Regio Sommergibile Scirè

Scirè was one of the Adua class, the largest group within the Regia Marina’s “600 Series” of coastal submarines — the name a nod to their approximate surface displacement. Built by OTO at Muggiano, near La Spezia, and launched on 6 January 1938, she was one of seventeen boats designed for short-range patrol work in the Mediterranean.

As a fighting submarine the class was unremarkable, and like most Italian boats she carried a bulky conning tower and dived slowly — a real liability in the confined, air-patrolled Mediterranean. Scirè’s place in history has nothing to do with these qualities. It rests entirely on her second career, as the delivery vehicle for the most effective Italian naval weapon of the war: the human torpedo.

As built, the Adua class displaced about 697 t surfaced and 856 t submerged on a hull just over 60 m long. Two diesels gave around 14 knots on the surface and electric motors about 7.5 knots submerged, with a range near 3,180 nautical miles and a test depth of roughly 80 m. Standard armament was six 533 mm torpedo tubes — four bow, two stern — and a single 100 mm deck gun.

For special operations Scirè was rebuilt. The deck gun was removed, the conning tower cut down and repainted in disruptive camouflage, and three watertight cylinders were fitted to her casing to carry the Siluro a Lenta Corsa (SLC) — the slow-running manned torpedoes the crews nicknamed maiali, “pigs,” for their awkward handling. Stripped for stealth rather than combat, she became a courier that fought without firing a shot of her own.

Each SLC was a 6.7 m electric craft ridden astride by two frogmen of the Decima Flottiglia MAS, creeping along at barely 2.3 knots with a detachable warhead of up to ~300 kg in the nose. The pilots steered into a defended anchorage, worked through or under the harbour nets, clamped the charge beneath an enemy hull on a time fuze, and then tried to escape.

It was a weapon of patience and nerve rather than power, and it needed a boat that could put the operators within a few hundred metres of their target undetected. Under her commander Junio Valerio Borghese, Scirè became that boat — the elite carrier of the Decima MAS, navigating submerged into some of the best-defended waters in the Mediterranean to release her riders and slip away.

Scirè’s first target was the British bastion of Gibraltar. Two early attempts, in October 1940 and May 1941, failed — defective craft, missed rendezvous, an anchorage found empty — but each mission proved the delivery method and mapped the harbour’s defences a little better.

On the night of 20 September 1941 the technique finally paid off. Her three SLC crews penetrated the roadstead and sank the storage hulk Fiona Shell while badly damaging the naval tanker Denbydale and the motorship Durham — some 30,000 tons of shipping in a single night, without the loss of a single attacker. It was the proof that the maiali could strike inside a defended fleet base.

The masterpiece came three months later. On the night of 18–19 December 1941, Scirè crept to within a few miles of Alexandria, the main base of the British Mediterranean Fleet, and released three SLC teams. The frogmen slipped through the harbour entrance behind British destroyers as the anti-submarine boom was opened to let the warships pass.

Inside, the three crews split to their targets. Luigi Durand de la Penne and Emilio Bianchi rode for the battleship HMS Valiant; Antonio Marceglia and Spartaco Schergat for HMS Queen Elizabeth; Vincenzo Martellotta and Mario Marino for a large tanker. Working in cold, black water beneath the hulls, each team clamped its charge and set the fuze for the early morning.

De la Penne’s craft broke down and sank short of Valiant, and his diver Emilio Bianchi lost consciousness from exhaustion and bad air; de la Penne dragged the warhead the last stretch alone along the harbour bottom and left it under the battleship’s hull. Both men were caught soon after and held aboard the very ship they had mined. Minutes before the charge was due, de la Penne warned Valiant’s captain that an explosion was coming but refused to say where — buying his own men time and, by the code of the thing, giving the enemy crew a chance to save themselves.

Just after 06:00 the charges went off. Valiant and Queen Elizabeth both settled onto the harbour bottom, and the tanker Sagona was wrecked along with a destroyer moored alongside her. Coming just weeks after U-boats had sunk the carrier Ark Royal and the battleship Barham, the raid left Admiral Cunningham with no operational capital ships in the Mediterranean at all — yet because the two battleships had settled upright in shallow water and still looked whole, the British disguised the damage for months, keeping up an elaborate pretence of a fleet still in being. All six operators were captured; de la Penne later received the Medaglia d’Oro al Valor Militare — reportedly decorated after the war in the presence of Admiral Charles Morgan, who had commanded the Valiant beneath which he laid his charge.

Scirè’s own luck ran out on 10 August 1942. Approaching Haifa on another human-torpedo mission — her plans betrayed by decrypted Allied signals — she was caught and depth-charged by the British armed trawler HMS Islay, and lost with her entire crew of around 60. In 1984 the Italian Navy recovered her crew’s remains from the wreck, in about 32 m of water, and brought them home for burial.

Small and technically ordinary, Scirè is nonetheless remembered as one of the most consequential submarines of the war. She embodied a distinctly Italian way of fighting at sea — trading audacity and specialised technology for the battle-fleet actions the Regia Marina could not risk — and the raid she delivered at Alexandria remains a model study of asymmetric naval attack, achieving with six men what a fleet action might not.

• Roger Chesneau (ed.), Conway’s All the World’s Fighting Ships 1922–1946 (Conway Maritime Press).
• Aldo Fraccaroli, Italian Warships of World War II (Ian Allan).
• Jack Greene & Alessandro Massignani, The Black Prince and the Sea Devils: Valerio Borghese and the Decima MAS (Da Capo Press).
• J. Valerio Borghese, Sea Devils: Italian Navy Commandos in World War II — memoir of the Decima Flottiglia MAS commander.