Decima Flottiglia Motoscafi Armati Siluranti

In the 1930’s the use of the Torpedine Rossetti and the Barchino Saltatore are still in the collective memory of the Regia Marina. Their ideas received little attention until 1935 when new fundings from the Regia Marina became available because of two events. First the Italian-Ethiopian war called for a modernisation of the Italian Armed Forces. and second, this war caused the British to station parts of their home fleet in Malta, shifting the balance of power in the Mediterranean.

On November 27^th, 1935, Admiral Aimone di Savoia-Aosta, Duke of Spoleto, submits a comprehensive study to the Ministry of the Navy. In 1935, during the Ethiopian crisis and the redeployment of the Home Fleet to the Mediterranean, the looming threat of armed conflict between Italy and Britain prompted Amedeo Duca d’Aosta, Commander and pilot of the fighter wing at Campoformido, to draft a proposal. In collaboration with his cousin Admiral Aimone Savoia Aosta, Duca di Spoleto, and Frigate Captains Giorgi and Margottini, he submitted the following memorandum to the Royal Navy General Staff:

The plan outlined the use of six small, lightweight, and high-speed motorboats (capable of 40 knots), each carrying an explosive charge of approximately 300 kilograms of TNT, the warhead of a torpedo. These motorboats would be suspended from six Savoia-Marchetti SM.55 seaplanes, positioned between the twin hulls.

1. On a night with calm seas, the six seaplanes would transport the motorboats to the vicinity of the target naval base, landing approximately 18 kilometres offshore to avoid detection by enemy patrols.
2. Once released, the motorboats would proceed silently towards the enemy base. Upon reaching the harbour entrance, the lead motorboat would ram the obstruction, detonating its explosive charge to create a breach.
3. The remaining motorboats would navigate through the gap, marked by a floating light left by the lead boat and its helmsman. If further obstructions were encountered, the second boat would repeat the process.
4. Once inside the port, the motorboats would accelerate towards anchored vessels, with the helmsman abandoning the craft just before impact, triggering detonation upon collision.
5. The operation could involve additional motorboats (nine to twelve) and be repeated at intervals, exploiting the difficulty of establishing an effective defence in a short period.

The document concludes with the authors, Amedeo Duca d’Aosta, Giorgi, and Margottini, expressing their desire to personally lead the mission if the project were approved. Fate, however, dictated otherwise. Frigate Captain Margottini lost his life commanding the destroyer Artigliere during the night of October 12^th,1940. Captain Giorgi fell in action while commanding the cruiser Fiume during the Battle of Cape Matapan on March 29^th, 1941. Admiral Aimone di Savoia-Aosta did not find rest in Italian waters, and Amedeo Duca d’Aosta died in captivity, laid to rest in Africa after the valiant defence of Amba Alagi.

Engineer Guido Cattaneo and by Comander Mario Giorgini were tasked with the design of the prototypes. They came up with two prototypes, the Motoscafo d’Assalto (M.A.) and the Motoscafo Avio Trasportato (M.A.T.), an airborne prototype. The prototypes were made of wood and canvas with a small, bow-mounted, impact-fused explosive charge.

During the same time period, two naval engineers. Teseo Tesei and Elios Toschi, at the Livorno Accademia Navale each produced a new design for the Torpedine Rossetti.

Major Ing. Teseo Tesei and Major Ing. Elios Toschi

These developments made Admiral Cavagnari, the Chief of Staff of the Regia Marina decide to approve the foundation of the 1° Gruppo Sommergibilli. This unit became the new base for the ideas of Major Ing. Teseo Tesei, Major Ing. Elios Toschi and Admiral Aimone Savoia D’aosta. For a brief period of time, they had enough funding to optimize their design for what become known as the Siluro a Lenta Corsa (SLC), or Slow Moving Torpedo. The unit also came up with the Motoscafi da Turismo Modificati, or modified tourist motorboat. This boat was based on the prototypes of the Motoscafo d’Assalto (M.A.) a few years earlier. The boat was commonly known as Barchino Esplosivi, explosive boat or simply barchino.


The SLC (Siluro a Lenta Corsa) in action.

However, by the end of 1936 the military tension between the Italians and British relaxed a bit and the funding for the 1° Gruppo Sommergibilli was again limited by the Regia Marina. First the Siluro a Lenta Corsa program was put on hold, shortly afterwards followed by Motoscafo d’Assalto program. It was not until the end of 1938, when international relations started to worsen up again before the unit received enough funding to start developing both programs again. In September 1939, the unit was renamed to 1° Flottiglia MAS. Capitano di Fregata Paolo Aloisi became the new commander of the unit. He was tasked was to continue training the unit and prepare for future actions.


