What if - we had not been caught with our pants down.

[Borgholio]

I remember awhile back, some wargamers decided to do a very thorough computer simulation about what would have happened if we had advance warning of the attack on Pearl Harbor. Their (highly controversial opinion) was that we'd lose even more ships because our BS were sunk in deep water instead of shallow water where they could be salvaged.

I think the wargamers forgot that if we sortied the fleet, they'd have massive land-based air cover from the islands.

So with that said, if we got a day advance notice or so of the attack, and deployed our full fleet to attempt to engage the Japanese...what would have happened? Would our BS have been fast enough to catch the Japanese carriers? Would they simply turn and run without launching an attack in the first place? Would a large battleship fleet with massive land-based air cover really be more vulnerable at sea compared to tied up at dockside with no air cover at all?

[Lord Revan]

the thing you got to remember was that like most senior officers of either side the admiral leading the Japanese attack was not a believer of the "carrier weapon", in fact he cancelled the third attack wave of he believed that the causalities would be too high compared to the effect it would cause and by destroying or crippling the battleships he had defanged the USN enough for them to no longer be a threat. So he would probably retreat then risk an encounter with a USN battle group in high seas

Also this assumes that any warnings would have been believed by high ranking officers that Pearl Harbor, since after this is 1940s America we're talking about and a lot of those officers were more then a bit racist.

[Sea Skimmer]

The very Japanese attack plan carried called for searching well south of Oahu if the US fleet had sortied, as the Japanese did not think they had a really high chance of taking the US entirely by surprise. That's why the launch position was so close to the island, when the strike otherwise could have been flown off from much further away.

As for racism, please, lets keep to actual facts. The USN never wanted its battlefleet at Oahu for the precise reason that this would make it vulnerable to an attack, while it was immune at San Diego. FDR disagreed and thought it would have a deterrent effect. Once at San Diego, the USN was so concerned about its battleships it decided it must keep all of them in port while its carrier’s forces were away on other duties. In other words, even on home turf, and with 300+ land based planes around, it did not think its battleships alone could face Japan! This is not very racist.

Normally at least one division of battleships was at sea at all times, with carriers accompanying it, to patrol the general area of the Hawaiian Islands.

The main problem was, faced with very limited reconnaissance assets, because they had been comprehensively stripped for two years to supply the British and the USN in the Atlantic, the Navy and Army Air Corps lacked the capability to patrol the islands. They choose to prioritize looking to the south west, in the direction of the closest Japanese bases and the only direction from which an unrefueled attack could come. Japan had never been known to refuel at sea, and indeed, never did so prior to preparing for the attack on Oahu. Assets stripped included one battleship division with some of the best ships of the fleet, one carrier and something like a third of all cruisers, destroyers and oilers. All to the Atlantic so FDR could better wage his undeclared war with Nazi Germany that was already killing Americans.

The Japanese came from the north instead, but only developed that capability at the last minute, and using some fairly exceptional measures such as carrying hundreds of barrels of drummed fuel on aircraft carriers to get the necessary range to sail all the way from Japan. That's besides the refueling at sea. This was one of many reasons why the third strike was aborted too, once it was clear that the number one objective was accomplished by the first two; sticking around even a few hours more would eat into the fleet’s fuel reserves to an even more dangerous degree.

If the USN battleline had been caught at sea at least several battleships would have been lost for good, possibly five or six even depending on how well the Japanese effort was spread and if they had the forewarning to equip the second wave with torpedoes instead of being bomb focused. Watertight integrity was lacking in most of the vessels, meaning that even a single torpedo, or even a good bomb hit, might sink them from progressive flooding.

[Borgholio]

If the USN battleline had been caught at sea at least several battleships would have been lost for good, possibly five or six even depending on how well the Japanese effort was spread and if they had the forewarning to equip the second wave with torpedoes instead of being bomb focused.

1. Is this factoring in land-based air cover from Hawaii?

2. The Japanese fleet was ~200 miles away from Pearl Harbor at the time of the attack. Had the US been given advanced warning, the fleet could have sortied and steamed to that location in ~12 hours. I don't recall reading anywhere about Japanese scouting efforts in that area prior to the attack. Would it have been possible to ambush the Japanese fleet if we had arrived at the intended launch coordinates several hours earlier?

