At 19.25 hours on 14 Oct 1944, U-1223 fired a spread of two Gnat torpedoes at the escorts on the starboard side of convoy ONS-33G 5 miles off Pointe des Monts in the Gulf of St. Lawrence and hit HMCS Magog (K 673) (Lt L.D. Quick, RCNR) with one torpedo after 2 minutes 5 seconds in the stern - the other Gnat detonated in the wake of HMCS Toronto (K 538) (A/LtCdr H.K. Hill, RCNVR) without damaging the vessel. HMCS Magog lost 65 feet of her stern, three men were killed and three injured. The ship was initially assisted by HMCS Toronto but she got a contact and went off to unsuccessfully hunt the U-boat. The frigate was then taken in tow by HMCS Shawinigan (K 136) (T/Lt W.J. Jones, RCNR) and later by the Canadian tug Lord Strathcona about 260 miles to Quebec City, where the ship was declared a total loss on 20 December. The wreck was broken up at Sorel in 1947.