Italian Naval Special Operations


Uomini Gamma. Divers of the special units of the Italian Navy.


Italian Maiale manned 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.


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

The Italian Navy had successfully employed novel attack methods using special light craft (including underwater vehicles) against the Austrian fleet in the First World War. Renewed interest in these special attack methods began in 1935, but it initially came from the bottom up, via a couple of Regia Marina shore-based engineers, who began work on what eventually became the ‘piloted torpedo.’ In fact, despite the fact that their viability had been vividly demonstrated in the previous war, the attempt to re-start development of such specialized equipment and tactics at first met with an incomprehensible bureaucratic resistance. The personnel involved in these efforts were only allowed to work on them in the hours available after completing their normal daily duties’ or on their own personal time. And in 1936 the project was suspended completely, due mainly to the fact that Cavagnari and the ‘gun club’ believed that they would be superfluous weapons in a war decided by the battleships in major fleet actions (though Cavagnari and the submarine commander Falangola had both originally approved the project). This decision was only reversed in 1939, and so most assault methods were not fully ready for action until 1941-42.

There were four basic methods of attack incorporated in the special unit known by the cover name 10th MAS (‘decima mas’ to the Italians). Most effective were the piloted torpedoes’ (‘siluranti pilotati’), a small underwater vehicle built using an actual (but highly-modified) torpedo body, on which two crewmen fitted with breathing apparatus sat, straddling it as if riding a horse. The ‘piloted torpedo’ had a detachable 300-pound explosive warhead with a timer fuse, which would be slung beneath the keel of the target vessel’ the intent being to attack the enemy fleet in harbor after a stealthy underwater approach. The ‘piloted torpedoes’ were at first usually delivered to the vicinity of the enemy base by conventional submarines, although these were modified with the installation of three waterproof containers on the deck for the ‘torpedoes’ (safe at depths of up to 300 feet).

There were also under development larger underwater vessels, these being legitimate midget submarines. The Italians had two models, the two-man CA and the four-man CB (both types mounting two 450mm torpedo tubes). Neither, however, was ready for service before 1942, whereas the ‘piloted torpedoes’ were actually employed operationally in 1940, albeit ineffectively because technical preparation of both the ‘piloted torpedoes’ and in some cases the launch submarines had not been completed.

The 10th MAS also had surface elements, mainly in the form of small, fast motorboats. The ‘explosive motorboat’ was an actual bomb, loaded with 660 pounds of explosives, and set to crash into enemy ships by its single operator, who after locking the controls bailed out over the stern on to a special raft when 100 yards or so from the target vessel. The ‘assault motorboat’ was a bigger, two-man craft, fitted with a pair of torpedoes outboard. Both types could operate from shore bases, but due to their short range were often carried aboard larger surface ships and launched as close as possible to their intended target area (destroyers Crispi and Sella performed this duty for the successful Suda Bay operation, picket ship Diana in the disastrous July 1941 Malta attack’ later several small freighters were also modified to serve as launch ships).

Finally, the unit employed the simple method of specially-trained swimmers with breathing gear, towing mines.

The wartime operations of 10th MAS began with a series of bitter failures. In August 1940, prior to a planned assault on the main British Mediterranean Fleet base at Alexandria, the poorly-prepared launch sub Iride was sunk by British planes, a sitting duck on the surface because it could not dive with the ‘ piloted torpedoes’ on deck. In September 1940 twin attacks were nonetheless planned against Alexandria and Gibraltar. But again the launch sub for the Alexandria operation (Gondar, which had waterproof containers for its ‘piloted torpedoes’) was sunk, in this case by a British destroyer and a Sunderland flying boat. Meanwhile, Borghese in Scire successfully delivered his ‘piloted torpedoes’ to the immediate approaches of the British base at Gibraltar, and the ‘torpedoes’ penetrated the fleet anchorage, but due to defects in the ‘piloted torpedoes’ they all sank before reaching position to emplace their mines (one getting within less than 100 yards of battleship Barham).

