At 02.05 hours on 14 September 1942, U-91 fired a spread of two torpedoes at a destroyer and observed a hit. Then they saw another destroyer, made a full circle and fired at 02.15 hours one torpedo, which hit amidships and caused the ship to blew up and sink immediately. Walkerling thought that they had sunk two destroyers, but in fact HMCS Ottawa (H 60) (LtCdr C.A. Rutherford, RCN), escorting convoy ON-127, was hit twice.

At 02.15 hours on 12 September 1942, U-92 (Oelrich) had fired a spread of four torpedoes at a destroyer in grid BD 2719 and heard two impacts after 46 seconds, but two detonations only much later that were apparently depth charges. The destroyer attacked was probably HMCS Ottawa (H 60). She had picked up 24 survivors from the Empire Oil that was torpedoed on 10 September, but one of the men died of wounds and 16 more were lost when the destroyer was sunk together with her commander and 115 crew members. Only seven of the shipwrecked men and 62 crew members were picked up by HMS Celandine (K 75) (Lt P.V. Collings, RNR) and HMCS Arvida (K 113) (T/Lt A.I. MacKay, RCNR) and landed at St. John’s on 15 September.