[Sea Skimmer]

The amount of air cover the USAAF could provide to the fleet at sea is little on a sustained basis. Large numbers of aircraft were nonserviceable, most of the pilots were only half trained or recently converted from obsolete types and the general endurance of the planes was low. Perhaps one squadron at a time. It isn't going to do much unless the fleet stays right off Oahu, so that the fighters can be all kept ready on the ground and scrambled on radar warning. If anyone pays attention to the radar posts. This assumes warning time was too low to recall the detached carriers, though frankly the value of the fighters on those ships was pretty bad anyway, and each had only 18 embarked for its own use.

The Japanese launched scouts before the main attack. Also it is implausible that US forces would have been able to respond without generating large amounts of radio traffic the Japanese would have intercepted and interpreted as surprise having been lost.

Also its physically impossible to force an action between the US battleship force and the Japanese carriers, the later's cruising speed alone is almost as high as the ~20 knots any of the US ships are good for. That leaves the US heavy cruiser force to attempt to engage, while the Japanese are escorted by two battleships and two heavy cruisers themselves. And USN gunnery was completely terrible even months into the war. This will not go well, best hope would be a suicidal destroyer attack, but such an attack position will never be gained. Kido Butai was the strongest naval force the world had yet seen in history, it wasn't going to die easily. That's why Japan was willing to take such a massive gamble dispatching it, and effectively risking loosing the war in its first hours if things went wrong.

They had a lot of reason to fear the land based bombers on Oahu, but in hindsight we know they simply would not have been very effective from lack of crew training and poor serviceability.

Really the movie Tora Tora Tora covers all of this, even some of it in single lines of dialogue.

[Thanas]

OT: Is the movie any good, Skimmer? I have it lying around but never got to watching it.

[Eternal_Freedom]

IIRC Oklahoma at least was sunk because she was tied up alongside with all her watertight doors open, surely they would have been sealed in action and better able to resist flooding?

[Borgholio]

OT: Is the movie any good, Skimmer? I have it lying around but never got to watching it.

It's a good movie. If you've ever seen "Midway", which shows the battle of Midway from the American POV, Tora Tora Tora shows Pearl Harbor mainly from the Japanese side. So it's a good look into the thought processes and training that took place. It's not a documentary, so take the drama with a good sized grain of salt...but it's a good movie.

The two movies are actually linked together, in a way. Not so much as they would be today with a movie + sequel, but several scenes in Midway are directly lifted from Tora Tora Tora.

[Sea Skimmer]

OT: Is the movie any good, Skimmer? I have it lying around but never got to watching it.

It might as well be a documentary on the event, and views like one movie wise, it was functionally made to be such though they ultimately cut much of the Japanese material and even more of the American politicking for running time and its never been restored. They built a life size replica of the battleship Nagato just to film a couple minutes on her deck.

The special effects models being blown up are also far less offensive to my eyes then the utter retardation that is 'Pearl Harbor' that shall never be mentioned further.

'Midway' BTW is a fairly bad movie at this point not only because it recycles footage and had little budget, but we now also know that its story line is simply inaccurate as to the conduct of the final battle. Nothing is wrong with Tora Tora Tora that I'm aware of. Technical stuff forced on them ect... but not anything meaningful.

IIRC Oklahoma at least was sunk because she was tied up alongside with all her watertight doors open, surely they would have been sealed in action and better able to resist flooding?

Oklahoma was hit by at least seven and perhaps as many as nine torpedoes, five of which struck directly under her foremast, while being the oldest ship in the fleet. Even Yamato most likely would have sunk from this attack. The overconcentration on her basically saved other ships from much more serious damage. On the open sea, torpedo hit rates will be lower, but the torpedoes are likely to be a lot better distributed. Also some Japanese torpedoes are thought to have hit the harbor mud (IIRC several dredged up over the years) and a good many may have been destroyed by proximity explosions, because its unlikely that as many actually missed, as we know didn't explode, and any actual misses should have 100% hit Ford Island. Only about half have known impacts IIRC. I'm not counting.

