At 05.31 hours on 30 Nov 1942, U-181 began shelling the unescorted Cleanthis in the Mozambique Channel about 42 miles south-southeast of Inhambane, after chasing the ship for four hours and missing her with two G7e torpedoes – the first missed at 05.11 hours because the ship suddenly changed course and the other passed underneath the ship without detonating one minute later. The U-boat approached from astern and continually fired 80 rounds from the deck gun, scoring about 70 hits and knocking out the anti-aircraft gun carried on the stern, the only armament of Cleanthis. The master was killed by one of the first shells that hit the bridge and no distress signals could be sent as the wireless was shot away at once. The survivors hastily abandoned ship in the last intact lifeboat. The gun crew of U-181 then carefully aimed and fired the last available round for the deck gun from a distance of only 400 meters into the waterline of the starboard side of the stern and then proceeded to fire small holes into the port side with the 20mm AA gun, until the burning ship sank by the stern at 06.55 hours. The master and eleven crew members were lost. On 2 December, the survivors were picked up by the Portuguese steam passenger ship Lourenço Marques after being spotted by a British aircraft and were landed at Lourenço Marques.