Decima Flottiglia MAS

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Decima Flottiglia MAS
Badge of the Xª MAS
Active	1941–26 April 1945
Country	Italy
Branch	Navy
Type	Naval commandos
Role	Frogmen, manned torpedoes
Nickname	Xª MAS
Equipment	SLC "Maiale" torpedoes MTM "Barchini" motor assault boats
Engagements	Alexandria raid Dec 1941; sank HMS York, HMS Jervis, HMS Eridge and 20 merchant ships
Decorations	Golden Medal of Military Valour
Commanders
Notable commanders	Vittorio Moccagatta Junio Valerio Borghese

The Decima Flottiglia MAS (Decima Flottiglia Mezzi d'Assalto, also known as La Decima or Xª MAS) (Italian for "10th Assault Vehicle Flotilla") was an Italian commando frogman unit of the Regia Marina (Italian Royal Navy) created during the Fascist regime.

The acronym MAS also refers to various light torpedo boats used by the Regia Marina during World War I and World War II.^[1]

In 1943, after the ouster of Italian dictator Benito Mussolini, Italy left the Tripartite Pact and joined the Allies. Many of the Xª MAS men who were stationed in German-occupied northern 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.

See Italian commando frogmen for the COMSUBIN frogman corps currently serving the Italian Republic, and for their post-WWII actions.

Contents 1 Historical background 2 Unit origins 3 Combat record 3.1 Chronicle of operations 3.1.1 1940 3.1.2 1941 3.1.3 1942 3.1.4 1943 3.1.5 1944 4 Service under the RSI 4.1 Ideology 4.2 Relations with the RSI 4.3 Anti-partisan actions 5 Organization of RSI X Mas 6 Summary of Allied ships sunk or damaged by Decima Mas 7 After 1945 8 See also 9 Books 10 References 11 External links

[edit] Historical background

In World War I, on November 1, 1918, Raffaele Paolucci and Raffaele Rossetti of the Regia Marina rode a manned torpedo (nicknamed Mignatta or "leech") into the harbour of Pula, where they sank the Austro-Hungarian/Croatian battleship SMS Viribus Unitis and the freighter Wien using limpet mines. 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 harbor.^[2]

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.

[edit] Unit origins

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 manned torpedoes.

In 1941, Commander Vittorio Moccagatta reorganised 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 manned 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.

[edit] 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 were refloated and returned to action), the heavy cruiser HMS York, the destroyers HMS Jervis and HMS Eridge, and 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, 104 Silver Medals of Military Valour and 33 Bronze Medals of Military Valour.

[edit] Chronicle of operations

[edit] 1940

• June 10, 1940: Mussolini declares war on Britain.
• August 22, 1940: While preparing for an attack on the British naval base at Alexandria, Egypt, the Italian submarine Iride (carrying four Maiale and five two-man crews) and the support ship Monte Gargano are attacked and sunk in the Gulf of Bomba off Tobruk, Libya, by British land-based Fairey Swordfish torpedo bombers. Teseo Tesei survives the attack, but casualties among the submarine crew are heavy.^[3]
• September 21, 1940: The Italian submarine Gondar departs La Spezia for Alexandria, carrying three Maiale and four two-man crews. On the evening of September 30, the Gondar reaches Alexandria, but a British destroyer spots the submarine, attacks and severely damages it, forcing it to the surface. Gondar's crew scuttles their ship and is captured, along with the Decima MAS crewmen (including Elios Toschi.)
• September 24, 1940: The Italian submarine Sciré, commanded by Commander Junio Valerio Borghese, departs La Spezia carrying three manned torpedoes and four crews, for a planned attack on the British naval base at Gibraltar. However, this operation is canceled as the British fleet leaves the harbor before the submarine arrives.
• October 21, 1940: Sciré departs La Spezia and again sails to Gibraltar carrying three manned torpedoes and four crews. The Decima MAS frogmen enter the harbour, but are unable to attack any ships due to technical problems with the torpedoes and breathing equipment. Two crewmen are captured by the British, but the other four (including Teseo Tesei) manage to escape to Spain and return to Italy. Valuable experience is gained in this operation.

