Japan badly damaged at Pearl Harbor

CalBear

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A lot of what happens depends on the amount of warning, and how solid the warning is.

If the warning is thought to be reliable intel there is a range of possibilities from a significant Japanese defeat to an utter disaster for the USN.

Scenario 1. Best case U.S. 7-8 Hours notice of the attack, no information on the position of the Kido Butai. Aircraft are on Dawn Patrol, probably close to a full squadron. Radar warning flushes the rest of the fighters (total of 12 A-20, 36 P-36, 99 P-40 (87 "B", 12 "C" models), 21 F4F, 8 F2A total of 164 fighters and 12 350 MPH attack bombers) while the PBY and bombers head out to sea in the opposite direction. All Army AAA is up and manned, ships in harbor have either gotten up steam or are at Condition One in port. 187 Japanese aircraft are hit by 164 American Fighters. Even with the great quality of the IJN pilots first wave loses close to half the strike force (probably 35 shot down, 60 or so mission killed). Second wave may be called off (it is already in the air), if it comes in, a significant percentage of the U.S. fighters will be on the ground rearming/refueling so this wave faces somewhere around 40-50 fighters, figure 35-40% loss (20 shot down, 50 mission killed) for a total of 90 aircrew and 155 aircraft. American aircraft losses are in the area of 30 shot down, 50-60 shot up. Pennsylvania get hit in the dry dock, maybe worse than IOTL, at lest one, possibly two of the BB get caught at anchor and eat torpedoes, Utah, thanks to her berthing site, get ripped to little bits. Four BB, several cruisers, and a number of destroyers sortie and head to the southwest toward the Mandates, which was the expected axis of any IJN attack on Hawaii which is the opposite direction from the actual IJN line of approach putting them out of range for the IJN aircraft.

Scenario 2. Good result U.S. 4 hours warning, no information on IJN position. Ships are able to set Condition One, Nevada, several cruisers (1 CA, 3-4 CL) 15-20 DD sortie and move toward Mandates. Army AAA 2/3 manned and with 50% or less ammo. ~40% of fighters get up at least partly armed. IJN first wave attack is disrupted, but not stopped completely. Attacks on airbases are only partly successful. Second wave finds Army AAA at 100% ships fully ready. IJN aircraft losses 10%, mission kill 20%-30% (105-140 aircraft). U.S. loses 100+ aircraft in air or on ground. Most BB take some damage, with at least one being a total loss (Oklahoma is a good bet, she's out board and has the worst internal compartmenting of the outboard ships).

Scenario 3. Draw 2 Hours warning, no information on IJN location. Most ships are at Condition One, Army AAA less than half manned with limited ammo, 20-30 fighters get up. Shipping losses are close to OTL, but with less damage to California & West Virginia thanks to less flooding but IJN aircraft losses are 10%, 15-20% mission kill (88 aircraft, 35 aircrew).

Scenario 4. OTL significant IJN tactical victory.

Scenario 5. Less favorable U.S. result U.S. 7-8 Hours notice of the attack, accurate information on the position of the Kido Butai. Aircraft are on Dawn Patrol, probably close to a full squadron. Three BB and some escorts head toward IJN and are caught in deep water with less than 15 fighters as CAP. All BB lost, at least one cruiser, all in deep water. Japanese force that continues to Pearl is savaged as in Scenario 1. American casualties are 3,000+.

Scenario 6 Strategic U.S. Defeat 12 Hours notice of the attack, accurate information on the position of the Kido Butai. Aircraft are on Dawn Patrol, probably close to a full squadron. Entire battle line heads out to engage IJN. Caught in open water by both IJN waves at edge of Fighter Cover. Five BB lost, two damaged in open water. Pearl facilities not struck, USAAF losses minimal. Japanese losses are under 30 aircraft. U.S. casualties 4,000+

Scenario 6 Utter U.S. Defeat 18 Hours notice of the attack, accurate information on the position of the Kido Butai. As in # 6 except Lexington TF moves into position to intercept. Lexington has 16 F2A Buffaloes for CAP/Raid escort against 6 Japanese carriers. Lexington lost, probably with one or two of CA escorts.

