“Viribius Unitis” An Austro- Hungarian sunk by frogmen during WW1. Old Postcard, unknown source.

During the first years of in their harbours, sur- World War II Italian rounded by mine-fields and anti-submarine frogmen demon- nets. This passivity was, strated to the world in the main, due to the how effective a ongoing submarine war. weapon a In 1915, after Italy had severed its connec- could be. Hidden tions with its German and by the water, these Austrian allies, and joined frogmen mined the the English-French Alliance, Allies’ ships as they Italian naval officers had thought long and hard about were moored ‘safely’ how the Austro-Hungarian fleet in their own waters. could be attacked in the harbour.

TBy Sven Erikh Jørgensene - The DanishF Society ofi Divingr Historys t Frogmen Even with quite small numbers, and using The first attempt, carried out from Viribus Unitis siinking after relatively small resources, the frogmen were Venice, was made by the Italian naval being mined by divers a very powerful . The English, especially, captain Pellegrine, who, with three other were quick to copy the equipment and train crew members in a motor-boat, tried to their own frogmen, and after the war many attack the Austro-Hungarian fleet in Pola. nations supplemented their armed with Pellegine’s boat Grillo was equipped frogmen units. with caterpillar tracks which enabled it The idea of such a weapon arose in World to crawl up over the various barriers in War I, when experiments were carried out us- Pola. Two torpedoes, which hung on the ing different vessels to carry mines into the Aus- side of the boat, were to be sent against tro-Hungarian naval base in Pola. The weapon the ships in the harbour. Pellegrine’s was developed during the inter-war years attempt failed because the boat was discovered as it was forc- 1915 ing a barrier. While the war was raging on the Pellegrine and his of Europe, and submarines were terrorising the crew spent the ships on the high seas, the Austro-Hungarian rest of the war in fleet and Italian fleet lay mostly well protected captivity.

Two attack divers astride a SLC - Siluro a Lenta Corsa (slowlly moving )

67 X-RAY MAG : 7 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED Naval-lieutenant Raffaele Paolucci

Pola, or Pula, lies at the tip of the peninsula of Istria, now in Croatia, at the top of the Adriatic sea

1918 whereby he was to be transported by motorboat to about a sea-mile out of Pola. From here he would swim into the harbour towing a mine. Under one of the he would tie a four meter-long Pellegine’s boat Grillo was equipped with caterpillar tracks which ena- rope to the mine and thereaf- bled it to crawl up over the various barriers in Pola ter sink it by letting the air out of its two floatation tanks. The Mignatta, a other end of the rope was to compressed Captain Constanzo Mignatta close in to Pola. At 22.13 the S2 be fixed to the hull of the ship. air minisub Ciano had been was released from the motorboat and The mine, which contained for carrying watching the efforts sailed in to Pola, which was reached at about 100 kg of TNT, had an divers of the two men, and 02.00 on 1 November, 1918. In the har- automatic timer, and would asked them to cooper- bour the two men passed three anti-sub- explode in about 4 meters of ate with him in com- marine nets by pulling the S2 over them. water close to the side of the pleting the project with Once inside the harbour they steered ship. As soon as the mine was Mignatta. This coop- in between two illuminated battleships activated Paolucci would eration soon proved to and directly towards the 21000 ton bat- swim out of the harbour towards the be effective, and after tleship Viribus Unitis. They fixed one of Targetting Pola outer breakwater and wait for the explo- several tests and modi- the mines and then rapidly sailed away The desire to hit the Austro-Hungarian sion. He would then swim out to sea and, fications Mignatta was – leaving a trail of silvery bubbles. fleet in Pola was, however, undimin- with his back to the enemy, signal to the pressed-air torpedo, named Mignatta, ready for action. Two models of Mignatta On their course away from the battle- ished, and much thought was put into motorboat to pick him up. which, half-submerged, would carry him were built, S1 and S2. ship they were discovered, but before possible . Naval-lieutenant and another crew member into Pola. The being taken prisoner they had managed Raffaele Paolucci worked out a plan in Mignatta men, in diving suits, would sit astride the Now or never to arm the second mine, and then left After months of nocturnal near torpedo and steer it into the harbour and However, in October 1918, an armistice the Mignatta to its own devices. It wan- Venice, towing a mock-up of the mine, thereafter over to one of the battleships. was in the offing, and it was obvious dered around in the harbour, and when Limpret mine being fixed to he abandoned the project. Two mines, each of 170 kg TNT, were that it was now or never if the Mignatta the compressed-air was exhausted it the bottom of a vessel Simultaneously with fixed to the head of the torpedo. The was to see action. In the evening of 31 finally came to rest against one of the the efforts of Paolucci, mines were to be hung in a 4 meter-long October, 1918, a motortorpedo boat ships. Italian engineer and rope under one of the battleships. Rosetti from Venice set sail for Pola. On board naval officer Raffaele had constructed a powerful magnet were Paolucci and Rossetti and, on the War’s over - well almost Rossetti was working which should keep the rope fixed to the deck, the S2 and a motorboat which That they were not discovered before on a modified com- side of the ship. would carry the two men and the was due to the fact that it was a day