[edit] 1941

• March 25, 1941: The Italian destroyers Crispi and Sella depart Leros island in the Aegean at night, each carrying 3 small (2-ton) MTM (Motoscafo da turismo modificato) motor assault boats of the Decima MAS. Each MTM (nicknamed barchini or "little boats") carries a 300 kg (660 lb) explosive charge in its bow. The one-pilot craft are launched by the destroyers 10 miles off Suda Bay, Crete, where several British Royal Navy warships and auxiliary ships are at anchor. The MTMs are specially equipped to make their way through obstacles such as torpedo nets; the pilot steers the assault craft in a collision course at his target ship, and jumps from his boat before impact and warhead detonation. Once inside the bay, the six boats locate their targets: the heavy cruiser HMS York, a large tanker (the Norwegian Pericles of 8,300 tons), another tanker, and a cargo ship. Two MTMs hit the York amidships, flooding her aft boilers and magazines. The Pericles is severely damaged and settles on the bottom, while the other tanker and the cargo ship are sunk. The other barchini apparently miss their intended targets, and one of them is stranded on the beach. All six of the daring Italian sailors are captured. The disabled York is later scuttled with demolition charges by her crew before the German capture of Crete, while the Pericles sinks in May 1941 enroute to Alexandria.

• May 25, 1941: The Sciré departs La Spezia carrying three manned torpedoes. At Cadiz, Spain it secretly loads eight Decima MAS crewmen. At Gibraltar, they find no warships because the HMS Renown, Ark Royal and Sheffield have been ordered to the Atlantic to hunt the German battleship Bismarck. The manned torpedoes once again experience technical problems as they unsuccessfully attempt to attack a freighter. The crew return to Italy via Spain.
• June 26, 1941: An attack on Malta similar to the July 26, 1941 operation (see below) is planned but is canceled due to bad weather.^[4]
• July 26, 1941: Two Maiale and ten MAS boats (including six barchini') unsuccessfully attack the port of Valletta, Malta. The force is detected early on by a British radar installation, but the British hold their fire until the Italians approach to close range. 15 Decima MAS crewmen are killed (including Commander Moccagatta) and 18 captured. Teseo Tesei and Petty Officer Alcide Pedretti on one torpedo are killed by gunfire from Fort St. Elmo as they attempt to destroy the outer defenses of the harbor. Lieutenant Franco Costa and Sgt. Luigi Barla on the other torpedo become lost, scuttle their craft and swim ashore at St. George's Bay two miles NW of Valletta; their Maiale is recovered by the British, the first example they have examined.^[5] All 6 MTMs, both SLCs and two MAS boats are lost. This disaster forces the unit to make a huge reassessment of its operations, and Commander Borghese (now leader of the sub-surface weapons group) is named as the interim commander of the Decima MAS.
• September 10, 1941: The Sciré departs La Spezia carrying three manned torpedoes. At Cadiz, Spain, it secretly loads eight crewmen for them. At Gibraltar, the manned torpedoes sink three ships: the tankers Denbydale and Fiona Shell and the cargo ship Durham. All six crewmen swim to Spain and return safely to Italy, where they are decorated, as are the crew of the Sciré. Borghese is promoted to the rank of captain and is confirmed as the unit commander.
• December 3, 1941: The Sciré departs La Spezia carrying three manned torpedoes. At the island of Leros in the Aegean Sea, six Decima MAS crewmen come aboard, including Lieutenant Luigi Durand de la Penne. On December 19 Sciré releases the manned torpedoes 10 miles from Alexandria harbor, and they enter the harbor when the British open their defenses to let three of their destroyers pass. After many difficulties, de la Penne and his crewmate Emilio Bianchi successfully attach a limpet mine under HMS Valiant but have to surface as they attempt to leave and are captured. Questioned, they refuse to speak, and are detained in a compartment aboard Valiant. Fifteen minutes before the explosion, de la Penne asks to speak to the Valiant's captain, informs him of the imminent explosion, but refuses to give other information. He is returned to the compartment, but both he and Bianchi are not injured by the detonation of the mine. The other four torpedo-riders are also captured, but their mines sink the Valiant, the battleship HMS Queen Elizabeth, the tanker Sagona, and the destroyer HMS Jarvis. Although the two battleships sink in only a few feet of water and are subsequently refloated, they are out of action for over one year.

