Between 03.37 and 03.41 hours on 17 March 1943, U-91 fired five torpedoes at convoy HX-229 about 400 miles east-southeast of Cape Farewell and observed detonations on two ships, but in fact only the Harry Luckenbach was hit and sunk.

The Harry Luckenbach (Master Ralph McKinnon) was assigned to station #111, the ship had been so exposed that the master had nervously steamed a zigzag course out in front of convoy until ordered to return to his station. The vessel was struck by two torpedoes on the starboard side amidships in the machinery spaces, causing her to sink within 3 minutes in the rough seas. However, some of the nine officers, 45 crew members and 26 armed guards (the ship was armed with one 4in, one 3in and eight 20mm guns) abandoned ship in three lifeboats, which were first spotted by HMS Beverley (H 64) (LtCdr R.A Price, RN) and HMS Volunteer (D 71) (LtCdr G.J. Luther, RN), but not picked up. HMS Anemone (K 48) (LtCdr P.G.A. King, RNR) was ordered to find the lifeboats, after HMS Pennywort (K 111) (Lt O.G. Stuart, RCNVR) had come across them and could not pick up the men because she already had 108 survivors on board. But the other corvette was unable to locate the boats and it is possible that the boats were also seen by HMS Abelia (K 184) (T/A/LtCdr F. Ardern, RNR) on her way from St. Johns to join convoy. None of the men from the Harry Luckenbach were seen or heard from again.