Sideview of the Mignatta

68 X-RAY MAG : 7: 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED Italian naval officer was one of the developers of feature Dive History a new branch of underwater weapon

thought to be no reason to keep the The First Frogmen Further developments watertight doors closed. Immediately It was two Italian divers and naval offic- Teschi and Tesei served as after this first explosion a second explo- ers, Teseo Tesei and Elios Toschi, inspired engineers for the subma- sion was heard. It was the second mine, by Rossetti’s Mignatta, who would rines at the naval base at La still attached to the Mignatta, that begin the development of the weapon Specia. The development and exploded directly against the side of the that the world would come to know as construction of an improved 7000 ton freighter Wien, and sent her to “Frogmen”. However, before this weap- Mignetta started in 1935, and in the bottom. Ten days after Viribus Unitis on could be brought into service, diving January two prototypes were had been sunk Germany accepted the suits, apparata and ‘torpe- tested. Later in the year the Armistice conditions, and World War I does’ had to be developed. new weapon was demonstrat- was brought to a close. ed, under the strictest secrecy, for the Admiralty in a dock at New weaponry Divers preparing a limpet the La Spezia basin. The attack at Pola was a suc- mine before a mission cess – the Italian fleet had The Maiale obtained insight into a new The weapon mostly resembled weapon. The weaknesses of a torpedo but was in fact a mini- the weapon were that the ature submarine designated SLC (Siluro a which permitted the crew to increase crew were visible above the Lenta Corsa) with the nickname Maiale or decrease the . A separate surface of the water, and (the pig). The torpedo was 7.3 m long, compartment contained compressed-air that the compressed-air tor- including the explosive head, the diam- tools to cut through a submarine net. A pedo sent out a stream of air- eter was 0.53 m, and two frogmen could screen in front of the leading frogman bubbles. These deficiencies sit astride it. The compressed-air motor protected the crew against the water would have to be corrected had been replaced by a 1.1 HP electric flow. Behing the screen were the steer- so that an attack could be motor. The power of the motor was later ing controls and the luminous navigation carried out with the torpedo increased to 1.6 HP. In 1935 the explosive equipment. The maximum diving depth and crew completely sub- weighed 220 kg, but was later increased was 40 meters. merged, and without air-bub- to 250 kg and thereafter to two amounts The crew wore waterproof Belloni suits bles giving evidence of the of explosive, each of 150 kg. The capac- (Vestito Belloni) constructed by Captain attack. ity of the batteries allowed a voyage of Belloni. The Belloni suit actually consisted 5 seamiles at 2.3 knots or 4 seamiles at of two suits, an inner suit of thin elastic The interwar years 4.5 knots. The torpedo had diving tanks rubber, and an outer suit of heavy can- The only known picture of In the inter-war years another the Viribus Unitis sinking alliance was formed, an alli- The Maiale ance in which Italy was not of festivity in the harbour, where they allied with England. Italy felt were celebrating the capitulation of the itself squeezed between the Austro-Hungarian fleet, which had been English fleet in and handed over to the South Slavic National the French fleet in Toulon. Council. However, Paolucci and Rossetti That England could rapidly had no knowledge of this, and, at 06.20, reinforce their Mediterranean the mine that was placed four meters fleet with units from their under the waterline of the Viribus Unitis Atlantic fleet didn’t make exploded. A quarter of an hour later the the Italian frustrations any the battleship rolled over and sank. less. Italy needed a weapon That it could go so completely wrong that could reduce the scope was due to the fact that there was of a possible blockade.