[edit] 1942

• April 29, 1942: The Italian submarine Ambra departs La Spezia carrying three manned torpedoes. At Leros it secretly loads six crewmen for them. On May 14 Ambra reaches Alexandria to sink a British floating dock, but the Ambra was spotted and could not sink anything. All six torpedo-riders were captured.
• July 1942: Italian frogmen set up in a secret base in the Italian tanker Olterra which was interned in Algeciras near Gibraltar. All materials had to be moved secretly through Spain and this limited operations.
• July 13, 1942: Twelve Italian frogmen swam from the Olterra into Gibraltar harbor and set explosives, and then returned safely. They sank four ships.
• August 29, 1942: Off El Daba, Egypt. The Hunt class destroyer HMS Eridge was torpedoed at close range by an MTSM, a torpedo-carrying version of the MTM. Six of her crew were lost. The Eridge was towed to Alexandria, but soon after was declared a "constructive total loss", and was scrapped in 1946.^[6]
• December 4, 1942: The Ambra left La Spezia to attack Algiers, carrying frogmen and two manned torpedoes. Ten frogmen carrying limpet mines swam with the manned torpedoes, but because of the distance they did not reach the harbor, but attacked ships outside it, sank two and damaged two others.
• December 17, 1942: Six Italians on three torpedoes left the Olterra to attack the three British warships HMS Nelson, HMS Formidable, and HMS Furious in Gibraltar. 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 (who dived with Davis Escape Sets and (up to here) breast stroke swimming and no fins) (Sydney Knowles and Commander Lionel Crabb). Another British patrol boat spotted another torpedo, and chased and shot at it and captured its two crewmen. The remaining torpedo returned to the Olterra without its rear rider.

[edit] 1943

• May 8, 1943: Three Italian manned torpedoes left the tanker Olterra to attack Gibraltar in bad weather and sank three British ships. All returned safely to the Olterra.

• July 25, 1943: Italian dictator Benito Mussolini was replaced by Field Marshal Pietro Badoglio as the head of the Italian government.
• July 1943: Xª MAS sank single frogman sank or crippled the ship Kaituna (10000 tons) at Mersin in Turkey.^[7]
• August 3, 1943: In the evening, three Italian manned torpedoes left the Olterra to attack Gibraltar and sank three ships and returned to the Olterra, but one of their men was captured.
• August 1943: Xª MAS single frogman sank or crippled the Norwegian cargo ship Fernplant (7000 tons) at İskenderun in Turkey.^[8]
• September 8, 1943: The new Badoglio government of Italy signed an armistice with the Allies and changed sides. The Olterra was towed into Gibraltar, and the British found what had happened in it.
• September 1943: During the siege of Leningrad, Russian commando frogmen entered a German naval base at Strelna near Leningrad and destroy combat boats of the Decima MAS.
• October 2, 1943: An attack on Gibraltar using the new and larger replacement for the SLC (the Siluro San Bartolomeo type) is called off due to the Italian surrender.
• October or November, 1943: British frogmen went to Brindisi in Italy, where they were combined with those Italian frogmen who were in the Allied-controlled areas (Italian Co-Belligerent Navy) and those Italian frogmen who had been prisoners in Britain, as a single organization. See British commando frogmen for further underwater action that those Italian frogmen took part in.
• German Admiral Karl Dönitz and RSI naval commander Junio Valerio Borghese planned to attack New York using midget submarines, but this attack never happened.

[edit] 1944

• November 1944: In Livorno (which the Allies had just taken): An Italian frogman (Vago) who had returned home when Italy surrendered, went over to the Allies and helped them as a clearance diver. 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. ^[9]

[edit] Service under the RSI

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. The reputation of the Xª MAS and Captain Borghese 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. ^[10]

[edit] Ideology

The main themes in the Xª MAS's ideology became "honour" in defending Italy from the "betrayal" of the armistice with the Allies, strong anti-semitism in the wake of stronger Nazi influence, and a call to defend the territorial integrity of Italy against the Allies. This was quite ironic, as the Third Reich was already annexing northeastern Italian territories and integrating them directly into the Reich as the Prealpine Operations Zone and Operational Zone Adriatic Coast.

