Worst Pearl Harbor for the US?

[phx1138]

Agree with most of what's been posted, to which I'd add, attack the power station (on which everything depends), the Sub Base, and the Engineering & Repair shop. (Blowing up the torpedo store could be a net plus for the Sub Force.) An attack on the old Admin Building would be a real plus: Hypo was in the basement.

Contrary to what you might expect, this could be worse for Japan than what happened OTL. It puts pressure on Nimitz to build up at Midway, with base facilities (esp fuel), to take up slack from losses at Pearl. And, since carriers are no longer right to hand, close recce of IJN bases is a waste of effort; perhaps Nimitz can be persuaded to switch to mining them by subs (for which the old Bass, Bonita, & Barracuda are well-suited, & Argonaut purpose-designed), while using direction-finding to monitor movements of IJN minesweepers. (Then shoot the 'sweepers.)

If this puts more subs in Home Waters, Luzon/Formosa Strait, & Yellow Sea, Japan loses the war sooner than OTL...

 

[Ravenflight]

If the fleet sortied it was sailing straight into a shooting gallery of subs with the best 21" torpedoes in the world.

Do you mean 24"???

[Edit] - no, you're right - I was thinking Type 93.

How much would it take to knock out a dry-dock, and how long would said dry-dock be out for?

A lot.

With heavy bombers, the British couldn't do it.

But if taken out, then it would be pretty hard to put back into service, so I'd say 6 months to a year minimum and quite possibly a lot longer.

It would be the gate that you're destroying, which means that you've got to replace the gate, and get rid of the crap left over of the last gate.

 

[CalBear]

How much would it take to knock out a dry-dock, and how long would said dry-dock be out for?

The caisson is the critical element of a shore based dock, followed by the doors of a floating dock.

The only way to get them in a practical manner at the time was with torpedoes. The Japanese tried to get the No. 1 dock, where USS Pennsylvania and two DD were already located, with a number of torpedo planes (the Pennsylvania's AAR isn't specific beyond "several"). It isn't an easy target being only ~100 feet/30 meters wide and only a solid hit will damage it suffiently. As noted the destroyers in the dock with Pennsylvania, were pounded (to the degree that initial post attack survey indicated that the ships were beyond full repair, although both were eventually completely repaired and returned to duty in 1943/44) and the battleship itself was hit by a 500 pound bomb. The damage to the drydock itself, where 2,100 ton ships were being beaten to pieces, was so minor that it isn't even mentioned in the AAR from either Kimmel or Nimitz.

Repair time is hard to say with any certainty since it is dependent on the inflicted damage, but 60 days would be a reasonable figure for anything other than utter destruction from multiple torpedo hits (and every torpedo used on the dock is one that isn't used against the primary targets, the warships).

The third wave argument always makes sense in hindsight, although the actual cost benefits for the IJN are, at best, debatable. Are a few more buildings and/or a couple oil tanks worth 100 aircraft lost or written off and 50+ aircrew (a resource that even the Japanese thought was crucial, to the point that they were evacuated off the carriers at Midway, even as the mechanics for the aircraft were left to their fates aboard ship).

The Japanese were expecting a short, sharp war, not a 44 month long slugging/attrition match with the largest industrial economy on the Planet. Machine shops and tank farms are critical if you expect to be fighting in 1944/5, if you expect to be victorious by mid 1943, if not sooner, they are not.

 

[CalBear]

Do you mean 24"???



A lot.

With heavy bombers, the British couldn't do it.

No. Type 95 Mod 2 21"/533mm torpedoes. The 24"/610mm Type 93, aka "Long Lance" was a surface warship weapon.

The British came up with the only practical way, at least until the Grand Slam. Sail a ship packed with explosives into the gates and blow it the hell up.

Crude, but effective.

 

[Ravenflight]

No. Type 95 Mod 2 21"/533mm torpedoes. The 24"/610mm Type 93, aka "Long Lance" was a surface warship weapon.

Yup, I had a momentary lapse of reason.

I was heavily interested in the IJN and the Japanese military as a whole in my youth, and knew the ins and outs, but I've forgotten a lot.

The British came up with the only practical way, at least until the Grand Slam. Sail a ship packed with explosives into the gates and blow it the hell up.

Crude, but effective.

Yes, but ineffective against Pearl.

 

[Zheng He]

Yup, I had a momentary lapse of reason.

I was heavily interested in the IJN and the Japanese military as a whole in my youth, and knew the ins and outs, but I've forgotten a lot.



Yes, but ineffective against Pearl.

I just watched a TV program on Operation Chariot the other day. That was a very difficult and complex operation and it shows just how hard it is to take out a target like that. Yes, with a serious effort against the docks the Japanese could have probably beat them up pretty badly and the US would have repaired them.

 

[phx1138]

The dry docks, in the end, were less an issue than the tank farm. Without fuel, the heavies don't sail. (Nor the subs, but that's easier to replenish.)

 

[CalBear]

The dry docks, in the end, were less an issue than the tank farm. Without fuel, the heavies don't sail. (Nor the subs, but that's easier to replenish.)

That is also the close to impossible target.

