| Page Created |
| January 17th, 2025 |
| Last Updated |
| January 17th, 2025 |
| Italy |
 |
| Length |
| 76.0 metres |
| Wide |
| 6.78 metres |
| Draught |
| 5.21 metres |
| Tonnage |
| 1,467 |
| Propulsion |
| diesel-electric engines |
| Armour |
| – |
| Armament |
- four bow 53.3-centimetre torpedo tubes
- four stern 53.3-centimetre torpedo tubes
- 16 torpedoes
- single 100/47-millimetre deck gun, capable of firing 220 rounds
- two twin 13.2-millimetre machine guns
| Marconi-Class Submarine Leonardo Da Vinci |
 |
The Marconi-class submarines were a group of six vessels constructed for the Regia Marina between 1939 and 1940, designed for long-range operations.
The Marconi-class submarines have a surfaced displacement of 1,171 metric tons and a submerged displacement of 1,467 metric tons. Their overall length is 76.0 metres, with a beam of 6.78 metres and a draught of 5.21 metres. These submarines are equipped with diesel-electric propulsion, producing 3,520 horsepower on the surface and 1,500 horsepower when submerged. This power enables a maximum speed of 18 knots on the surface and 8 knots underwater.
The submarines have an operational range of 10,500 nautical miles at 8 knots when surfaced, while their submerged range is limited to 110 nautical miles at 3 knots. The class carries no mines but is armed with 16 torpedoes, distributed across four bow and four stern 53.3-centimetre torpedo tubes. For surface engagements, the submarines are equipped with a single 100/47-millimetre deck gun, capable of firing 220 rounds, and their anti-aircraft defences consist of two twin 13.2-millimetre machine guns.
The crew complement includes seven officers and 50 enlisted men, and the submarines are capable of diving to a maximum depth of approximately 100 metres. Of the six submarines in the class, only Luigi Torelli survived the war, while the others were lost in action.
| Xa Flottiglia MAS |
The Marconi-Class Submarine Leonardo da Vinci is selected as an approacher by its extensive operational range of 10,500 nautical miles at a cruising speed of 8 knots on the surface. This range makes it ideal for long-distance missions as an approacher submarine for the CA-class mini-submarine, which weighs 12–14 tons and is designed to carry eight large explosive charges and a group of Gamma divers. Planned targets include Atlantic and American harbours such as Freetown in Sierra Leone, Cape Town in South Africa, and New York in the United States.
In the summer of 1942, following a routine war patrol in the Atlantic, the Leonardo da Vinci undergoes conversion at the Betasom base in Bordeaux, France, to accommodate a CA 2 mini-submarine that had been transported from Italy by rail. A 10-metre cradle replaces the submarine’s forward 100/47-millimtre deck gun. The cradle is equipped with side coamings, keel blocks, and two retaining clamps operable from inside the submarine to securely hold the mini-sub.
The conversion includes a pipeline linking the mini-sub to the carrier submarine’s compressed air circuit, allowing it to replenish onboard air supplies. Electrical connections are also installed to enable the mini-sub’s batteries to be recharged at sea. To compensate for the weight of the mini-submarine, the deck gun, its ammunition, and approximately 8 tons of lead ballast are removed. The modifications require minimal alterations to the pressure hull and are completed in less than a month.
In September 1942, the Leonardo da Vinci, under the command of Lieutenant Gianfranco Gazzana-Priaroggia, and the CA 2, piloted by Lieutenant Eugenio Massano, carry out a series of trials. These tests include successful release and recovery of the mini-sub, as well as submerged manoeuvres with the mini-sub secured on deck. The results are promising, demonstrating the feasibility of the configuration.
Following the completion of these trials, the Leonardo da Vinci is returned to its original role as a commerce raider in the Atlantic. It resumes operations against Allied merchant shipping, achieving remarkable success.
| H.M.S. Active and H.M.S. Ness Attack |
After completing its final sinking mission in late April 1943, the Leonardo da Vinci begins its return journey to base. On May 22nd, 1943, while off the coast of Spain, the submarine’s commander transmits a signal declaring the vessel’s intention to head for Bordeaux. This decision proves unwise, as the signal is intercepted and its position triangulated through direction-finding techniques.
The following day, May 23rd, 1943, the British destroyer H.M.S. Active and the frigate H.M.S. Ness, both escorting convoys W.S.30 and K.M.F.15. The two convoys are traveling together and will remain so until May 25th, 1943. At 11:30, H.M.S. Active escorting convoy K.M.F.15 en route from the Clyde to Algiers is alerted when a submarine is spotted at a distance of 5,490 metres. Moments later, H.M.S. Ness, screening convoy W.S.30 bound for Bombay, also sights the submarine.
The submarine immediately crash-dives as H.M.S. Active closes in, obtaining a sonar contact at 2,650 metres. At 11:43, H.M.S. Active releases a pattern of ten depth charges, set to detonate at depths of 46 and 91 metres. Seven minutes later, at 11:50, H.M.S. Ness drops another ten depth charges, targeting the same depths. The hunt intensifies as H.M.S. Active delivers a second round of depth charges at 11:58, this time set to 107 and 168 metres. At 12:12, H.M.S. Ness follows with an identical pattern, after which a double explosion is heard by both escorts.
At 12:23, H.M.S. Active executes a third attack with another pattern of ten depth charges, set to detonate at 107 and 168 metres. By 12:40, wreckage begins surfacing, including wood, cork, life jackets, coffee tins labeled “Napoli,” and a pair of human lungs. Despite this evidence of destruction, the escorts continue their operation. At 13:05, H.M.S. Ness releases a final round of ten depth charges, now targeting depths of 152, 168, and 213 metres.
This attack is believed to have sunk the Leonardo da Vinci 480 kilometres west of Vigo at an estimated position of 42°16′0″N 15°40′0″W. The submarine is widely regarded as the most successful submarine in the Regio Marina. Tragically, all 63 crew members, including nine officers and 54 ratings, perish. The submarine’s commander, Gianfranco Gazzana Priaroggia, had been informed of his promotion to Capitano di Corvetta just one week earlier, on May 16th, 1943.
According to German records, Leonardo da Vinci was scheduled to rendezvous at Point Gabel (position BF 9312, 45°33’N, 01°42’W) on May 29th, 1943 at 18:00. Escorts including M 84, M 363, Sperrbrecher 21, and two sub-chasers waited in vain for the submarine until 22:53 before returning to La Pallice.
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