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BETASOM, the Italian submarine base in the Atlantic

by Giulio Poggiaroni

Unknown to many, the Italians participated to the Battle of the Atlantic with a small group of Submarines that fought until 1943, operating form the “Betasom” base.

Early deployments 

The deployment of Italian submarines in the Atlantic began in June 1940, already before the official declaration of war. Five submarines were assigned to the task, but two of them aborted the mission due to a series of inconveniences. 

The other three, “Finzi”, “Pietro Calvi” and “Sebastiano Veniero” reached their ambush zones west of the Canarian islands but sighted no allied ships. The three then returned to Italy, crossing again undetected the strait of Gibraltar. This brief experience underlined the impracticability of operating submarines in the Atlantic from bases in Italy. In July, the Regia Marina proposed to the Kriegsmarine to deploy 25-40 submarines in one of the bases located in occupied France, an option that would have facilitated the conduct of offensive operations. Admiral Dönitz, who at the time could not rely on many submarines, warmly accepted the proposal and thus began the story of the Betasom base.


After the Kriegsmarine approval, Admiral Angelo Parona departed for France, in search of a suitable location that could host the new Italian base.

Admiral Parona, in agreement with Maricosom (the submarine command), selected the port of Bordeaux and, consequently, the Regia Marina issued a directive on the 23 of August 1940 establishing the “Gruppo Sommergibili Atlantici” (Atlantic submarines group), with Admiral Parona in command. Twenty-seven submarines were initially assigned to the new base (codename BETASOM), 10 of the Marcello class, 6 of the Marconi class, 3 of the Calvi and Liuzzi classes, 2 of the Otaria and Argo classes and one of the Brin class. 

These units started to arrive in Bordeaux in September 1940, and although being dependent on the command in Italy, they received operational directives from the Kriegsmarine U-boot command. Given the lack of experience in the Atlantic environment, Dönitz ordered the Italian submarines to operate in the central areas of the Atlantic, less patrolled by enemy warships and with better sea conditions. This should have provided a training ground essential for new future operations in the North Atlantic.

Admiral Dönitz and Admiral Parona

Admiral Dönitz and Admiral Parona


In the first period of operation (June-December 1940), the Betasom submarines managed to sink 18 ships, totalling 69.000 tons for the cost of two submarines lost. Not a great score if compared to the German U-boot performances. The Italians indeed operated in the vast spaces of the central Atlantic, where the allied traffic was less intense (fewer targets available). For a short period, some submarines operated in the North Atlantic alongside the Germans, but with scarce success. 

The first 6 months of Atlantic experienced brought to the surface several problems inherent to Italian submarine warfare: 

  • the Submarines took too much time to submerge
  • the speed was often not sufficient to pursuit enemy targets
  • the visibility of the conning towers facilitated sightings from enemy vessels 
  • commanders and crew had no real training in convoy hunting nor oceanic operations
  • commanders age was often high, thus limiting physical resistance
  • the submarines suffered more from the rough sea conditions of the North Atlantic 

Towards the end of the year, Admiral Parona asked to have some of his men trained at the German submarine school of Gotenhafen. Two submarines were detached there, and the training started in March 1941.

Submarine Calvi protected by mimetic nets in Betasom in 1941

Submarine Calvi protected by mimetic nets in Betasom in 1941


In January 1941, the Italians returned to the central Atlantic area of operations, more suited for their submarines. In May, there was the first offensive operation west of Gibraltar. Seven submarines were deployed and sunk six merchant ships. 

Between May and June, the Germans concluded that it was better to withdraw the Italians from Betasom, this was for three reasons:

  • Low performances
  • Need for bases and space for the increasing numbers of U-boots
  • More forces needed in the Mediterranean

Hitler personally communicated the decision to Mussolini, and the Comando Supremo ordered Supermarina (Regia Marina high command) to dismantle Betasom on the 8th of June. However, Admiral Parona was not happy with the decision and managed to convince Admiral Dönitz to maintain Betasom and leave the larger submarines (eleven in total) not suitable for operations in the Mediterranean. The deteriorating relations between Parona and Maricosom led to his replacement with Commander Romolo Polacchini already in September.

Marines of the “San Marco” regiment in front of submarine Finzi

Marines of the “San Marco” regiment in front of submarine Finzi

In November, the existence of Betasom was put in question once more, this time by the Italians. Marshal Cavallero, chief of General Staff, wanted to withdraw all the Atlantic submarines and use them for transport duties between Italy and Libya. When the decision took shape in December, the Germans intervened and stopped the dismantling of Betasom. The strategic picture had changed and, with the USA entering the war, the Kriegsmarine wanted to use all the available submarine forces.

The balance of 1941 was 33 ships sunk (160.254 tons) at the high cost of 8 submarines lost. 


In January 1942, the Betasom command sent its available submarines (Tazzoli, Da Vinci, Finzi, Torelli and Morosini) to hunt down allied traffic in the area between Florida and the Bahamas. The mission lasted until April and the Italians managed to sink 16 ships (96.077 t), with the Tazzoli sinking 6 of them alone. It was then the turn of the submarine “Calvi” that left for a 52 days-long operation in Brazilian waters where it sunk 5 ships (29.000 t). The summer saw the few remaining Italian submarines sinking 6 more ships (33.000 t) with the loss of the Morosini and Calvi, while the Torelli was severely damaged. 

In October, only the Tazzoli and Da Vinci were available for new offensive operations and managed to sink 4 large merchant ships (totalling 46.000 t).  These two submarines were commanded by Carlo Fecia di Cossato and Gianfranco Gazzana-Priaroggia.

Betasom officers making plans

Betasom officers making plans


At the beginning of 1943, Betasom Commander Enzo Grossi (who had replaced Polacchini back in November) could rely only on eight submarines (Tazzoli, Archimede, Bagnolini, Barbarigo, Cappellini, Torelli, Finzi, Da Vinci) and they departed for the last cycle of offensive operations along the Brazilian and African coasts. The Archimede was lost at the end of February while the mighty Da Vinci was sunk in May by British destroyers while returning from a successful mission in the Indian Ocean where it sunk 6 merchant ships. 

The Italian Atlantic submarines, already few in numbers, were rapidly becoming obsolete and thus the Germans saw the opportunity to send them in the far east to transport strategic materials (like rubber) from the Japanese controlled East Indies. 

Between May and June, the submarines Cappellini, Torelli, Tazzoli, and Barbarigo departed for such missions but only the first two arrived at their destination.

When Italy signed the armistice with the Allies, the Germans sized the last two remaining subs (Bagnolini and Finzi). Officers and men still in Betasom “chose” (the alternative being prison camps or slave labour) to join the new fascist state set-up in German-occupied Italy by Mussolini and returned home.


Giorgerini, G. (1994). Uomini sul fondo.

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