Pearl Harbor Alerted

[Joe Kemper]

Sorry if this has been discussed previously but I tried to search with no luck.

What if Pearl Harbor had been alerted to the approach of the Japanese fleet and we knew the Japanese were under orders to attack.

What would have been the response? If we knew it was a carrier strike force and its location and heading were known would the battleships have been sent to intercept or would they wait to join with the Lexington and/or Enterprise, if practical?

Would the fleet try to remain within land based fighter protection?

I am sure there are many variables to consider but I wonder what the response would have been based on the tactical and strategic doctrine of the US Navy at that time.

Thank you

Joe

[Terminus]

If the battle fleet had sortied, they'd have been sunk at sea, rather than in port.

[John Lansford]

The Pacific Battlefleet had next to no defense against a carrier strike; maneuvering at 21 knots wasn't going to accomplish much at all, and the BB's anti-air defenses were very meager.  The USN would have probably lost at least half the battleships and their crews, and smaller ships would have been lost as well. 
 
They would have been better off sitting in port, all guns manned and ready, with full watertight integrity established and the USArmy planes up and waiting.  That wouldn't have saved Arizona but the other ships would have probably suffered less damage.

[51st Highland Div]

Yeah i agree better to keep the fleet in port with AA batteries and fighter cover ready to meet the attack...the defender could have taken a greater toll on the carrier aircraft from the start rather than from no opposition at the commencement of the attack, and dealt a blow to future IJN operations in terms of losses..

[CaptDave]

ORIGINAL: John Lansford
They would have been better off sitting in port, all guns manned and ready, with full watertight integrity established and the USArmy planes up and waiting.  That wouldn't have saved Arizona but the other ships would have probably suffered less damage.

Who knows? Maybe it would have saved Arizona. Maybe the planes attacking it would have been among those shot down before the fact.

[marky]

i wouldve kept them in port and sent up as many fighters as possible and told the carriers to run.

much better they be sunk in shallow water where they can be salvaged, as historically they were except Arizona, and Oklahoma, which never returned to service and if i remember right sank being towed to the west coast.

[witpqs]

A hit like the one on Arizona is a percentage deal - even on an exact 'do-over' it would only happen some of the time.

[Joe Kemper]

Thank you for the responses.

What I am curious about is how the navy would have responded with this information based on the pre-war doctrine.

Would they sortie the fleet and if practical join with the carriers before attempting to intercept?

Sortie the fleet and withdraw to safer waters?

Sortie the fleet and attempt to engage without the carriers but remain within land based air cover?

Remain in port at battle stations and hope for the best?

I know there are many more variables but I was just curious what the decision makers would have tried based on the doctrine they had at the time.

Thank you

Joe

[witpqs]

Re: Pre-war doctrine, that's a good question.

However, Kimmel was damn smart. He might not have reacted per pre-war doctrine!

[anarchyintheuk]

Was Nevada acting on her own when she tried to exit PH or was she acting pursuant to pre-existing orders?

[bigbaba]

i remember that in the german translation of the great movie "tora tora tora" kimmel gave "bull halsey" the order to take the "Big-E" and bring some aircrafts to wake or midway before the japs attacked pearl. and after he was not able to give halsey an clear answer about what to do, when halsey spots japanese units, halsey himself said to kimmel something like "even when i see a small japs sailing ship, i send it to the forefathers"[:)].

now if halsey was the CIC pacific fleet, then the answer would be clear about what he would do when he had some intel informations about immineintly japanese attacks. about kimmels reaction? no idea.

[herwin]

ORIGINAL: Joe Kemper

Sorry if this has been discussed previously but I tried to search with no luck.

What if Pearl Harbor had been alerted to the approach of the Japanese fleet and we knew the Japanese were under orders to attack.

What would have been the response? If we knew it was a carrier strike force and its location and heading were known would the battleships have been sent to intercept or would they wait to join with the Lexington and/or Enterprise, if practical?

Would the fleet try to remain within land based fighter protection?

I am sure there are many variables to consider but I wonder what the response would have been based on the tactical and strategic doctrine of the US Navy at that time.

Thank you

Joe

The local Japanese spies would have reported back that the fleet was out of its anchorage, and the KB would have aborted the operation.

[witpqs]

ORIGINAL: herwin

The local Japanese spies would have reported back that the fleet was out of its anchorage, and the KB would have aborted the operation.

Wait a minute - that depends upon when the fleet sortied and what were the means of communications available to the spies. Could they contact the fleet directly? Did they have to go through the embassy?

[Hornblower]

It is a good thing that the Fleet didn’t sortie.  Would have been a higher death toll on the USN side, and the sunk ships would be permanently sunk.
 
Now, lets suppose on the 6th a B-17 happened to locate the KB while still steaming into launch range.  AND Nagumo knew without a doubt that his approach was no longer, well, a surprise.
 
Would they have continued the mission or zipped away?      Obviously its opinions at this point..           I feel that the die was already cast

[Joe Kemper]

Thanks again for the responses.

I guess for the purpose of my question, please indulge me, and assume for whatever reason the KB is unaware and proceeding as planned.

Thank you

Joe

[anarchyintheuk]

They expected to have to fight their way in. IIRC once the signal 'climb niitaka' went out to KB on 12/2 or 12/3 they were on autopilot to attack.

