At 15.18 hours on 8 Aug 1942, U-176 fired two spreads each of two torpedoes at convoy SC-94 southeast of Cape Farewell and heard two hits after 1 minute 20 seconds and one hit each after 1 minute 34 seconds and 2 minutes 11 seconds, then sinking noises were heard. The victims were Trehata in station #51, Kelso in station #52 and the Mount Kassion in station #53.

The Mount Kassion (Master Elias Piperis) was hit on the starboard side in the engine and boiler room by two torpedoes. The explosions opened a large hole well below the waterline, stopped the engines due to ruptured steam pipes and disabled the steering gear and wireless station. As she began to settle by the stern the crew of 52 (the ship was armed with six machine guns) and two Greek passengers abandoned ship in the lifeboats in a moderate sea. The survivors were picked up after about 30 minutes by HMS Primrose (K 91) (LtCdr A. Ayre, RNR) which had to leave the still floating wreck behind to rejoin convoy and landed 47 of the survivors at Londonderry in the morning of 13 August. On 11 August, seven survivors had been transferred to HMS Sennen (Y 21) (LtCdr R.S. Abram, RN) in order to search and salvage the abandoned and drifting Mount Kassion, but she could not be found as the ship presumably sank during the morning on 9 August.