How the Royal Navy tested Far East strategy

War Memorandum Eastern and tactical instructions could not by themselves solve the logistical and fighting problems of a war with Japan. The Royal Navy tested them in staff exercises at Greenwich and Portsmouth and in maneuvers by the Atlantic and Mediterranean Fleets. These examined the battle fleet and the integration of submarines and aircraft carriers, while allowing mistakes to be made in peacetime. Results depended on the exercise's purpose and on whether participants were an experienced squadron or a newly assembled force. Planners' preferred questions could further limit what an exercise established. The initial assumption that war might come from 1929 reflected the Ten Year Rule's planning horizon rather than an estimate of Japanese intentions.