Decima Flottiglia MAS
Teseo Tesei, Italian naval officer who organized the Decima Flottiglia MAS and pioneered the use of underwater raids
Active	March 1941–September 1943
Country	Italy
Branch	Regia Marina
Type	Marines Commando frogman
Role	Human torpedo Raiding Sabotage
Nickname	Xª MAS
Motto	"Memento Audere Semper" (Remember to always be bold)[1]
March	Inno della Xª MAS
Equipment	SLC "Maiale" torpedoes MTM "Barchini" motor assault boats
Engagements	Souda Bay,Gibraltar,Alexandria,Algiers, sankHMS York and 20 merchant ships
Decorations	Golden Medal of Military Valour Individual decorations: 29Golden Medals of Military Valor 104Silver Medals of Military Valor 33Bronze Medals of Military Valor
Commanders
Notable commanders	Mario Giorgini Vittorio Moccagatta Ernesto Forza Junio Valerio Borghese

TheDecima Flottiglia MAS (Decima Flottiglia Motoscafi Armati Siluranti, also known asLa Decima orXª MAS) (Italian for "10th Torpedo-Armed Motorboat Flotilla") was an Italianflotilla, withmarines andcommando frogman unit, of theRegia Marina (Royal Italian Navy). The acronymMAS also refers to various lighttorpedo boats used by the Regia Marina duringWorld War I andWorld War II.^[2]

Decima MAS was active during theBattle of the Mediterranean and took part in a number of daring raids on Allied shipping. These operations involved surfacespeedboats (such as theraid on Souda Bay),human torpedoes (theraid on Alexandria) andGammafrogmen (againstGibraltar). 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 dictatorBenito Mussolini wasousted, Italy left theTripartite Pact. Some of the Xª MAS men who were stationed in German-occupied northern and central Italy enlisted to fight for Mussolini's newly formedItalian 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 theItalian Co-Belligerent Navy as part of theMariassalto (Naval Assault) unit.

InWorld War I, on 1 November 1918, Raffaele Paolucci andRaffaele Rossetti of theRegia Marina rode ahuman torpedo (nicknamedMignatta or "leech") into the harbour ofPula, where they sank the battleshipJugoslavija, of the navy of theState of Slovenes, Croats and Serbs, formerly theAustro-HungarianbattleshipSMS Viribus Unitis, and thefreighterWien usinglimpet mines.^[3] They had nounderwater 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, sportspearfishing without breathing apparatus became popular on theMediterranean coast ofFrance and Italy. This spurred the development of modernswimfins,diving masks andsnorkels.^{[citation needed]}

In the 1930s Italian sport spearfishermen began using industrial or submarine-escape oxygenrebreathers, startingscuba diving in Italy.^{[citation needed]}

This new type of diving came to the attention of the Regia Marina which founded the firstspecial forces underwater frogman unit, later copied by theRoyal Navy andUnited States Navy.Capitano di Fregata (Commander) Paolo Aloisi was the first commander of the1ª Flottiglia Mezzi d'Assalto ("First Assault Vehicle Flotilla"), formed in 1939 as a result of the research and development efforts ofMajorsTeseo Tesei and Elios Toschi of the navalcombat engineers. The two resurrected Paolucci's and Rossetti's concept of human torpedoes.

In 1941, CommanderVittorio Moccagatta re-organised the First Flotilla into theDecima Flottiglia MAS, and divided the unit into two parts – a surface group operating fast explosive motor boats, and a sub-surface weapons group usinghuman torpedoes calledSLC (siluri a lenta corsa or "slow-running torpedoes", but nicknamedMaiale 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 theItalian Naval Academy inLivorno.

TheSiluro Lenta Corsa (SLC, slow speed torpedo), known asMaiale (pig), was designed by Tesei and Toschi during 1935 and 1936. By late 1939 about eleven were ready and in July 1940 the production version, Series 100, began to arrive. In 1941 the improved Series 200 became ready for use. The standard 533 mm (21.0 in) torpedo with double propellers was changed to one larger propeller in a cowling; seats for a two-man crew were installed, with shields housing the controls. The SLC weighed 1.3–1.4 long tons (1.3–1.4 t) and was 22–24 ft (6.7–7.3 m) long. The 1.6 hp (1.2 kW) electric motor moved themaiale at 2–3 nmi (3.7–5.6 km; 2.3–3.5 mi) at a maximum depth of 50 ft (15 m). At the target the crew detached a 6 ft (1.8 m)-long warhead with 510 to 570 lb (230 to 260 kg) of explosive, detonated by a timer. Themaiale crews the Gamma frogmen wore Belloni rubberised suits with a closed-circuit re-breathing apparatus to avoid bubbles. The Gamma frogmen carried explosive charges, five 9.9 lb (4.5 kg)cimici (bedbugs) or two 26 lb (12 kg)bauletti, (little trunks) and attached them to a ship's hull, with a timed detonation.^[5][a]

