Operation Collar. At 3:05 on 28 November, she sighted a naval column consisting of three capital ships. Dessiè launched two stern torpedoes from 3,500 meters against a middle target, and disengaged by diving. An explosion was heard, but British official documents mention no attack by Dessié or any damage inflicted. The Royal Navy's 3rd Cruise Division, consisting of the heavy cruiser and light cruisers and was indeed passing through the area at the time of the attack. Between 16–25 December 1940, Dessiè together with submarines and patrolled around Malta. In January 1941, she was deployed off Derna. Both patrols were uneventful. On 20 May 1941, Dessiè together with numerous other submarines was deployed to an area between Crete, Alexandria and Sollum to support the German invasion of Crete (Operation Merkur). On 21 and 22 July 1941, Dessiè along with three other submarines was deployed to area between Pantelleria and Malta. Her task was to intercept a British convoy, part of Operation Substance, but she did not sight any enemy ships. On 3 January 1942, Dessiè was sent to patrol an area south off Malta with the task of detecting and attacking any British naval forces that might attempt to intercept Italian convoy "M 43", bringing supplies to Libya. No ships were detected. In mid-June 1942, she was sent along with four other submarines, including and to patrol between Malta, Pantelleria and Lampedusa, with the task of intercepting a British convoy, part of Operation Harpoon. However, the submarine did not sight any enemy ships. On 11 August 1942, Dessiè, now under command of Captain Renato Scandola, was among eleven submarines deployed off the coast Tunisia between Scoglio Due Fratelli and Skerki Banks. Her task was to intercept a British convoy for Malta, part of Operation Pedestal. Around 19:00 on 12 August, Dessiè sighted the convoy, counting 14 merchants and ten destroyers. At 19:10, she closed in to within and at 19:38 she launched four torpedoes. After one minute and forty seconds, a loud explosion was heard, as SS Brisbane Star (12,791 GRT) was hit. However, the steamship succeeded in restarting her engines and reaching Malta on 14 August after a short stop in Soussa, even though she was further damaged by German torpedo bombers. At 19:56, Dessiè, while preparing to launch her stern torpedoes, was attacked by enemy destroyers, who continued their attacks until 21:27 without causing any damage to the