, and there were presumably other minor modifications as well. Somewhat surprisingly, none of the sources mentions the replacement of the radio set with a German type, which was quite standard practice with captured equipment.

The captured assault guns were distributed among various German units — primarily, of course, those serving in Italy. Unspecified numbers of vehicles were received by, among others, the 44th, 65th, 71st, 305th and 334th Infantry Divisions, the 90th Panzergrenadier Division, the 1st Parachute Division Hermann Göring, the 26th Panzer Division, and the independent assault gun battalions (Sturmgeschütz-Abteilung) No. 210 and 914. With these units, the ex-Italian vehicles saw action against the Allies on the so-called Gustav Line — including the defence of the famous Monte Cassino — and also fought at Anzio, near Florence and on the Gothic Line. The majority of the self-propelled guns were deployed directly in Italy, though smaller numbers also saw service in Yugoslavia, in Hungary and in the final stages of the war possibly even on German soil itself. According to a report from May 1944, German forces fighting in Italy still had 85 Italian Beute Sturmgeschütz of all types at their disposal.

a destroyed Beute Sturmgeschütz M42 da 75/18; the vehicle does not have the four large teeth on the drive sprocket, confirming it is one of the vehicles seized directly from the Italian army, source: Worldwarphotos.info, Public Domain, edited

To close, it is worth noting that the German Sturmgeschütz III served as inspiration not only for the original creation of the Semovente da 75/18 but also for its subsequent development. Just as the StuG III was later rearmed with a longer-barrelled 75 mm gun to make it a more effective destroyer of enemy armour, so too was the Semovente — and you can read about that version HERE. And just as the Stug III had its derivative variant armed with a 105 mm howitzer (the StuH 42), a variant of the Semovente with a howitzer of the same calibre was developed as well.

ARTICLE
CONTENTS:

AN ITALIAN SPG

DESIGN DESCRIPTION

THE OBICE da 75/18

SECOND GENERATION

THIRD GENERATION

INTO GERMAN HANDS