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WW2 Italian SPG Prototypes

Semovente M43 da 149/40

Kingdom of Italy (1942-1943)
Self-Propelled Gun – 1 Prototype Built

Prior to and during the Second World War, the Italian industry generally lacked the capacity to fulfill all the military demands placed upon it. This was probably most obvious in regards to producing and developing more modern armored vehicles. Italian armored formations mostly consisted of obsolete light tanks, which were no match for the Allied armor. Even in regards to the medium tanks they produced, these were severely lacking. On the other hand, Italians introduced a number of vehicles that proved to be useful, although their number was small. These were the so-called Semoventi (Eng. self-propelled vehicles), which proved to be quite effective, but with some issues. They were armed with 47 mm, 75 mm, 90 mm, or 105 mm guns. In the later stages of the war, one installation of an even larger weapon was tested in the form of the highly mysterious and poorly documented Semovente M43 da 149/40.

The Semovente M43 da 149/40. Source: comandosupremo.com

History

When it entered the war on the German side in 1940, the Italian Army was mostly equipped with the CV series of small fast tanks. While cheap, these were only lightly armed and protected and were virtually obsolete even before the war started. The development of more powerful vehicles, such as the M-series of medium tanks, was underway but the small production capabilities and some bad decisions (like limiting the overall strength of the engine) ultimately led to rather a slow production and introduction. These tanks were armed with a 47 mm gun, which may have been effective in the earlier stages of the war, but struggled to do anything against newer Allied tank designs.

The Italians turned to their German allies for help, and after observing the StuG III, they came up with the idea of developing a similar vehicle utilizing components that were already in production. This would lead to the creation of a series of vehicles that, armed with a 75 mm gun, offered the Italians a means to fight back more effectively. The early and later improved versions were used as anti-tank vehicles. These could also act, if need be, as mobile self-propelled artillery.

While the 75 mm gun could fulfill this role, something with more firepower was preferable. It is for this reason that the Italian Army began showing interest in the development of a more dedicated design of self-propelled artillery armed with much larger caliber guns.

Unfortunately, due to a general lack of information about this vehicle in the sources, determining its precise developing history is quite difficult. Based on limited available information, it appears that the firm responsible for developing this vehicle was Ansaldo. When it was built and on which chassis it was based is somewhat confusing in the sources.

According to C. Bishop (The Encyclopedia of Weapons of World War II), work on such a vehicle was initiated by Ansaldo in late 1942. Ansaldo engineers used a heavily modified M15/42 chassis and placed the Cannone 149/40 Modello 1935 on it. When a fully working prototype was completed in late 1942, it was given to the Army for testing.

Author P. Battistelli (Italian Medium Tanks 1939-45) mentions that it was based on the improved P26/40 chassis. According to this source, the Semovente M43 da 149/40 was actually developed and completed by August 1943.

Authors C. Falessi and B. Pafi (Veicoli da combattimento dell’esercito Italiano Dal 1939 Al 1945) give a more detailed account. According to them, the Semovente M43 da 149/40 was not even a project requested by the Italian Army, but instead a private venture from Ansaldo. Ansaldo engineers, who had designed the large Cannone 149/40, were interested in increasing its mobility. Like all towed guns, it needed some time to be properly set up before it could effectively engage enemy positions. Mounting this gun onto a fully tracked chassis would resolve the mobility issue greatly. So, during 1943, Ansaldo engineers set out to develop such a vehicle. The prototype was completed by August 1943 and appears to have been presented to the Army.

The completed prototype at Ansaldo. Source: Ansaldo Archives

Sources, such as Gli autoveicoli da combattimento dell’esercito italiano, volume secondo (1940-1945) by Pignato and Cappellano., mention that Ansaldo started the whole project at the end of 1941, when a wooden mock-up was completed. The actual work on the first prototype began in April 1942. Due to many delays, the prototype took some time before it was finally completed in August of 1943.