Each tank was separately bermed and was reasonably spaced. They could be hit, but as was noted earlier, we are talking bunker fuel, that about a half step over the tar they use on roads. It will burn, rather robustly and with huge amounts of smoke, but it is not easy to touch it off. You need direct bomb hits, light machine gun rounds aren't going to manage it. If a tank is set ablaze, the smoke would make it damned near impossible to target the rest. A reasonable example is the general failure of the Allies to destroy the Ploiesti tank farm during numerous heavy attacks by strategic bombers.

You can damage the farms, but no eliminate them, certainly not to the point that the fleet is pushed back to the West Coast. The U.S. also has considerable refinery capability on the West Coast, and close to half the oil tankers in the world at the time are U.S. flagged.

You can hurt the efficiency of the base, but it is pretty much impossible to eliminate it with the forces available.

 

[ThePest179]

You can hurt the efficiency of the base, but it is pretty much impossible to eliminate it with the forces available.

Would it be possible to have more forces available?

 

[Zheng He]

Would it be possible to have more forces available?

Not really, the carriers that attacked Pearl Harbor already had plussed up air groups. They had a few light carriers that theoretically could have contributed but their air groups were mostly older airplanes and combined they probably would not have added more than 100 planes. PH is also too far for land based aircraft.

 

[Eternity]

How much would it take to knock out a dry-dock, and how long would said dry-dock be out for?

Do you mean 24"???

[Edit] - no, you're right - I was thinking Type 93.



A lot.

With heavy bombers, the British couldn't do it.

But if taken out, then it would be pretty hard to put back into service, so I'd say 6 months to a year minimum and quite possibly a lot longer.

It would be the gate that you're destroying, which means that you've got to replace the gate, and get rid of the crap left over of the last gate.

No. Type 95 Mod 2 21"/533mm torpedoes. The 24"/610mm Type 93, aka "Long Lance" was a surface warship weapon.

The British came up with the only practical way, at least until the Grand Slam. Sail a ship packed with explosives into the gates and blow it the hell up.

Crude, but effective.

I would just add that the St. Nazaire raid also took out the pump houses and winches along with ALL equipment related to the dry-dock. HMS Cambeltown was overkill really, as all she did was blow up the dock gate. this can be fixed with the installation of a new dock gate (They had plans, so what..... 3 Months to rush build a new one?). The real damage that took until 1947 to repair was the fixed equipment such as the pumps and whatnot. An aerial attack of 1941 could not do this. You need a special ops raid to accomplish this sort of damage.

Personally, I think the worst case result would be a Japanese invasion of Pearl and the destruction of the US carriers. If successful, this would mean a forward base for the IJN, especially valuable if the dock facilities and oil tanks were captured intact. This would force the US to fight from the West Coast, a logistical nightmare.

Now, I fully agree that a surprise attack and US building power will mean an ultimate IJN loss, unless other factors stepped in (Say NAZI Germany defeating England, leaving the US alone in the war), but from a worst case point, that is about as bad as it gets:

No US carriers.
No US forward base to operate from.
IJN gets desperately needed fuel.
IJN gets a forward operating base.

 

[ThePest179]

Not really, the carriers that attacked Pearl Harbor already had plussed up air groups. They had a few light carriers that theoretically could have contributed but their air groups were mostly older airplanes and combined they probably would not have added more than 100 planes. PH is also too far for land based aircraft.

Understood.

 

[CalBear]

Would it be possible to have more forces available?

No. As was the Japanese had to wait for Zuikaku and Shokaku to shake down before they could have the minimum forces needed to enact their plan. The Japanese could throw a few more light carriers into the mix, but nowhere near enough to alter the math, combined they could add around 30 B4Y1/B5N torpedo planes (of course this means the Philippine operations now have no carrier support at all).

You need either heavy bombers, and lots of them, or something like 1945's TF 38/58 with 16 fleet carriers, a thousand aircraft that can loft 1,000 pound bombs, and the ability to stay as long as it takes to do the job.

Japanese had none of those requirements. They couldn't remain on station, they had severe fuel issues with their escorts, had, after the first two waves around 200 attack aircraft left in operational condition, and were completely unaware of the location of the American carrier forces (In fact the two carriers were ill-equipped to enter combat, low on fighters, Lexingtonsailed with 16 F2A Buffaloes and Enterprise was left with 15 F4F Wildcats after flying off aircraft to Wake, but the Japanese had no way of knowing that).

Pearl was a RAID, not an invasion or designed to be a pitched battle. The goal was to sprint in, launch two deck loads of aircraft, recover the strikes and beat feet.

 

[wcv215]

Now, I fully agree that a surprise attack and US building power will mean an ultimate IJN loss, unless other factors stepped in (Say NAZI Germany defeating England, leaving the US alone in the war), but from a worst case point, that is about as bad as it gets:

No US forward base to operate from.
IJN gets desperately needed fuel.
IJN gets a forward operating base.

Okay, I may be misreading this, and if so please let me know.

