In terms of a knockout blow U.S. War Plan Orange and the corresponding Japanese plan, which was generally known to us, envisioned the supreme naval battle would be fought in the Western Pacific. Both navies were disciples of Alfred Thayer Mahan who wrote the outcome of war at sea would always be decided by the “decisive naval battle”. Past history bore that out at Trafalgar, Tsushima, and Jutland. For Jutland Churchill said, “Jellicoe was the one man who could have lost the war in an afternoon”.
When Yamamoto proposed this radical departure from Japanese strategic principles only his firm commitment to resign at a meeting in October 1941 forced the Naval General Staff to accept his radical departure from existing plans or find another fleet commander. In this country Plan Orange continued to determine the most probable interpretation to place on intelligence and events.
Submarine action, sabotage, and an air raid were considered possibilities, but a six carrier task force was not on anyone’s radar. (Sorry about the pun.)