 The ships were fitted with a single above-water quadruple mount for torpedoes.The Tribals were not intended as anti-submarine ships, but they were provided with ASDIC, one depth charge rack and two throwers for self-defence, although the throwers were not mounted in all ships; Twenty depth charges were the peacetime allotment, but this increased to 30 during wartime.Heavy losses to German air attack during the Norwegian Campaign demonstrated the ineffectiveness of the Tribals' anti-aircraft suite and the RN decided in May 1940 to replace 'X' mount with two QF Mark XVI dual-purpose guns in a twin-gun mount.