There would be other failures for 10th MAS during the war’ for instance, sub Scire was sunk with all hands (including the crews of its ‘piloted torpedoes’) off Haifa in August 1942, after Borghese had moved on to other assignments. The most traumatic blow came in July 1941, an ambitious attempt to penetrate Malta’ s Grand Harbor by surface attack’ the plan was for ‘piloted torpedoes’ to blow a gap in the harbor boom, allowing ‘explosive motorboats’ to enter and target shipping just arrived in a major convoy. However, the Italians were detected by British radar on their approach, and massacred by Malta’ s efficient shore defenses, a grievous loss of 33 highly-trained specialists (15 killed, including 10th MAS commander Vittorio Moccagatta).

Despite these setbacks, from 1941 the special attack methods of 10th MAS achieved an impressive series of successes. The first was in March 1941, when ‘explosive motorboats’ entered the British naval base at Suda Bay on Crete, hitting the British heavy cruiser York (which was beached as a result, never to sail again), and also sinking tanker Pericles. In September 1941, the ‘piloted torpedoes’ had their first success, as three deposited off Gibraltar by Scire sank British fleet oiler Denbydale, small tanker Fiona Shell, and 11,000-ton merchantman Durham in the roadstead. December 1941 saw the greatest achievement for 10th MAS during the war, when Borghese and Scire deployed three ‘piloted torpedoes’ to Alexandria, their crews severely damaging battleships Queen Elizabeth (sank but settled in shallow water: raised and repaired, but out of action a year and a half) and Valiant (out eight months: of the ten First World War battleships possessed by the Royal Navy at the start of the war, Queen Elizabeth and Valiant’ along with Warspite’ were the only ones that had undergone complete modernization refits). The third ‘piloted torpedo’ in this attack mined tanker Sagona (so badly damaged that henceforth it was only used as a stationary fuel bunker: destroyer Jervis, tied alongside Sagona for fueling, was also damaged by the blast, and was under repair for a month).

The 10th MAS never replicated such spectacular results again, but did continue to strike blows. In July 1942, ‘frogman’ swimmers, covertly based at a house on the neutral Spanish shore nearby, sank four small freighters (Meta, Shuma, Snipe, and Baron Douglas, total about 11,000 tons) at Gibraltar. In September 1942 these swimmers sank another small merchantman at Gibraltar, Raven’ s Point. In December 1942 the 10th MAS tried to counterattack a target of opportunity following the Allied ‘Torch’ landings in French North Africa. The submarine Ambra (which had since been converted to carry ‘piloted torpedoes,’ in order to make up for previous submarine losses of 10th MAS) penetrated the harbor of Algiers, still crammed with Allied military shipping, and after a careful reconnaissance (one officer swam to the surface with a telephone connection to the submarine to survey the scene and pick targets before the actual launch), deployed three ‘piloted torpedoes’ plus swimmers. The results were somewhat disappointing to the Italians, after such a well-prepared attack: the small Norwegian freighter Berto (1,400 tons) was sunk, and freighters Ocean Vanquisher (7,000 tons), Empire Centaur (7,000 tons), and Armattan (4,500 tons) damaged.


The Italians had meanwhile devised a new way to attack Gibraltar’ s naval base. They converted the derelict Italian freighter Olterra, interned by neutral Spain at Algeciras, just across the bay from Gibraltar, into a secret base for ‘piloted torpedoes,’ complete with a hidden underwater sally port (reportedly taking great care to hide these extensive preparations from the neutral Spanish, although some collusion with sympathetic members of Franco’ s government was suspected). In May 1943 three ‘piloted torpedoes’ from Olterra sank freighters Pat Harrison (7,000 tons), Marhsud (7,500 tons), and Camerata (4,800 tons). In August 1943 ‘piloted torpedoes’ from Olterra struck Gibraltar again, sinking tanker Thorshoud (10,000 tons) along with merchantmen Harrison Grey Otis (7,000 tons) and Stanbridge (6,000 tons). And in July 1943, in an even more novel form of assault, a specialist swimmer, Lt. Luigi Ferraro, was smuggled into neutral Turkey (along with a supply of mines), with help from undercover agents of SIS in a special operation. Ferraro’ s task was to mine merchant ships of combatant nations in neutral Turkish harbors, using mines with long delay fuses. He claimed one victim sunk, the Greek steamer Orion (4,800 tons)’ the mine exploding a week after he planted it’ and managed to mine three other ships. One of these, the 4,900-ton freighter Kaituna, was damaged when one of the mines went off, but this prompted an examination which found a second, unexploded mine. The British then carefully inspected all the other ships in the area, finding and disarming Ferraro’ s mines on the two other vessels.

