The Italian Submersible

Two young sub-lieutenants, Teseo Tesei and Elios Toschi, with the Italian submarine service in La Spezia, had been influenced by the First World War exploits of Lieutenant Raffaele Paolucci and Major Raffaele Rossetti, and worked together on the idea of sneaking into an enemy harbour on a small underwater machine carrying explosive mines.

Tesei and Toschi had followed the amazing First World War career of submariner Lieutenant-Commander Angelo Belloni, who designed submarine escape apparatus, which brought him in contact with the Davis Submarine Escape Apparatus. Belloni also designed a flexible rubber suit and was encouraged by the Italian navy to continue to try to develop the new form of underwater breathing apparatus that gave a continuous air supply for at least six hours. The breathing apparatus was essential if Tesei and Toschi’s underwater weapon was to succeed.

In 1935 Admiral Cavagnari, the Chief of Naval Staff, took a personal interest in the unusual drawings produced by Teseo Tesei and Elios Toschi of their Siluro lenta corsa (slow-speed torpedo), and he immediately ordered the building of two prototypes by the San Bartolomeo submarine weapons factory in La Spezia.

The two young Italian engineers continued with their general naval duties: only in their spare time could they supervise the building work and organise the detailed system of attack. Finally the prototypes were ready for testing and the two excited inventors gazed on their strange creation.

The Italian chariot looked like an ordinary 21-inch rocket-shaped torpedo, but with a superstructure added to protect the two pilots, and driven by a small electric motor. At the front of the 7.3-m (24-ft) hull was the familiar, round nose of the warhead, containing 300 kg (660 lb) of explosive that was detonated by a timing device set by the pilot. Behind the explosive warhead the pilot sat astride the submersible, his feet in stirrups, crouching like a jockey on horseback, behind a small screen protecting him from being swept off as the torpedo slowly made its way through the water at 3 knots (6 km/h).

The pilot operated the rear rudder and hydroplanes by means of a wheel on the end of a joystick. By turning the wheel he could steer to the left or right, and by pushing the joystick forward or pulling back could dive or surface. In front of the joystick were an illuminated instrument panel, compass, depth gauge, pressure gauge and ammeter. On either side two valves operated the internal fore and aft trimming tanks, which balanced the machine.

The main ballast tank was situated just behind the first pilot and could be operated by reaching back to a lever just behind the pilot’s hip. The second diver crouched behind the main ballast tank, holding onto a bar, and it would be his job to cut through any submarine defence nets and remove the warhead and suspend it beneath the hull of their target. On the conical rear section was the boson’s locker, where their cutting equipment, spare breathing set, rope, clamps and limpet mines were stored. Inside the watertight hull were a bank of batteries, the electric motor and air pumps.

On a chilly January morning in 1936 the two inventors experienced the exhilaration of underwater travel for the first time as they put their small submersible through its paces in a quiet corner of La Spezia harbour. The real test for the submersible had to be carried out in front of Admiral Falangola, who was sent down from the Ministry of Defence.

The docks in La Spezia were cleared and cordoned off by the police, making certain this naval project remained top secret. The submersible demonstrated its manoeuvrability in the small dock, watched eagerly by Admiral Falangola, who saw the advantages of this revolutionary weapon and gave the immediate order to construct some more. However, in Rome there were many sceptics; some considered that two men on a torpedo would have little effect against a well-organised navy, while others considered the risk to life was too great because of the many unknown factors.

For example, the submersible may not complete the long, hazardous journey to the harbour entrance because of mechanical failure, battery failure or leaks and trimming failure. In addition, the crude breathing equipment was dangerous and unreliable; if it failed, the operator could not dive and enter the harbour hidden from view.

In the early months of 1936 Commander Catalano Gonzaga, from La Spezia submarine flotilla, ordered the selection of the first volunteers, who were picked for possessing outstanding physical fitness and the highest possible courage. This would be a requirement in the selection process for operating the piloted torpedo.

In charge of training were the two inventors Toschi and Tesei, who were joined by Lieutenant Franzini, Sub-Lieutenant Stefanini and Midshipman Centurione. Their secret base was on the River Serchio (Bocca del Serchio), which ran north of Pisa out into the Gulf of Genoa some 45 kilometres (24 miles) south of La Spezia harbour. Hidden in a thick pine forest far from the main road on the secluded estate of the Dukes of Salviati, the mouth of the River Serchio was the perfect entrance for naval craft to slip in and out unseen. The testing of the new top secret naval weapon began.

The Italian invasion of Abyssinia started on 3rd October 1935, but by the time the men had completed their training, the war in Africa ended abruptly in success for the Italians. The sinister new weapon was stored in a naval depot, carefully shielded from prying eyes, and the tough band of volunteers returned to their normal naval duties.

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