Maiali and SLCs needed transport close to the target because the re-breather lasted no more than six hours andmaiali had a range of only 4 nmi (7.4 km; 4.6 mi) at full speed and a maximum of 15 nmi (28 km; 17 mi) at cruising speed.^[5] The modified destroyersFrancesco Crispi andQuintino Sella, had carried the MTM used in the successfulRaid on Souda Bay (25/26 March 1941). TheMotoscafo trasporto lento (MTL, slow transport motorboat) was a wooden-hulled boat 28 ft (8.5 m) long by 9 ft 6 in (2.9 m) wide, to carrymaiali close to the target. The MTL had a range of only 60 nmi (110 km; 69 mi) cruising at 5 kn (9.3 km/h; 5.8 mph), few were built and they were rarely used. Surface transport gave way to submarines; early in 1940 the Italian submarine Ametista began tests as amaiale transport. The maximum depth of submersion was only 98 ft (30 m); Italian submarine Iride was converted in July 1940 but was sunk on 21 August. Italian submarine Gondar was sunk on 30 September, even though the threemaiali cylinders could be flooded, allowing the boat to reach a depth of 295 ft (90 m).^[7]

The firstMotoscafo turismo (MT) became known asbarchini (little boats) were built in late 1938, six MT being delivered in early 1939. An improved versionMT Modificato (MTM) tested in November 1940, was 20 ft (6.1 m) long. Both types carried an explosive charge of 660–730 lb (300–330 kg) in the bows at up to 31 kn (57 km/h; 36 mph). The MTM was fitted with a seat back/life raft behind the pilot for him to float on after dropping off the MTM, while waiting to be rescued. Twelve MTs were built and about forty MTMs. Early in 1941, a smallerMT Ridotto was built with a height of 3 ft 9 in (1.14 m) to fit inside the deck cylinders of submarines with the same explosive charge but they were never used in this manner.^[8]

TheMT Siluranti (MTS, torpedo motorboat), was a small boat carrying one or two modified 450 mm (18 in) torpedoes, the MTS being more manoeuvrable than the usualMotoscafo armato silurante. The first MTS, of early 1941, could reach 28 kn (52 km/h; 32 mph) with a range of 85 nmi (158 km). TheDecima MAS was assisted byRegia Marina MAS boats, which by June 1940, had fifty Class 500 MAS and another 25 in 1941 in four versions. The Class 500 was 61 ft (18.7 m) long by 15 ft (4.7 m) wide at the beam, with a displacement of 21.7–28.9 long tons; 24.3–32.4 short tons (22–29.4 t). The MAS had a crew of 9 to 13 men and had two 18 in (450 mm) torpedoes, 6–10 depth charges and a 13.2 mm (0.52 in) heavy machine-gun (replaced in 1941 with a Breda 20 mm cannon). The MAS could move at 44 kn (81 km/h; 51 mph) and had a range of 348–864 nmi (645–1,600 km).

The Decima MAS saw action starting on 10 June 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-eraRoyal Navy battleshipsHMS Valiant andHMS Queen Elizabeth (both of which, after months of work, were refloated and returned to action), wrecked theheavy cruiserHMS York and thedestroyerHMS Eridge, damaged the destroyerHMS Jervis and sank or damaged 20merchant ships, including supply ships and tankers. During the course of the war, the Decima MAS was awarded theGolden Medal of Military Valour and individual members were awarded a total of 29Golden Medals of Military Valour,^[b] 104Silver Medals of Military Valour and 33Bronze Medals of Military Valour.

