WI: WAllies discover Japanese plans for Dec 7

[Icarus II]

Say the US discovers the Japanese plans for the December 7/8 attacks on Pearl Harbor, the Pacific Islands, and Southeast Asia. How much could they do to stop the Japanese? The Japanese forces attacking Pearl Harbor, Wake, and Guam are going to the bottom for sure, but what about the Philippines, Malaya, the Dutch East Indies and Thailand?

I imagine the US would put its fleet in position to destroy the KB at Pearl , then move west to relieve Guam and Wake. However, that puts it out of position to relieve the Philippines or Malaya. If the Japanese intentions are known early enough, could the Allied forces in Malaya, the DEI and the Philippines destroy the Japanese forces before they land?

I thought about putting this in ASB, but it seems possible that the Allies could get a hold of the Japanese plans without tipping them off.

 

[SsgtC]

See War Plan Rainbow 5

 

[Carl Schwamberger]

Indeed, the answer from the men who made the plan.

 

[Histor32]

see not ready for war 1.0 beta

 

[Carl Schwamberger]

As always it depends on how much advance notice there is. The War Warning sent to that Pacific Commands 26 Nov caused a full alert across the Pacific. Had the Kids Butai arrived on the 28 the Nov OTL they'd have encountered a robust CAP, a hefty dose of ready squadrons on the ground. Fully operating radar, command posts properly manned, AAA on standby, and the fleet at sea & over the horizon to the SE. By 5 Dec the Army and fleet we're exhausted, aircraft piling up on the maintinance line, & the two commanders making a concious decision to stand down and rest the men for the weekend before restarting a intense repair, training, and patrolling program.

Had the Japanese been able to stick with their plan & attack on the Thanks giving holiday they'd have encountered an alerted defense on US territories.

 

[Riain]

For the British, discovery of detailed Japanese plans would have allowed them to launch Operation Matador and send Army units into Thailand to meet the Japanese on the landing beaches. This could also be assisted by Force Z, who would know exactly where to go to attack the IJN landing forces.

This would cause a major problems for the Japanese who we know were operating on a shoestring.

 

[Mark E.]

The Japanese would have sustained greater losses and the Arizona could have been battle-ready. Since they attacked other islands, the biggest advantage could be the strategic value of the Arizona.

 

[M79]

Such a discovery could have notable butterflies that might also reinforce the die-hard battleship dominance types and prevent the Navy's transition to a carrier-centric service

 

[Icarus II]

I was wondering more if, given that the US has foreknowledge of Japanese plans, it might be possible to destroy or disable the KB and defend a forward line of troops at Malaya/Philippines and Wake/Guam. The US can still follow its pre-war plans, but now it can fire a debilitating first shot to blunt Japanese expansion, or at least stop it earlier and at a much higher cost for the Japanese.

 

[sloreck]

It depends on how much in advance they know. Of course being on alert at PH and in the PI would work wonders, the latter if Doug actually does what should be done. With a little notice Wake can be full up ready.

 

[Carl Schwamberger]

The Japanese actually thought the US would be better prepared, and alert. They were expecting a tougher fight than they had and were surprised by how easy the attacks on Oahu & Luzon actually were.

... it might be possible to destroy or disable the KB ...

The wet dream scenario of the USN would be to ambush the KB at dawn. The BB opening fire from the west, with the carriers sillouted against the dawn and the strike group all staged on the decks.

 

[Icarus II]

The Japanese actually thought the US would be better prepared, and alert. They were expecting a tougher fight than they had and were surprised by how easy the attacks on Oahu & Luzon actually were.



The wet dream scenario of the USN would be to ambush the KB at dawn. The BB opening fire from the west, with the carriers sillouted against the dawn and the strike group all staged on the decks.

I read your post on the KB ambush scenario from a while back. That was one of the things that gave me the idea for the thread. Maybe tomorrow I'll post a link to the thread.

One question, though. Wouldn't the USN BBs be blinded by the Sun if they're shooting to the East? I would think it would be the other way around, where the USN is in the East so they have the sun to their back and the KB is blinded by the sun.

I'm going to assume that Doug slipping on a banana peel and breaking his skull in 1932 isn't part of War Plan Red. So how much advance notice would the Allies need to prepare for the assaults on the Philippines and Malaya? IIRC the US had 20-something subs at Manila. Is it outside the realm of possibility to track the landing forces headed for Luzon, Mindanao and Malaya, and launch combined sub/surface/air attacks on all three before they land?

 

[BobTheBarbarian]

What if the US just went public with the plans and described them in great detail to the world before the attack had a chance to take place? They might have averted the war altogether and forced the Japanese diplomats to cave in.

 

[Carl Schwamberger]

...
One question, though. Wouldn't the USN BBs be blinded by the Sun if they're shooting to the East? I would think it would be the other way around, where the USN is in the East so they have the sun to their back and the KB is blinded by the sun.

Only if looking directly into the sun. Otherwise at sea the dawn horizon silhouettes ships. Conversely the ships on the western side are backed by darkness & more obscured by predawn haze. All you are going to see at 14,000 yards range is gun flashes if looking into the darkness.

... IIRC the US had 20-something subs at Manila. Is it outside the realm of possibility to track the landing forces headed for Luzon, Mindanao and Malaya, and launch combined sub/surface/air attacks on all three before they land?

They tried with the submarines, & were not very successful. The landings came several days after the initial air attacks. Air attacks would have had some effect on anchored ships. A few months later at Rabaul the 5th AF hit ships anchored or docked in the harbor. Otherwise the US AF proved the bomber techniques of 1941 were useless against moving ships. Even slowly moving ships.

The Japanese landing forces of 1941/42 succeeded because the opposition on the beaches was relatively light. Where they ran into a dense & well organized defense, such as at Wake Island, they took heavy losses. If the Allied forces can identify the landing sites well enough ahead and heavily reinforce them, then they have a chance of destroying the invaders on the beach. But that requires a strong counter attack force.

 

[michael1]

Given the inability of the British to prevent a landing at Khota Bahru despite pre-prepared defenses and the failure of Force Z to even reach the landing areas in OTL I'm doubtful of any significant implications for the Malay campaign other than possibly an earlier capitulation as the defenders are defeated in detail in the North. I think the main effect of matador was a lack of focus on a single defense plan.

Pearl Harbour is likely to be better defended, so the Japanese suffer more losses, the US fewer. Unless a Midway style ambush can be arranged the effects may even be beneficial to Japan, preventing "victory disease" taking quite so strong a hold, and leading to a better pilot training programming being introduced to replace losses. Of course this is unlikely to significantly delay the Japanese surrender and may even slightly accelerate it as the US doesn't start its advance from quite as far East.

Given US torpedo problems and the inability of B17s to hit shipping at this point, there likely is no significant effect on SE Asia operations, although again, higher losses on the Japanese might be inflicted, especially from bombing airfields.

 

[Alanith]

What if the US just went public with the plans and described them in great detail to the world before the attack had a chance to take place? They might have averted the war altogether and forced the Japanese diplomats to cave in.

These are the same people who kept shouting 'DOUBLE OR NOTHING!' for all intents and purposes whenever anyone in the government brought up the conflict in China. All it will encourage them to do is attack with even more fervor, for having cunningly forewarned the Americans we can now lure them into a decisive battle on our terms...

 

[SsgtC]

These are the same people who kept shouting 'DOUBLE OR NOTHING!' for all intents and purposes whenever anyone in the government brought up the conflict in China. All it will encourage them to do is attack with even more fervor, for having cunningly forewarned the Americans we can now lure them into a decisive battle on our terms...

The sad thing is, you're not being facetious. This is actually what they would have done.