At 22.53 hours on 20 Sep, 1943, U-305 (Bahr) missed HMS Itchen (K 227) with a Gnat in 57°30N/31°10W, after sinking HMCS St. Croix (I 81) near convoy ON-202.
At 04.35 hours on 21 September, U-270 (Otto) fired a Gnat in grid AK 2882 and heard an end-of-run detonation after 11 minutes. The target of the attack must have been HMS Itchen (K 227) or HMS Narcissus (K 74).
At 23.57 hours on 22 September, U-952 (Curio) fired a Gnat in grid AK 7156 and heard an end-of-run detonation after 10 minutes 3 seconds. The target of this attack may have been HMS Itchen (K 227) or FFL Renoncule (J 1162).

At 01.56 hours on 23 September, U-666 fired a Gnat, which detonated after 8 minutes 21 seconds in the wake of the HMCS Morden (K 170). At 02.01 hours, the U-boat fired another Gnat, which hit HMS Itchen (K 227) (Cdr C.E. Bridgman, RNR, DSO) after 1 minute 10 seconds. The frigate blew up after the hit. Debris from the vessel was later found on the conning tower of the U-boat and on HMCS Morden (K 170).
The HMS Itchen (K 227) had picked up 81 survivors from HMCS St. Croix (I 81) and one from HMS Polyanthus (K 47), which had been sunk by U-952 (Curio) on 21 September. Only two men from HMS Itchen (K 227) and one from HMCS St. Croix (I 81) were rescued.