How much difference would a prepared Pearl Harbor have made?

[Derek Jackson]

Suppose US Intelligence had enabled American forces on Hawaii to be ready. I do think that the attack could have been defeated. Further the Japanese force might have been hit and more or less defeated.

How big a differemce would have been made in the Phillipines.

Could Japan's balance of power have changed? MIght the Militarists have been discredited .

If Japan is defeated early on does the US still declare war on the Nazis?

 

[David Floyd]

Suppose US Intelligence had enabled American forces on Hawaii to be ready. I do think that the attack could have been defeated. Further the Japanese force might have been hit and more or less defeated.

How big a differemce would have been made in the Phillipines.

Could Japan's balance of power have changed? MIght the Militarists have been discredited .

If Japan is defeated early on does the US still declare war on the Nazis?

Well, first of all, Germany declared war on the US first, not the other way around.

I am unsure why a different result at PH would have changed much in the PI, as the Battle Fleet wasn't gonna be sailing west regardless.

Obviously, wrecking First Air Fleet's air groups would have had significant long term effects, but I doubt much would change initially.

 

[CV(N)-6]

How much more ready are we talking about? A handful of fighters in the air, while watertight doors are closed and what crew is available does its best to button up the ships, form damage control parties, and man AA guns? Or the KB is spotted way out to sea and the fleet puts to sea? If it's the former, the first attack likely suffers casualties on par with the second one of OTL, with further attacks taking even more damage. Arizona may still explode if that's not butterflied, while the torpedoes will do less damage and most likely not sink California.

 

[Hugh Third of Five]

The best way to prepare Pearl Harbor would be to have anti-aircraft guns ready and fighters in the air, or at least have the fighters in a position to take off quickly.

The Japanese militarists would remain in power until either the Emperor surrenders or Japan-proper gets invaded. Japan would not be defeated fast enough to prevent an American war against Germany, since Hitler declared war on the USA on December 11th.

A faster defeat of Japan could butterfly away the Communist victory in the Chinese Civil War.

 

[Riain]

I believe that the general defense scheme was that the Army protected the fleet when it was in port so the fleet could rest. The Army would then stand down at reduced activity during the week as it didn't have this crucial task when the fleet was at sea. Thus 'ready' would be Army aircraft at high availability, defensive weapons manned or ready to be manned at short notice, CAPs aloft and a busy flying programme planned so rapid reaction to an emerging threat was possible.

Therefore the Army might plan to intercept the incoming B17s as an exercise or the radar operators would generally be more onto it. The Army would put up a reasonable fight, but be outclassed by the Japanese . However I think this would provide significant damage limitation, for example the level bombers using heavy AP bombs needed to fly a tight and precise formation both to get the huts and for the hits to be effective. With alert and manned AAA and a decent amount of fighters in the air this would be a struggle.