Vian sailed Cossack, Ashanti, Maori, and Sikh on short notice to intercept a convoy off southwest Norway. He admitted that he had either missed or failed to absorb the operation order issued earlier. Independent attacks would offer flexibility if the merchant ships scattered, but darkness and smoke risked friendly ships firing or launching torpedoes at one another. Keeping destroyers moving at 20 knots or more against a convoy making about seven knots demanded repeated changes of course, and the navigator ruled out circling because there was too little sea room. Vian chose a close-order approach to point-blank range, directing main guns and torpedoes against the merchantmen and pom-poms and small arms against the escorts. The attack succeeded, and its details were withheld to preserve the chance of repeating it. Vian credited William Agnew with subsequently perfecting this form of interception, while admitting that he did not know which tactics Agnew had used. His report also helped prioritize flashless cordite and star-shell illumination for destroyers.
Chapter · 53:41-58:23
A Norwegian convoy attack became a lesson in night fighting
A hurried night attack on German supply shipping required Vian to divide his weapons between escorts and merchantmen while limiting friendly-fire risks in confined waters.