Decima Flottiglia MAS
Ernesto Forza, commander of the Decima Flottiglia Mas from July 1940 to May 1943
ActiveMarch 1941–September 1943
Country Italy
Branch Regia Marina
Commando frogman
RoleHuman torpedo
Nickname(s)Xª MAS
Motto(s)"Memento Audere Semper" (Remember to always be bold) [1]
MarchInno della Xª MAS
EquipmentSLC "Maiale" torpedoes
MTM "Barchini" motor assault boats
EngagementsSouda Bay, Gibraltar, Alexandria, Algiers, sank HMS York and 20 merchant ships
DecorationsGolden Medal of Military Valour
Individual decorations:
29 Golden Medals of Military Valor
104 Silver Medals of Military Valor
33 Bronze Medals of Military Valor
Mario Giorgini
Vittorio Moccagatta
Ernesto Forza
Junio Valerio Borghese

The Decima Flottiglia MAS (Decima Flottiglia Motoscafi Armati Siluranti, also known as La Decima or Xª MAS) (Italian for "10th Assault Vehicle Flotilla") was an Italian flotilla, with marines and commando frogman unit, of the Regia Marina (Royal Italian Navy). The acronym MAS also refers to various light torpedo boats used by the Regia Marina during World War I and World War II.[2]

Decima MAS was active during the Battle of the Mediterranean and took part in a number of daring raids on Allied shipping. These operations involved surface speedboats (such as the raid on Souda Bay), human torpedoes (the raid on Alexandria) and Gamma frogmen (against Gibraltar). During the campaign, Decima MAS took part in more than a dozen operations which sank or damaged five warships (totalling 78,000 tons) and 20 merchant ships (totalling 130,000 GRT).

In 1943, after the Italian dictator Benito Mussolini was ousted, Italy left the Tripartite Pact. Some of the Xª MAS men who were stationed in German-occupied northern and central Italy enlisted to fight for Mussolini's newly formed Italian Social Republic (Repubblica Sociale Italiana or RSI) and retained the unit title, but were primarily employed as an anti-partisan force operating on land. Other Xª MAS men in southern Italy or other Allied-occupied areas joined the Italian Co-Belligerent Navy as part of the Mariassalto (Naval Assault) unit.

Historical background

In World War I, on November 1, 1918, Raffaele Paolucci and Raffaele Rossetti of the Regia Marina rode a human torpedo (nicknamed Mignatta or "leech") into the harbour of Pula, where they sank the battleship Jugoslavija, of the navy of the State of Slovenes, Croats and Serbs, formerly the Austro-Hungarian battleship SMS Viribus Unitis, and the freighter Wien using limpet mines.[3] They had no underwater breathing sets, and thus had to keep their heads above water to breathe. They were discovered and taken prisoner as they attempted to leave the harbour.[4]

In the 1920s, sport spearfishing without breathing apparatus became popular on the Mediterranean coast of France and Italy. This spurred the development of modern swimfins, diving masks and snorkels.

In the 1930s Italian sport spearfishermen began using industrial or submarine-escape oxygen rebreathers, starting scuba diving in Italy.

Unit origins

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This new type of diving came to the attention of the Regia Marina which founded the first special forces underwater frogman unit, later copied by the Royal Navy and United States Navy. Capitano di Fregata (Commander) Paolo Aloisi was the first commander of the 1ª Flottiglia Mezzi d'Assalto ("First Assault Vehicle Flotilla"), formed in 1939 as a result of the research and development efforts of Majors Teseo Tesei and Elios Toschi of the naval combat engineers. The two resurrected Paolucci's and Rossetti's concept of human torpedoes.

In 1941, Commander Vittorio Moccagatta re-organised the First Flotilla into the Decima Flottiglia MAS, and divided the unit into two parts – a surface group operating fast explosive motor boats, and a sub-surface weapons group using human torpedoes called SLC (siluri a lenta corsa or "slow-running torpedoes", but nicknamed Maiale or "Pig" by their crews), as well as "Gamma" assault swimmers (nuotatori) using limpet mines. Moccagatta also created the frogman training school at the San Leopoldo base of the Italian Naval Academy in Livorno.