It was California that was caught with something far worse then her watertight doors open, she had several dozen inspection manholes open in her double bottom. Normally these manholes are bolted down with wrenches because they accessed counterflooding tanks and other voids in the hull which men do not normally need to be in. This meant that closing her watertight doors, which were all open but could be closed in a few minutes, was almost useless. She actually took three days to finish sinking though, because of the snake like routes the flooding was taking through these manholes, and through all the bad pipe and wiring preforations and poorly fitted doors allowing progressive flooding. But that was also with a lot of tugs and other pumping capacity being used to try to save her.

That's one of those things that would be a killer at sea, because she'd rapidly loose propulsive power, as will other ships with progressive flooding. Nevada also fell to progressive flooding in her famous run to the sea, one torpedo and six bombs of only 250kg forced her to be beached, and she then just kept flooding even with condition zebra (that's close everything order) set until everything below the waterline was filled. All the battleships had similar problems. This actually could be massively corrected once noticed by mere days of dockyard work restuffing the preforations, resealing doors ect... but not in 12 hours when nobody knows its become such a big problem in the peacetime navy.

Even the newer carriers were found to have these problems, but none was lost as a result before corrective action was taken. Fixing them is part of the reason why Yorktown was so near unsinkable at Midway. On December 7th, it would be best to avoid action.

[Simon_Jester]

Is there any course of action the USN could have taken to avoid catastrophe at Pearl Harbor, supposing a vast amount of advance warning of the broad nature of the attack but no other information?*

Sortieing the battleline with no other precautions would be a mistake, the air assets to make a fight of it apparently didn't exist... am I missing something?




*[I.e., a time-traveling middle-school history textbook or something similarly absurd, which says "Japanese planes bombed Pearl Harbor on December 7, 1941 and sank many American ships."]

[Borgholio]

Well there are a few options if we had more than a few hours warning.

1. Sortie the fleet, meet the Japanese at sea. As pointed out, this might result in even greater losses of men and ships.
2. Sortie the fleet, run like hell. Make a beeline for the West Coast. Aside from the idea of a full-scale retreat from the enemy, it leaves the fuel storage and drydocks the only targets left in Pearl...and those would probably be flattened.
3. Reinforce Hawaii with more fighters. Question is, where are they going to come from?

[Lord Revan]

IIRC the poor air cover at Pearl Harbor was more due to clashing egos with the USN and USAAF commanders then lack of resources, I could be wrong though.

[Borgholio]

I know that the planes were bombed on the ground due to being "prepared" against sabotage instead of being ready to scramble vs an air attack. I don't recall ever reading anything about the actual overall air strength of Pearl Harbor.

[Simon_Jester]

Just getting all the existing AA defenses fully armed and prepared to meet an attack would help- it might not stop the Japanese from devastating the fleet, but it would inflict more casualties. And because of their chronic inability to rapidly produce new well-trained pilots to replace losses in the Kido Butai, those losses would hurt Japan literally throughout the war.

It'd still be a catastrophe for the US though.

[Eternal_Freedom]

As I understand it Pearl Harbour had a significant fighter presence, I think the first wave hit airbases en route to the harbour. Surely it would have been a significant advantage to have those fighter airbournes, perhaps to intercept the Japanese planes just off the coast?

[Simon_Jester]

Well, if you knew the approximate timing of the attack you could do that maybe- especially if you're primed to pay attention to the radar.

[Replicant]

Is there any course of action the USN could have taken to avoid catastrophe at Pearl Harbor, supposing a vast amount of advance warning of the broad nature of the attack but no other information?*

Sortieing the battleline with no other precautions would be a mistake, the air assets to make a fight of it apparently didn't exist... am I missing something?




*[I.e., a time-traveling middle-school history textbook or something similarly absurd, which says "Japanese planes bombed Pearl Harbor on December 7, 1941 and sank many American ships."]

Several things could be done. This is assuming you had 100% believed intel that was received say the morning before the attack.

1. Cancel all leave for military persons starting at say 7pm the night before the expect attack.

2. Order full battle prep a couple hours before the attack, all AAA manned, all watertight doors closed, all pilots at the ready with planes prepared for immediate launch.

