WI: Pearl Harbor attack does not commence Pacific War, but comes later?

[psteinx]

So, let's say for one reason or another Japan intentionally goes to war with the US/UK/etc in early December 1941, but does NOT attack Pearl Harbor, instead using the carriers etc. for other roles/attacks (SE Asia).

Then, circa Jan-Feb 1942, Japan DOES attack Pearl Harbor, roughly in the same way, with the ~same ships, as in OTL.

How much worse would the attack fare?

Assume that the degree of good (or bad) luck the Japanese experience is broadly consistent with what they had in OTL.

On the one hand, one would expect/hope for better awareness and preparedness on the part of the Americans.

On the other hand, in Dec 1941, the Americans were already expecting the Japanese to strike SOMEWHERE - it was hardly out of the blue. Also, Taranto (British strike on Italian naval base) shows that such a strike could be successful, even if it occurs in the middle of a war, rather than as the initial strike.

 

[Sekhmet_D]

Would there even be a point to attacking the Pearl anchorage once America is on a full war footing and has presumably mobilised most of its naval units to South East Asia where the action is taking place?

 

[psteinx]

Presumably there'd still be a reasonable number of aircraft and ships in Pearl. So yeah, if the Japanese could bomb it with little damage to their own attacking force, that would be good for them.

 

[kham_coc]

So the change is that, what the US is forced to declare war, and then the Japanese manage a PH level of attack, well it won't change much if anything.

 

[psteinx]

The change is that the Japanese use their carriers etc. elsewhere in the theatre in early December 1941 (and the war still starts around Dec. 7), then go attack Pearl a month or two later.

 

[Spencersj345.346]

The change is that the Japanese use their carriers etc. elsewhere in the theatre in early December 1941 (and the war still starts around Dec. 7), then go attack Pearl a month or two later.

with the declaration of war pearl's defenses will be beefed up fast and there's basically no way to sneak up on it if the place is on war footing and thus always has several radars active and a lot of Catalinas and maybe the B-17s doing search patterns.

 

[psteinx]

with the declaration of war pearl's defenses will be beefed up fast and there's basically no way to sneak up on it if the place is on war footing and thus always has several radars active and a lot of Catalinas and maybe the B-17s doing search patterns.

Well, that kind of begs the question.

A war warning had been issued shortly before OTL Pearl attack. So why wasn't OTL Pearl at the level of readiness that a not-yet-raided ATL Pearl might be in mid January, 1942?

OK, humans are humans - the urgency of an ACTUAL war is higher than being under a war warning. Still...

 

[Sekhmet_D]

Well, that kind of begs the question.

A war warning had been issued shortly before OTL Pearl attack. So why wasn't OTL Pearl at the level of readiness that a not-yet-raided ATL Pearl might be in mid January, 1942?

Because absolutely no one in the States was expecting the blow to fall at Pearl, simple as that. Plus, the response to said war warning was lackadaisical in the extreme.

 

[psteinx]

Because absolutely no one in the States was expecting the blow to fall at Pearl, simple as that. Plus, the response to said war warning was lackadaisical in the extreme.

No one except those who knew about the 1932 and 1936 wargames?

And also excluding the commander of Pearl immediately before Kimmel, who felt the location was too vulnerable and protested FDR's decision to put so much of the Pacific Fleet there?

 

[Sekhmet_D]

No one except those who knew about the 1932 and 1936 wargames?

And also excluding the commander of Pearl immediately before Kimmel, who felt the location was too vulnerable and protested FDR's decision to put so much of the Pacific Fleet there?

I would argue that the war games merely proved that Pearl could be successfully attacked.

They did not necessarily predict that the Japanese would open the dance with a 350 carrier plane surprise strike against the facility.

 

[CaptainCalvert]

I would argue that the war games merely proved that Pearl could be successfully attacked.

They did not necessarily predict that the Japanese would open the dance with a 350 carrier plane surprise strike against the facility.

A fair point, but carrier attack - however unlikely - was the only viable option other than a submarine attack, which was largely covered through well established nets etc (and indeed was thwarted OTL).

I think the original question comes back to why did the Japanese attack in OTL. If buying time to take and consolidate the outer defence perimeter, then it only makes sense to do it as one of the opening acts, when chances of detection, chances of success and value from success are highest in what was always a risky proposition.