• 10 June 1940:Benito Mussolini declared war onUnited Kingdom.
• 22 August 1940: While preparing for an attack on the British naval base atAlexandria,Egypt, the Italian submarineIride (carrying fourMaiale and five two-man crews) and the support shipMonte Gargano were attacked and sunk in theGulf of Bomba offTobruk,Libya, by British land-basedFairey Swordfishtorpedo bombers. Teseo Tesei survived the attack, but casualties among the submarine crew were heavy.^[10]
• 21 September 1940: The Italian submarineGondar departedLa Spezia for Alexandria, carrying threeMaiale and four two-man crews. TheGondar reached Alexandria on the evening of 30 September, but was spotted by British and Australian destroyers, which attacked. Severely damaged, it was forced to the surface and scuttled by the crew. They were captured, along with the Decima MAS crewmen (including Elios Toschi).
• 24 September 1940: The Italian submarineSciré, commanded by CommanderJunio Valerio Borghese, departed La Spezia carrying three human torpedoes and four crews, for a planned attack on the British naval base atGibraltar. The operation was cancelled when the British fleet left harbour before the submarine arrived.
• 21 October 1940:Sciré departed La Spezia and sailed again to Gibraltar carrying three human torpedoes and four crews. TheDecima MAS frogmen entered the harbour, but were unable to attack any ships due to technical problems with the torpedoes and breathing equipment. Only one human torpedo managed to get close to a target, the battleshipBarham. The charge exploded but did not cause significant damage. The two crewmen, Gino Birindelli and Damos Paccagnini, were captured by the British. The other four (including Teseo Tesei) manage to reachSpain and returned to Italy. Valuable experience was gained in this operation by the Decima.Gino Birindelli received theMedaglia d'Oro al Valor Militare (MOVM), his second, Damos Paccagnini received theMedaglia d'Argento al Valore Militare (MAVM).

• 25 March 1941: The Italian destroyersFrancesco Crispi andQuintino Sella departedLeros island in theAegean at night, each carrying 3 small (2-ton)Motoscafo da Turismo motor assault boats of the Decima MAS. Each MT (nicknamedbarchini or "little boats") carried a 300 kg (660 lb) explosive charge in itsbow. The one-pilot craft were launched by the destroyers 10 miles offSuda Bay,Crete, where several British Royal Navy warships and auxiliary ships were at anchor. The MTs were specially equipped to make their way through obstacles such astorpedo nets; the pilot steered the assault craft in a collision course at his target ship, and jumped from his boat before impact and warhead detonation. Once inside the bay, the six boats located their targets: theheavy cruiserHMS York, a large tanker (the NorwegianPericles of 8,300 tons), another tanker, and a cargo ship. Two MTMs hitYork amidships, flooding her aft boilers and magazines.Pericles was severely damaged and settled on the bottom, while the other tanker and the cargo ship were sunk. The otherbarchini apparently missed their intended targets, and one of them was stranded on the beach. All six of the Italian sailors were captured. The disabledYork was later scuttled in shallow waters with demolition charges by her crew before theGerman capture of Crete, whilePericles sank in April 1941 en route to Alexandria.
• 25 May 1941: TheSciré departed La Spezia carrying three human torpedoes. AtCádiz,Spain it secretly embarked eight Decima MAS crewmen. At Gibraltar, they found no warships becauseRenown,Ark Royal, andSheffield had been ordered to theAtlantic to hunt the German battleshipBismarck. The torpedoes once again experienced technical problems as they unsuccessfully attempted to attack a freighter. The crew returned to Italy via Spain.
• 26 June 1941: An attack on Malta similar to the 26 July 1941 operation (see below) was planned but was canceled due to bad weather.^[11]