69 X-RAY MAG : 7: 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED a watertight closure and hidden behind ������������������� the flap in the outer suit. This suit was used by the Italian frogmen throughout the whole war. The English made similar suits, and the principle was employed in ������������������������������� the first suits that were produced after ������������ the war. ������������������������������ ���������������� �� � ������� ���������������� The breathing equipment that was ������������������� required in order to sail completely sub- ��������������������� merged, was initially a modified Davis ����������� jacket – an ascent jacket designed for submarine crews. The equipment had ������������������ a closed-circuit system with manual control of the , and a potassium ����������������������������������������������������������������������������������������������������� cartridge to absorb the carbon-dioxide. Captain Belloni mounted a helmet with two windows onto the equipment and be steered towards enemy ships. a high speed towards the tatget. opinions regarding the weapons were modified it with bigger chalk containers The boat carried a 300 kg explosive The training of the crew started with so strongly diverse that it was necesary and a bigger oxygen supply, thereby charge which detonated on contact great enthusiasm, but not everyone to terminate the project, and the torpe- obtaining a greater operational time. with the objective. At an appropriate dis- was convinced of the effectivity of the does, equipment and boats at the naval- Later, a Pirelli daughter-company pro- tance from the target the rudder was to new weapon – what could two men base in La Spezia were hidden well away duced an oxygen apparatus ‘model 49’ be fixed and the crewman to abandon accomplish against a battleship? Political from curious eyes. for the unit. Dosing of the oxygen was the boat, which would then continue at now continuous, so that the frogmen did not have to keep filling oxygen into the breathing-bags. Model 49 was replaced in1936 by Model 49/bis. This appara- tus was employed The Belloni suit. Picture electronically towards the end of the enhanced from bad original Second World War after which it was vas. The suits collectively comprised a replaced by ‘model single unit. When worn, the inner suit 50’ from Pirelli. This could only be seen at the wrists of the apparatus had one frogman where the cuffs ensured a close large window. Its watertight fit, and at the throat where operational there was also a close watertight fit. In time was the middle of the stomache there was a more than buttoned flap in the outer suit. This flap four hours. The two mines (1) are fixed to the indicating the engines load and con- (18) is opened whereby the SLC dives. covered the opening to the inner suit. At the same front. They are held onto the SLC by sumption. For surfacing the buoyancy can be The opening was a round tube of thin time, fast metalbuckles (4). The mines are hung 10. Lever by which the pump 13 is restored with air from from the tank of rubber which emerged perpendicularly motor-boats under enemy ships by wires trough operated controlling the buoyancy pressurised air (19). from the inner suit around the stomache (called the screw eyes (2) and the detona- and trim by moving water between The frogmen who are subject to a of the frogman. This tube was nicknamed MTM) were tor mechanism (3) activtived. 5. Tiller ballasttanks (11) and (12). The revolu- considerable force from the water ‘the kangaroo’. When the frogman was developed (steering rod), which are connected tions of the engine (14) can controlled while sailing are protected by a dressed the tube was twisted together to which could through wires (6) to rudder (7) and by a wheel over the regulator (15) “windshield” and their legs are held and stabilisor (8) controlling the SLC. which controls the supply from the into position by stirrups (20). At the Console (9) with compass, depht batteries (16). Between the frogmen rear there is another bouyancy tank The later version, Salvus, of the gauge and libelle (measuring there is an container of air for bouy- (21) compensating for the of early adapted ascent jacked angle) Also in same consol there ancy while sailing at the surface (17). I the engine and a toolbox (22) with turned CCR . This ver- is a voltmeter and amperemeter case a rapid descent is desire a valve wirecutters, clamps etc. sion has only one window in the mask

70 X-RAY MAG : 7: 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED The early breathing apparatus model 49/bis - this one with the two windows in the mask