Barchino Esplosivi in Action.

World War 2 broke and Italy entered the war the unit was not fully prepared for their task. In June 1940 when Italy joined Germany in the attack on France the unit had eleven Siluro a Lenta Corsa’s and the submarine Iride for transport of these vessels. Besides that, it had seven Motoscafo Turismo’s for surface assaults.

On February 24^th, 1940, Paolo Aloisi is replaced by Mario Giorgini as commander of the 1° Flottiglia MAS, the special operations unit of the Regia Marina. While Aloisi is recognised for his technical knowledge, Giorgini earns distinction for his organisational skills. Giorgini selects submarines as the optimal method for deploying Siluro a Lenta Corsa manned torpedoes near enemy ports. In May 1940, he arranges and supervises the first tests involving submarine transport and release of these torpedoes. The submarine Ametista serves as the Siluro a Lenta Corsa carrier, and the obsolete cruiser Quarto, anchored at La Spezia, acts as the target. Giorgini is joined by Teseo Tesei, Elios Toschi, Junio Valerio Borghese, and Gino Birindelli aboard Ametista. During the exercise, three Siluro a Lenta Corsa’s are launched, with one successfully reaching Quarto undetected and attaching a dummy charge to its hull, demonstrating the Siluro a Lenta Corsa’s effectiveness. Following this, Supermarina assigns three submarines, Iride, Gondar, and Scirè, to the 1° Flottiglia MAS.

In June 1940, the unit set up a secret base at Villa Carmella in Spain to attack the harbour of Gibraltar. This base was soon replaced by a secret Siluro a Lenta Corsa base inside an interned ship in the harbour of Algeciras.

In July 1940, Admiral Raffaele de Courten instructs Giorgini to select his four best crews for an assault on the capital ships of the Mediterranean Fleet in Alexandria. Although Giorgini protests that his teams are not yet adequately prepared, he proceeds with the mission. The operation, codenamed G.A.1, ends in failure when, on August 22^nd, 1940, the submarine Iride is sunk by British torpedo bombers in the Gulf of Bomba as it prepares to depart. Giorgini, aboard Iride at the time, narrowly escapes alongside the Siluro a Lenta Corsa operators, but most of the submarine’s crew are killed. The SLC operators, including Tesei, Toschi, Luigi Durand de la Penne, and Birindelli, manage to rescue several survivors from within the wrecked submarine.

A second attempt, G.A.2, is swiftly planned with modifications. The submarine Gondar is equipped with pressurised containers to house the Siluro a Lenta Corsa’s, replacing the previous method of lashing them to the deck. Gondar departs from Messina rather than a lightly defended Libyan anchorage, as Iride had done. Leaving Messina on September 24^th, 1940, Gondar reaches Alexandria during the night of 28-29 September. However, Supermarina informs them that the mission is aborted because the Mediterranean Fleet has departed to escort a convoy to Malta. While en route to Tobruk, Gondar is detected and pursued by H.M.A.S. Stuart and H.M.S. Diamond. Severely damaged by depth charges, Gondar surfaces and is scuttled by its crew. Giorgini, along with the crew and Siluro a Lenta Corsa operators, is captured and interned in a prisoner-of-war camp in India, where he remains for nearly six years.

For a short while during the end of 1940 and at the beginning of 1941 the unit is renamed to Flottiglia MAS Speciale.

On March 15^th, 1941, it receives its final name the X^a Flottiglia MAS. The number in the name is chosen in honour of Julius Caesar’s favorite legion, the Tenth Legion. By that time Capitano di Fregata Vittorio Moccagatta was already commander of the unit and he reorganised it with an underwater and surface assault group. Besides these two assault units he also created several support units.

The unit was disbanded in September 1943 after the Italian armistice. However, the last commander of the X^a Flottiglia MAS, Capitano di Fregata Junio ​​Valerio Borghese chose the side of the Republica Sociale Italiana (RSI). This “Italian” government was created by Germans after the Italian armistice. On September 12^th, 1943, he signed a treaty of alliance with the German Kriegsmarine. Many of his colleagues volunteered to serve with him, and the Decima Flottiglia was revived. Under command of Capitano di Vascello Ernesto Forza another unit was raised that joined the Allied. The unit with the name of the Mariassalto was a combined unit with the British. It had a similar goal as the X^a Flottiglia MAS and was active a few times during the rest of the war.