Probably the first wooden mock-up of the Semovente M43 da 149/40, dating back to November 1941. Source: 2020.fondazioneansaldo.it

Design

The Hull

The Semovente M43 da 149/40 hull was divided into a few sections. In the front part were the transmission and two crew members. The engine was positioned in the center of the vehicle. To the rear was the gun mount.

Which precise chassis was used for the construction of the Semovente M43 da 149/40 is not clear. Sources mention that it could have been either that of an M15/42 or the larger P26/40. The hull front and the upper glacis do not resemble any of the M-series (even the chassis used for the later Semoventi). The M15/42 front hull had a rounded shape. The P26/40 hull has some similarities, but its design was also different. A more plausible solution is that the Anslado engineers simply took the best components from both chassis and combined them into a single-vehicle with some modifications. Authors C. Falessi and B. Pafi (Veicoli da combattimento dell’esercito Italiano Dal 1939 Al 1945) claim that, while the chassis of the Semovente M43 da 149/40 was new, it incorporated a steering gear unit taken from the M15/42, together with a strengthened suspension copied from the P26/40. The upper glacis on the Semovente M43 da 149/40 had two small hatches used as access points to the transmission and brakes for repairs and maintenance.

Close-up view of the front hulls of the Semovente M43 da 149/40, M15/42, P 40, and the Semovente M42. While the latter two are somewhat similar, they were still different from the Semovente M43 da 149/40 front hull shape. Sources: tvd.im/land-systemshttps:, forum.warthunder., beutepanzer.ru/Beutepanzer
Front view of the Semovente M43 da 149/40. Note the two smaller maintenance hatches placed on the upper glacis. Source: Ansaldo Archives

Suspension

The suspension used was the Italian standard semi-elliptical leaf spring type. On each side, there were four bogies with eight doubled rubber road wheels, paired onto two suspension units. This suspension type was obsolete by the early 1940s and did not allow the vehicle to reach a high top speed. 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. Interestingly, the front-drive sprockets had an unusual design not seen on other Italian armored vehicles. The tracks had a width of 400 mm.

The Semovente M43 da 149/40 suspension was the standard Italian type used on all mediums and later developed heavy tanks. While it did the job, it was far from perfect. Note that the front sprockets had a completely new design in comparison to the one used on previous vehicles. Source: tvd.im/land-systems/2946-semovente-da-149-40

Engine

The Semovente M43 da 149/40 was powered by an unspecified 250 hp SPA petrol engine. With a weight of 23.5 to 24 tonnes, the maximum speed was around 35 km/h. This engine somewhat complicates the matter of determining which chassis was used. The M15/42 used a SPA 190 hp engine, while the P 40 was powered by a 330 hp SPA engine. Neither of them matches the known data. Ansaldo engineers had plans to equip the first small production series with a similar engine, which was to be slightly lighter and smaller in size, but nothing came of this. Some sources also mention a completely different power plant, an eight-cylinder V-shaped 185 hp @ 2,400 rpm engine. The use of the engine from the experimental Sahariano tank was also proposed, but nothing came of it.

The engine was placed in the central part of the hull. It was fully enclosed, with two exhaust pipes placed on each side. Ventilation grills were placed to the rear, close to the gun installation. On top of the engine compartment were several smaller hatches.

Superstructure

The superstructure of the Semovente M43 da 149/40 consisted of a simple box-shaped and fully enclosed crew compartment. As was the standard for Italian designs, this was constructed using a metal frame on which armored plates were mounted, connected with bolts. On top of this compartment, two hatches were placed, one for each crew member. In addition, on top, a simple round-shaped travel lock was located. To the front were two protective observation ports without any slits. These too were of a standard Italian design, which was commonly used on other armored vehicles. No side ports nor slits were used on this vehicle.