Combat record

The Decima MAS saw action starting on June 10, 1940, when Fascist Italy entered World War II. In more than three years of war, the unit destroyed some 72,190 tons of Allied warships and 130,572 tons of Allied merchant ships. Personnel from the unit sank the World War I-era Royal Navy battleships HMS Valiant and HMS Queen Elizabeth (both of which, after months of work, were refloated and returned to action), wrecked the heavy cruiser HMS York and the destroyer HMS Eridge, damaged the destroyer HMS Jervis and sank or damaged 20 merchant ships, including supply ships and tankers. During the course of the war, the Decima MAS was awarded the Golden Medal of Military Valour and individual members were awarded a total of 29 Golden Medals of Military Valour,[a] 104 Silver Medals of Military Valour and 33 Bronze Medals of Military Valour.


Italian Maiale human torpedo "Siluro San Bartolomeo" displayed at the Royal Navy Submarine Museum, Gosport, UK.


Wreck of HMS York inspected by the crew of the Italian torpedo boat Sirio, moored alongside
The remains of St. Elmo Bridge in Valletta, which was destroyed in the attack of 26 July 1941



This drawing shows the Norwegian tanker Thorshøvdi, broken in two by human torpedoes launched from the Italian base-ship Olterra, August 1943


Summary of Allied ships sunk or damaged by Decima MAS

Date Place Ship(s)
26 March 1941 Suda Bay Cruiser HMS York (8250 t standard displacement) [b]
Tanker Pericles (8234 t)[c]
19 September 1941 Gibraltar Tanker Denby Dale (8145 t)[d]
Tanker Fiona Shell (2445 t)[e]
Motorship Durham (10900 t) [f]
19 December 1941 Alexandria Battleship HMS Queen Elizabeth (30600 t)[g]
Battleship HMS Valiant (30600 t)[h]
Tanker Sagona (7554 t)[i]
Destroyer HMS Jervis (1690 t)[j]
13 June 1942 Sebastopol Military transport (USSR)[k]
14 July 1942 Gibraltar Steamship Meta (1575 t)[l]
SS Empire Snipe (2497 t)[m]
Steamship Shuma (1494 t)
Steamship Baron Douglas (3899 t)
29 August 1942 El Daba Destroyer HMS Eridge (1050 t)[n]
15 September 1942 Gibraltar Steamship Raven's Point (1787 t)[o]
12 December 1942 Algiers Steamship Ocean Vanquisher (7174 t)[p]
Steamship Berta (1493 t)[q]
Steamship Armattan (6587 t)[14]
Tanker Empire Centaur (7041 t) (repaired)[14]
USN Military Transport N.59[14]
8 May 1943 Gibraltar Steamship Pat Harrison (U.S.) (7191 t)[r]
Steamship Mahsud (7540 t)
Steamship Camerata (4875 t)
30 June 1943 İskenderun Motorship Orion (Greek) (7000 t)[s]
9 July 1943 Mersin Motorship Kaituna (4914 t)[s]
1 August 1943 İskenderun Motorship Fernplant (Norwegian) (7000 t)[s]
4 August 1943 Gibraltar Steamship Harrison Gray Otis (U.S.) (7176 t)[t]
Steamship Stanridge (5975 t)[u]
Tanker Thorshøvdi (Norwegian) (9944 t)[v]

Successor units

Guardiamarina (Ensign) of the Barbarigo Battalion standing in viale Carso near piazza Bainsizza, in Rome, during a review parade by General der Luftwaffe Kurt Mälzer before being sent to face the Allied beachhead at Anzio-Nettuno, March 1944.

Following the armistice of Italy on September 8, 1943, the Xª MAS was disbanded. The Badoglio government in the south of Italy under Allied occupation declared war on Germany and became a co-belligerent. Some Decima MAS sailors joined the Allied cause to fight against Nazi Germany and what remained of the Axis as part of the Italian Co-Belligerent Navy. A new unit was formed, led by Forza and joined by some of the pioneers such as de la Penne newly released from British POW camps. The new unit was named Mariassalto, but continued to be an elite naval force mounting special operations at sea.

In the German-occupied north of Italy. Mussolini set up the Italian Social Republic (Repubblica Sociale Italiana, or RSI) to continue the war as part of the Axis. Led by Borghese, Decima Flottiglia was revived, as part of the National Republican Navy (Marina Nazionale Repubblicana) of the RSI with its headquarters in Caserma del Muggiano, La Spezia. By the end of the war, it had over 18,000 members, and although Borghese conceived it as a purely naval unit, it gained a reputation as a savage pro-fascist, anti-communist, anti-resistance force in land campaigns alongside the German forces, under the command of SS General Karl Wolff.