• 26 July 1941: TwoMaiale and ten MAS boats (including sixbarchini)unsuccessfully attacked the port ofValletta,Malta. The force was detected early on by a Britishradar installation, but the Britishcoastal batteries held their fire until the Italians approached to close range. FifteenDecima MAS crewmen were killed (including Commander Moccagatta), and 18 were captured. Teseo Tesei andPetty OfficerAlcide Pedretti [it] on one torpedo died byFort St. Elmo as they attempted to destroy the outer defenses of the harbour.Lieutenant Franco Costa andsergeant Luigi Barla on the other torpedo became lost, scuttled their craft, and swam ashore at St. George's Bay two miles NW of Valletta. TheirMaiale was recovered by the British, becoming the first example they had been able to examine.^[11] All 6 MTMs, both SLCs and two MAS (MAS 451 and MAS 452^[12]) boats were lost, one of them being found adrift in open seas by the British and towed to port by a seaplane. This disaster forced the unit to make a huge reassessment of its operations. CommanderErnesto Forza was named as commander of the Decima MAS,^[13] and Borghese became leader of the sub-surface weapons group.^[14]
• 10 September 1941: TheSciré departed La Spezia carrying three human torpedoes. At Cádiz, Spain, it secretly embarked eight crewmen for them. At Gibraltar, the torpedoes sank three ships: thetankersDenbydale andFiona Shell, and thecargo shipDurham. All six crewmen swam to Spain and returned safely to Italy, where they were decorated, as were the crew ofSciré.
• 3 December 1941:Sciré departed La Spezia carrying three human torpedoes to conduct what became theRaid on Alexandria (1941). At the island ofLeros in theAegean Sea, six Decima MAS crewmen came aboard, includingLieutenantLuigi Durand de la Penne. On 18 DecemberSciré released the torpedoes 1.3 miles from Alexandria commercial harbour, and they entered the harbour when the British opened the boom defence to let three of theirdestroyers pass. After many difficulties, de la Penne and his crewmate Emilio Bianchi successfully attached a limpet mine underHMS Valiant, but had to surface as they attempted to leave, and were captured. They refused to answer when questioned and were detained in a compartment aboardValiant. Fifteen minutes before the explosion, de la Penne asked to speak to theValiant's captain and informed him of the imminent explosion but refused to give other information. He was returned to the compartment and neither he nor Bianchi were injured by the detonation of the mine. The other four torpedo-riders were also captured, but their mines sankValiant, the battleshipQueen Elizabeth, and the Norwegian tankerSagona, and badly damaged the destroyerHMS Jervis. The two battleships sank in only a few feet of water and were subsequently re-floated and repaired, being out of action for over a year.

• 29 April 1942: The Italian submarineAmbra departed La Spezia carrying three human torpedoes. AtLeros six crewmen were secretly loaded for them. On 14 MayAmbra reached Alexandria and sank a British floating dock. TheAmbra was spotted and could not sink anything. All six torpedo-riders were captured.
• July 1942: Italian frogmen set up a secret base in the Italian tankerOlterra which wasinterned inAlgeciras near Gibraltar. All materials had to be moved secretly through Spain and this limited operations.
• 13 July 1942: Twelve Italian frogmen swam from the Algeciras coast into Gibraltar harbour and set explosives, and then returned safely. Four ships were sunk.
• 10 August 1942: TheItalian submarineScirè was sunk byHMSIslay while attempting to attack the port ofHaifa in BritishPalestine. She had 11 frogmen on board.^[15]
• 29 August 1942: OffEl Daba, Egypt. TheHunt-classdestroyerHMS Eridge was torpedoed at close range by anMTSM, a torpedo-carrying version of theMTM. Six of her crew were lost.HMS Eridge was towed to Alexandria, but soon after was declared a "constructive total loss", and was scrapped in 1946.^[16]
• 4 December 1942: TheAmbra leftLa Spezia to attackAlgiers, carrying frogmen and two human torpedoes. Ten frogmen carrying limpet mines swam with the human torpedoes, but because of the distance, they did not reach the harbour, but attacked ships outside it, sank two and damaged two others.
• 17 December 1942: Six Italians on three torpedoes left theOlterra to attack the three British warshipsNelson,Formidable, andFurious in Gibraltar. A British patrol boat killed one torpedo's crew (Lt. Visintini and Petty Officer Magro) with adepth charge. Their bodies were recovered, and theirswimfins were taken and used by two of Gibraltar's British guard divers. Another British patrol boat spotted another torpedo, and chased and shot at it and captured its two crewmen. The remaining torpedo returned to theOlterra without its rear rider.

• 8 May 1943: Three Italian human torpedoes left theOlterra to attack Gibraltar in bad weather and sank two British freighters and an AmericanLiberty ship. All returned safely to theOlterra.

• May 1943: Borghese becomes unit commander when Forza returned to sea^[17]
• 25 July 1943: Italian dictatorBenito Mussolini was replaced by Field MarshalPietro Badoglio as the head of the Italian Government.
• 9 July 1943: Xª MAS single frogman sank or crippled the shipKaituna (4,917 tons) atMersin inTurkey.^[18]
• 3 August 1943: In the evening, three Italian human torpedoes left theOlterra to attack Gibraltar. They sank three cargo ships, one of them an AmericanLiberty and returned to theOlterra. One of the Italian divers was captured.
• 1 August 1943: Xª MAS single frogman sank or crippled the Norwegian cargo shipFernplant (7,000 tons) atİskenderun inTurkey.^[18]

• 8 September 1943: The new Badoglio government of Italy signed an armistice with the Allies. TheOlterra was towed into Gibraltar, and the British found what had happened in it. Further attacks on Gibraltar using the new and larger replacement for the SLC (theSiluro San Bartolomeo type), and a planned raid onNew York City were called off due to the Italian surrender.