A couple notes:

The BB at Pearl had not received their planned 1940's upgrades (Colorado was not at Pearl because she was getting this major upgrade which included addition of 5"/38 DP guns). They had a 4 76mm AAA and some 1.1" pom-poms along with .50 cal machine guns for anti-aircraft. In port, tied up, they could put up a reasonable amount of small caliber flak into a small area. At sea, at normal formation spacing, they were almost helpless, something the the Navy had recognized from the early battle in the North Atlantic and was one of the main goals of the planned modernization.

The AAA at Pearl was fairly dense, for the time. It was totally inadequate for the attack at hand, especially in heavy flak. The 76MM guns topped out at 20k feet, something that was know to the IJN, with most of the remaining AAA being 20mm and .50 cal. It is likely that, in ideal conditions, the AAA would have taken down more no more than 10% of the enemy aircraft in each wave, with 5% being a much more likely (and quite good) outcome, with a similar number mission killed and pushed over the side when they returned to the carriers.

The Fleet was not up to handling the Kido Butai at sea, anything that creates that sort of engagement is a disaster. Although he wouldn't have done it, Kimmel's best play was to run to the southwest, collecting the Enterprise Group as he went. The USN was at least a solid year from having a surface force that could defend itself from a serious air attack, even with a carrier in support.
 

Markus

Banned
The BB at Pearl had not received their planned 1940's upgrades (Colorado was not at Pearl because she was getting this major upgrade which included addition of 5"/38 DP guns). They had a 4 76mm AAA and some 1.1" pom-poms along with .50 cal machine guns for anti-aircraft.

??? No 5"/25 guns at all? I checked the wiki-articles for the BB and navweaps.com too. It seems all had 8 such guns each. So did most of the modern cruisers, the rest had the 5"/38.
 

CalBear

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??? No 5"/25 guns at all? I checked the wiki-articles for the BB and navweaps.com too. It seems all had 8 such guns each. So did most of the modern cruisers, the rest had the 5"/38.


You are correct. Braincramp.

The 5"/25 however, was not the weapon that the 5"/38 proved to be.
 
Calbear, you seem to be assuming highly aggressive movement by the U.S. in response to any available intelligence. Is it likely that Kimmel would actually take the fleet and relentlessly pursue a Japanese force that he should know he could never catch out beyond effective land based air cover? I mean, if his scouts are able to get an accurate location fix, they should also see nothing but carriers and the pretty distinctive Kongos. If Halsey were in charge, this would be a reasonable assumption, but Kimmel? What would be the likely effects of the fleet on maneuvers near Pearl, fully under air cover? No backup from land based AA, but the ships can move to evade air attack.
 

CalBear

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Calbear, you seem to be assuming highly aggressive movement by the U.S. in response to any available intelligence. Is it likely that Kimmel would actually take the fleet and relentlessly pursue a Japanese force that he should know he could never catch out beyond effective land based air cover? I mean, if his scouts are able to get an accurate location fix, they should also see nothing but carriers and the pretty distinctive Kongos. If Halsey were in charge, this would be a reasonable assumption, but Kimmel? What would be the likely effects of the fleet on maneuvers near Pearl, fully under air cover? No backup from land based AA, but the ships can move to evade air attack.

Intel: 90% probability that Imperial Japanese Navy will launch air attack against your position in next 24 hours.

Take all necessary steps to ensure any such attack fails.

Up until 7:50 AM on 12/7/41 the Pacific Battle Squadron was considered to be an OFFENSIVE force. The Fleet had been moved to Pearl specifically to face down the Japanese. Kimmel was actually a very good officer who was handed the dirty bit of the stick post attack. Moving into open water and toward the enemy was exactly what he would have learned since Canoe U.

A good officer would not sit around and await enemy attack in port or in littoral waters, not when he had the opportunity to get open water around him and meet the enemy on the High Sea, and, hopefully, face him down. Based on battle theory of the time, major surface combatants were not vulnerable to aircraft if able to maneuver, so there would be no reason to worry since he would out gun the IJN fleet by a comfortable margin. Given his lower force max speed, it would also be advantageous to get across the enemy line of withdrawal before any attack occurred.

In any case, if the fleet is at sea, within range of Kido Butai, and spotted by any of the submarine scouting force or air search assets sent out by the IJN permanent losses would almost certainly be much higher than IOTL. The Japanese proved, on more than one occassion, that they were fully capable of putting air dropped torpedoes into the sides of ships making high speed maneuvers at 30+ knots. The 20 knot BB in Kimmel's force would have been target sleeves.

