| Date |
Chronicle of operations of the Decima Flottiglia MAS in Gibraltar |
| August 21, 1940 |
The Italian submarine Iride left La Spezia (Italy) with plans to attack Gibraltar on 22 August 1940. |
| September 24, 1940 |
The Italian Submarine Sciré, commanded by Junio Valerio Borghese, left La Spezia carrying three manned torpedoes and eight crewmen. The attack was called off and the submarine ordered back to La Maddalena because the British fleet had left Gibraltar before the Sciré could get into position. |
| October 21, 1940 |
The Sciré left La Spezia and sailed to Gibraltar carrying three manned torpedoes and eight crewmen. The manned torpedoes entered the harbour, but damaged no ships. Two of the crewmen were captured and the other six escaped to Spain, eventually returning to Italy. The six escapees included Teseo Tesei and Alcide Pedretti. Their manned torpedo later washed ashore at Espigon Bay, and was interned by Spanish authorities. |
| May 25, 1941 |
The Sciré left La Spezia carrying three manned torpedoes. At Cádiz (Spain), it secretly loaded six crewmen. They found no warships in Gibraltar because the Renown, Ark Royal and Sheffield had been ordered into the Atlantic as part of the search for the German battleship Bismarck, which was sunk on May 27. |
| September 10, 1941 |
The Sciré left La Spezia bearing three manned torpedoes. It secretly loaded six crewmen in Cádiz and sank three ships: two tankers named Denbydale and Fiona Shell, and a cargo ship, the Durham. The crews of the torpedoes swam to Spanish territory after firing their weapons and later returned to Italy. |
| July 1942 |
Italian frogmen set up a base in the Italian cargo ship Olterra which was interned in Algeciras near Gibraltar. All materials had to be moved secretly through Spain thus limiting operations. |
| July 13, 1942 |
12 Italian frogmen swam from the Olterra into Gibraltar harbour and set explosives, sinking four ships. |
| December 17, 1942 |
Six Italians on three torpedoes left the Olterra to attack the British warships HMS Nelson, HMS Formidable, and HMS Furious. A British patrol boat killed one torpedo's crew (Lt. Visintini and Petty Officer Magro) with a depth charge. Their bodies were recovered, and their swimfins were taken and used by two of Gibraltar's British guard divers; Sydney Knowles and Commander Lionel Crabb. A British patrol boat detected another torpedo, and pursued and shot at it, capturing its two crewmen. The remaining torpedo returned to the Olterra, having lost its rear rider. |
| May 8, 1943 |
Three Italian manned torpedoes left the cargo ship Olterra to attack Gibraltar in bad weather and sank three British ships. |
| August 3, 1943 |
Three Italian manned torpedoes left the Olterra to attack Gibraltar, and again sank three ships. |
| October 2, 1943 |
A larger Italian frogman-carrier named the Siluro San Bartolomeo (SSB) left Italy with plans to attack Gibraltar. The boat was 33 feet (10 m) long and carried four frogmen. The surrender of Italian forces to the Allies ended the plan before it could be put into operation. |
