The Semovente L.40 da 47/32 served with Italian and German army elements throughout World War 2. Though never noted for their armored vehicle designs in the conflict, the Italians were actually forward-thinking in their embracing of the concept of a dedicated tank-killing platform to support their armored advances. The L.40 began production in 1942 as a budget-minded conversion of the L.6 combat light tanks and served from 1942 to 1945 across several notable scuffles in North Africa and the East Front. After the Italian armistice with the Allies, the German Army took hold remaining L.40s. In all, some 280 to 300 L.40s examples were delivered before the end of the war.
The Italians began their foray into designing a capable tank destroyer by fitting their proven and highly-potent 47mm main gun to the chassis of an L.3 tankette (light tank). The new system - designated formally as the Semovente L.3 da 47/32 - was to be crewed by two personnel and used in the support of advancing army units in a given assault. The main gun was fitted onto the front hull of the L.3 chassis, interestingly left in an open-air mounting. However, it was inevitably realized that this new arrangement did little in the way of protecting its crew. The tank was severely lacking in any sort of crew-based armor along the critical sides, rear and top angles, leaving the gunner and driver's defense only a simple forward-facing shield mounted on the main gun itself. As such, a new solution was put into action while the L.3 conversion concept was retained for testing and further evaluation.
When Italy officially entered the war in 1940, it put a great deal of faith into their fleet of light-armored, fast-moving tanks which included the L.6/40 light tank. These vehicles quickly proved to be inadequately armored and outgunned (armed with 37mm guns) in early engagements. After actions in North Africa against the Allies, the L.6's shortcomings were revealed and led to it being used as a basis for an "up-gunned" tank killer conversion program to serve the Italian Army in support of their tanks. Fiat-SPA and Ansaldo joined forces to make the new system a reality.
The new solution became the L.40 da 47/32 ("47" indicating the caliber of the main gun and "32" indicating the main gun's length"). The 47mm main gun of the L.40 was a license-production version of the Austrian Bohler 47mm (1.8 inch) anti-tank gun that also doubled as an infantry support weapon. At the time, the Bohler gun was one of the best dual-role weapon systems of its day. The main gun was rated with a muzzle velocity of 2,100 feet per second when launching a 3.25lb armor piercing shell.
The L.40 crew was increased to three personnel over the two of the L.3 conversion - now made up of a driver, loader and commander. The system fitted a conventional track scheme along both sides of the hull. The rubber-tired road wheels (four to a track side) were mounted as pairs with each group supported by a curved cantilever and torsion bar system. The rear wheel served as the track return and load carrier. Three return rollers were fitted to a track side while the forward-mounted drive sprocket gave the L.40 a unique "hull up" appearance. The forward hull featured a slab face plate and an angled glacis plate, the latter leading to a fixed open-topped "box-type" superstructure with slab side armor. The limited traverse main armament was off-set to the left front side of the superstructure. The offensive-minded main gun was complimented by a single defensive 8mm anti-infantry machine gun. The L.40 superstructure could house up to seventy 47mm projectiles. Armor thickness included a front facing of 1.5 inches (30mm) and side facings of 0.63 inches (14mm). The front turret mantlet supported up to 2 inches of armor thickness.
The powerplant was a rear-mounted 4-cylinder water-cooled gasoline engine (SPA 18D, Fiat 18D or Model 18 VT type) spitting out up to 70 horsepower at 2,500rpm. Fuel was limited to 44 gallons and stored in two internal fuel tanks offering fuel efficiency numbers of 2.8 miles per gallon along roads while degrading to 1.1 miles per gallon cross country. The engine was mated to a transmission system that offered 4-forward and 1-reverse modes. A reduction gear offered four lower speeds. Steering was accomplished via a clutch brake while the starter was an electrically-based system tied to a magneto ignition.
Performance specifications set the L.40 a top speed at 26.3 miles per hour. Road range radius was limited to 125 miles with a 50-mile limit cross country radius. Fording depth could be no deeper than 2 feet, 7.5 inches with this being the same limit for vertical obstacle traversing. The L.40 could tackle slopes of up to 40 degrees.
The L.40 saw its first action in the Western Desert during the 1942 campaign. The system initially fared well against the likes of the light- and medium-armored Allied tank systems. However, crew protection was still a glaring issue for the L.40 despite its armored superstructure. The L.40 crew would only later receive some light overhead protection in the form of a retractable canvas top.
As the war progressed in favor of the Allies, theL.40s days seemed numbered, particularly as Allied tank armor increased and Allied air support was ever-present. Despite the inherent limitations, the L.40 was one of the better tank-killing systems available to the Italian army. It was also a relatively painless and cheap conversion project for the outclassed and outgunned L.6 tank series.
The Italian Army also showcased their L.40s in battles against the Red Army along the Eastern Front as part of the German Army Group South, seeing some limited successes there. The signing of the armistice with the Allies by the Italians signaled the local end for the L.40. Germany retained whatever L.40 components it had access to and tried to keep them in service during the battles ranging across Italy. However, the unforgiving terrain of the Italian Theater made many-an-armor confrontation a difficult prospect. As such, the L.40 was relegated to service as mobile armored command posts for the Third Reich. The L.40 in command form had their 47mm main guns replaced with a "disguised" 8mm machine (the machine gun made up to look like a 47mm main gun). Additionally, these L.40s carried applicable radio equipment onboard wherever possible. The lack of onboard projectiles provided for the needed space. Still other L.40s were converted as ammunition carriers.
Some L.40s were delivered to Axis-allied Croatia.