WI US realises Japan's plans. Loses at Hawaii. What happens eslwhere in the Pacific?

[Derek Jackson]

Suppose the intelligence had been put together. So The Phillipines are on the alert. Warships have all watertight doors close. People there to man guns. US aircraft in the air

Japanes forces lose a lot. They have to fly back fairly early because of fuel shortage.

Then the Japanese fleet is detected. Hit hard by US carrier based and land based forces.

What would happen in other places?

Might Japan have rapid political changes, the militarists losing face and prestige?

 

[Mark E.]

A battle-ready USS Arizona, offshore, would make a big difference.

 

[gladiator8085]

It would have helped if they listened to the radar operators.

 

[GarethC]

Do the British share in this belief? How early? When Nagumo puts to sea on 26th November? When Konoe resigns 15th October?
If they are certain that the balloon is going to go up, then they may be able to put a bigger spoiling attack (Matador/Krohcol) into Malaya or even get a few more bodies into Burma.

Enterprise gets a scratch air group flow out to it and puts a strike in on Kido Butai on the afternoon of the 7th, sinking Kaga before being sunk herself.

MacArthur has less autonomy with more US preparation, and indeed may be recalled to the mainland, and so may screw things up less. Implementing the war plan as written makes Bataan more tenable, and maybe not losing half the air force in less than an hour on the first day of the war will help too.

Force Z may still get sunk - those bombers weren't involved in the Philippines campaign, and a better show by the USAAF isn't likely to make Phillips less dismissive of Japanese air power. Still, if anything changes at all, that golden BB may not happen. Equally, he may find Ozawa's covering force and get slaughtered in a night torpedo action. Or with higher priority the degraded 2lb shells might be replaced and all the radars working, in which case he may get away with it until some Buffalos come to save his bacon while he runs south.

If CarDiv 5 gets its air wing damaged over Pearl, then Wake will hold out longer. If a second wave doesn't have Shokaku and Zuikaku it will be delayed, and then the Pensacola convoy may be pushed through (because the USN correctly estimates that Kido Butai has taken sufficient losses to require the air wings be reconstituted).

The whole of Operation R (New Britain and Ireland, particularly Rabaul) probably has its timeline extended - that used 4 CVs in support, and if they are reconstituting their air groups or repairing damage then they aren't available to strike the Australians.

 

[CalBear]

A battle-ready USS Arizona, offshore, would make a big difference.

Well it is more likely to lose the WHOLE crew that way. The fleet sorties, assuming it goes in the right direction (which was about 160° different from what was actually expected) it gets caught in deep water with minimal fighter cover (AAF is going to stay inshore and defend the base, leaving only whatever the Fleet Reserve has to launch as cover for the fleet (10 F4F-3 and 8 F2A, Marines could contribute 11 more F4F-3). So you get 21 Wildcats and 8 Buffaloes to deal with the first wave of 171 aicraft (B5N of the 2nd Wave were armed with GP bombs, not the 800kg AP ship killers (converted 40cm AP shells) carried by the first wave or torpedoes). Figure four, maybe five heavies take enough damage (two torpedoes, couple 250kg GP bombs, MAYBE one or two of the 49 800kg bombs hit, but I'll bet the under on those) that they go down in open water, decent chance (50:50) at least one of the I-boat screen manages an attack, that happens and chalk up a BB or CA in addition to the air strikes.

U.S. KIA hit 4-5,000 (roughly double OTL). Kido Butai loses probably 150, maybe 180, aircraft (including those with so much battle damage that they are simply pushed over the side, IIRC that was the fate of around 30 Japanese aircraft IOTL).

To the OP: If the fleet is clearly alerted several days ahead of time (which is the only way there are enough naval strike aircraft available to make even a decent strike) Nagumo's orders were to abort and haul ass back to Japan. On December 5th Nagumo was still 700+ miles out to sea, the U.S. would be hard pressed to conduct an attack at that range even if they wanted to. The Enterprise was off Wake, the Lexington was approaching Midway on December 5th, both carriers were deliver Marine aircraft (F4F to Wake, SBU2 to Midway), they are three days away from getting into strike range, and both TF will need to refuel their destroyers before taking off to attack the Kido Butai The Japanese still have an active Consulate on Hawaii, the Battle Fleet sorties and anyone sitting on Ewa Beach (and the Japanese had folks watching) is going to see it happening.

As far as elsewhere -

The Philippines still depends on MacArthur. He screwed the pooch with what turned out to be half a day's warning. MacArthur's command was alerted to the Pearl Harbor attack at around 02:30 on December 8th (local time), Hap Arnold PERSONALLY called FEAF CO General Brereton at 08:00 (PI local) and warned him not to get his forces caught on the ground. At 11:30 (PI local) MULTIPLE radar stations warned of an incomes strike. The Japanese hit Clark at 12:40 PM, two full squadrons of B-17s were caught on the ground. There is no reason to believe that MacArthur and his senior staff, especially his nitwit Chief-of-Staff Sutherland would do anything useful with extra warning time.

Wake may be able to have more fighters up (IOTL they had two of 12). That will further increase the cost to the Japanese in taking the Island.