Following thearmistice of Italy on 8 September 1943, theXª MAS was disbanded.The Badoglio government in the south of Italy under Allied occupation declared war on Germany and became aco-belligerent.Some Decima MAS sailors joined the Allied cause to fight against Nazi Germany and what remained of the Axis as part of theItalian 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 BritishPOW camps.The new unit was namedMariassalto, but continued to be an elite naval force mounting special operations at sea.

In the German-occupied north of Italy. Mussolini set up theItalian 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 inCaserma 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 ofSS GeneralKarl Wolff.

Mariassalto
Active	October 1943–26 April 1945
Country	Kingdom of Italy
Branch	Italian Co-Belligerent Navy
Type	Naval commandos
Role	Human torpedo Raiding Sabotage
Equipment	Chariot
Engagements	Raid on Genoa Raid on La Spezia
Commanders
Notable commanders	Ernesto Forza

TheMariassalto was set up atTaranto alongside theBritishfrogman force in the Mediterranean. Forza was pleased to demonstrate Italian expertise in this area to the British,^[20] and the group was also keen to be in action, though if they were caught they would almost certainly have been shot.^[21]

In June 1944 came an opportunity to take action, in Operation QWZ, a joint mission against targets inLa Spezia harbour.The attack was against the Italian cruisersBolzano andGorizia, 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 whilstMariassalto's Gamma Frogmen would attack U-boats penned in the harbour.On 2 June 1944 the Italian destroyerGrecale sailed fromBastia inCorsica toLa Spezia carrying three speedboats, and Italian frogmen includingLuigi Durand De La Penne, and two British chariots.One chariot broke down and was abandoned, though the other successfully sankBolzano. However, theGamma men were unsuccessful in their attack on the U-boat pens. All the participants escaped, linking with partisan groups on land.^[21]

In April 1945 a final mission, Operation Toast, was planned.^[22] This was aimed at sinking the newly converted shipping liner now the aircraft carrierAquila, just completed in Genoa.For thisMariassalto men would make use of two British chariots, as they had none of their own SLCs available.On 18 April 1945 the destroyerLegionario, 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 ofAquila 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 Flottiglia MAS
Active	September 1943–26 April 1945
Country	Italian Social Republic
Branch	Navy
Type	Marines Naval commandos
Role	Amphibious warfare Anti-partisan Close-quarters combat Counter-insurgency Counterintelligence Direct action Raiding Reconnaissance Sabotage
Nickname	Xª MAS
Motto	Memento Audere Semper (Remember to dare always)
Commanders
Notable commanders	Junio Valerio Borghese

Some Xª MAS men who were in German-occupied Italy remained part of theAxis forces, joining theItalian 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.^[23]

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 asGiovanni Preziosi wrote vehemently anti-Semitic articles aboutJewishconspiracies. The magazine had problems in its distribution, as it was thought that Borghese's popularity among the Fascist hardliners might reduce Mussolini's influence.^[24]

Relationships with the Italian Social Republic were not easy. On 14 January 1944Benito Mussolini arrested Borghese while receiving him inGargnano, in order to gain direct control of the Xª MAS. Word of the arrest reached the officers of theDecima, who considered marching on Mussolini's capital atSalò. 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.^[25]

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.^[20]In November 1944 four frogmen (Malacarne, Sorgetti, Bertoncin, Pavone), who had stayed underGerman command, were delivered by fast motorboat and swam intoLivorno harbor to set up a secret sabotage base, but were captured.^[26]

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

• Forno 68 persons, civilians and some partisans, were killed by SS men and Xª MAS forces.^[27][28]
• Guadine Random violence to terrorize a population believed to be supporting the rebels, almost complete destruction of the village by fire.^[29]
• Borgo Ticino Together with the SS, murdered 12 civilians, pillage and destruction of the village by fire because three German soldiers had been wounded by partisans.^[30]
• Castelletto Ticino To give a demonstration of firmness against crime, an Xª MAS officer had five petty criminals publicly shot, in front of a large crowd.^[31]
• Crocetta del Montello: Episodes oftorture withwhips andgasoline andsummary executions of partisans.^[32]

However, the Xª MAS units also earned a good combat reputation fighting on the frontline against the Allies atAnzio and on theGothic Line. In the last months of the war Xª MAS units were dispatched to the eastern Italian border againstJosip Broz Tito'spartisans who marched intoIstria andVenezia Giulia.