To enter their positions, the front crew had two hatches placed on top of the fighting compartment. Source: beutepanzer.ru/Beutepanzer
Two protected observation ports (the left port has number 262 painted on it) without any slits were placed in front of the crew compartment. Source: Pinterest
Such protective observation ports were also common on Italian vehicles, like this Semovente. Source: http://beutepanzer.ru

Armor Protection

As it was intended to use the Semovente M43 da 149/40 for long-range support, the vehicle was only lightly protected. The front armor was, depending on the source, 25 to 30 mm thick. The side armor was 14 mm thick, while the top armor was 6 mm. No armor protection was provided for the gun operating crew.

Armament

This vehicle was armed with the long Cannone 149/40 gun. Its official name was Cannone Ansaldo da 149/40 Mod. 1935 (Eng. Ansaldo Cannon 149 mm L/40 Model 1935). The development of this gun was initiated in 1929, when the Regio Esercito (Eng. Italian Royal Army) asked OTO, Ansaldo, and Arsenale Regio Esercito di Napoli, or AREN (Eng. Royal Army Arsenal in Naples), to develop a new 149 mm artillery gun to replace some aging artillery pieces which dated to before the First World War. It was requested to have a firing range of 20 km with a maximum weight of some 11 tonnes. In order to ease transport, it had to be dividable into two parts. In addition, it had to be assembled in half an hour. While OTO did not participate in this competition, both Ansaldo and AREN proposed their projects.

Ultimately, the Ansaldo project was chosen over its competitor. After some testing in 1934, the gun was officially adopted in July of 1935. In total, some 180 guns of this type would be produced (this number may have been lower as 63 to 64). These were used on various fronts, including in the Soviet Union and North Africa, and were deemed good designs. The Germans managed to capture some guns after 8th September 1943, renaming them to 15 cm K 408(i). After the war, the surviving guns were kept in reserve by the new Esercito Italiano (Eng. Italian Army) until 1969.

The Cannone 149/40 had a 6,360 mm long barrel and could fire a 46 kg round (with a muzzle velocity of 800 m/s) at ranges up to 23,700 m. It could fire a standard high-explosive, armor-piercing, and training round. The rate of fire was only one round per minute. Elevation was 0° to 45°, while the gun traverse was 57° (or 60° depending on the source).

The Ansaldo Cannon 149 mm L/40 Model 1935. Source: www.italie1935-45.com

This gun had modern twin-split trail legs. Additionally, in order to further absorb the recoil, the trail spades had metal bars that could be hammered into the ground. Both of these would be used on the self-propelled vehicle. Given the rather large size of the original trail legs, shorter ones were instead placed to the rear of the vehicle. When on the move, these would be raised from the ground and then folded down toward the vehicle. The spades would be placed on each of these two trail legs when the vehicle was prepared for firing. On the move, these would be removed and placed on each side of the gun for transport. In order to fully prepare the vehicle for action, the crew needed around 3 minutes. In contrast, the towed version of the same gun needed 17 minutes to be ready for action.

Elevation of the Semovente M43 da 149/40 gun was the same as on the towed version, but the traverse was slightly reduced, at 53°. The ammunition load allegedly consisted of only six rounds, which seems unlikely due to the lack of storage space for them.  Additional spare rounds were carried by an auxiliary ammunition supply vehicle. No secondary armament besides the crew’s personal weapons was to be carried.

Rear view of the Semovente M43 da 149/40. The two shortened trail legs and the left spade are clearly visible here. In addition, note the rear positioned engine ventilation grilles. Source: Wiki
The Semovente M43 da 149/40 gun was placed at zero elevation. Source: www.militaryimages.net
Elevation of the Semovente M43 da 149/40 gun was the same as on the towed version, but the traverse was slightly less, at 53°. Source: Ansaldo Archives

Crew

Like most information regarding this obscure vehicle, the number of men needed to effectively operate it is unknown. Often, sources mention that the vehicle only had two crew members, but this is likely referring only to those that were stationed inside the vehicle. This would include the driver, and likely the commander, but it could also be anyone from the crew. The remaining crew would be transported in an auxiliary vehicle. Ideally, in order to keep up with the Semovente M43 da 149/40, a fully tracked vehicle would be used in this role.

