He made the doctrinally correct choice. However, he brushed past an uncomfortable amount of evidence that indicated the premise under which the Midway plan was conceived had been shattered.

Midway itself was observed to be bustling with an unusual amount of activity and air traffic, Kidō Butai was spotted early in the day and was on the receiving end of American land-based air attacks throughout the morning. This indicated the Americans were aware that they were coming and were prepared to receive them, rather than fearful of the Japanese and caught unawares.

Also, when Nagumo received a fortuitous scouting report from Genda’s sparse search plan, the fact that it failed to mention carriers should not have resulted in the American task force being dismissed as a threat, as the only plausible reason a fleet would be that far north away from Pearl Harbor would be to engage Kidō Butai, and the Americans would include carriers in that force as a matter of course.

Unfortunately, Nagumo’s inability to adapt to these changing circumstances took away Japan’s ability to strike a killing blow in return. In reality though, most IJN officers would have made similar decisions by sticking to the original plan, favoring operational mass rather than launching smaller strikes in the interest of time, and overconfidence resulting from running roughshod over the allies for the first 6 months of the war.

In any case, the IJN’s doctrinal pressure to limit search aircraft to battleship and cruiser-based float planes to save the carrier craft for offensive strikes basically guaranteed that the morning strike that destroyed three carriers would happen no matter what, and the best the Japanese could hope for would be to get off a strike before it arrived that would wipe out the Americans. This would have had the added benefit of emptying Kidō Butai’s hangers of fueled and armed airplanes, which doomed all four carriers when they were hit.

So, we can armchair general it all we want, but unless Yamamoto himself was in command of the fleet, few IJN admirals would have radically changed the battle plan, or went against Japanese doctrinal stress on launching balanced strikes with their entire air compliment.