Reading 1941 capabilities backward into early 1939 gives Japan forces and preparations it did not yet possess. The rapid southern campaigns required a long buildup, while this scenario begins with forces where they actually were in January 1939. The First Air Fleet had not been formed, Hiryū was not yet ready, Shōkaku and Zuikaku were not launched, and the Yamato-class ships were unavailable. Japan would have to mobilize, concentrate, and work up these forces during the war instead of beginning with the coordinated striking system familiar from December 1941.
Notable Point · 11:41-15:30
Japan starts from January 1939 readiness
Japan would have to assemble and train its striking force during the war, without the preparations or ships available in December 1941.