Pearl Harbor thought.

[Admiral Halsey]

Ok I was originally going to put this in my Alternate History thread but I want more responses then I normally get for this post. Ok so here it goes. In this scenario FDR, Kimmel and Short and MacArthur(Plus anyone else who'd need to know) know Japan is going to attack Pearl and the Philippines a few months before the attacks happen. They decided to let Japan hit Pearl BUT they also decide to put all the American Carriers on the Japanese flank and wait for them to blunder into their sights.(So basically Midway at Pearl.) They don't launch the attack on the carriers until the Opana Radar Site sends a signal to them that the planes have been spot on the screen. So basically i'm asking you guys this. Once the American carriers launch their planes into the air what happens next? Oh and yes Pearl will be put on full alert the moment the Japanese planes are confirmed to be heading there.

[Dread Knot]

Admiral Nagumo goes swimming and I think you will likely end up with a super-Midway event. The Japanese are bringing six carriers and veteran pilots true, but in this case Oahu is a far more formidable installation than Midway, capable of basing and dispatching far more aircraft into the air. As always, a lot depends on who gest the first blow in, but foreknowledge is a huge advantage. The only fly in the ointment might be if the US carriers are spotted early by Japanese search planes. Nagumo might elect to retreat at that point.

Even if both carrier fleets end up in a shambles, USN pilots and personnel are far more likely to be rescued by their side than Kido Butai pilots.

[mapuc]

My first impression? The war would end a lot earlier.

Markus

[Dread Knot]

Of course, one political drawback might be no declaration of war by Hitler after seeing his ally in the Pacific getting an embarrassing thumping early on. That puts Roosevelt over a barrel in Congress, trying to get involved in the war in Europe, while one is already raging in the Pacific.

[Admiral Halsey]

Originally Posted by Dread Knot

Of course, one political drawback might be no declaration of war by Hitler after seeing his ally in the Pacific getting an embarrassing thumping early on. That puts Roosevelt over a barrel in Congress, trying to get involved in the war in Europe, while one is already raging in the Pacific.

True but Hitler might be insane enough to still declare war. As for Nagumo retreating he'd have no choice but to fight it out at that point. He'd know that it couldn't be a coincidence that there are American carriers waiting for him on his flank.

[CCIP]

My favourite response to this kind of thing is that real historians hate what-ifs

The real question is just how they would know that much operational detail about the way the Japanese would carry out the Pearl attack. It's one thing to know that the Japanese might attack, another thing to know the exact composition of the task force and attack plan and tactics, and being able to find the ships without the Japanese putting up necessary precautions. And radar during that time didn't really have a great deal of precision, or at least I don't think there was quite that much operational experience in its use. So, that's quite the gamble. I don't think there would be enough confidence in this working.

Something like this would be basically threading the eye of the needle - sure, maybe, but it's one of those things where a whole bunch of things would conveniently have to turn out precisely right for the Americans to pull it off, against an already-wary Japanese task force (they themselves knew they were running big risks, which is why they got out of there fast instead of sending another wave of attacks). Considering this would all be happening while their planes were bombing American soil, I don't think this kind of plan would be approved. Too many things that could go wrong at too high a cost.

[Wolferz]

There was no radar in '41 so no IJN plane could have been spotted except with the MKII eyeball.