It is worth noting that most USAAF pursuit pilots were not comfortable with over water navigation at this point in time and their aircraft were not properly instrumented to aid them in such navigation. The Army was also responsible for protecting the base and harbor, including the ships while they were inside the harbor. Once at sea, the fleet was supposed to be able to take cart of itself. It is unlikely that Short would have assigned most of his fighter force to cover the fleet at sea. The fleet would get very lonely once it was out of sight of land.

I firmly believe that the best place for the fleet would have been in Pearl, either at anchor or at station keeping with Condition One set and full watertight intergity in place with the land based AAA and fighter cover taking the IJN attackers under fire 15 or 20 miles off the North Shore of Oahu and hammering them all the way in. That is seven-eight hours of warning. The next best would be at sea, advancing toward the enemy fleet's expected line of advance (i.e. moving generally toward Wake) and directly away from the Japanese strike force.
 
Gents,

I would think that a sortie by the Pacific Fleet from Pearl will depend heavily on just when the IJN Strike Force is detected. Kimmel may have been schooled at Canoe U and may be itching to hit the Japanese with everything he's got, but even he isn't going to sortie the battleline without his carriers along to provide air cover.

During the first of December 1941, Enterprise has just delivered planes to Wake and isn't scheduled back until the 6th, Lexington is off delivering planes to Midway, Saratoga is steaming to San Diego after leaving drydock at Bremerton, Langley is moored off Cavite in the Philippines, and all the others, Yorktown, Ranger, Wasp, and Hornet are in the Atlantic.

I don't think a signals intercept coup is going to cut it. The Strike Force maintained a very strict radio silence and, while decrypted Japanese radio messages did point to an attack on the US forces, they didn't specifically mention Pearl. Squinting at the Strike Force's approach course, the Japanese could have been physically sighted as early as the 5th, but at that date Lexington has already departed with her delivery aboard and Enterprise has yet to return.

From the 5th to the actual time of the attack, Kimmel will have no carriers at hand and I seriously doubt he'll sortie without them.


Bill
 
Gents,

I would think that a sortie by the Pacific Fleet from Pearl will depend heavily on just when the IJN Strike Force is detected. Kimmel may have been schooled at Canoe U and may be itching to hit the Japanese with everything he's got, but even he isn't going to sortie the battleline without his carriers along to provide air cover.

During the first of December 1941, Enterprise has just delivered planes to Wake and isn't scheduled back until the 6th, Lexington is off delivering planes to Midway, Saratoga is steaming to San Diego after leaving drydock at Bremerton, Langley is moored off Cavite in the Philippines, and all the others, Yorktown, Ranger, Wasp, and Hornet are in the Atlantic.

I don't think a signals intercept coup is going to cut it. The Strike Force maintained a very strict radio silence and, while decrypted Japanese radio messages did point to an attack on the US forces, they didn't specifically mention Pearl. Squinting at the Strike Force's approach course, the Japanese could have been physically sighted as early as the 5th, but at that date Lexington has already departed with her delivery aboard and Enterprise has yet to return.

From the 5th to the actual time of the attack, Kimmel will have no carriers at hand and I seriously doubt he'll sortie without them.


Bill

Given hindsight, you are quite correct.

However the mentality at the time (among the battleship admirals) was that big ships were safe underway against aircraft. Indeed, safer than in port tied up as a target...so I think Kimmel would sortie, given the prevailing 'wisdom'.

Remember, the only ship seriously affected at sea (let alone sunk...!) by aircraft up till this time was Bismark. And the argument would be it was a lucky shot, and she was sunk by surface ships.

I think Kimmel would think it a great opportunity to savage the Japanese carriers (grabted with damage to his ships, but a very acceptable loss ratio).

Of course, we know he is completely wrong, but did he know this?
 

Markus

Banned
You are correct. Braincramp.

The 5"/25 however, was not the weapon that the 5"/38 proved to be.

True, but what kind of weapon was the 5"/25? I guess an inferior anti-ship gun but its not like capital ships needed help in that department. ;)
Navweaps indicates the 5"/25 was a good AA-gun, the effective AA-ceiling was much lower but in case of a torpedo bomber attack that does not matter, does it.
 
Given hindsight, you are quite correct. (snip) Of course, we know he is completely wrong, but did he know this?


Astro,

Carrier aviation had a very well defined inter-war role, one that had been developed in the yearly Fleet problems, one that even the battleship admirals understood and counted on.

