WI: Kido Butai Spotted En Route to Pearl

[Sekhmet_D]

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!

 

[Emman]

Possible suspicion of Japanese Expansion on the Asian territories of the Western Powers.

 

[Sekhmet_D]

Possible suspicion of Japanese Expansion on the Asian territories of the Western Powers.

This has to be the understatement of the year.

I really don't see how anyone could merely conclude 'possible suspicion' after receiving word of six carriers steaming straight for Hawaii. There would be sufficient grounds to attack and sink that fleet if the means and opportunity were available to do so.

 

[Emman]

This has to be the understatement of the year.

I really don't see how anyone could merely conclude 'possible suspicion' after receiving word of six carriers steaming straight for Hawaii. There would be sufficient grounds to attack and sink that fleet if the means and opportunity were available to do so.

yes I agree It would be a full mobilization and an earlier war in the Pacific.

 

[Dalriadan Archangel 21]

This has to be the understatement of the year.

I really don't see how anyone could merely conclude 'possible suspicion' after receiving word of six carriers steaming straight for Hawaii. There would be sufficient grounds to attack and sink that fleet if the means and opportunity were available to do so.

Really?

I am not sure I see the US opening hostilities as much as many in the chain of command might want to.

Having worked so hard to remain neutral to this point in the face of Axis provocation and Allied invocation it would be a strange change to suddenly throw that away on a battle fleet steaming in international waters on a heading away from US territory.

 

[TDM]

This has to be the understatement of the year.

I really don't see how anyone could merely conclude 'possible suspicion' after receiving word of six carriers steaming straight for Hawaii. There would be sufficient grounds to attack and sink that fleet if the means and opportunity were available to do so.

if they are in international waters then I actually doubt the US will just go and sink them (even if they could scramble a big enough fleet to do so).

Don't get me wrong Japan's plan in screwed and even if they mutter some nonsense about a training exercise the US isn't dumb and will mobilise and be on a hair trigger. and will instantly be ratcheting up pressure on Japan.

Another issue is what happens at the Philippines, Singapore and HK, will the Japanese abort those attacks, will they even have time to and what would doing so look like to the world that just focused itself on them

 

[Sekhmet_D]

Really?

I am not sure I see the US opening hostilities as much as many in the chain of command might want to.

Having worked so hard to remain neutral to this point in the face of Axis provocation and Allied invocation it would be a strange change to suddenly throw that away on a battle fleet steaming in international waters on a heading away from US territory.

On a heading TOWARDS US territory.

There is no way the Japanese can innocently explain why a huge attack fleet is Hawaii bound during a time of failing negotiations, international waters or otherwise.

This action can be interpreted as an opening of hostilities on their part and I very much doubt any reasonable observer, even without the benefit of hindsight, can infer otherwise.

In any case, our hypothetical scenario already has Kido Butai open fire and eliminate the craft that spotted them, which removes any lingering doubt that might surround the issue.

Do you really think Kido Butai, if spotted, would opt to hold their fire and calmly change course?

 

[Sekhmet_D]

Another issue is what happens at the Philippines, Singapore and HK, will teh Japanese abort those attacks, will they have time to and what would doing so look lie to the world that just focussed itself on them

I can't see them calling off Malaya and Singapore. Those are too vital to their quest for SEA's natural resources.

The Philippines, though, is something to ponder. With America now on full alert, they might at least momentarily pause on making a move there, if only to retailor their attack plan.

As for Hong Kong, I wonder how vital it truly was to the Japanese plan that the island should be taken. Sure, it was a British outpost sitting practically in Japan's backyard, but I don't recall the British having much in the way of airpower or seapower stationed there, certainly not enough to pose any major threat. There could potentially be an argument for deploying the Hong Kong invasion force elsewhere if American alertness forced an acceleration of the timeline, and for leaving Hong Kong to just wither on the vine.

 

[thedarkmaster]

I think an unsubstantiated, posdibly garbled call from a merchant ship is going to go up the chain of command of the US forces ....be investigated.

How accurate is the report ?
All you really have is a location in international waters?

The merchant ships radio officer cannot comment much more than warships seen... i doubt more than a few have been spotted, and location, possibly general heading but as they likely to be watching the destroyer screen racing to intercept ( possibly a cruiser or two) its not likely on their list of priorities.

