With the concentration of Allied anti-submarine forces that had built-up in and over Bermuda's waters by late 1942, and the resultant diminished threat from enemy submarines inside the reefline, HMS Castle Harbour was deemed unnecessary at Bermuda and was consequently ordered to the Mediterranean. She was travelling as part of Convoy TRIN-19 from Trinidad, with a Merchant Navy crew, when at 2120 hours on 16 October 1942, she was torpedoed by the German submarine U-160. The explosion broke her in two and she sank within twenty seconds with the loss of nine of her twenty-two crewmembers.[27][28]