It looks like you are suggesting Japan INVADE Hawaii. That's a terrible idea. The terrain of the most important island was perfect for defense, there was no way to flank positions, and Japan couldn't get enough soldiers on the ground to overwhelm the number of defenders. Furthermore, an attempt to invade Hawaii means taking soldiers from more important attacks like the Philippines or Malaya, both of which actually are needed to secure the southern resource area, Hawaii is not.

Hawaii is also twice as far from Japanese supply as it is from the United States, and they don't have the capacity to supply any garrison even in the event the attack actually works.

 

[Imperator Maximilianius]

Okay, I may be misreading this, and if so please let me know.

It looks like you are suggesting Japan INVADE Hawaii. That's a terrible idea. The terrain of the most important island was perfect for defense, there was no way to flank positions, and Japan couldn't get enough soldiers on the ground to overwhelm the number of defenders. Furthermore, an attempt to invade Hawaii means taking soldiers from more important attacks like the Philippines or Malaya, both of which actually are needed to secure the southern resource area, Hawaii is not.

Hawaii is also twice as far from Japanese supply as it is from the United States, and they don't have the capacity to supply any garrison even in the event the attack actually works.

Indeed. It would be as utterly moronic as Germany and Italy trying to invade Newfoundland.

 

[Carl Schwamberger]

... This would force the US to fight from the West Coast, a logistical nightmare.

...

As I understand most of the US battles of 1942, the Coral Sea & other battles fought around the Solomons were based on New Zealand & lesser extent Australia, with forward bases in Fiji, Samoa, Santa Cruz... It is correct the many of the cargo ships that replenished those bases stopped off at Oahu, to pick up escorts to the south Pacific & fill the galley with fresh food. But delivering direct from the West Coast to Wellington NZ is not somehow impossible.

The raids made on the central Pacific or Tokyo are more demanding on at sea refueling, but not impossible.

If Oahu is not the primary Pacific fleet base in 1942 then Yamamotos concept for the Midway operation is unworkable. Midway itself might very well be abandoned. It is certainly not worth defending if Oahu is only a construction site, or less. That leaves the even more demanding FS operation for Japan. About anything else is either beyond reach, or not worth the risk.

 

[Ravenflight]

That is also the close to impossible target.

Each tank was separately bermed and was reasonably spaced. They could be hit, but as was noted earlier, we are talking bunker fuel, that about a half step over the tar they use on roads. It will burn, rather robustly and with huge amounts of smoke, but it is not easy to touch it off. You need direct bomb hits, light machine gun rounds aren't going to manage it. If a tank is set ablaze, the smoke would make it damned near impossible to target the rest. A reasonable example is the general failure of the Allies to destroy the Ploiesti tank farm during numerous heavy attacks by strategic bombers.

You can damage the farms, but no eliminate them, certainly not to the point that the fleet is pushed back to the West Coast. The U.S. also has considerable refinery capability on the West Coast, and close to half the oil tankers in the world at the time are U.S. flagged.

You can hurt the efficiency of the base, but it is pretty much impossible to eliminate it with the forces available.

To add to this, even PETROL (gasoline to you lot from the 13 colonies) is hard to ignite with machine gun fire. Even tracer is fighting an uphill battle.

 

[Eternity]

Okay, I may be misreading this, and if so please let me know.

It looks like you are suggesting Japan INVADE Hawaii. That's a terrible idea. The terrain of the most important island was perfect for defense, there was no way to flank positions, and Japan couldn't get enough soldiers on the ground to overwhelm the number of defenders. Furthermore, an attempt to invade Hawaii means taking soldiers from more important attacks like the Philippines or Malaya, both of which actually are needed to secure the southern resource area, Hawaii is not.

Hawaii is also twice as far from Japanese supply as it is from the United States, and they don't have the capacity to supply any garrison even in the event the attack actually works.

I'm not saying that it is not a terrible idea, I am just saying that it is part of the worst-case Pearl Harbor for the USA.

Indeed. It would be as utterly moronic as Germany and Italy trying to invade Newfoundland.

Agreed, but then again, the whole Pearl Harbor attack falls into that category does it not? I mean, the IJN and IJA KNEW that it could not win a protracted war against the USA, yet attacked anyway.

 

[TFSmith121]

An IJA-IJN assault on Oahu in 1941-42 requires

An IJA-IJN assault on Oahu in the winter of 1941-42 requires essentially the entire available amphibious element of the December offensives (so no Phillippines, Malaya, Guam, etc.) to secure something resembling a SLOC worth the name (Wake, Midway, and Kauai), as well as all the follow-on shipping for Oahu itself... and cancels the NEI, which conquest of was (essentially) the entire point of the Japanese war effort.

And the likely outcome is still something resembling 1st Wake and Ichiki's destruction on the Tenaru/Alligator Creek, except at the reinforced corps level ("army" to the IJA).

The above is a not a recipe for success, at any level.

Put it this way - even the Japanese at their most reckless - were not insane enough to attempt it, and that's saying something...

Best,

 

[Glenn239]

So, as an opposite to the thread "Best possible Pearl Harbor for US", what chain of events would lead to the most devastating Pearl Harbor attack?

Had Nagumo done a full scale 300nm search on the morning of the battle seeking the US carriers.