A novelty of the design was the placement of the final reduction gears inside the front-mounted drive sprockets, eliminating the need for enlarged final drive housings in the bow armour.
Type: Medium tank
History: In service 28 July 1939 – c. 1944.
Used: Italy and Australia
Number built: 100 (96 operational tanks, 4 prototypes)
Variants: /40, M14/41, M15/42
Weight: 11,175 kg
Length: 4.7 m
Width: 2.2 m
Height: 2.3 m
Crew: 3 (commander/radio operator, loader/gunner, driver)
Armour: Front 30 mm, Side14.5 mm, Top/floor 6 mm, Rear 8 mm, Turret 30 mm
Armament: 37 mm Vickers-Terni L/40 / 84 rounds
Secondary: 2 × 8 mm Breda 38 machine gun / 2,808 rounds
Engine: Fiat SPA 8T V-8 diesel, 105 hp
Power/weight: 9.5 hp/tonne
Suspension: Two 4 wheel bogies, semi-elliptic leaf spring
Range: 200 km
Speed: 32.2 km/h road
Service use of the M11/39 was short due to several deficiencies in its design, particularly the placement of the main 37 mm gun in the hull. The design concept was to use the main gun against other tanks and to defend the tank with the turret armament. The gun was in a fixed position with traverse restricted to 15° to port and starboard. Dual 8 mm machine guns were housed in a small rotating one-man turret, with manual controls.
The M11/39 had other shortcomings: its endurance and performance were poor, it was relatively slow, it was mechanically unreliable and its 30 mm maximum riveted steel armour, designed to withstand 20 mm fire, was vulnerable to British 2-pounder guns at any range at which the M11/39s main gun was effective. The tank was designed to carry a radio but none were fitted to the production vehicles. The M11/39 hull was modified for use its successor the Fiat M13/40, which was redesigned to put the main gun in the turret; an order for 100 M11s was placed as a stop-gap.
In Libya 72 × M11/39s were used in the North African Campaign, 24 operated in the East Africa Campaign and the first four prototypes remained in Italy. The M11 was vastly superior to the 36 × L3/33 and L3/35 tankettes stationed in East Africa. The M11/39 proved somewhat successful in early encounters with the British Light Tank Mk VI. The 37 mm gun of the M11 acted as a deterrent against attacks by these relatively fast but thin-skinned vehicles, armed only with machine guns. The tank was outclassed by heavier British cruiser and Infantry tanks, the Cruiser Mk I (A9), Cruiser Mk II (A10), Cruiser Mk III (A13) and Matilda.
On 13 September 1940, M11s participated in the Italian invasion of Egypt. On 9 December 1940, M11s also operated defensively in the opening stages of the British counter-offensive, Operation Compass. When Operation Compass was launched, many of the M11/39s were damaged, broken, or immobilized inside some of the static Italian positions. The British used Matilda tanks to overrun many of the Italian positions and the M11s could do little against the heavy armour of the Matildas.
From 10 April 1941, during the siege of Tobruk, some captured M11s were employed by the 6th Australian Division Cavalry Regiment over some months. The Australians painted large white kangaroo symbols on the tanks and used the captured M11s, together with several M13s, until they ran out of diesel fuel. The tanks were then destroyed to deny them to the advancing Axis forces in the spring of 1941.