Elements of 10th MAS were also deployed to the Black Sea in 1942, in response to a German request for help. These included six of the CB-type midget submarines, getting their first operational use. In June 1942, during the Axis blockade of Sebastopol (the main Soviet base in the Crimea) CB-3 sank the Russian Stalin-class submarine S-32, and three days later CB-2 sank the smaller Shchuka-class sub Shch-306. The ‘assault motorboats’ also claimed to have sunk a 3,000-ton Soviet freighter with no survivors in operations interdicting traffic to Sebastopol. The ‘assault motorboats’ had one success in the Mediterranean, when a unit based in North Africa struck British destroyer Eridge while the latter was conducting shore bombardment operations. Eridge was towed back to Alexandria, but damage was so severe that the ship was subsequently written off rather than repaired.

Perhaps the most ambitious project of 10th MAS was one which never came to fruition. There were plans in 1942 to attack New York harbor using the smaller CA-type midget submarine. The submarine Da Vinci was removed from normal operations in the Atlantic and modified as a launch sub for this mission’ mainly by having its deck gun removed so that a single ‘CA’ midget submarine could be carried on its foredeck in a special cradle that was installed. But the operation was postponed and then eventually cancelled, Da Vinci having its deck gun remounted and returning to normal commerce raiding activities.

The term MAS also came to mean Mezzi d’Assalto, (Assault Vehicle) in the unit name Flottiglia MAS (Assault Vehicle Flotilla), the most famous of which was the Decima MAS of World War II.

Notable war actions performed by MAS include the torpedoing of the Royal Navy C-class cruiser HMS Capetown by MAS 213 of the 21st MAS Squadron working within the Red Sea Flotilla off Massawa, Eritrea; and the failed attack on the harbour of Malta in January 1941, which caused the loss of two motorboats, one of them recovered by the British. Five MAS were scuttled in Massawa in the first week of April 1941 as a part of the Italian plan for the wrecking of Massawa harbor in the face of British advance. MAS 204, 206, 210, 213, and 216 were sunk in the harbor; four of the boats were in need of mechanical repairs and couldn’t be evacuated. On 24 July 1941, MAS 532 torpedoed and crippled the transport Sydney Star, which managed to limp to Malta assisted by the destroyer HMAS Nestor. MAS 554, 554 and 557 also sank three allied freighters on 13 August 1942, in the course of Operation Pedestal, for a total tonnage of 28,500 tn. On 29 August 1942, a smaller type of MAS boat, the MTSM, torpedoed and disabled for the rest of the war the British destroyer HMS Eridge off El Daba, Egypt.

Four MAS served at German request as Black Sea reinforcement in their intended attack on Sevastopol in June 1942. The MAS squadron came under intense air attack from Soviet fighter-bombers and torpedo boats but performed well in the role. They sank a 5,000 ton steamer and disabled a 10,000 ton transport, which was subsequently destroyed by Stuka dive-bombers. MAS boats destroyed troop barges and damaged Soviet warships. One MAS boat commander was killed in battle. One MAS was destroyed and three damaged by fighter-bombers in September 1942 during a heavy attack on Yalta.

The obsolescence of small MAS became apparent during the conflict, and they were increasingly replaced by larger Yugoslavian E-boats built in Germany and local copies of them (classified “MS” – Moto Siluranti by the Regia Marina).

Indeed, the Decima Mas did plan many spectacular missions for Italian midget submarines. Attacks on the British base at Freetown, Sierra Leone, on the west coast of Africa – and incredibly, on harbours along the east coast of the USA. The Freetown plan, for which the sub C.A.1 was allocated, was abandoned when it was decided that British defensive measures allowed no chance of success. However, the attack on New York reached an advanced stage. The operation was planned for December 1943.