Guam was indefensible. The Marine and milita forces only had enough personal weapons for 198 troops (170 M1903 Springfields, 13 Lewis Guns, 15 BAR) and the local police numbered 80 men with revolvers. No heavy weapons of any kind on the island. No fortifications, not even a minefield. Heaviest warship there was a 24 year old minesweeper with two 3' guns, and two harbor patrol boat, each with a single 1 pounder (i.e. 37mm) gun.

With better information the British may be able to get PoW and Repulse in position to tear up the initial Malaya landings before daylight when the IJNAAF will arrive and blow them out of the water.

 

[CV(N)-6]

If possible the USN sends subs at the KB, though I doubt if they can be in position on time. Enterprise and maybe Lex hit the KB, though since, as you can guess from my username, I like the E too much for her to be sunk. The battle line takes heavy losses but might screw up enough of the IJN strike to save Enterprise (yay, plausibility!). A wounded KB means a more aggressive USN earlier.

 

[marathag]

Figure four, maybe five heavies take enough damage (two torpedoes, couple 250kg GP bombs, MAYBE one or two of the 49 800kg bombs hit, but I'll bet the under on those) that they go down in open water,

Maryland showing damage from a Type 91 Torpedo.
She steamed in reverse the whole way back to Pearl after the battle of Saipan.
Torp hits aren't instakills on Standards. Maryland never got the full modernization that her sunk then raised sisters got.
I don't see the Level Bombers getting any hits on moving ships with the converted shells

 

[CalBear]

Maryland showing damage from a Type 91 Torpedo.
She steamed in reverse the whole way back to Pearl after the battle of Saipan.
Torp hits aren't instakills on Standards. Maryland never got the full modernization that her sunk then raised sisters got.
I don't see the Level Bombers getting any hits on moving ships with the converted shells

That was why I said 2 torpedoes and a couple 250kg bomber.

Put that damage back about 8 or 9 frames and give it a twin 5-6 frames or so behind the first one.

You now have a ship with no power, except maybe a back up diesel generator, and damage close to if not into the secondary magazine.

 

[raharris1973]

If the fleet is clearly alerted several days ahead of time (which is the only way there are enough naval strike aircraft available to make even a decent strike) Nagumo's orders were to abort and haul ass back to Japan.

Were the orders for Nagumo just to abort the Pearl operation, or for Japan to abort every new offensive in all directions? IE, were all the moves in Southeast Asia to proceed if Pearl were to be aborted?

 

[1Big Rich]

Suppose the intelligence had been put together. So The Phillipines are on the alert. Warships have all watertight doors close. People there to man guns. US aircraft in the air

What would happen in other places?

Might Japan have rapid political changes, the militarists losing face and prestige?

Yamamoto was actually expecting to lose some of the carriers Even if detected 24 hours before the launch, the Kido Butai was to press home the attack.

I think the Philippines will still be hard hit. Brereton and McArthur didn't execute the plans to make the Bataan Peninsula a fortress. Supplies were supposed to be stockpiled, swamps drained (to cut down on malaria as well as provide 'better' ground) and air fields were to be set up there. Remember, US fighters were up after word of Pearl Harbor was received. But the Japanese strikes from Formosa were delayed because of weather (fog, IIRC). When the Japanese did show up, the fighters had been called down and were on the ground.

In Malaya, Phillips still has the only force that can stop or delay the Japanese. Not sailing was not an option. With some forewarning, someone in the Admiralty might have the sense to assign the three D-class light cruisers to his force as well.

As far as elsewhere -

The Philippines still depends on MacArthur. He screwed the pooch with what turned out to be half a day's warning. MacArthur's command was alerted to the Pearl Harbor attack at around 02:30 on December 8th (local time), Hap Arnold PERSONALLY called FEAF CO General Brereton at 08:00 (PI local) and warned him not to get his forces caught on the ground. At 11:30 (PI local) MULTIPLE radar stations warned of an incomes strike. The Japanese hit Clark at 12:40 PM, two full squadrons of B-17s were caught on the ground. There is no reason to believe that MacArthur and his senior staff, especially his nitwit Chief-of-Staff Sutherland would do anything useful with extra warning time.

Wake may be able to have more fighters up (IOTL they had two of 12). That will further increase the cost to the Japanese in taking the Island.

Concur.

Maryland showing damage from a Type 91 Torpedo.
She steamed in reverse the whole way back to Pearl after the battle of Saipan.
Torp hits aren't instakills on Standards. Maryland never got the full modernization that her sunk then raised sisters got.
I don't see the Level Bombers getting any hits on moving ships with the converted shells

Thanks for that marathag. As an aside, several years ago I had the pleasure of bumping into a gent wearing a USS Penssylvania BB-38 ball-cap. His name was John Alsop, and he was a World War II veteran. We had brief talk about his time aboard her, and mentioned the torpedoing of Maryland. They were at anchor, and at night many of the crew would sleep out on the deck because of the heat. He was out on the bow, and the Betty that topedoed Maryland flew right over Pennsylvania's bow. Mr. Alsop said he could see the pilots face in the light of his cockpit instruments.

Regards all,