 

[psteinx]

I think the original question comes back to why did the Japanese attack in OTL. If buying time to take and consolidate the outer defence perimeter, then it only makes sense to do it as one of the opening acts, when chances of detection, chances of success and value from success are highest in what was always a risky proposition.

What I was hoping to get at, in part, was alluded to by another respondent:

We tend to think that Pearl was so vulnerable on Dec. 7 because of the surprise factor. Push the Pearl attack back by ~6 weeks, and HOPEFULLY we do a lot better.

But why? Didn't we have enough notice pre-Dec 7th to take appropriate protective measures?

One possible answer is that the Japanese planners didn't know the exact extent of defensive counter-measures, but reasonably assumed that things would be tightened up in wartime conditions - the initial blow was their best chance. But better practices by Kimmel, Short, and the Washington intelligence community, and maybe just better luck, *MIGHT* have dulled the blow from the get-go, and/or resulted in US air and/or submarine strikes on an over-extended Japanese strike force, causing something Midway-like 6 months earlier than OTL.

 

[Spencersj345.346]

Well, that kind of begs the question.

A war warning had been issued shortly before OTL Pearl attack. So why wasn't OTL Pearl at the level of readiness that a not-yet-raided ATL Pearl might be in mid January, 1942?

OK, humans are humans - the urgency of an ACTUAL war is higher than being under a war warning. Still...

to put it simply a war warning is not the same as there's a war going on.

 

[1Big Rich]

How much worse would the attack fare?

I think the attack would be detected after war was declared. There will be air patrols from Dutch Harbor, Midway and Hawaii that will be covering the historical Japanese approach path to the islands.

Attacking the alerted base could be disastrous for the Japanese. There will be US Army Air Corps CAP in place, and if the attack is detected before hand they are likely to run into more fighters they the carriers possess. Splitting between two strikes makes it even worse.

Remember, one of the reasons the Japanese went after Kaneohe Bay was to prevent a counter attack on the carriers.

In addition, with war declared and ongoing, I would think the ships at Pearl Harbor would have improved AA, be much faster to General Quarters and have Condition Zebra for all watertight doors and hatches closed much faster than they did on December 7th.

In my opinion the historic attack was badly executed. Fuchida sent the signal flare the surprise had been achieve, but the fighter escort didn't see it. He fired a second flare for them, but the dive bombers saw that as well and thought surprise had been lost, so they attacked WITH the torpedo bombers when they were supposed to attack AFTER the torpedo bombers' runs. The historic over-concentration on West Virginia (seven or nine torpedoes, depending on the source) and Oklahoma (five) by the experienced air crews from Akagi and Kaga is another example. They were specifically assigned to get the battleships because of their experience. The less experience crews of Soryu and Hiryu got the other side of Ford Island where the carriers normally berthed and green crews from Shokaku and Zuikaku got the land targets. It shows as well how impactful the 'fog of war' can be. It's a cliché, but it's a cliché because it's true.

Assume that the degree of good (or bad) luck the Japanese experience is broadly consistent with what they had in OTL.

On the one hand, one would expect/hope for better awareness and preparedness on the part of the Americans.

On the other hand, in Dec 1941, the Americans were already expecting the Japanese to strike SOMEWHERE - it was hardly out of the blue. Also, Taranto (British strike on Italian naval base) shows that such a strike could be successful, even if it occurs in the middle of a war, rather than as the initial strike.

True on Taranto, but the Med was unique environment. The strategic offensive and defensive regularly switched between the British and the Italians. Seeing a Royal Navy task group in the central Med was no unexpected. Finding a Japanese task group in the eastern Pacific would cause a massive reaction, in my opinion. Plus the British carried out the attack at night, something the Japanese could not accomplish in going after Pearl Harbor and it surroundings.

Well, that kind of begs the question.

A war warning had been issued shortly before OTL Pearl attack. So why wasn't OTL Pearl at the level of readiness that a not-yet-raided ATL Pearl might be in mid January, 1942?

OK, humans are humans - the urgency of an ACTUAL war is higher than being under a war warning. Still...

The War Warning was issued in late November (the 27th, IIRC). Pearl Harbor was ordered to stand down from the War Warning on December 6th.


