WI: Kido Butai Spotted En Route to Pearl

We know that the Kido Butai was short of fuel, so an important question is whether or not the US command would assume this.
I suspect they'd know it was a big stretch to attack Hawai'i. So the US fleet can win (and possibly decisively) by forcing the Kido Butai to manouevre or to speed up [1]. I have no idea how easy this would be to arrange, but sound reasoning or blind luck for the US and bad planning or panic by the Japanese cpuld be enough.

[1] If they run out of fuel or think that this could happen, the entire Kido Butai(or at least a substantial part of the smaller ships) could be at risk. Can aircraft carriers launch when out of fuel?
The Japanese have fuel to launch the strike - it doesn't really matter if they launch it at Pearl or they launch it at a fleet steaming towards them. If they abort before their strike position for Pearl that will increase their fuel reserves. There are also the mini-subs which if they were deployed as the fleet sortied would have excellent attack positions.

It would be a very long stern chase for the USN and they would be under threat of air attack all the way unless they could co-ordinate with the missing carriers. Enterprise is in a good position but it's only one carrier. Lexington is out of position and both were undertaking aircraft ferry missions so may be understrength in their a/c complement.

If the Japanese got three strikes in on the USN at sea and the mini subs had their chance the outcome in terms of lives lost for the USN could be much more expensive. The number of battleships sunk might be less but there would be no chance of refloating them in this scernario.
 
What would the Americans do after the sighting?

If they sortied a large portion of the fleet based at Pearl, doesn't that actually put them in a more vulnerable position?

The idea of the 'sortie' would be to position the main fleet further from the possible attack location since this would obviously be an 'air attack'. (This had been simulated in previous Fleet Exercises and the idea was to force the 'enemy' to search for the fleet wasting time and fuel) At the same time Pearl Harbor and surrounding bases would be on higher alert and ready for the attack which would increase enemies loses and some elements (cruisers/destroyers of the USN and long range heavy and medium aircraft of the USAAC) would be searching for and trying to attack the Kido Butai if possible.

Again the main element is that the KB for the most part can outrun the surface units but as every possible submarine and aircraft available would be headed their way it would severely limit Nagumo's options.

We know that the Kido Butai was short of fuel, so an important question is whether or not the US command would assume this.
I suspect they'd know it was a big stretch to attack Hawai'i. So the US fleet can win (and possibly decisively) by forcing the Kido Butai to manouevre or to speed up [1]. I have no idea how easy this would be to arrange, but sound reasoning or blind luck for the US and bad planning or panic by the Japanese could be enough.

[1] If they run out of fuel or think that this could happen, the entire Kido Butai(or at least a substantial part of the smaller ships) could be at risk. Can aircraft carriers launch when out of fuel?

While the US would assume the KB is at the edge of their range they also won't assume that they won't run like hell if the US sends a sufficient force to confront them. Keep in mind that Nugumo's orders were to NOT proceed if detected before the 5th and more importantly he was to preserve his forces in any event.

He's between a rock and a hard place after the 5th because he's essentially committed to the attack but he can't really risk his carriers so he'd have to send his support force on a suicide run to 'block' any approaching USN elements and weigh the risk of not being able to recover his strike force is he has to launch in the face of opposition.

His carriers are fully fueled and quite able out run any USN surface combatants sent from Pearl but if he's gotten at least one strike in (or any reconnaissance) Pearls he knows the US carriers are still out there and a threat. Plus the USAAC and USN aircraft out of Hawaii, submarines and possible units from the mainland if there's enough warning. Keep in mind that the 'plan' assumed they would be detected at least before the first strike went in and even they were surprised by how total the surprise was.

Randy
 

Geon

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A while back, on a documentary program, Larry Bond writer and creator of the Harpoon wargame was asked to run a war game based on this very premise.

Two groups of navy veterans were assembled with one side playing the Japanese and one side playing the Americans. While I don't recall the exact results, the premise was the same. The Kido Butai is detected and the USN sorties the fleet at Pearl plus the available carriers to intercept them. The result is a victory...for the Japanese. The Americans end up losing at least three of their battleships and one or two of their carriers. In OTL the battleships that were lost would be repaired and play a significant role in future operations. Here, given they are at sea, the ships are simply lost.

How plausible is this?
 

