At 09.01 hours on 24 Sep 1944, U-739 fired a Gnat at T-120 (CaptLt D.A. Lysov) northwest of the Skott-Hansen Island and hit her in the stern. The minesweeper had been escorting convoy VD-1 in the West Siberian Sea and was ordered the day before to search for survivors from Brilliant (No 29), but only one man was picked up who died shortly afterwards from exposure. At 07.45 hours on 24 September, the ship was ordered to proceed to Dikson but was shortly thereafter torpedoed. The stern section was almost completely destroyed, but a skeleton crew (the master, three officers, gunners and engineers) managed to keep the ship afloat while 26 men abandoned ship in a cutter, 20 men on a large pontoon and two men on a raft. The survivors reported that the U-boat was spotted after about 90 minutes and forced to dive when the gunners opened fire, but the minesweeper was then torpedoed again around 13.30 hours, broke in two and sank within 15 minutes.

Later that day, the survivors became separated due to fog and the men on the raft were never seen again. The cutter made landfall after 12 hours at Podkova Island where they were assisted by hunters to reach Cape Vhodnoy. The men on the pontoon constructed an improvised sail and after three days reached the Skott-Hansen Island. A man died in an accident during the landing and another later on the island. While the eight weakest men were left behind with a stock of water and food, the others continued their journey and finally landed near a shore battery on 1 October. The Soviet patrol craft BO-210 was sent out from Dikson to rescue the men left behind on Skott-Hansen Island and returned to the harbour on 6 October.