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Olterra: A Trojan Horse in the Strait of Gibraltar During WWII

Soraya Fernández

“Olterra” … the name of the Italian tanker scuttled in the Bay and from which one of the most extraordinary stories of espionage and sabotage played out. From the outside, it appeared to be abandoned, but inside it was the base of operations for manned-torpedo attacks on the Royal Navy in Gibraltar. Researcher Alfonso Escuadra takes us on a journey into this dark chapter of our history.

David Gutierrez Algeciras
Italian Tanker “Olterra” the base of operations for manned-torpedo attacks on the Royal Navy in Gibraltar

The pages of history are often filled with intense and little-known sagas. For example, the roleplay game created by Algeciras resident David Gutiérrez “Operation Olterra”, has enabled many in the area to delve into a complex operation which took place in the Bay of Gibraltar During WWII.

Operation Olterra David Gutierrez Algeciras Game Campo de Gibraltar

Stories of espionage continue to garner fascination these days, and Olterra, a chapter of our history which really is worth delving into, has attracted the curiosity of many.

Operation Olterra was executed from the tanker in the Bay in 1942 by the Italian Tenth Submarine Assault Media Flotilla (MAS), called the “Osa Mayor” (Ursa Major), whose target was Gibraltar. It served as a modern-day Trojan Horse in the Strait.

The mission was like something invented in Hollywood, and indeed, in 1965, Terence Young produced the film “Thunderball” with Sean Connerry starring as “ James Bond”.

The operation had all the ingredients of a typical cinema suspense blockbuster: a seemingly abandoned ship anchored in the Bay which became the centre of espionage.

The attacks were carried out via “Maiali” (Italian for hogs) or “Human Torpedos”; Italian, low speed torpedoes which were manned by two people, with the objective of sinking British ships stationed in Gibraltar which were controlling the Strait. Once the frogmen reached their target, they would attach explosives which were stored in the bow of the torpedo and would then return to Olterra to monitor events.

Italian Operation Olterra World War Gibraltar Algeciras Alfonso Escuadra
“Miali” Human Torpedo

To get a deeper understanding of the operation, ReachExtra once again spoke to writer and historian specialising in WWII in our area, Alfonso Escuadra.

Olterra was the name of the ship which became the headquarters for operations. According to Escuadra, it was an Italian tanker weighing 5,000 tons and which had been caught in the Bay when Italy declared war.

“In principle, and like the rest of the Italian merchant ships, they attempted to sink or beach [Olterra] on the nearby coast so that it would not be captured by the British. Then, since the summer of 1940 it was left stranded on the Puente Mayorga beach in Campamento.”

“From there it was re-floated and taken to the dock in Algeciras to guarantee the Genoese shipping company (Andrea Zanchi) rights to the ship without the risk of a salvage claim. The crew had remained onboard for almost a year and a half to ensure this”.

Escuadra said that at the beginning of 1942, the Italian Navy had realised that this ship presented an opportunity to coordinate a naval assault against Gibraltar.

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“During the following summer, a group of engineers and officers from the Regia Marina converted the tanker into a real base of operations for manned torpedoes against the Royal Navy base on the Rock.”

Up until this point, Escuadra explains that manned torpedo attacks had been carried out from submarines which would transport them to the Bay.

“At this point, it was about having a permanent secret base close by to their target. The Olterra was equipped with maintenance workshops, weapon depots and an interior pool which had an opening below the waterline, where the torpedoes could exit and carry out their mission.”

Italian Operation Olterra World War Gibraltar Algeciras Alfonso Escuadra
“Miali” Human Torpedo

Materials for repairs and maintenance works, including work on the torpedoes, were sent in piece by piece from Italy to Algeciras by land using official diplomatic bags.
Once prepared inside the ship, the torpedoes would go out to sea and, after carrying out the attack, the expensive power cells would no longer need to be abandoned in the Bay, as had happened in previous missions, but instead were returned to Olterra to be reused.

This, according to Escuadra, coupled with the speed with which the operation could be organised if the right occasion arose, determined that from that moment on the Olterra would be the secret base that the X Flotigglia MAS would use for the attacks.

Three casualties and a diving world champion

Italian Operation Olterra World War Gibraltar Algeciras Alfonso Escuadra

The mission that would test the effectiveness of the new operation was organised at the beginning of December 1942 with the great ships of the Royal Navy as the objective: three of the six Italian divers died, including Lieutenant Commander Licio Visintini, one of the organisers and first head of the unit; who, along with his second in command, was killed by depth charges that, as a security measure, the British regularly dropped at the accesses to the port, according to Escuadra.

“A few months later, command of the so-called Flotiglia Orsa Maggiore, as the Olterra battle group was called, was taken over by a former world freediving champion, Lieutenant Commander Ernesto Nottari. During his time in command, it was merchant ships anchored in the Bay of Gibraltar that were targeted because they transported supplies to the Allied deployments in the Mediterranean Theatre of Operations.”

Italian Operation Olterra World War Gibraltar Algeciras Alfonso Escuadra

Escuadra adds that neither the permanent surveillance of the sea, nor the anti-submarine protection nets, nor the barbed wire curtains arranged as a security measure around the ships, could prevent the two operations organised under the command of Nottari, on May 7 and August 4, 1943, from closing with a hundred percent success.

“This added six more names to the list of ships sunk or seriously damaged by the flotilla in the Bay, adding some 40,000 tons to the register of affected tonnage.”

Although there were certain suspicions about it, Great Britain had to wait for the Italian surrender to obtain permission from the Spanish to move the Olterra to the port of Gibraltar, access its interior and confirm that it had been used as a secret base for manned torpedoes.

Finally, Escuadra explains that the Olterra was returned to Italy and in 1964 it was scrapped. Today the log, the steering wheel or the ship’s bell are on display in the Navale Museum in the Italian Naval base at La Spezia.

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