Then some sort of confirmation has to be found, a search and rescue possibly started if its in range.

None of this really changes much in Pearl Harbour....im sure they have had warship warnings before, and lost ships before but without confirmation and orders from above over it.....what changes ?

It's more down to if the IJN feels it can still achieve its objective of not.

 

[CaptainCalvert]

The big problem the Kido Butai has is that fuel is very limited. If they don't attack, they have to turn back pretty much straight away, although they do have a little more opportunity to do something extra compared with OTL on the way back to base if the opportunity arises.
The original plan was supposed to be to call off the attack if spotted on the way there, but maybe they would persist if they shot down a scout plane and didn't detect any radio transmissions. However, I don't know what (if any) alternate plans they had in case the Pearl Harbour attack had to be called off [1].

[1] Maybe I should read the collection of Pearl Harbour-related books my partner acquired over several visits she made to Pearl Harbour.

 

[Dorknought]

The IJN southern force was spotted and reported days before the invasion. They shot at the snoopers and downed one on Dec 6th. I think Nagumo would press on with the attack. There we no alternate plans. The initial report would have to be confirmed. All this would take time. The US did expect attacks on its naval forces in China.

 

[CaptainCalvert]

I think an unsubstantiated, posdibly garbled call from a merchant ship is going to go up the chain of command of the US forces ....be investigated.

How accurate is the report ?
All you really have is a location in international waters?

The merchant ships radio officer cannot comment much more than warships seen... i doubt more than a few have been spotted, and location, possibly general heading but as they likely to be watching the destroyer screen racing to intercept ( possibly a cruiser or two) its not likely on their list of priorities.

Then some sort of confirmation has to be found, a search and rescue possibly started if its in range.

None of this really changes much in Pearl Harbour....im sure they have had warship warnings before, and lost ships before but without confirmation and orders from above over it.....what changes ?

It's more down to if the IJN feels it can still achieve its objective of not.

Bearing in mind the OTL response to a submarine sighting or two and a probable sinking, and also the general attitude of military intelligence to civilians, it probably wouldn't change much even if a merchant ship sent in a clear and concise report with photographs, a marked chart and the Japanese admiral's personal phone number.

 

[Sekhmet_D]

The IJN southern force was spotted and reported days before the invasion. They shot at the snoopers and downed one on Dec 6th. I think Nagumo would press on with the attack. There we no alternate plans. The initial report would have to be confirmed. All this would take time. The US did expect attacks on its naval forces in China.

To be fair, Nobutake Kondo and Jisaburo Ozawa commanded the southern force and they were made of far sterner stuff than Nagumo was, especially Ozawa.

 

[Sekhmet_D]

However, I don't know what (if any) alternate plans they had in case the Pearl Harbour attack had to be called off [1].

[1] Maybe I should read the collection of Pearl Harbour-related books my partner acquired over several visits she made to Pearl Harbour.

I don't know if any of the available literature covers that topic, honestly. It seems to be a rather large question mark in a field otherwise brimming with information.

The more I think about it, the more I'm considering the possibility that they steam for Truk, then unleash hell upon Rabaul earlier than scheduled. Bit anticlimactic and akin to smashing a walnut with a sledgehammer, but it seems in keeping with Nagumo's overwhelming desire to play things safe. Tamon Yamaguchi might have opted to raid Wake and/or Midway in order to lure the Pacific Fleet into battle, but he wasn't in the hot seat. Quite something to contemplate, though - the Battle of Midway unfolding in December of '41 rather than June of '42.

 

[PMN1]

On a heading TOWARDS US territory.

There is no way the Japanese can innocently explain why a huge attack fleet is Hawaii bound during a time of failing negotiations, international waters or otherwise.

This action can be interpreted as an opening of hostilities on their part and I very much doubt any reasonable observer, even without the benefit of hindsight, can infer otherwise.

In any case, our hypothetical scenario already has Kido Butai open fire and eliminate the craft that spotted them, which removes any lingering doubt that might surround the issue.

Do you really think Kido Butai, if spotted, would opt to hold their fire and calmly change course?

A goodwill visit?