My thoughts,

 

[marathag]

Even without the wide success of December 7th, you would get much of the same effect as the Doolittle Raid, US would be more worried about defense, and pull back units from the Front.
Without the sneak attack on Pearl, there would still be the sneak attack on the Philippines.
Kimmel and Short keep their jobs, Dugout Doug would not, and likely not be in command long enough to get that nickname.

 

[Spencersj345.346]

Also in addtion to the stuff already mentioned with a war formally on its far more likely any capital ships in pearl harbor will have torpedo nets set to protect them at anchor

 

[psteinx]

What steps were taken at OTL Pearl in the weeks/months after the attack to protect it against a recurrence?

 

[DougM]

-If the war starts with Japan attacking the philippine islands and not Peril then the US is still at war
-if Japan later attacks peril.
a). Thier will be less ships in the harbor as wartime maneuvers will see most out and about. The USN in the Pacific is not the German or Italian navy. They did not go home to port regularly. The distances are to far.
b). Japan will not get compete surprise.
- war warning patrols and caution is not the same as being at war. The rules change at war. Troops dont get treated as well and work more and coast is not as much a factor so putting hours on airframes and other expendables is not being watched. So you can sdo things in actual war you can not get away with before it. Even in alerts.
- on Dec 6th aircraft carriers were not as well “respected” as on dec 8th. Look at the arguing over the war games and the judging of them. No one wanted to believe that the carrier guys were now top dog, After Dec 7 they had to accept it. Even without peril. The month of Dec and Jan will see a LOT of carrier actions and aircraft doing bad bad tgings to ships and bases. So while carriers may mot be as respected as after Peril they will be more respected then they were on Dec 6th.

Frankly i cant see Japan risking sending the fleet that far after a war starts while the US fleet is intact.The risk is huge. A lot larger then it waS on Dec 1-7. and the reward will be less as most of the fleet is out and about. And dont forget you are risking the support vessels as well.
And on Dec 5th if you stumble into the US fleet or a random sub at worst you blow your cover and have yo return home. Do that on Feb7 and you carrier goes for a dive from a sub.. (remember Japan did not know how bad US torpedos were). So way to much risk.
More likely you see some sort of Midway style trap with Japan trying to draw the US into action in Japanese waters. Frankly with out PH levels of lose early on in the war i think that Japan is a lot less bold. I don't think you see the long range raids and such like OTL. Japan does not try the Midway Trap if the US Navy is in one piece. That was a plan based on the weakened state of the USPacific fleet. It is easy to be bold when you have a large advantage. But without the advantage of Peril Harbor i tgink the Japanese stay a lot closer to homr..

 

[CaptainCalvert]

If not used to attack Pearl Harbour, it means that there is powerful Japanes fleet (or two) available for other missions.
Anyone have some good suggestions on where and what it might mean?

 

[BlackDragon98]

So, let's say for one reason or another Japan intentionally goes to war with the US/UK/etc in early December 1941, but does NOT attack Pearl Harbor, instead using the carriers etc. for other roles/attacks (SE Asia).

Then, circa Jan-Feb 1942, Japan DOES attack Pearl Harbor, roughly in the same way, with the ~same ships, as in OTL.

How much worse would the attack fare?

Assume that the degree of good (or bad) luck the Japanese experience is broadly consistent with what they had in OTL.

On the one hand, one would expect/hope for better awareness and preparedness on the part of the Americans.

On the other hand, in Dec 1941, the Americans were already expecting the Japanese to strike SOMEWHERE - it was hardly out of the blue. Also, Taranto (British strike on Italian naval base) shows that such a strike could be successful, even if it occurs in the middle of a war, rather than as the initial strike.

If America is a full war footing, then Japan would have to get through a submarine picket line and wartime level air and sea patrols.

In OTL, the Americans knew the Japanese were going to strike soon (the oil embargo was basically fight or flight ultimatum) but they didn't put their units in the Pacific on full alert. They'd broken the Japanese code as well, as Midway was only possible because they manipulated the code to find out the Japanese target.

Roosevelt wanted to draw America into WW2 on the side of the Allies. He needed a big event to do so, a Lusitania type event; something with a lot of dead US servicemen. Pearl Harbor and the US forces in the Philippines ended up becoming his sacrificial pawns.

If US was already fighting Japan, a strike on Pearl Harbor would be nowhere near as successful. There would be no element of surprise. And Roosevelt wouldn't need any sacrificial pawns.