British cruisers and submarines could make Japanese merchant routes a major pressure point. Britain had submarines in the Far East and others in the Mediterranean already considered deployable eastward. HMS Liverpool's interception of the Japanese liner Asama Maru in 1940 illustrates how well Britain understood those routes and could reach shipping close to Japan. Japan's resources were already strained by capital-ship construction, leaving less industrial capacity for a comprehensive trade-protection fleet. British anti-submarine habits, ASDIC, and routine zig-zagging would also complicate Japanese attempts to impose equivalent attrition. Even a cautious Japanese defensive strategy would face opponents able to pause, rebuild damaged forces, and return with greater industrial strength.
Notable Point · 1:07:03-1:12:40
Commerce raiding exposes Japan's escort shortfall
British knowledge of Japanese trade routes and Japan's limited escort capacity would turn a long war into an industrial and logistical contest.