Given the general lack of such vehicles in Italian service, a more plausible solution would be to use simple trucks. The crew would most likely consist of a driver, commander, gunner, and possibly up to two (if not more) loaders. In the original towed version the 149/40 gun needed 10 crew members to be fully operational. The crew operating the gun were completely exposed, but given the firing range of more than 23 km, this should not have been a major issue most of the time.

The Fate of the Project

The Semovente M43 da 149/40 was used by the Italian Army for testing and evaluation. It is not clear if the Italian Army officials were satisfied with this vehicle. Nevertheless, Ansaldo made preparations for the production of a small series of some 20 vehicles, which were scheduled to be completed by the end of 1943. Unfortunately for them, in September of that year, Italy surrendered to the Allies and any further work on this project was terminated.

Following its former ally’s capitulation, the Germans took over what was left of the Italian industry and weapons. This included the sole-built Semovente M43 da 149/40 prototype. In German service, it was renamed to gepanzerte Selbstfahrlafette M 43 854(i). Its precise usage by the Germans from this point is not clear. Some sources suggest that this vehicle may have been used to defend the German Gothic Line against the Allies in Italy.

What happened next to it is also not clear. According to the American archives from the Museum of the Aberdeen Proving Grounds, the prototype was captured near Rome by the advancing American forces. In 1944, it was transported to America for evaluation. There is another version of the story, for which there is photographic evidence. The prototype was transported to Germany for examination. What the Germans thought of this design is unknown, but appears to have not influenced the development of German self-propelled artillery in any way. The prototype would eventually be captured by the Allies, possibly somewhere in France, during 1944-45, after which it would be shipped to America for examination and evaluation. Luckily, the prototype survived to this day. While initially located at the Military Museum Aberdeen Proving Grounds, it was later moved to the U.S. Army Field Artillery Museum at Fort Sill, Oklahoma. Unfortunately, at some point during the 1970s, its tracks were removed and ultimately lost.

A number of German vehicles together with the Semovente M43 da 149/40 prototype, were captured by the advancing Allies. This photo was taken in a military depot near Paris in 1944. Source:beutepanzer.ru/Beutepanzer
The Surviving Semovente M43 da 149/40. Source: comandosupremo.com

Conclusion

The Semovente M43 da 149/40, while not unique, was quite an interesting vehicle from Italy. It was designed and built with the intention of providing mobility to heavier guns. Alas, due to the deteriorating Italian industrial situation, lack of resources, and urgent need for tanks and self-propelled vehicles, there was simply no place for the new Semovente M43 da 149/40. In addition, taking into account that it was actually developed just prior to the Italian capitulation, there was simply no time for its introduction to service. Other nations also developed somewhat similar projects, like the American 155 mm armed M12 GMC, which saw some service during the war. Unfortunately, due to a general lack of information about the Semovente M43 da 149/40, a precise conclusion about its overall performance cannot be made.

The author would especially like to thank Art and Roshindow for providing valuable sources.

Semovente M43 da 149/40

Semovente M43 da 149/40 specifications

Dimensions (L-W-H) 6.6 -6.5 x 3 x 2 m
Total weight, 23.5 to 24 tonnes
Crew 2 (Driver and possibly the Commander)
Propulsion SPA petrol engine 250 hp
Speed 35 km/h
Armament Cannone 149/40
Armor 6 to 25 mm

 

Sources

2 replies on “Semovente M43 da 149/40”

Given the information, is it safe to assume the main armament could not be fired on the move? The trail legs needed to be down and other preparations made?

Probably, it could. But it would be nonsense firing it at the move. The recoil would probably overstress the suspension if travelling through rough terrain. Plus, aiming and reloading would become more and more difficult as you start to travel faster.

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