WI: Pearl Harbor Was Foiled

Assume that FDR receives information that the Japanese intend to attack Pearl Harbor in December of 1941. How does the United States respond to this threat?
What's the source? Is it a personal telegram from the Japanese Emperor - 'Help! My crazy military chiefs are planning to attack your nation at Pearl Harbour and in the Philippines on <insert dates and times here>' or is it a vague rumour picked up from a friend of a friend of a low-ranking US embassy intelligence man in Tokyo?
Details and credibility of the information determine the levels of response (if any).
 
Actually, they were expecting an attack of some sort IIRC or at least some sort of trouble. But an air attack caught them completely out-of-sorts.
 
Actually, they were expecting an attack of some sort IIRC or at least some sort of trouble. But an air attack caught them completely out-of-sorts.

From what I understand, they were expecting an attack at one of the Phillipines, Malaya, the DEI, or Hong Kong and Singapore. They didn't expect the Japanese to choose "all of the above" and go for the whole thing plus Pearl Harbor.
 
I think it is fairly easy. The existing notices to Kimmel and Short IOTL should have prompted them to take action. Throughout late November and early December messages from Admiral Stark (the Chief of Naval Operations) and General Marshall (US Army Chief of Staff) told them to expect enemy action at any moment and to take such preparations as needed. For some reason though, Kimmel did nothing. He blamed the contradictory commands in the messages. However, where he saw contradictory messages, I only see the routine bureaucratic language organizations routinely use. The intent was always clear - expect enemy action at any moment, and take all measures necessary for defense.

Kimmel and Short were not derelict of their duty, but they did massively screw up.

If we want something more than just Kimmel and Short removing their heads from their ass, giving them some of the Magic intercepts would probably be sufficient to prompt them to do more.

Ideally, all this means is that the radar is up and air cover is up and flying when the Japanese planes attack. An actual sortie of the fleet leaving Pearl Harbor would result in a worse result as it would mean more loss of life and less likely to refloat the ships.
 
An actual sortie of the fleet leaving Pearl Harbor would result in a worse result as it would mean more loss of life and less likely to refloat the ships.
Depends on how much notice the USN gets. The attack commenced after 7am. If the USN gets notice of the attack the night before, at 20 knots, the slowest battleships could be anywhere within 150 miles.
 
Assume that FDR receives information that the Japanese intend to attack Pearl Harbor in December of 1941. How does the United States respond to this threat?
Move the ships out of port the day before. Have CAP up to stop the IJN aircraft. And........ have a significant submarine force off Japanese ports to kill the returning carriers.
 
I think it is fairly easy. The existing notices to Kimmel and Short IOTL should have prompted them to take action. Throughout late November and early December messages from Admiral Stark (the Chief of Naval Operations) and General Marshall (US Army Chief of Staff) told them to expect enemy action at any moment and to take such preparations as needed. For some reason though, Kimmel did nothing. He blamed the contradictory commands in the messages. However, where he saw contradictory messages, I only see the routine bureaucratic language organizations routinely use. The intent was always clear - expect enemy action at any moment, and take all measures necessary for defense.
The problem was, all indications of 'enemy action' were that it would be sabotage of some kind, not an air-raid.
 
I think it is fairly easy. The existing notices to Kimmel and Short IOTL should have prompted them to take action. Throughout late November and early December messages from Admiral Stark (the Chief of Naval Operations) and General Marshall (US Army Chief of Staff) told them to expect enemy action at any moment and to take such preparations as needed. For some reason though, Kimmel did nothing. He blamed the contradictory commands in the messages. However, where he saw contradictory messages, I only see the routine bureaucratic language organizations routinely use. The intent was always clear - expect enemy action at any moment, and take all measures necessary for defense.

Kimmel and Short were not derelict of their duty, but they did massively screw up.

....

Thats the most common version. The War Warning message sent late November did result in a surge of frantic activity, in part because it was assumed the Japanese would attack on the Thanksgiving holiday. As one enlisted Navy Vet described it, 'Everyone went nuts for a week preparing for a Japanese attack.' As that week ran out & Thanksgiving passed by it was clear a state of frantic activity was not going to defend the island. ie: The sortie rates for the PBY reconissance planes had been so high that maintenance was neglected and the ready or operational numbers dropped below that needed to keep a minimum patrol in the air. Another problem was the aircraft accident rate was starting to climb. A third problem was that a state of hyper alertness and constant activity was not effective training. Thee were a lot of green units on Oahu that did not benefit from the week+ of headless chicken imitation. Kimmel & Start made a concious decision to start over, to reset as it were, and after a brief stand down proceed with a more methodical and practical level of combat readiness and preparation.

Note that the original Japanese intent was to attack on the Thanksgiving holiday. For technical reasons they delayed & it was their good luck they arrived Sunday the 7th vs the previous weekend while the defense command was 'going nuts'.
 
The problem was, all indications of 'enemy action' were that it would be sabotage of some kind, not an air-raid.

That has a bit of myth as well. The USN and Hawaian Defense command had done staff studies, table exercises, and fleet exercises that showed it was practical to attack the island with carriers. Fleet plans and exercise had been run to attack such a raid. There was a concern about Japanese sabatoge, but it was not the only or even primary concern.
 
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Depends on how much notice the USN gets. The attack commenced after 7am. If the USN gets notice of the attack the night before, at 20 knots, the slowest battleships could be anywhere within 150 miles.