[AW1Steve]

ORIGINAL: witpqs

Re: Pre-war doctrine, that's a good question.

However, Kimmel was damn smart. He might not have reacted per pre-war doctrine!

Kimmel was smart, but aggressive. And he was a battleship man through and through. I belive that he would have lead his battleships to sea, confident that Enterprise and Lexington would provide aircover. No battleship had been sunk at sea by aircraft yet, he wouldn't know Japanese strenght and even if he did, how long would he have remained in command if he just stayed passive during a Japanese attack? We need to think like they did on December 6, 1941, not December 8th! [:)]

[Anthropoid]

ORIGINAL: anarchyintheuk

They expected to have to fight their way in. IIRC once the signal 'climb niitaka' went out to KB on 12/2 or 12/3 they were on autopilot to attack.

Yeah, but didn't the lead Japanese dude decide not to send the second (or third) wave primarily because they no longer had surprise? That's what it said in that old movie . . .

In any event, the one class of things that I think would have been dramatically different had PH been alerted is that US soldiers sailors and airmen would not have been lounging around enjoying a lazy Sunday morning, all hands would've been at battle stations or general quarters or whatever, water-tight compartments would've been prepped, aircraft would've been on patrol or else fueled, armed and ready to launch, etc., etc.

No matter what effect being in port or being out of port (or whether they would have sortied or not) would have had, being prepared for an attack in all the above noted ways surely would've made a very big difference? After all, isn't the advantage in most combat for the defender, except in those instances where a surprise attack catches the defender unprepared?

Sure, Kimmel sortying might have led to more boats lost to U.S. but on the other hand if they were not all in port in the first place what is the chance that the Jap airplane formations would have been able to find them, let alone buzz-in in such effective and orchestrated high-densities and score so many devastating hits?

Sure 15knt is not that fast but it will put distance between you and PH if it is sustained for a few hours and just being out there at sea, where the ability of the Japanese attack to find them would've been reduced could've led to some very different results. For that matter, if the KB leadership thought a flotilla of US BBs was heading their way, would they have just lingered in the area waiting for all their planes to complete their attacks on a (potentially in large part empty) Pearl Harbor?

So many contingencies . . . I think the only things you can say with any certainty are: it would not have turned out the way it did; and more Japanese planes would likely have been shot down.

US losses might not have been much different, and indeed as pointed out because of the benefit of the shallow harbor for subsequent recovery efforts, more ships might have been totally lost. But then again, if the departure of large fractions of the fleet occurred the evening before, giving 12 hours of steaming away from PH to some obscure spot 80 or 90 miles removed from the harbor, maybe very few high value ships would've been lost at all.

[TSCofield]

Nagumo was somewhat conservative in his approach but he did know what his mission was and would have carried through with the attack IMHO.
 
He pulled back after the attack because he honestly didn't think that the risk to his warships was worth the potential gain in attacking US port and fuel facilities.  It is easy to look back in retrospect and realize that this was a mistake but back then he didn't have the convenience of today's information.
 
1.  He had no idea where the US Carrier forces were.  He didn't know if the US had two or three carriers available (Lexington, Saratoga, Enterprise).  If those forces suprised the IJN as or after they launced a second wave (something that did happen at Midway) then the Japanese Navy could have been down two or three carriers starting out the war.  There would have been no support from the IJN for campaigns in Java or around the Phillipines if it was needed. 
 
2.  He had preliminary reports of the success of the attack but he had no idea how deeply the US Army Air Corps was hurt and how hurt the US Navy was.  He was ordered to render the US Pacific Fleet non battle ready and he did that.  His orders didn't say he was to render Pearl Harbor neutralized although it probably should have.  Another wave would have put his pilots in greater danger since every gun not destroyed in the first wave would now open up on all attackers.  Pilots coming in during the later part of the first wave noted how fast the AA had recovered from the shock of the attack.  I suspect another wave would have lost probably 40 to 60 more aircraft, along with the valuable pilots that Japan needed for naval battles. 
 
3.  There was still a fear of sub attack.  Nagumo probably would have figured that the US might have figured out the direction of the attack and would be sending out search planes and vectored subs to the location.  The fact that the US still had no idea of the specific location of the IJN fleet wasn't known by Nagumo.  The longer he spent deep in enemy waters the greater risk to his ships.  If one carrier took a torpedo and had to limp back to port it would have meant either the entire KB would have to slow down to protect it or it would have meant risking an entire ship by leaving it alone to try to get back.  The quicker the KB could get out of the area the safer the fleet would be. 
 
Whether he was ultimately right or not can be debated.  He did do his job though.  Many of his fears, like the sudden appearance of US carriers, were shown to be valid just six months later when the Japanese lost four carriers at Midway. 

[marky]

ORIGINAL: bigbaba

i remember that in the german translation of the great movie "tora tora tora" kimmel gave "bull halsey" the order to take the "Big-E" and bring some aircrafts to wake or midway before the japs attacked pearl. and after he was not able to give halsey an clear answer about what to do, when halsey spots japanese units, halsey himself said to kimmel something like "even when i see a small japs sailing ship, i send it to the forefathers"[:)].

now if halsey was the CIC pacific fleet, then the answer would be clear about what he would do when he had some intel informations about immineintly japanese attacks. about kimmels reaction? no idea.

his exact words were: "If i see so much as a sampan near us, ill blow it out of the water"[:D]