During this span she carried out 46 training missions. Carlo Todaro and Mario Resio served as her commanders during this time. In mid-March 1941 Adua was transferred back to Taranto, and she was again put under command of captain Luigi Riccardi. From March to May 1941 Adua was deployed in the Gulf of Taranto, and also off the coast of Greece, carrying out three unsuccessful missions: In March, forty miles west of Lefkada, then in the Gulf of Taranto; In April, south of Cape Krio and in Kythira Strait; In May, between Alexandria and Kasos Strait at first, then south of Crete. On May 10, 1941, she was transferred to Leros. At 01:30 on June 3, 1941, she intercepted a small motor barge carrying gasoline and 72 British troops on board, including 8 officers, attempting to reach Egyptian coast. Adua took officers prisoner, and escorted the vessel to Crete, where other soldiers were taken prisoners. On June 4, 1941, she headed back to Taranto where the submarine underwent a three-month long maintenance at the Arsenal of Taranto. In the middle of September Adua operated near Menorca returning to Cagliari on September 16. On September 23, 1941, the submarine left Cagliari to set an ambush on the route of the British convoy to Malta (Operation Halberd) together with three other submarines. On September 26 Adua was near Cape Palos, north of Spanish city of Cartagena. The British convoy went undetected and reached Malta. The submarines, including Adua spotted and attacked British ships on their return. On September 30, 1941, at 3:50 Adua detected a group of eleven English destroyers, and attacked them with a four-torpedo salvo, but missed them and then moved north. Shortly after at 5:25, Adua sent a radio transmission to the headquarters informing them of British convoy position. She was never heard from again. After the war, it was discovered that the submarine had been traced by two destroyers, and (perhaps it was the radio communication with the base that allowed British ships to locate her). After having detected Adua with ASDIC, they started depth charge attacks, and at 10:30 hit and sank Adua with all hands in the position or . Notes References Adua-class submarines World War II submarines of Italy Lost submarines of Italy Maritime incidents in September 1941 World War II shipwrecks in the Mediterranean Sea 1936 ships Ships built by Cantieri Riuniti dell'Adriatico Ships