On 26 April 1945, in what is now the Piazza della Repubblica inMilan, Borghese finally ordered the Xª MAS to disband. He was soon arrested by partisans, but rescued by OSS officerJames 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 createcounterintelligence units for the Americans.

• Naval units
  • Combat swimmers and frogmen
• 1st Combat Group
  • 'Barbarigo', 'Lupo' battalions
  • 'NuotatoriParacadutisti' Parachute battalion
  • 'Colleoni' artillery battalion
  • 'Freccia' Engineer battalion – 1st company only
• 2nd Combat Group
  • 'Valanga' Assault Engineer battalion
  • 'Sagittario', 'Freccia', and 'Fulmine' battalions
  • 'Castagnacci' recruitment and replacement battalion
  • 'Da Giussano' artillery battalion
  • 'Freccia' engineer battalion – 2nd and 3rd companies
• 8 independent infantry battalions
• 5 independent infantry companies
• Women's Auxiliary Service

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 filmThe Silent Enemy based on the exploits of the team ofLionel Crabb.

Today theComando Raggruppamento Subacquei e Incursori Teseo Tesei is the frogman corp currently serving theItalian Republic.

• The Decima MAS' Gibraltar operations are depicted in the 1952 Italian filmI sette dell'Orsa maggiore and the 1958 British filmThe Silent Enemy.
• The Uniforms of the Decima Flottiglia MAS are used by the collaborationists in the filmSalò o le 120 giornate di Sodoma.
• TheRaid on Alexandria in 1941 is depicted in the 1962 British filmThe Valiant.
• In the Italian filmMy Brother is an Only Child, set in the 1960s, a young Communist refers to the Decima Mas, and their "dungeon" onVia Tasso.

Prince Valerio Borghese escaped capital punishment after the war (thanks toJames 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 infamousgolpe Borghese).The Golpe Borghese and its leader are spoofed in a film byMario Monicelli calledVogliamo i Colonelli (We want the Colonels) where Borghese part is played by Italian actorUgo 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).

• Italian auxiliary ship Olterra – Undercover Italian auxiliary ship from World War II
• Brandenburgers – Members of the German Brandenburg special forces unit during WWII
• Fukuryu – Japanese divers intended to manually detonate mines on invading ships
• Comando Raggruppamento Subacquei e Incursori Teseo Tesei – Italian special forces diving unit, theCOMSUBIN
• MAS (motorboat) – Boat used by the Italian Royal Navy
• Military history of Gibraltar during World War II

• Caruana, J. (1991). "Decima Flotilla Decimated".Warship International.XXVIII (2):178–186.ISSN 0043-0374.
• Crociani, P.; Battistelli, P. P. (2013).Italian Navy & Air Force Elite Units & Special Forces1940–45. Elite (No. 191) (ePub ed.). Oxford: Osprey.ISBN 978-1-78096-372-3.
• Jørgensen, Sven Erik."The First Frogmen 2: Naval Operations with the SLC"(PDF).X-Ray Mag: International Dive Magazine.8. Copenhagen: AquaScope Media ApS:85–93.ISSN 1901-9238.

• "Frogmen First Battles" by retired U.S Captain William Schofield's book (ISBN 0-8283-2088-8)
• "The Black Prince and the Sea Devils: The Story of Valerio Borghese and the Elite Units of the Decima Mas", by Jack Greene and Alessandro Massignani, Cambridge, Mass.:Da Capo Press, 2004 284 pages, hardcover (ISBN 0-306-81311-4)
• "Sea Devils" by J. Valerio Borghese, translated into English by James Cleugh, with introduction by theUnited States Naval Institute (ISBN 1-55750-072-X)
• Paul Kemp :Underwater Warriors (1997)ISBN 1-85409-455-6

• The origin of the Xa Flottiglia MAS
• La Decima MAS(in Italian)
• [4] Image of Italian wartime frogman with rebreather whose breathing tube andfullface mask resemble an old type ofgasmask, but with the mask's blowoff valve blanked off.

• Military units and formations of Italy in World War II
• Italian special forces of World War II
• MAS fleet
• Military units and formations established in 1941
• Military units and formations disestablished in 1943
• Military units and formations established in 1943
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