I have a video of Jurgen Oesten telling about attacking a convoy from Freetown, accompanied by the old Battleship Malaya, in U-106 with U-105. He states that the Malaya was inside the convoy during the day, using its plane to hunt for u-boats, and left at night for the first 5 days they attacked. Once they had sunk a number of ships, the Malaya didn't leave the convoy one night. Jurgen said he was unaware it hadn't left the convoy when he attacked with the last of his torpedoes, and put one into the Malaya, damaging it, and causing it to travel to New York for repairs.