3. Cancel the incoming flight of B17 bombers and have your best crews on radar duty and believe them the instant they say they notice the attack.

4. Deploy any and all available torpedo netting. Any major ships you cannot cover will be relocated or have destroyers or cargo ships moved so their ships physically screen the capital ships.


Once the attack is picked up on radar, which is was historically, then you launch every single fighter plane you possibly can. The Japanese were going for surprise and only 40 Zekes were included in the first attack, this is not enough to protect all the torp bombers, level bombers, and dive dombers which now also must contend with AAA in action.

If you do this I can see the Japanese casualties being massive, a very large percentage of both strikes are lost and barring luck you will have no US battleships lost permanently to enemy damage.

[Sea Skimmer]

As I understand it Pearl Harbour had a significant fighter presence, I think the first wave hit airbases en route to the harbour.

About 50% of each Japanese wave consisted of fighters and dive bombers assigned to hit the airfields and conduct escort duties. Total raid strength was 351 planes. The most important were forty Kate's with torpedoes assigned to hit battleship row, which inflicted essentially all significant damage to the battleline, except the sinking of Arizona by a Kate level bomber. That group of Kate's also suffered by far the heaviest losses of any portion of the strike and several were shot down before they could release.

Surely it would have been a significant advantage to have those fighter airbournes, perhaps to intercept the Japanese planes just off the coast?

Yes it would be, No effective fighter direction system existed on the island at the time, it was still being setup with the recent arrival of six radar sets with largely untrained operators, which is why the actual radar report that did come into the primitive operations center wasn't taken seriously. Fighters could have stacked directly over the harbor and airfields though and conducted visual patrols to find the enemy themselves.

The US had about 187 fighters available, including some P-26 Peashooter's, armed with the most inspiring fighter name ever, but in varying degrees of repair due to heavy use for training. A couple planes status is unknown thus the 'about' bit, they may have still been under assembly as planes normally arrived crated. Only bombers could fly from the mainland to the islands directly. Some F4Fs where present only because the carriers had unloaded certain fighters in ordered to embark different MARINE fighters to deliver to Wake and Midway.

Of the historical attack, involving 352 aircraft, 9 were shot down in the first wave, and 20 in the second wave. 20 more were written off and a further 91 damaged to varying repairable degrees. IIRC seven kills are credited to US fighters but I don't feel like tracking down a source to check. A lot of fighters had gotten airborne by the end of the second attack, many never found anything to fight.

About 200 army anti aircraft guns did not fire a shot in the battle because they had no ammunition, certain random army machine guns not assigned to anti aircraft units or in storage at garrisons which had the ammunition supplies did fire. Also large numbers of rifles, pistols (multiple accounts!) and similar highly effective anti air weapons were employed, as well as aircraft machine guns stripped out of damaged planes or aviation maintenance depots.

The fleet mounted approximately 1000 weapons capable of anti aircraft fire though a large proportion were .50cal machine guns. None had ready ammunition, but some were in action before even the torpedo planes had finished attacking, leading to multiple losses as they swept over moored heavy cruisers in the naval yard.

So... given even 15 minutes of warning... it goes from zero guns firing when the first bomb falls on the Seaplane Ramp, to 1,000 naval guns firing, and an hour or more of warning, 1,200+ as every random thing that can shoot is deployed and given ammunition.

Edit: I'm also very sure a search of the forum would have turned up all of this without me typing.

[Eternal_Freedom]

How effective would all those AA guns be at reducing the damage taken? I always get the impression from WW2 books that fixed AA was not as effective as friendly fighters were in dealing with attacking planes.

[Sea Skimmer]

Generally when you have multiple weapons per enemy plane, and the enemy planes have no armor what so ever, planes start falling out of the sky. Beyond that, well for one example, the single Japanese attack on Midway, conducted with the same aircrews and planes (basically the attack was equal to one wave of the Oahu strike), and against similar but much smaller numbers of fighters and land based anti aircraft weapons on Midway, but fully alerted, suffered about 23% losses of downed and damaged planes.