CalBear

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If detected Nagumo had VERY specific instructions on how to act:


In accordance with instructions from CinC Combined Fleet, the Task Force sortied from Hitokappu bay at 0600, 26 November and proceeded along the track shown in Appendix 2. On 2 December instructions were received to the effect that negotiations had failed and that 8 December was designated as "X"-day. The refueling was successfully completed on 3 December without mishap. (In the event of failure of the fueling operation it had planned to continue without the destroyers.) After refueling, the Task Force proceeded along the track without incident. No shipping was encountered and the force successfully escaped detection. During the approach, the following instructions were in effect:
  1. If discovered prior to "X"-minus-2-day, the Task Force was to return to Japan without executing the attack.
  2. If discovered prior to "X"-1-day, the decision as to what action to take was the responsibility of the Task Force Commander.



--15--




  1. If discovered on "X"-minus-1-day or the morning of "S"-day the Task Force was to continue with the attack.
  2. If at any time during the approach to Pearl Harbor the negotiations with the United States had been successful the attack would have been cancelled.
Cut and dried. Discovered before December 5, 1941, withdraw and return to Japan. Discovered on December 5, 1941 Nagumo's call (he was not a huge fan of the attack plan, good chance, but not a certainty, that he withdraws). Located on December 6th or early on December 7th, they go.

 
A while back, on a documentary program, Larry Bond writer and creator of the Harpoon wargame was asked to run a war game based on this very premise.

Two groups of navy veterans were assembled with one side playing the Japanese and one side playing the Americans. While I don't recall the exact results, the premise was the same. The Kido Butai is detected and the USN sorties the fleet at Pearl plus the available carriers to intercept them. The result is a victory...for the Japanese. The Americans end up losing at least three of their battleships and one or two of their carriers. In OTL the battleships that were lost would be repaired and play a significant role in future operations. Here, given they are at sea, the ships are simply lost.

How plausible is this?

I don't know as it's a question of what the US can really do since they (at this point) still don't take naval aircraft all that seriously. I'd question the idea they would sortie to try and attack the KB given they KNOW their battle line can't catch them unless the Japanese want to allow it. If the Japanese press the attack on Hawaii, then maybe the KB is open to attack by some of the faster elements of the fleet but if they risked the carrier maybe there are more fleet units around? Even then the KB should still be able to put up enough of a cap to defeat any USN air attack rendering the carrier(s) pretty much useless.

As CalBear says pretty much detection on the 5th or early they likely withdraw without attacking because they need to preserve the force and no one on the US side can really interfere. Once the clock rolls over to the 6th the main danger is air attack and possibly the USN throwing some cruisers and destroyers at them while they get the battle line out of harbor and away from the line of attack. Meaning the attack still hits the bases and support structure but the loses are much higher. I'm almost sure that there would be little incentive for the USN to actually attack the KB as simply denying them the opportunity to hit the battle line would negate most of the Japanese plan for the attack. A primary option I'd think is if the Japanese know they've been discovered then wrecking infrastructure and facilities becomes a higher priority for the attack. If they can do enough damage then the battle line has to retreat to the mainland which assures they are out of the way for the follow on operations, which is really what counts.

What really counts here is less the KB's response but the US response to spotting the KB. As I noted the USN had 'gamed' an air attack and knew it could be a danger but saw it as a low probability option. And now the KB was RIGHT there and maybe still hits Hawaii even if they don't catch much (or any) of the battle line how does this effect USN Pacific operations?

Randy
 

Coulsdon Eagle

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IMHO the USN will sortie from Pearl, if only because they would believe their chances against aerial attack are less in a closed harbour with no room to manoeuvre than instead of on the open sea. They may be wrong in that, but that hasn't been proven to them yet.
 
Japanese are limited in speed on the way home, while the USN has full tanks, and can chase at a faster speed than normal cruise.
Kaga, for example, could go 10,000 miles at 15 knots, while a Colorado could 8,000 at 10 knots.
So normally, a Standard would have no chance at interception, unless they use2/3rds more fuel to hit 17knots.
Yeah, they will be empty in 2000 miles, but might be enough to get into range.
The Japanese have already used half of their fuel.
 
