The Tsingtao scenario begins in February 1939, so it cannot simply replay Pearl Harbor two years early. Doctrine changes with leadership and with the ships and logistics a navy can sustain. A plan built around a mass carrier strike means little before the necessary carriers and organization exist. The opening question is which choices remained available to a still-evolving Imperial Japanese Navy.
Chapter · 0:09-3:41
Why a 1939 war would not repeat 1941
The counterfactual starts from an Imperial Japanese Navy whose doctrine, leaders, and available forces still differed from those of 1941.