Auxiliary ship Olterra

Italian auxiliary ship Olterra
Part of the Battle of the Mediterranean of World War II
Olterra at anchor shortly before being broken up at Vado Ligure, 1961
Date 8 December 1942 – 4 August 1943 Location Gibraltar, Western Mediterranean Result 42,000 tn of Allied shipping sunk
Belligerents
United Kingdom	Italy
Commanders and leaders
Lionel Crabb	Licio Visintini † Ernesto Notari
Strength
Harbour defences	1 Mother Ship 9 manned torpedoes
Casualties and losses
6 merchant ships sunk 2 sailors killed	3 divers killed 3 prisoners 2 manned torpedoes lost

The auxiliary ship Olterra was a 5,000 ton Italian tanker scuttled by her own crew at Algeciras in the Bay of Gibraltar on 10 June 1940, after the entry of Italy in World War II. She was recovered in 1942 by a special unit of the Decima Flottiglia MAS to be used as an undercover base for manned torpedoes in order to attack Allied shipping at Gibraltar.

Olterra started life as the tanker Osage. She was built in 1913 by Palmer's Ship Building and Iron Co Ltd, Tyneside, United Kingdom, for a German company. Osage was sold to the Standard Oil Co in New York in 1914 and renamed Baton Rouge. In 1925 she was again sold, this time to the European Shipping Co. Ltd of London and renamed Olterra. As Olterra she passed through the hands of the British Oil Shipping Co. Ltd and in 1930 was bought by Andrea Zanchi in Genoa. On 10 June 1940, when Italy entered World War II by declaring war on France and the United Kingdom, Olterra found herself in the Bay of Gibraltar off Algeciras, Spain. She was sabotaged and partially sunk by British commandos that day.

From 24 September 1940 to 15 September 1942, there were six submarine-borne assaults on Gibraltar. Three of them resulted in the destruction or sinking of a number of Allied freighters, with a total tonnage of some 40,000 tn. Three of them were carried out by human torpedoes launched from the submarine Scirè; the other two were the work of combat swimmers.

After the attacks carried out by Scirè, the commander of the Decima MAS realised that, given the limitations of using a submarine as a mother ship for human torpedoes in Gibraltar, it would be more feasible to mount a secret base in neutral Spain. A first step in that direction was taken when a member of the Decima, Antonio Ramognino, rented a bungalow along the coast road near Algeciras, right in front of a bay used by Allied convoys to drop anchors. The operations from Villa Carmela were carried out by combat swimmers. Because Ramognino's wife was a Spanish citizen, he had little difficulty establishing his ‘home’ there.

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