On 14 October 1944 "Magog" joined Convoy ONS 33G in the Gulf of St. Lawrence. At 1925 local time, "Magog" was torpedoed and damaged by "U-1223" near Pointe-des-Monts, Quebec (near Baie-Trinité, Quebec), losing of her stern, killing 3 crew and injuring 3 others. After the torpedoing, "Magog" was taken in tow first by , then to the safety of a bay, and later to Quebec by the salvage tug "Lord Strathcona" where she was eventually declared a total constructive loss. The crew was ordered not to discuss the action at the time by the Prime Minister, William Lyon Mackenzie King.