Free-swimming frogmen were also trained, these being designed Gamma-men. Their equipment was modified in several ways in order to make it easier for them move under their own power. The suits were tight- fitting, and they had fins on their feet. The oxygen equipment had a smaller oxygen-cylinder with con- sequently a shorter operation time. The underwater operation time for the Gamma -men was about 40 minutes. The Gamma-men were trained to cover a distance of 6 – 7 km at a speed of more than 1.5 km per hour. The oxygen equipment was only to be used when they were close to the objec- tive. As camouflage the 1938 Gamma-men had a net In 1938 commander Paolo Aloisi was with seaweed over their promoted to head of the First Light heads. It was intended that Flotilla, which consisted of very fast the Gamma-men should be boats. The Ministry also asked Aloisi to brought close to the objective by sub- take over the torpedos as well as the marine or fast motorboat, or that they MTM-boats. Aloisi quickly saw the pos- should operate from a neutral coast. sibilites in these weapons, and under his leadership both Maiale and the Minelaying MTM-boats underwent several improve- Two types of mine were developed, ments. which the Gamma-men could carry In July 1939 the political situation in around their necks or in a belt. Europe was such that it was obvious ‘Leech’ was a mine with 2 kg of that a war was imminent. As a conse- explosive. The mine was held under quence of this, the Naval authorities the ship by means of an inflated rub- asked Aloisi to accelerate the develop- ber bladder which held the mine ment of the weapons and begin the against the bottom of the ship. When training of the crews. The earlier pilots the mine had been placed the Professor Luigi Ferraro, founder of were transferred to the First Light Flotilla Gamma-man activated a detona- Technisub, was one of the select together with the new trainees. The tor which detonated the mine after a Gamma-men and Italian hero. carefully selected crew undertook a given interval. hard physical training as well as a thor- The other type of mine, the propeller on the mine. The pro- ough mental training. ‘Limpet’, contained 4.5 kg of explo- peller first began to turn when sive, and was fixed to the keel by the speed of theship was above The elite means of a clamp. The detonation 4 knots. After a given number of Only the absolutely most suitable were of this mine was arranged so that it revolutions, which corresponded accepted. Those that were found not would sink the vessel out in the open to a given sailed distance, the to be suitable were returned to their sea. The point at which the mine mine exploded. The ship was previous unit with a diving certificate. would explode was controlled by a thus sunk where salvaging of the

71 X-RAY MAG : 7 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED ship and its cargo was impossi- ble or more complicated than in harbour, and the suspicion of a frogman attack probably did not arise. It was originally intended that the torpedoes should be launched from amphibious air- craft, but it was the submarines that were given the job. Several submarines had airtight contain- ers fixed to their decks, each of which could hold a torpedo. The containers were intended to protect the torpedoes from dam- age from depth-bombs and from damage if the submarines were forced down into deeper water.

In containers on a sub The submarine crew could either open the containers while the Illustration of laying a mine under an enemy ship. From the submarine lay awash at the sur- Italian Ministry of Defence. See maintext for explanation face, or they could exit from the submarine while it lay on the ning of 1940. The objective was oped when Italy declared war bottom and thereafter open the the cruiser Quarto which was on England on 10 June 1940. The containers, pull the torpedoes anchored in the bay outside La first attack with Maiale should out and start the operation. Both Spezia. Three Maiales took part in have taken place on the night forms of launch were trained. the exercise, two of them broke between the 25 and 26 August Attempts were made with short- down and couldn’t complete the 1940 against the Engliah war- wave radios with which the crew exercise, but the third managed ships in og Alexandria – but things could find their way back to the to place a dummy mine under turned out quite differently from submarine after the operation Quarto. what the Italians had hoped. had been carried out. The trials A two-year break in the work were not successful and were on the weapons and in the train- To be continued in our next issue thereafter dropped. It was real- ing of the crew meant that the ised that it would not be possible weapons were not fully devel- to bring the torpedoes and crew back with the subma- rine. The crew had to find a neutral coast and drop the torpedoes there. That the crew didn’t have to worry about getting back to the submarine would give them greater motivation for the operation. The first practice attacks were carried out at the begin-

Italian Submarine Scire in the port of La Spezia with containers for two SLCs mounted on her deck

72 X-RAY MAG : 7 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS������ SCIENCE & ECOLOGY� EDUCATION PROFILES��������������������� PORTFOLIO CLASSIFIED