 

[jlckansas]

It will also depend on where they are spotted on their way to the attack. Spotted where they turned south and began their run in to launch, Nagumo might just do it if he is convinced by Genda nobody got a message off. Spotted somewhere along a line west of Midway or especially Wake islands longitude, turn back and head for Truk. This is one of the situational ones.

 

[1Big Rich]

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.

As I recall, a Soviet transport was encountered in the North Pacific, and AFAIK, we still don't know what transpired between them.
IIRC, Nagumo was under orders to abort if he was detected, unless it was in the last 24 hours before the attack. In that case, the attack was to be carried out, regardless of detection.

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?

A couple of the KB destroyers did bombard Midway, Ushio and Sazanami

I don't think there was much at Midway beyond the airfield at this point. It certainly wasn't the fortress it would be in seven months facing invasion.

Hiryu and Soryu did hit Wake on the return trip to Japan, after Wake proved to be a tougher nut than the Japanese expected to crack.

Assuming the strike south still goes as planned even with aborting the Pearl Harbor attack, I would think Yamamoto would want to have his forces ready for any kind of US counter offensive, I'm not sure they would be sent much farther than the Philippine Sea

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!

Depending on where the KB is detected. I don't think intercept would be a possibility except for Lexington (bringing aircraft to Midway). Halsey and Enterprise were too close to Hawaii from the mission to bring aircraft to Wake, and they needed replenishment. Enterprise's task force was actually due in Pearl on the 6th, but encountered heavy weather and were delayed.

The IJN southern force was spotted and reported days before the invasion. They shot at the snoopers and downed one on Dec 6th. I think Nagumo would press on with the attack. There we no alternate plans. The initial report would have to be confirmed. All this would take time. The US did expect attacks on its naval forces in China.

I think Tarrant has that episode in his book on the KGV class.

In the early hours of December 8th local time, an RAF Hudson of No. 1 Squadron sighted three separate Japanese convoys of transports escorted by warships in the South China Sea. It was fired on by escorting heavy cruisers.

Historically Pearl Harbor would have been attacked about 2:00 am on the 8th local time in Singapore. IIRC, the first radio news reports of the raid were a couple hours later. So without a Pearl Harbor raid, the war would be all-Western Pacific.

A goodwill visit?

Without prior notice?

Regards all,

 

[jsb]

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.

I think an unsubstantiated, posdibly garbled call from a merchant ship is going to go up the chain of command of the US forces ....be investigated.

How accurate is the report ?
All you really have is a location in international waters?

The merchant ships radio officer cannot comment much more than warships seen... i doubt more than a few have been spotted, and location, possibly general heading but as they likely to be watching the destroyer screen racing to intercept ( possibly a cruiser or two) its not likely on their list of priorities.

Then some sort of confirmation has to be found, a search and rescue possibly started if its in range.

None of this really changes much in Pearl Harbour

Would it not depend a lot on the quality of the signal?

A RN Sub going from Vancouver to Hong Kong that gets a good look and dives, & survives sighting them and send back clear signals would be very different from a merchant that gets jammed and sunk quickly and ignored?

 

[nbcman]

It would depend on when the Japanese Task Force was spotted according their instructions:

HyperWar: USSBS: Campaigns of the Pacific War

United States Strategic Bombing Survey: 'The Campaigns of the Pacific War' (2. Japanese Attack on Pearl Harbor).

www.ibiblio.org

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.
3. If discovered on "X"-minus-1-day or the morning of "S"-day the Task Force was to continue with the attack.
4. 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.
5. If, at any time during the approach to Pearl Harbor the American Fleet attempted to intercept the Japanese Task Force, the Japanese planned to counterattack. If the American Fleet advanced into Japanese home waters in pursuit of the Task Force it was planned to commit the Main Body of the Japanese Fleet as a support force.

If, after arriving in Hawaiian waters, it was found that the American Fleet was at sea and not in Pearl Harbor, the Japanese planned to scout a 30-miles radius around Oahu and attack if contact was made; otherwise they were to withdraw.

 

[Sekhmet_D]

As I recall, a Soviet transport was encountered in the North Pacific, and AFAIK, we still don't know what transpired between them.

I would LOVE to know more about this incident. It appears to have escaped my knowledge entirely, up until now. If it did occur, and the attack went ahead anyway, one can only presume that the neutrality pact between Japan and the Soviets somehow prevented the encounter from ending in violence and disclosure.