In this period US fighters are just not that good, were talking about mainly P-36s and early model P-40s, some F4F-3 Wildcats, but if 80 odd were airborne they would stand a high chance of breaking up the Japanese raids and making the task of the anti aircraft guns much easier. This would also prevent all the Japanese fighters from concentrating on strafing to suppress AA fire and hit parked planes, further increasing the value of the AA.

With total hindsight I think the the best thing to do would be to remain at anchor, but deploy a line of destroyers and heavy cruisers in front of battleship row in about mid channel. This would make torpedo attacks on the main body of the fleet impossible. Utah ect... would still be screwed unless more floating walls were placed on that side of Ford Island as well. This is all very highly implausible as a strategy at the time though.

[Adam Reynolds]

'Midway' BTW is a fairly bad movie at this point not only because it recycles footage and had little budget, but we now also know that its story line is simply inaccurate as to the conduct of the final battle. Nothing is wrong with Tora Tora Tora that I'm aware of. Technical stuff forced on them ect... but not anything meaningful.

What was wrong with Midway? I haven't seen it in forever but it seemed at least somewhat correct for a movie (ignoring the awful clip show special effects).

[Tribble]

If America had been given advance warning and prepared to the best of their ability, I doubt the Japanese would have caused anywhere near as much damage as they did. The survival of the US battleships wouldn't have really changed the balance of power though because they were already obsolete. And strategically speaking, even if every single US ship including the carriers had been sunk, Japan still wouldn't have stood a chance in the long run. Regardless of the outcome Pearl Harbour will have always remained the biggest mistake Japan ever made.

There could be one negative consequence for the Americans if they had fought the battle prepared. Pearl Harbour was specifically designed to be a surprise attack. When the Japanese realise that the Americans had been prepared for them, they may come to the conclusion that their plan had been compromised. Although they maintained radio silence both before and during the attack, they may have changed their naval codes to be on the safe side. Again, long term America still curb-stomps, but it would mean a period of time where the Americans would have less intelligence available than they did.

[Lord Revan]

correct me if I'm wrong but weren't the IJN and USN rather reluctant to employ carriers in any significant capacy until well after Pearl Harbor with IJN having been show the effectiveness by the attack and USN having no other choice and most of the battleships it had were either at the bottom of the sea or under major repairs.

[Spoonist]

Regardless of the outcome Pearl Harbour will have always remained the biggest mistake Japan ever made.

I think I get what you are trying to say but a slight nitpick if I may? Starting a war with the US would be the mistake. However this was seen as inevitable from the big six in Japan - Yamamoto himself was against a war with the US. This since the Navy didn't have many illusions regarding american capabilities, but it was the Army men that was in power so war it was.
But given the cards dealt to the Navy the suprise attack on Pearl Harbour is genious both in planning and execution.

[Tribble]

Carriers had been proven to be superior to battleships earlier in the war. The Pearl Harbour attack was directly inspired by the Royal navy's attack on the Italian fleet at Taranto. In that battle, 21 obsolete aircraft (half of which attacked the fleet while the other half dropped flares and acted as a diversion) were able to penetrate the Italian defences and sink one battleship while crippling 2 others. Even if the attack on Pearl Harbour had not been as successful, I believe that the fact that the Japanese were able to launch an all out attack at the heart of US naval operations would have proven the carrier's worth. And don't forget that in this scenario the Americans would have known that had they not been warned beforehand, the results would have been far worse. Perhaps both sides would be slower in fully utilising the potential of carriers, but I think they still would have known that the days of the battleship were over.

I agree that the surprise attack was genius both in planning and execution. And I agree that the Japanese Navy had little choice. However, I feel that the nature of the attack itself was part of their mistake. Would the attack have still been "a date which will live in infamy" if Japan had formally declared war a couple days beforehand? I could be wrong here, but as I understand it part of the reason for America's overwhelming response was because they were attacked by surprise and taken off guard. Had the Americans been formally at war with Japan a couple of days before Pearl Harbour I doubt their response and buildup would have been quite so overwhelming and fast. Again, America wins no matter what, but they might have taken a bit more time in doing so.