It depends a lot on how well the US fighters do. The Japanese crews were the best in the world at the time and in the open sea could have done hammer and anvil or dive bomb plus torpedo attacks which weren't an option in Pearl Harbour. If the US fighters can disrupt the set up then they won't suffer too badly, but if the fighters get tangled in dogfights or are poorly controlled it will be a bad day. Bearing in mind that sunk = lost forever and badly damaged = risk from sub or carrier based attack and it doesn't look particularly clear-cut, with at least some possibility that credible luck could cause equal or worse damage than OTL, and a possibilty of doing better.
They may have been the best trained in the world at the time, yes. But the fact remains that before Pearl, they had absolutely zero experience attacking maneuvering ships while under fire from fully prepared AA defences, never mind ready and waiting fighter opposition.

IOTL the Kido Butai torpedo crews achieved 19 hits out of 36 torpedoes launched - against berthed ships and with the element of surprise.

I would expect results in a high seas engagement to be more along the lines of what happened off Malaya IOTL, when the Kanoya, Mihoro and Genzan torpedo crews achieved a mere 8 hits out of 49 torpedoes launched against Prince of Wales and Repulse (which had significantly less AA capability than the US battle line and zero air cover).

The dive bombers had no true battleship killing capability so I would not consider any hits they score to be of significance except perhaps with regards to AA suppression. What they achieved against Nevada IOTL was a fluke.
 
Thanks for the responses.
I hadn't appreciated the US carriers were on ferry missions and the other points show that US options weren't that great.
 
The scenario: a US naval vessel/aircraft, or more likely, a civilian vessel/aircraft from a neutral nation or one sympathetic to America, spots Kido Butai en route to Pearl several days before the Japanese reach their launching point.

The Japanese are not stupid. They cannot let the interloper escape, because if they do, there is no way they can innocently explain to the Americans, much less to the world, the presence of a huge attack fleet so far away from the Home Islands and heading in the direction of Hawaii. So they opt to sink or shoot it down before its crew can broadcast a warning.

They fail. A warning goes off before the interloper is eliminated, and is picked up by listening posts at the nearest American naval station.

The question: what happens next?

My take: knowing Nagumo, he would probably be sufficiently spooked as to call the whole thing off. Even Yamamoto the gambler and Mad Dog Genda would not be so reckless as to press on, despite their zeal to eliminate the Pacific Fleet. Where it gets hazy for me, however, is where the fleet goes next. I don't see Yamamoto ordering Nagumo to return to Hittokapu Bay; that would be wasteful. Would they end up hitting Wake instead, or perhaps Midway? Wind up attacking Rabaul earlier than planned? Or supporting the South East Asian moves in some fashion, because it's a given that those operations proceed anyway even if Japanese secrecy is rumbled?

Hazier yet for me is how the Americans and the international community might react to this early warning, beyond putting Pearl on full alert obviously. I recall Bull Halsey was at sea in Enterprise at the time. Are arrangements made to immediately sortie the fleet and intercept Kido Butai before it makes for its alternative objective? Or do the Americans play things a bit safer, concentrate their naval strength first and wait to see what happens? It probably goes without saying that America would share this information with Britain - does it help them mitigate what happens to Malaya, Burma and Singapore in OTL? Does Roosevelt reveal Japan's underhandedness to the entire world? How do the Nazis react now that their ally's plan has gone off half-cocked?

Opinions welcome and appreciated!
The Japanese fleet detected approaching Hawaii is effectively a declaration of war - as it would have no other business being there other than to attack the US

It would be almost as bad as far as the USA is concerned as the OTL attack was even if the fleet turned tail and returned to Japan
 
The Japanese fleet detected approaching Hawaii is effectively a declaration of war - as it would have no other business being there other than to attack the US

It would be almost as bad as far as the USA is concerned as the OTL attack was even if the fleet turned tail and returned to Japan
For the political establishment, but what about society at large? Roosevelt rejected all suggestions of pre emptive attack.

For the US to fight WWII, the country had to be united. If it entered divided as it had WWI, measures like rationing would be unavailable.

If 30% of able men either redused to register for the draft, report when called or deserted begore finishing boot camp ( the WWI figure), its hard to see America fighting anything like the war she fought
 
For the political establishment, but what about society at large? Roosevelt rejected all suggestions of pre emptive attack.

For the US to fight WWII, the country had to be united. If it entered divided as it had WWI, measures like rationing would be unavailable.

If 30% of able men either redused to register for the draft, report when called or deserted begore finishing boot camp ( the WWI figure), its hard to see America fighting anything like the war she fought
Remember the Maine, to hell with Spain was good enough to doom the Spanish Empire?
 