Indeed. The actual operational plan distributed was for the fleet to deploy SE of Oahu or the islands. Far enough a attack aimed at the naval base would not be able to spot it, but close enough to benefit from reconnaissance and combat air cover. That position would also place the fleet on the flank of a raiding force launched from the Marrianas islands, where Truk the nearest Japanese naval base lay.
 
That has a bit of myth as well. The USN and Hawaian Defense command had done staff studies, table exercises, and fleet exercises that showed it was practical to attack the island with carriers. Fleet plans and exercise had been run to attack such a raid. There was a concern about Japanese sabatoge, but it was not the only or even primary concern.
Maybe, but the Japanese hadn't even declared their intention to cease negotiations before they attacked, never mind declaring war, so whether or not it had been wargamed, it wasn't expected.
 
All WI and AH changes, but it would have been ideal if the US carriers had been in a position to launch strikes after Japan launched theirs. Then have the planes on Oahu loaded and airborne. With all AAA manned and ready the US might have been able to take out Japanese planes and carriers.

I admit very big changes from OTL, but I can think it and dream. :evilsmile:
 
Perhaps then Roosevelt can move the fleet into diverse areas to avoid damage perhaps to San Diego. There may be ways to intercept the armada as it is coming across the Pacific. The island being battle ready may be able to repel the aerial attack, but this is all.
 
Maybe, but the Japanese hadn't even declared their intention to cease negotiations before they attacked, never mind declaring war,

Yet the War Warning made it clear that negotiations had ceased, and that hostile action should be expected. It also made it clear any Japanese military aircraft or ships sighted were to be considered hostile and could be attacked.

so whether or not it had been wargamed, it wasn't expected.

Not expecting a attack Oahu had become the most densely defended bit of territory of the US. Hmm... When the war warning came the fleet went to sea, submarine picket line was deployed, the Army manned the combat posts, and the air groups run ragged on reconissance missions.
 
All WI and AH changes, but it would have been ideal if the US carriers had been in a position to launch strikes after Japan launched theirs. Then have the planes on Oahu loaded and airborne. With all AAA manned and ready the US might have been able to take out Japanese planes and carriers.

I admit very big changes from OTL, but I can think it and dream. :evilsmile:

It is a nice dream. OTL the radar stations went back into action after the attack started. They tracked and reported the departing aircraft. The information was misunderstood & the surviving reconissance aircraft sent SW for their primary search. It seems to have taken the better part of the day before the Army and Navy intel sections figured out the enemy was to the north.
 
Yet the War Warning made it clear that negotiations had ceased, and that hostile action should be expected.
No, the war warning made it sound like the negotiations were in trouble, not that they'd actually failed.

It also made it clear any Japanese military aircraft or ships sighted were to be considered hostile and could be attacked.
which is quite different from knowing there's an enemy fleet just days away from your main naval base.

Not expecting a attack Oahu had become the most densely defended bit of territory of the US. Hmm... When the war warning came the fleet went to sea, submarine picket line was deployed, the Army manned the combat posts, and the air groups run ragged on reconissance missions.
The war warning was vague and a little contradictory, and placed greater emphasis on sabotage and other subversive operations than an outright attack. This is why they were exonerated in 1999.
 
Move the ships out of port the day before. Have CAP up to stop the IJN aircraft. And........ have a significant submarine force off Japanese ports to kill the returning carriers.

All good ideas except the sub one won't work. At this time the US is lumbered with defective torpedos that weren't fixed otl until 1943. They tended to breakup as often as they detonated and are unlikely to do any real damage.

Although a failed sub attack on the returning fleet (assuming at least some boats escape) might make the USN realise what's going on earlier and fix it.

If nothing else that would be embrassing. Pearl harbor turns into a gung ho American victory, a few hundred dead, some damage to the harbor but no ship sank and the Japanese mauled. As Japan still steamroller's SE Asia pearl is seen as the victory that proves Japan isn't invincible (like midway or coral sea in OTL). Indeed there is only one problem...their attempt to strike back was a farce.

Probably the USN is told to find out what happened and fix it on pain of pain.
 
The problem was, all indications of 'enemy action' were that it would be sabotage of some kind, not an air-raid.

Really, my understanding was that the 'War warning' was interpreted by Short - because sabotage was the only possible danger to the base, air attack and/or invasion were just too ridicules to consider from his point of view - though they may follow-on. They perceived the more overt action to take place to the west, Philippines, Wake, Guam, whereas the danger to PH was more subversive in character. While Washington, may not have had PH as being on the danger list - their war warning was to all bases to take all means to guard against an attack.
 
Really, my understanding was that the 'War warning' was interpreted by Short - because sabotage was the only possible danger to the base, air attack and/or invasion were just too ridicules to consider from his point of view - though they may follow-on. They perceived the more overt action to take place to the west, Philippines, Wake, Guam, whereas the danger to PH was more subversive in character. While Washington, may not have had PH as being on the danger list - their war warning was to all bases to take all means to guard against an attack.
Well as far as I'm aware, there was nothing in the warnings that got sent about a military attack on Pearl Harbour, but some warnings about potential sabotage attacks, thus Kimmel and Short were raked over the coals for stuff that wasn't really their fault. Also, it should be noticeable that Macarthur somehow survived with his career intact, despite screwing up far worse than Kimmel and Short (the message to him was explicit about potential attacks, he had better codebreaking capabilities at his command, and PH occurred nine hours before any attack on PI).
 
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