ActiveOctober 1943–April 26, 1945
Country Kingdom of Italy
BranchItalian Co-Belligerent Navy
TypeNaval commandos
RoleHuman torpedo
EngagementsRaid on Genoa
Raid on La Spezia
Ernesto Forza

The Mariassalto was set up at Taranto alongside the British frogman force in the Mediterranean. Forza was pleased to demonstrate Italian expertise in this area to the British,[15] and the group was also keen to be in action, though if they were caught they would almost certainly have been shot.[16]

In June 1944 came an opportunity to take action, in Operation QWZ, a joint mission against targets in La Spezia harbour. The attack was against the Italian cruisers Bolzano and Gorizia, which had been taken by the Germans after the Italian surrender. This was to thwart a German plan to sink them where they would block the harbour entrance. The mission also aimed to attack German U-boats in the harbour. British chariots would attack the cruisers whilst Mariassalto's Gamma Frogmen would attack U-boats penned in the harbour. On 2 June 1944 the Italian destroyer Grecale sailed from Bastia in Corsica to La Spezia carrying three speedboats, and Italian frogmen including Luigi Durand De La Penne, and two British chariots. One chariot broke down and was abandoned, though the other successfully sank Bolzano. However, the Gamma men were unsuccessful in their attack on the U-boat pens. All the participants escaped, linking with partisan groups on land.[16]

In April 1945 a final mission, Operation Toast, was planned.[17] This was aimed at sinking the newly converted shipping liner now the aircraft carrier Aquila, just completed in Genoa. For this Mariassalto men would make use of two British chariots, as they had none of their own SLCs available. On 18 April 1945 the destroyer Legionario, carrying two high-speed motorboats equipped with chariots sailed from Venice for Genoa led by Captain Chavasse SOE and Forza. Both chariots were deployed and succeeded in penetrating the defences but found the hull of Aquila so encrusted with barnacles and seaweed the limpet mines could not be attached to it. The frogmen had to lay the charges on the seafloor of the outer harbour mole and when the charge exploded as planned the ship remained afloat in spite of the attack. All of the frogmen escaped safely. The German commander never put his extensive demolition plans for Genoa into action and thus Aquila was never sunk as a blockade to the harbour.

Decima MAS (RSI)

Decima Flottiglia MAS
ActiveSeptember 1943–26 April 1945
Country Italian Social Republic
Naval commandos
RoleAmphibious warfare
Close-quarters combat
Direct action
Nickname(s)Xª MAS
Motto(s)Memento Audere Semper (Remember to dare always)
Junio Valerio Borghese
Junio Valerio Borghese (right) and Umberto Bardelli of the Decima MAS.

Some Xª MAS men who were in German-occupied Italy remained part of the Axis forces, joining the Italian Social Republic under the command of Captain Borghese. His reputation and that of the Xª MAS enabled him to negotiate an agreement with the German forces that gave the Xª MAS significant autonomy, allowed them to fight under an Italian flag (under the command of the Germans), and not to be employed against other Italians. Borghese was recognized as the leader of the corps.[18]


The main themes in the Xª MAS's ideology became "honour" in defending Italy from the "betrayal" of the armistice with the Allies and a call to defend the territorial integrity of Italy against the Allies. The corps had its own weekly magazine, L'orizzonte ("The Horizon"), in which authors such as Giovanni Preziosi wrote vehemently anti-Semitic articles about Jewish conspiracies. The magazine had problems in its distribution, as it was thought that Borghese's popularity among the Fascist hardliners might reduce Mussolini's influence.[19]


Relations with the RSI

Marines of the Decima, in 1944

Relationships with the Italian Social Republic were not easy. On January 14, 1944 Benito Mussolini arrested Borghese while receiving him in Gargnano, in order to gain direct control of the Xª MAS. Word of the arrest reached the officers of the Decima, who considered marching on Mussolini's capital at Salò. However, the German command used their influence to have Borghese released, as they needed the equipment, expertise and manpower of the Xª MAS as an anti-partisan force.[20]

