Cagni - class submarine The Cagni - or " Ammiraglio Cagni " - class was a class of submarine s built for Italy ' s " Regia Marina " during World War II . Design . These submarines were designed as commerce raiders for oceanic operations . They had high endurance and a large torpedo load for extended patrols . A smaller 450 mm torpedo was chosen , rather than the standard 533 mm , as the Italians believed this was adequate to deal with merchant ships . The boats were designed to have the range to sail non - stop from Italy to Kismayu , Italian Somaliland where a new submarine base was to be built . In order to operate in the Indian Ocean Monsoon the submarines were fitted with large conning towers and armed with two 100 mm guns . The large conning towers were rebuilt to a smaller German style as a result of war experience . The " Ammiraglio Cagni " carried out a 4 . 5 month patrol in the South Atlantic during 1942 - 43 . The other three boats were used as transport submarines to supply Italian forces in North Africa . Ships . All four boats were built by CRDA Monfalcone , laid down in 1939 and completed in 1941 12 more boats were planned for the 1940 and 1941 ship building programmes but were cancelled as a result of the outbreak of World War II Operational history . Ammiraglio Cagni . Her first operational patrols were in the Mediterranean , doing five transport missions and 16 patrols . Her first mission in the Atlantic was of 136 days , sinking the British tanker " Dagomba " and the Greek sloop " Argo " 29 November 1942 . Ammiraglio Cagni was used in two theatres , the Mediterranean and South - Atlantic / Indian Ocean . She made 21 sorties in the Mediterranean , and 2 sorties in the South Atlantic / Indian Ocean in 1942 – 43 . On 9 September 1943 , while on her 2nd Atlantic sortie , she received news of the armistice . She surrendered to the British in Durban on 20 September 1943 . HMS " Jasmine " took part in the formal surrender . Mediterranean Missions : While under the command of Lieutenant Commander Charles Liannazza , on 15 October 1941 , she sailed from Taranto to Bardia , with a cargo of 140 tonnes of fuel cans and ammunition . She returned to Taranto on 22 October , while en route was attacked by guns and depth charges but suffered no damage . She carried out a similar mission on 18 November . She completed further 5 offensive and 16 transport missions . Atlantic 1st Mission : On 5 or 6 October 1942 , she sailed from La Maddalena to the South - Atlantic for her 1st Atlantic mission , against the convoy " TS 23 " . She crossed the Strait of Gibraltar on 12 October without any contact . But on 3 November , while submerged at daytime , she attacked and sank a 3 , 845 GRT British ship " Dagomba " . On 29 November , while patrolling off Cape of Good Hope , Africa ( in the immediate vicinity of Capetown ) she sank the 1 , 995 GRT Greek ship , " Argo " . On 3 January 1943 , she attempted to re - arm by torpedo transfer on Tazzoli , but failed due to adverse weather conditions . But she was successfully fuelled on 13 January , with 45 tonnes of fuel by a German submarine . On 15 February , in the Bay of Biscay , she was attacked from the air , by bombs and machine - gun fire , that led to the death of Sergeant Gunner Michelangelo Cannistraro . This single mission ( began on 6 October 1942 in Magdalene , and ended on 20 February 1943 in Bordeaux ) lasted for 136 days . Atlantic 2nd Mission ( Indian Ocean 1st Mission ) : The second and last mission of Cagni began on 29 June 1943 and ended in Durban on 20 September 1943 , lasted for over 84 days . She was commanded by Lieutenant Commander Joseph Roselli Lorenzini on this mission . She had received orders to proceed to Singapore , to attack merchant shipping in the South Atlantic and Indian Ocean , and returned with a load of rubber and tin . On 17 July 1943 , off the Canary Islands , she encountered a steamer of 5 , 500 GRT of unknown nationality . On 25 July , she torpedoed the 22 , 048GT British Armed Merchant Cruiser , HMS " Asturias " ( in position 06°52 ' N ; 20°45 ' W ) . HMS " Asturias " was thought to have her boilers and machinery spaces flooded , but the badly damaged Armed Merchant Cruiser managed to escape to Freetown , under tow . On 30 July , Cagni crossed the equator , and on 28 August , she entered into Indian Ocean . On 8 or 9 September , while just 1 , 800 miles from Singapore , she received the news of the armistice and was ordered to make the port of Durban . On 20 September , she arrived , was intercepted by HMS " Jasmine " and escorted into Durban , where she formally surrendered to the British . On 8 November , she left for Taranto , where she arrived on 2 January 1944 . Located in Palermo , she was used for anti - submarine training activities for Allied planes . On 10 February 1948 , she was decommissioned and later broken up . Ammiraglio Caracciolo . On 11 December 1941 , she unsuccessfully attacked a British convoy and suffered damage by depth charges and gunfire from the destroyer HMS " Ferndale " . She was scuttled to avoid capture . 53 men were rescued - and taken prisoner - by the British destroyer . Ammiraglio Millo . Only carried out 8 missions and all were transport operations . On 14 March 1942 , returning from patrol in the waters of Malta , she was torpedoed and sunk by the submarine HMS " Ultimatum " , with the loss of 57 members of her crew . Ammiraglio Saint - Bon . Only carried out 10 mission , all transport operations . She was sunk by the submarine HMS " Upholder " on 5 January 1942 ; only 3 crewman survived .