Quoting from Richard O’Neill’s ‘Suicide Squads’ book:

‘ In mid-1942, in preparation for the New York raid, C.A.2 was transported overland to Bordeaux(France), where “Betasom”, headquarters for Italian submarines operating in the Atlantic, was commanded by Capt Enzo Grossi. There, too, came the Marconi-class submarine Leonardo da Vinci of 1,190/1,489 tons (1209/1513 tonnes), selected as the midget’s carrier. Under the direction of Cdr Borghese and SubLt Massano, Italian workshops at Bordeaux under Major (naval rank) Fenu removed Da Vinci’s 3.9-inch (100mm) gun and in its place, just forward of the conning-tower, constructed a semi-recessed “pouch” with retaining shackles for C.A.2. This arrangement led to the mother boat being designated the Canguro (“Kangaroo”). Sea trials under Borghese’s command proved to his satisfaction that the midget could be launched from the submerged Kangaroo and could be recovered when the mother boat surfaced beneath it. The latter point was important in avoiding any indication that the projected mission was regarded as suicidal: just so had the IJN made “official” plans to recover its midgets after Pearl Harbor.

According to Borghese, the Kangaroo (not Da Vinci, which was sunk by British warships off the Azores in May 1943) would launch its midget while submerged off New York Bay. C.A.2 (or, in the later stages of the operational planning, the near identical C.A.3 or C.A.4) would make its way by night into the crowed harbour at the mouth of the Hudson. Two of the three crewmen, in frogmen’s gear, would leave the boat to plant time-fused explosive charges-eight 220lb (100kg) charges and twenty 4.4lb (2kg) “limpets” were carried-under ships and against dock installations. Then C.A.2 would slip downriver to make rendezvous at sea with Kangaroo.’

Many operational and technical difficulties made this operation very dubious: the assumption that New York harbour defences were weak and that the range of the C.A. series (no more than 70nm (129km) was sufficient for the craft to remain up the Hudson River for two days). ‘Yet according to Borghese, only Italy’s collapse in September 1943 prevented the mission from being carried out, as planned, in December of that year.’

The explosive boat concept was adopted by the German Navy and ‘The Black Prince’ Cdr. J. Valerio Borghese, remaining faithful to the Axis cause even after Italy’s surrender, passed on his experience to German volunteers. Indeed the Italian military/navy pre-war had taught the Germans aerial torpedo bombing…and some other things as well…

Before Italy’s collapse, however, two abortive missions were launched with the smaller MTR explosive boats. In mid-1943, following the Allied invasion of Sicily, it was planned to attack shipping in Syracuse harbour with MTRs. The submarine Ambra (Lt. Cdr. Renato Ferrini), carrying three MTRs in deck cylinders originally designed for transportation of Maiale (“pig” Italian manned torpedo with detachable warhead with two crew), stood off Syracuse on the night of 25th July 1943. But the activities of German U-Boats had put the harbour defences on full alert: picked up on the radars of patrolling aircraft, Ambra was bombed, depth charged, and forced to retire with heavy damage, including the crushing of the MTRs cylinders.

A similar mission was planned for 2nd October 1943, when the submarine Murena (Cdr. Longanesi), equipped with four transportation cylinders, was to launch four MTRs from the Spanish side of the Algerciras Bay. The boats were to make their way along the neutral shore and, at 1100 hours, carry out a near-suicidal daylight attack on merchant shipping at Gibraltar. In the resultant confusion, it was hoped, a Maiale launched from a secret base aboard the Olterra* would penetrate the military harbour and attack the largest warship in sight. The operation was forestalled by Italy’s surrender on 8th September 1943.


*Olterra was an Italian freighter had been deliberately sabotaged at the beginning of the war and lay half-sunken in Spanish territorial waters. On the pretext of being repaired and handed over to Spain, she was raised and towed into Algeciras harbour, across the bay from the Allied military anchorage. In her hold was Maiale and Italian navy men, who slipped out through an underwater door for a series of raids on the Algeciras roadstead between September 1942 and August 1943 damaging 11 Allied merchant ships totaling some 55, 700 tonnes. At the time of Italy’s collapse, preparations were being made aboard Olterra to launch the newly-received SSB-type Maiale against Gibraltar.



1 thought on “Italian Naval Special Operations

  1. Pingback: Maiale | Weapons and Warfare

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