Fiat M13 / 40 The Fiat - Ansaldo M13 / 40 was an Italian medium tank ( " M " for " Medio " ( medium ) according to the Italian tank weight standards at the time : 13 tonnes was the scheduled weight and 1940 the initial year of production ) , designed to replace the Fiat L3 , the Fiat L6 / 40 and the Fiat M11 / 39 in the Italian Army at the start of World War II . The design was influenced by the British Vickers 6 - Ton and was based on the modified chassis of the earlier Fiat M11 / 39 . Indeed , M11 / 39 production was cut short in order to get the M13 / 40 into production . Although designated a medium tank , the M13 / 40 was closer to contemporary light tank s in armor and firepower . Specifications . The M13 was constructed of riveted steel plates as follows : 30 mm front ( as M11 ) , 42 mm on turret front ( 30 mm for M11 ) , 25 mm on the sides ( M11 had only 15 mm ) , only 6 mm bottom ( that made it very vulnerable to mines ) and 15 mm on top . The crew were housed in a forward fighting compartment , with the engine at the rear and transmission at the front . The fighting compartment accommodated the crew of 4 : driver and machine - gunner / radio operator in the hull , and gunner and commander in the turret . The Vickers - derived running gear had two bogie trucks with eight pairs of small wheels on each side , using leaf - spring suspension . The tracks were conventional skeleton steel plate links , and were relatively narrow . Together , this system was thought to allow good mobility in the mountainous areas in which future combat was expected . In the desert where most M13s were actually employed , mobility was less satisfactory . The tank was powered by a diesel engine . This was an innovation that many countries had yet to introduce . Diesel engines were the future for tanks , with lower cost , greater range and reduced danger of fire compared to gasoline - powered engines . The tank ' s main armament was a 47 mm gun . It could pierce about 45 mm of armor at 500 meters . This was sufficient to penetrate the British light and cruiser tank s it would face in combat , though not the heavier infantry tanks . One hundred four rounds of armor - piercing and high explosive ammunition were carried . The M13 was also armed with three or four machine - guns : one coaxially with the main gun and two in the forward , frontal ball mount . A fourth machinegun was sometimes carried in a flexible mount on the turret roof for anti - aircraft use . Two periscopes were available for the gunner and commander , and a radio was also theoretically available as standard equipment . Operational use . The M13 / 40 was used in the Greek campaign in 1940 and 1941 and in the North African Campaign . The M13 / 40 was not used on the Eastern Front ; Italian forces there were equipped only with Fiat L6 / 40 s and Semovente 47 / 32 s . Beginning in 1942 , the Italian Army recognized the firepower weakness of the M13 / 40 series and employed the Semovente 75 / 18 self - propelled gun alongside the tanks in their armored units . First actions . The first of over 700 M13 / 40s were delivered following a rate of production of about 60 - 70 a month , before the fall of 1940 . They were sent to North Africa to fight the British . Its baptism of fire came with a special unit , the Babini Brigade . Arriving too late to fight in the September offensive , this unit was ready the next December , for Operation Compass . Further action took place in Derna , where the V battalion had just arrived . Tanks of III battalion were also present near this position , at Bardia . In 2 days of fighting ( January 3 – 4 , 1941 ) , the Australians suffered 456 casualties , the Italians lost 45 , 000 men captured . On February 6 – 7 , the British offensive penetrated so far that the Babini Brigade sought to open a breach in the British lines at Beda Fomm in an effort to allow cut - off Italian troops to retreat along the Libyan coast . The brigade ' s action was unsuccessful and all their tanks were lost . The last six surviving tanks entered a field near the local British command post . They were destroyed one after another by a single 2pdr ( 40 mm ) anti - tank gun . Many tanks were lost in this campaign to artillery fire rather than other tanks . A number of captured M11 and M13s were re - used by the 6th Australian Division Cavalry Regiment and the 6th battalion , Royal Tank Regiment , until the spring of 1941 , when their fuel ran out and they were destroyed . The M13s also fought in Greece , in difficult terrain . Subsequently , in April , 1941 , M13s of the Ariete division took part in the Siege of Tobruk , with little success against British Matilda s . The first successful action for the M13 was the Battle of Bir - el Gobi . Later use in the desert war . In April 1941 , at the time of the arrival of the Afrika Korps , the Italians had around 240 M13 and M14 tanks in first line service . In 1942 , as the allies began deploying Grant s and Crusader III s , along with towed 6 pounder anti - tank guns in their infantry units , the weaknesses of the M13 were exposed . The Italians equipped at least one company in each tank battalion with more heavily - armed Semovente 75 / 18 assault guns . In an attempt to improve protection , many crews piled sandbags or extra track links on the outside of their tanks , but this made the already underpowered vehicles even slower and added to maintenance problems . The Second Battle of El Alamein saw the first appearance of the M4 Sherman , while some 230 M13s were still in front line service . In several days of battle , the Ariete and Littorio divisions were used to cover the Axis retreat . The Centauro Division was virtually destroyed fighting in Tunisia . Strengths and weaknesses . The M13 / 40 was a conventional light tank of the early war period , similar in capability to other Vickers - derived designs such as the Polish 7TP and Soviet T - 26 . With a weight of 13 tons , it carried armor comparable to its opponents of 1940 - 41 , and sufficient firepower to engage the British tanks of 1940 - 41 . The main gun ' s HE round was useful against towed guns and infantry . The diesel engine was an advantage , and the simplicity of production suited the state of Italian industry . However , the tank also had shortcomings : the engine gave good range , but reliability was a problem . The M13 ' s engine was the same as the M11 ' s , but the newer tank was heavier , which resulted in lower speed and more strain on the power - plant . The suspension and tracks were reliable enough , but resulted in relatively low speeds , not much better than infantry tanks such as the Matilda . Armament was sufficient for 1940 - 41 but did not keep up with the increased armor and firepower on Allied or German tanks . The method of construction , using rivets , was outdated . Most tanks of the era were switching to the use of welding for construction , since rivets can shear off when hit , becoming additional projectiles inside the tank . The two - man turret was less efficient in combat than the three - man turrets used in many other tanks of the era . Radios were not fitted to many tanks . Despite heavy operational attrition , the M13 were present at the war ' s end and a few even managed to survive into the post - war period . Variants . The M13 / 40 series was Italy ' s most - produced tank of the war , including later variants such as the M14 / 41 , over 3 , 000 were built . The last version was the M15 / 42 tank produced in 1943 , with a better petrol engine and a longer 47 / 40 gun . The Semovente 75 / 18 self - propelled gun was built by utilizing the M13 / 40 or M14 / 41 chassis . The Fiat M14 / 41 was a variant of the same tank with a more powerful engine and better air filters for operations in North Africa . The Semovente Comando M40 was an M13 / 40 tank with the turret replaced by a large multi - piece hatch . The hull housed additional radios and other communication equipment .