Remember the Maine, to hell with Spain was good enough to doom the Spanish Empire?
That may be but fighting WWII is a lot bigger than a little colonial war fought with volunteers.

Pearl Harbor united America behind the war. A preemptive strike would likely cause a constitutional crisis.

An American President starting a war with Japan without Congress first authorizing it is just unimaginable. Roosevelt would never have done it.
 
For the political establishment, but what about society at large? Roosevelt rejected all suggestions of pre emptive attack.

For the US to fight WWII, the country had to be united. If it entered divided as it had WWI, measures like rationing would be unavailable.

If 30% of able men either redused to register for the draft, report when called or deserted begore finishing boot camp ( the WWI figure), its hard to see America fighting anything like the war she fought
I fail to see how attacking a fleet headed straight for your base with hostile intent is a preemptive strike. If anything, it would be an act of self defence.

Nor can I see why the American public would not be united in opposing Japan (or at least majority-in-favour), upon finding out that Japan was intent on landing a sucker punch.
 
I fail to see how attacking a fleet headed straight for your base with hostile intent is a preemptive strike. If anything, it would be an act of self defence.

Nor can I see why the American public would not be united in opposing Japan (or at least majority-in-favour), upon finding out that Japan was intent on landing a sucker punch.
How you see it isnt important. its how Roosevelt and the American people of 1941 would see it

Roosevelt flat out rejected the idea for the reasons I gave you. He would only seek a DOW only if the incident galvanized the American people. That means the people have to know about it.

His response is most likely to be simply to put all American forces on high alert and let Japan make the move.

In OTL, Marshall realized the significance of the timing of the Japanese message and only tried to warn Pearl.
 
That may be but fighting WWII is a lot bigger than a little colonial war fought with volunteers.

Pearl Harbor united America behind the war. A preemptive strike would likely cause a constitutional crisis.

An American President starting a war with Japan without Congress first authorizing it is just unimaginable. Roosevelt would never have done it.
Again there is no other reason for the Japanese Navy to be were it was found in this scenario

Finding the KB near the Hawaiian islands is a declaration of war - no one in congress (probably might be a couple to be fair) is going to view it as anything but an attempt at what it was - a surprise attack on the US Pacific fleet and they will act accordingly

I am not talking about the tactical response but the political reality of the USA finding out that the Japanese were planning to attack them in such a fashion

And I do not see this as being a hard sell to the American people - after all these are the Japanese responsible for the rape of Nanking
 
Again there is no other reason for the Japanese Navy to be were it was found in this scenario

Finding the KB near the Hawaiian islands is a declaration of war - no one in congress (probably might be a couple to be fair) is going to view it as anything but an attempt at what it was - a surprise attack on the US Pacific fleet and they will act accordingly

I am not talking about the tactical response but the political reality of the USA finding out that the Japanese were planning to attack them in such a fashion

And I do not see this as being a hard sell to the American people - after all these are the Japanese responsible for the rape of Nanking
that s all very nice and I agree with most of it.

But we are talking about how Roosevelt would react and ordering a strike without a DOW is very unlikely.

He was adamant about Japan making the first blow. He was a very good politician and knew how far he could push the American people.

They werent into first strikes and a lot didnt trust Roosevelt. Roosevelt will ask Congress for the DOW before starting a war.
 

Geon

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So, assuming the Kido Butai are discovered and have to cancel the attack on Pearl Harbor, what happens then? The Japanese have lost their best chance to neutralize the American Pacific Fleet. What will be their strategy now? Also, will they still try for Wake Island and Guam given that the USN could intercept then and/or reinforce those islands?
 
So, assuming the Kido Butai are discovered and have to cancel the attack on Pearl Harbor, what happens then? The Japanese have lost their best chance to neutralize the American Pacific Fleet. What will be their strategy now? Also, will they still try for Wake Island and Guam given that the USN could intercept then and/or reinforce those islands?
The Japanese can't hide it. The U.S. will DEMAND why is a fleet of carriers heading to Hawaii. The diplomats in DC have a hard time explaining it. There is no way the Japanese are going to get away with this. The U.S. will declare war regardless.

The U.S. cannot reinforce Guam, Wake Island, and the Philippines in December 1941. The defense of the Philippines only started in July 1941, but even then it was not enough.
 
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