Siluro Lenta Corsa

A Siluro Lenta Corsa (SLC) or "Maiale", at the Sacrario delle bandiere delle Forze Armate in Rome, Italy.
Class overview
Name	Siluro Lenta Corsa
Builders	Officina Siluri San Bartolomeo di La Spezia
Operators	Regia Marina
Succeeded by	Siluro San Bartolomeo
Built	1935–1943
Completed	around 50
General characteristics
Displacement	1,8t
Length	6,77m
Beam	530 mm
Installed power	1 Battery (60 volts 150 ampere)
Propulsion	1,1 hp to 1,6 hp electric Motor
Speed	3 knots (max) 2,3 knots (max range)
Range	15 nautical miles
Armament	260 kg explosive charge

The Siluro Lenta Corsa ("slow-running torpedo" in Italian), also known by its acronym SLC or as the "maiale" ("pig" in Italian), was a human torpedo used as an underwater assault vehicle by the Italian Regia Marina. Similar in shape to a torpedo, it was adapted to carry at low speed two operators, equipped with autonomous underwater breathing apparatus and a limpet mine to be applied covertly to the hull of an enemy ship at mooring.

It was used by the Decima Flottiglia MAS during World War II for sabotage actions against enemy ships, often anchored in heavily defended ports, such as during the 1941 Raid on Alexandria.

History

Teseo Tesei, one of the naval engineers who conceived the "maiale" and was awarded the Medaglia d'Oro

The slow-running torpedo was derived from Raffaele Rossetti's Mignatta (Italian for "leech"), used in World War I to sink the Austrian battleship Viribus Unitis. The nickname "maiale" (Italian for "pig") was adopted as a code name by Tesei to protect the secrecy of the craft. The idea was born during training, when an exasperated sailor used the term to refer to the torpedo.

Modello di siluro guidato detto "maiale" esposto al Museo nazionale della scienza e della tecnologia Leonardo da Vinci di Milano

This project was conceived in 1935 by the Naval Engineer diver captains Teseo Tesei and Elios Toschi. Teseo Tesei later died in action with one of his pigs in Malta. The first two prototypes of the SLC were tested in October 1935, in the San Bartolomeo torpedo workshops of La Spezia in the presence of Mario Falangola who at the time directed the Submarine Inspectorate. Falangola was so enthusiastic about it that he commissioned the construction of two more SLCs. In 1939 the navy department that trained in the use of the SLC was transferred to a secret base located in Bocca di Serchio, in the stretch of sea in front of the mouth of the river Serchio. During repeated training tests, the weapon was perfected (see Mario Giorgini and Gino Birindelli) and between 1939 and ’43 the Italian navy manufactured more than 50 SLCs.

The Siluro San Bartolomeo, successor of the SLC

On December 19, 1941 the "maiali" carried out their most famous action, the raid on Alexandria, Egypt, in which they and sank the British battleships HMS Valiant and HMS Queen Elizabeth, the tanker Sagona and the destroyer Jervis. The three SLCs had been transported close to the enemy base by the submarine Sciré inside three cylinders placed on deck. SLCs operated secretly from the oil tanker Olterra, interned in the neutral port of Algeciras, 2 miles from the Port of Gibraltar. The Italians smuggled SLCs parts and reassembled them within the Olterra before launching them from a hidden underwater hatch. They sank or damaged nine Allied cargo vessels totaling 42,000 tons. Only after Italy capitulated in September 1943 did the Allies discover Olterra’s role. The British used captured specimens of the SLC to develop their own Chariot manned torpedo. SLCs sank or damaged a total of three warships and 111,527 tons of merchant shipping. Italy developed an improved version, the SSB (Siluro San Bartolomeo) but fielded only three of them before the armistice.

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  SLC specimen displayed in Taormina.
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  Display piece at the Arsenal in Taranto
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  Schematic of a Siluro Lenta Corsa
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  Artist depiction of an SLC attack