On August 11, 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 August 12 "Dessiè" sighted the convoy, counting 14 merchants and ten destroyers. At 19:10 she closed in to within 1,800 meters 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 August 14 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 submarine. "Dessiè" surfaced at 22:12 and continued her patrol. In the evening of August 13 she was bombed by an aircraft, that killed one crew member and wounded several others and caused damage to her batteries which forced her to return to the base.