Naval actions

The Xª MAS (RSI) took little part in the war at sea. Its equipment had been abandoned in the south, and its naval activities were frustrated by Allied action.[15] In November 1944 four frogmen (Malacarne, Sorgetti, Bertoncin, Pavone), who had stayed under German command, were delivered by fast motorboat and swam into Livorno harbor to set up a secret sabotage base, but were captured.[21]

Anti-partisan actions

Ferruccio Nazionale, Italian partisan hanged by the Xª MAS in Ivrea. The sign says: "He attempted to shoot the Decima"

The Decima was mostly employed in anti-partisan actions on land, rather than against the Allies at sea. However, their actions were mostly reprisals following the massacre of soldiers of "Decima" by partisans forces – see Bardelli's homicide. Their anti-partisan actions usually took place in small villages, where the partisans were stronger. Some examples:

Defense of Italian national borders

However, the Xª MAS units also earned a good combat reputation fighting on the frontline against the Allies at Anzio and on the Gothic Line. In the last months of the war Xª MAS units were dispatched to the eastern Italian border against Josip Broz Tito's partisans who marched into Istria and Venezia Giulia.


On April 26, 1945, in what is now the Piazza della Repubblica in Milan, Borghese finally ordered the Xª MAS to disband. He was soon arrested by partisans, but rescued by OSS officer James Angleton, who dressed him in an American uniform and drove him to Rome for interrogation by the Allies. Borghese was tried and convicted of war crimes, and sentenced to 12 years imprisonment, but was released from jail by the Italian Supreme Court in 1949. The Americans were keenly interested in infiltrating the Italian Communist groups, something which Borghese had done, and he was enlisted to help create counterintelligence units for the Americans.

Organization of RSI Xa MAS

After 1945

Further information: Italian commando frogmen

In 2006 the admiralty of the Italian republic recognized the Xth M.A.S. RSI veterans as combatants of WWII and gave the association the battle flag.

Counter-operations against Italian frogmen by British frogmen in Gibraltar was the subject of a 1958 British film The Silent Enemy based on the exploits of the team of Lionel Crabb.

Today the Comando Raggruppamento Subacquei e Incursori Teseo Tesei is the frogman corp currently serving the Italian Republic.

In popular culture

Prince Valerio Borghese escaped capital punishment after the war (thanks to James Jesus Angleton of the CIA) in the cold war context and remained an active neo-fascist activist: He attempted a failed fascist coup in the early 1970s (the infamous golpe Borghese). The Golpe Borghese and its leader are spoofed in a film by Mario Monicelli called Vogliamo i Colonelli (We want the Colonels) where Borghese part is played by Italian actor Ugo Tognazzi impersonating an ultra right-wing parliament representative called Tritoni (Triton or Newt). One of the best scenes features a boisterous and crazy assault diver and parachute Commando frogman called Barbacane (Giuseppe Maffioli).