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. ^[11]

[edit] Relations with the RSI

Relationships with the Italian Social Republic were not easy. On January 14, 1944 Mussolini arrested Borghese while receiving him in Garniano, 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.^[12]

[edit] Anti-partisan actions

The Germans used the Decima mostly in anti-partisan actions on land, rather than against the Allies at sea. The Xª MAS became infamous for the numerous war crimes both on partisans and civilians. They are generally considered to have been similar in ferocity to the SS, and it is with this part of their history that most Italians associate the Xª MAS today.

Their war crimes usually took place in small villages, where the partisans were stronger. Some examples:

• Forno: 68 persons, mostly civilians and some partisans, were killed by a combination of German and Xª MAS forces. ^[13]
• Guadine: Random violence to terrorize a population believed to be supporting the rebels, almost complete destruction of the village by fire.^[14]
• Borgo Ticino: Together with the SS, murder of 12 civilians, pillage and destruction of the village by fire on the grounds that three German soldiers had been wounded by partisans.^[15]
• Castelletto Ticino: In order to give "a demonstration of firmness" against "crime", a Xª MAS officer had five petty criminals publicly gunned down, having taken care to gather a large crowd in order to terrorise them.^[16]
• Crocetta del Montello: Episodes of torture with whips and gasoline and summary executions of partisans. ^[17]

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 Tito's partisans. 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. This left many of Borghese's previous companions in the hands of the partisan resistance^{[citation needed]}. Borghese was tried and convicted of war crimes, sentenced to 12 years imprisonment, but 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.

[edit] Organization of RSI X Mas

• 1st Combat Group
  • 'Barbarigo', 'Lupo' battalions
  • 'Nuotatori Paracadutisti' 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
• Naval units
  • Combat swimmers and frogmen

[edit] Summary of Allied ships sunk or damaged by Decima Mas

Date	Place	Ship(s)
March 1941	Suda Bay	Cruiser York Tanker Pericles Tanker (name missing) Steamship (name missing)
September 1941	Gibraltar	Tanker Denby Dale Tanker Fiona Shell Motorship Durham
December 1941	Alexandria	Battleship Queen Elizabeth Battleship Valiant Tanker Sagona Destroyer Jervis
June 1942	Sebastopol	Military transport (Russian) Small craft (Russian) Two Russian submarines
July 1942	Gibraltar	Steamship Meta Steamship Empire Snipe Steamship Shuma Steamship Baron Dougla
August 1942	El Daba	Destroyer Eridge
September 1942	Gibraltar	Steamship Raven's Point
December 1942	Algiers	Steamship Ocean Vanquisher Steamship Berta Steamship Armattan Tanker Empire Centaur Military Transport N.59 (U.S)
May 1943	Gibraltar	Steamship Pat Harrison (U.S) Steamship Mahsud Steamship Camerata
July 1943	Alexandretta	Motorship Orion (Greek)
July 1943	Mersina	Motorship Kaituna
August 1943	Alexandretta	Motorship Fernplant (Norwegian)
August 1943	Gibraltar	Steamship Harrison Gray Otis (U.S) Steamship Stanridge Tanker Thorshovdi (Norwegian)

[edit] After 1945

See Italian commando frogmen.

[edit] See also

• MAS (ship)
• Military history of Gibraltar during World War II

[edit] Books

More information about the Decima Mas is in these books:-

• "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, $27.50 (ISBN 0-306-81311-4)
• "Sea Devils" by J. Valerio Borghese, translated into English by James Cleugh, with introduction by the United States Naval Institute (ISBN 1-55750-072-X)

[edit] References

[edit] External links

• La Decima MAS (Italian)
• Comando Supremo: Italy at War - Italian naval assault units: Decima Flottiglia MAS (English)
• Decima Flottiglia MAS Network (Italian)