The carriers were there to "scout and snipe". They were there to find the enemy, to harry the enemy, and to slow the enemy so that the battleline could swoop in and put the enemy under.

Given even as much as two days warning, Kimmel will not leave Pearl with a 20 knot battleline to attempt to catch a much faster Japanese Strike Force without a carrier anymore than he'd leave Pearl without destroyers because, without a carrier, Kimmel can't catch the Japanese. There's no "shortcut" he can take, no intercept course that will allow his much slower force to engage the Kido Butai. His own navy's inter-war doctrine and wargames prove the necessity of carriers in this situation, a necessity not as the "arm of decision" but as scouts and snipers.


Bill
 
Astro,

Carrier aviation had a very well defined inter-war role, one that had been developed in the yearly Fleet problems, one that even the battleship admirals understood and counted on.

The carriers were there to "scout and snipe". They were there to find the enemy, to harry the enemy, and to slow the enemy so that the battleline could swoop in and put the enemy under.

Given even as much as two days warning, Kimmel will not leave Pearl with a 20 knot battleline to attempt to catch a much faster Japanese Strike Force without a carrier anymore than he'd leave Pearl without destroyers because, without a carrier, Kimmel can't catch the Japanese. There's no "shortcut" he can take, no intercept course that will allow his much slower force to engage the Kido Butai. His own navy's inter-war doctrine and wargames prove the necessity of carriers in this situation, a necessity not as the "arm of decision" but as scouts and snipers.


Bill


But wasnt the US war plan to take all those slow battleships all the way to the Phillipines??

And true, he doesnt have his carriers. yet he has USAAF bombers, and he doesnt have to find the fleet, so why not attack (I'm sure the USAAF will tell him how wonderful they are agaisnt ships....:rolleyes:)
 
But wasnt the US war plan to take all those slow battleships all the way to the Phillipines??

And true, he doesnt have his carriers. yet he has USAAF bombers, and he doesnt have to find the fleet, so why not attack (I'm sure the USAAF will tell him how wonderful they are agaisnt ships....:rolleyes:)

Not by 1940. War Plan Orange had basically be rewritten by then (and discarded) and the 'Manila Express' portion of the idea had been dropped.
 
But wasnt the US war plan to take all those slow battleships all the way to the Phillipines??


Astro,

As already discussed in this thread, Plan Orange was dead by at least 1940.

Besides, attempting to catch an enemy who has a 6 or 7 knot advantage in speed and an over 150 mile head start isn't a smart move.

And true, he doesnt have his carriers. yet he has USAAF bombers, and he doesnt have to find the fleet, so why not attack (I'm sure the USAAF will tell him how wonderful they are agaisnt ships....:rolleyes:)

He has those assets as long as the Kido Butai stays within a certain range of Pearl. Very soon after the Japanese begin to withdraw, they'll be beyond the range of land-based aircraft.

Leaving aside an ASB-ish cryptographic or espionage coup, the Japanese can't be plausibly physically spotted before December 5th. At that time, all three USN carriers in the Pacific are elsewhere and the 20-knot battleline can't intercept the Japanese before they enter launch range of Hawaii.

While the various options in CalBear's post are the most plausible results for a range of initial starting conditions, I do not believe Kimmel would sortie without navy air cover being available.


Bill
 
Don't forget that Japan must launch a strike on a series of targets in and around Pearl Harbor so if the first scouts start screaming that battleship row is empty, the AA fully manned and everything the American's can fly is coming at them Nagumo doesn't have any choice. He can not run back to Japan or even pull out of reasonable range of his targets until he's finished a strike or two.

At best he throws out a search pattern and orders the two battleships with him to get between his carriers and where the American battleships are likely to be in hopes of taking out the American battleships at sea. If he finds them this would involve much heavier American casualties but if Japan also loses two battleships, most of the lighter ships involved and most of the planes and pilots...

A follow-up might be Wake Island holding out because the IJN orders the six carriers, none of them with even half their allotted planes, to get home and not intervene at Wake. This means even more Japanese destroyers and cruisers lost and...
 
Battleship action

One thing Nagumo would know for certain: His force is fast, but has fuel issues. But, he can NOT fight a surface action; he will loose. The US Pacific fleet has 8 battleships, and the weakest of them is a more powerful fighting ship than either of his.

Worts case for the Japanese, though it would take amazing luck, is for the Americans to bag the tankers. What would they do if they were out of fuel?
 
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