This tank was first accepted for service in March, 1940, with a production rate of 22 per month. Although the M 13/40 was designated as a medium tank, it was more in step with a light tank.

A total of 3 battalions were deployed into Libya in October 1940, most of which were destroyed with the British counter offensive. The M13/40 never achieved significant numbers until the end of the African campaign, but it did not take long before this tank and other armored Italian vehicles to be outclassed by Allied armor, and eventual evolutions of this tank, M14/41 and M15/42's, did little to help.

It was very unreliable and caught on fire easily after being hit by rounds. The M-13 mounted a respectable 47/32 gun whose muzzle velocity was 2,060 feet per second. Unfortunately, this velocity could only penetrate 38 mm of armor plating at 750 yards and 32 mm of armor plating at 1,000 yards. Most Italian tank operators, receiving new M.13's straight from the factory, had to manage with an outclassed tank, no radio and approximately one week of actual training.

A command version of the tank, the Semoventi Comando M.40 was built, which removed the turret in order to fit command and communication equipment. The same chassis was used on a number of Italian self propelled guns. (Information furnished by Flagtower WWII