Carro Armato M13/40

Italy entered the Second World War with an armoured force built largely around the tiny L3 tankette — a two-man, machine-gun-armed vehicle barely able to scratch an enemy tank. It was painfully obvious that the Regio Esercito needed a real battle tank, and the answer came from the Fiat-Ansaldo partnership in the form of a family of “M” (medio, medium) tanks. The first, the M11/39, mounted its main gun awkwardly in the hull; its successor put the gun where it belonged.

That successor was the Carro Armato M13/40 — the designation reading “medium tank, 13 tonnes, 1940.” With a 47mm gun in a fully traversing turret it represented Italy's serious attempt at a modern medium tank, and it became, for better or worse, the principal Italian tank of the war, the vehicle that equipped the armoured divisions sent to fight in the Western Desert.

On paper the M13/40 was a conventional and not unreasonable design for 1940. Its 47mm Cannone da 47/32 gun was, at the time of its introduction, genuinely competitive — able to penetrate the early British cruiser and light tanks it first faced, and backed by a useful high-explosive capability and a heavy battery of four machine guns. Riveted construction made it straightforward for Italian industry to build.

The problem was that 1940 did not last. The 47/32 put 47 mm through armour at 100 m and 31 mm at 800 m against plate at 30°, which was enough for a British cruiser or a Stuart and was never enough for a Matilda II, whose 78 mm frontal armour the gun could not defeat at any range. By 1942 the same gun was being asked to deal with Grants and Shermans, and the tank around it still weighed 14 tonnes and made 30 km/h on 125 hp of diesel.

The defect that the crews talked about was not the gun. The M13/40 was of riveted construction, chosen because it suited an industry short of the presses and welding capacity for large armour plate, and riveting has a specific failure mode: a shot that strikes the plate without penetrating can still shear the rivet heads on the inside, driving them through the fighting compartment at the speed of a bullet.

A crew could therefore be killed or maimed by a round that never came through the armour. The armour itself was thin enough anyway, and it was flat. The M13/40 got no protection from sloping: the hull was riveted plate work standing essentially upright, 30 mm on the front and 25 mm on the sides as plate thickness and as nothing more, with only the rounded transmission cover at the nose presenting a curve. The single set of angled plates on the vehicle was the turret — 30 mm at 16° on the face, 25 mm at 22° on its sides. All of it was carried on a chassis whose air filters clogged with desert sand. The M13/40 broke down in the approach march about as often as it was hit in the battle.

The received picture of Italian armour is uniform failure, and the record does not support it. On 19 November 1941 the 22nd Armoured Brigade, freshly arrived with Crusaders, was sent to drive the Ariete division off Bir el Gubi and then take 21. Panzer-Division in the rear. It ran into roughly 130 M13/40 of the 132° Reggimento Carri dug in with the divisional artillery, and it did not get through.

The brigade lost 52 tanks destroyed, 100 killed and wounded and 32 taken prisoner. Ariete lost 34 tanks destroyed and 15 damaged, 95 killed and wounded, 82 missing and 12 guns. As always the claims diverge — the British brigade reported 45 Italian tanks destroyed and 205 prisoners taken, while Italian accounts credit between 52 and 80 British tanks — but the outcome is not in dispute: the attack was repulsed by the tank that is supposed never to have won anything.

The other side of the ledger came first. During Operation Compass in the winter of 1940–41 the M13/40 was captured in quantity, often intact and often with its fuel and ammunition aboard, and the British and Commonwealth forces in the desert were short enough of tanks to use what they had taken.

They went to the British 6th Royal Tank Regiment and to the Australian 6th Cavalry Regiment, whose three squadrons of captured Italian mediums were named Dingo, Rabbit and Wombat. Because the silhouette was the enemy’s, the crews painted large white kangaroos on the hull sides, the glacis and the turret rear so that their own side would not shoot at them. Italian tanks in Australian markings then helped hold Tobruk against the Afrika Korps.

The end came at El Alamein. As the Axis front broke, the Ariete was left fighting a rearguard on 3 and 4 November 1942 to hold open the retreat of formations that had transport when it did not.

Its final transmission was logged at 15:30 on 4 November 1942: enemy tanks had broken through south of the division, Ariete was surrounded five kilometres north-east of Bir el Abd, and Ariete’s tanks were still fighting. The division was destroyed where it stood, with the M13/40s of the 132° Reggimento firing 47 mm rounds at Shermans and Grants that their gun could not penetrate frontally at any range on the field.

The obvious fixes were made, late and small. The M14/41 was the same vehicle with an uprated and properly desert-filtered diesel, an answer to the sand that had been killing engines since 1940, and it became the most-produced Italian tank of the war: 752 by the usual count, 744 by another, the difference being whether hulls converted to semoventi are counted in the tank column.

It did nothing about the two things that mattered. The gun was the same 47/32 and the construction was still riveted, so the M14/41 arrived in the desert in 1942 to fight American mediums with a weapon designed to fight British cruisers in 1940.

The M15/42 was the first real attempt at a new tank rather than a revision. It was longer and heavier at about 15 tonnes, gave up the diesel for a more powerful petrol engine, and carried the longer 47/40 gun in place of the 47/32. About 112 were completed as gun tanks and barely 90 are thought to have reached the army before the armistice; higher figures up to 220 appear in the later literature, the divergence turning on whether hulls finished as semoventi and vehicles completed under German occupation are counted in the same column.

It reached units in 1943, by which time the desert war it had been designed for was over and the tanks it had been designed to fight were in Sicily. Its lasting contribution was the hull: the M15/42 chassis carried the later Semovente assault guns, which is where Italian armour actually worked.

The most effective vehicle to come out of the M-tank programme had no turret. The Semovente 75/18 put a 75 mm howitzer in a low casemate on the M13/40 hull, and it did two things the tank could not: it fired a shell heavy enough to matter, including a shaped-charge round that could defeat armour the 47/32 could only scratch, and it presented a target well under two metres high.

The pattern is the one German industry found with the StuG III at the same moment. A turretless vehicle on an obsolete tank chassis can carry a gun a generation larger than the turret ring allows, and can be built faster. Italy’s best armoured fighting vehicle was built on the hull of the tank the Regio Esercito is most criticised for.

Counted together the gun tanks come to roughly 1,570 vehicles — 710 M13/40, some 744 to 752 M14/41 and about 112 M15/42 — which is the entire medium-tank output of a country that fought for three years in North Africa, and less than Germany built of the Panzer IV in 1943 alone. The design was conventional and sound enough for the year it appeared, and it was undone by riveted construction, 125 hp, and an industry that could neither multiply it nor modernise it at the pace of the war.

What the record will not support is the idea that it was never fought well. The same tank was repulsed at Bardia and captured by the hundred in the winter of 1940, and it broke the 22nd Armoured Brigade at Bir el Gubi eleven months later; its crews were still transmitting at half past three on the afternoon of 4 November 1942, surrounded, five kilometres from Bir el Abd.

• Nicola Pignato & Filippo Cappellano, Gli Autoveicoli da Combattimento dell’Esercito Italiano (Ufficio Storico SME).
• Filippo Cappellano & Pier Paolo Battistelli, Italian Medium Tanks 1939–45 (Osprey, New Vanguard 195).
• Nicola Pignato, Italian Armoured Vehicles of World War Two (Squadron/Signal).
• Ian W. Walker, Iron Hulls, Iron Hearts: Mussolini’s Elite Armoured Divisions in North Africa (Crowood) — for Bir el Gubi and the Ariete.