See also


  1. ^ The highest number awarded to personnel serving in any single unit of the Italian armed forces.
  2. ^ Disabled by two MT explosive speedboats piloted by Lt.(jg) Angelo Cabrini and SCPO Tullio Tedeschi. Abandoned and never repaired.
  3. ^ Sunk by an MT explosive speedboat piloted by PO2 Lino Beccati.
  4. ^ Sunk by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Licio Visintini and PO1 Giovanni Magro.
  5. ^ Disabled by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Amedeo Vesco and PO1 Antonio Zozzoli. Later repaired and returned to service.
  6. ^ Damaged by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Decio Catalano and PO1 Giuseppe Giannoni. Later repaired and returned to service.
  7. ^ Sunk in shallow water by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Antonio Marceglia and PO1 Spartaco Schergat. Later raised from the bottom and repaired.
  8. ^ Sunk in shallow water by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Luigi Durand De La Penne and MCPO Emilio Bianchi. Later raised from the bottom and repaired.
  9. ^ Damaged by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Vittorio Martellotta and PO1 Mario Marino. Later repaired and returned to service.
  10. ^ Damaged by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Vittorio Martellotta and PO1 Mario Marino. Later repaired and returned to service.
  11. ^ Damaged by MTSM 210 torpedo speedboat piloted by Lt.(jg) Aldo Massarini and PO1 Eliodoro Grillo. Later sunk by German aircraft while being towed back to port.
  12. ^ All damaged by limpet mines positioned by assault frogmen (Lt.(jg) Agostino Straulino and Giorgio Baucier, SCPO Alfredo Schiavoni, PO1 Alessandro Bianchini, E4 Giovanni Lucchetti, Carlo Del Valle, Giuseppe Ferodi, Vago Giari and Evideo Boscolo, E3 Bruno Di Lorenzo, Rodolfo Lugano and Carlo Bucovaz).
  13. ^ Repaired and returned to service in October 1942.
  14. ^ Disabled by MTSM 210 torpedo speedboat piloted by Lt.(jg) Piero Carminati and E4 Cesare Sani. Never repaired.
  15. ^ Sunk by limpet mines positioned by assault frogman E3 Bruno Di Lorenzo.
  16. ^ Sunk during a combined raid of human torpedoes (Lt.(jg) Giulio Arena and E4 Ferdinando Cocchi; Ens. Giorgio Reggioli and E4 Colombo Pamolli) and assault frogmen (Lt.(jg) Agostino Morello, PO1 Oreste Botti, E4 Giuseppe Ferodi and Evideo Boscolo, Sgt. (Army) Luigi Rolfini and Alberto Evangelisti).
  17. ^ Sunk
  18. ^ All disabled by explosive charges positioned by three human torpedoes (Lt.Ernesto Notari and E4 Ario Lazzari; Lt.(jg) Camillo Tadini and E4 Salvatore Mattera; Lt.(jg) Vittorio Cella and E4 Eusebio Montalenti.
  19. ^ a b c unk by limpet mines positioned by assault frogman Lt. (Blackshirts) Luigi Ferraro.
  20. ^ Sunk by an explosive charge positioned by the human torpedo piloted by Lt. Ernesto Notari and E4 Andrea Gianoli.
  21. ^ Sunk by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Camillo Tadini and E4 Salvatore Matera.
  22. ^ Sunk by an explosive charge positioned by the human torpedo piloted by Lt.(jg) Vittorio Cella and E4 Eusebio Montalenti.


  1. ^ [1] Archived June 25, 2007, at the Wayback Machine
  2. ^ [2] Archived December 19, 2007, at the Wayback Machine
  3. ^ Quick, D. (1970). "A History Of Closed Circuit Oxygen Underwater Breathing Apparatus". Royal Australian Navy, School of Underwater Medicine. RANSUM-1-70. Archived from the original on 9 May 2008. Retrieved 20 March 2009.((cite journal)): CS1 maint: unfit URL (link)
  4. ^ "Trenches on the Web – Special Feature: Assault on the Viribus Unitis". Retrieved 18 August 2015.
  5. ^ "Principal Operations of the 10th Light Flotilla". Archived from the original on 17 April 2009.
  6. ^ a b pp 6-11, issue 39, Historical Diving Times
  7. ^ Our Name Wasn't Written — a Malta Memoir, Caroline Vernon, Canberra, 1992, p36 ISBN 0-646-07198-X
  8. ^ "Ernesto FORZA - Capitano di Fregata". Archived from the original on 21 June 2007. Retrieved 17 September 2009.
  9. ^ Kemp p51
  10. ^ "Scire' 2008 : Archaeological Survey" (PDF). Retrieved 18 August 2015.
  11. ^ "HMS Eridge, escort destroyer". Retrieved 18 August 2015.
  12. ^ Kemp p57
  13. ^ a b Jørgensen 2005, p. 93.
  14. ^ a b c Damaged
  15. ^ a b Kemp p61
  16. ^ a b Kemp p63
  17. ^ [3][dead link]
  18. ^ "Il Mito della difesa del fronte orientale". Retrieved 18 August 2015.
  19. ^ "Junio Valerio Borghese". Retrieved 18 August 2015.
  20. ^ "Junio Valerio Borghese". Retrieved 18 August 2015.
  21. ^ pp 16-20, issue 41, The Historical Diving Times, ISSN 1368-0390
  22. ^ " – Documento Tribunale Militare di La Spezia" (PDF) (in Italian). Retrieved 1 September 2012.
  23. ^ "Junio Valerio Borghese". Retrieved 18 August 2015.
  24. ^ "Stragi Guadine". Retrieved 18 August 2015.
  25. ^ "Stragi eccidio di borgo ticino". Retrieved 18 August 2015.
  26. ^ "Stragi Castelletto Ticino". Retrieved 18 August 2015.
  27. ^ "L'eccidio di Crocetta del Montello (TV)". Retrieved 18 August 2015.


Further reading