A more effective Dec 1941 preemptive attack on the USA

[Admiral Beez]

Japan believes it needs to hit the US hard so they have six months to run wild. How can they do it best?

Some ideas to consider.
1) Target the fuel farms at Pearl Harbour with a third strike.
2) Send all eight (unless #5) Japanese CVs to increase size of attack force.
3) Have plan to search for and destroy CV-2 and CV-6 if they not found at PH
4) Use fleet subs to hit Saratoga (and anything else) at San Diego (about 5,000 nmi from Japan, well within range of the IJN's 1st class subs)
5) Also sub attacks or two CVL strikes on Panama Canal locks
6) Sub attacks on US carriers in Atlantic. This one needs some good spies and German support, but IJN subs were in the Atlantic in 1942, so let's have this earlier.

 

[Thumpalumpacus]

8 CVs in 1941? Which two didn't climb Mt Niitaka? I thought IJN had six CVs and several light flattops.

As for the tank farm, from my understanding there were two risks associated with attacking it: 1) longer loitering increases the chance of KdB being detected, and 2) it's my understanding that the IJN destroyers were very low on fuel and didn't have the remaining bunkerage to perform their escort mission if KdB launched a third strike.

I definitely agree that the IJN could and perhaps should have been more aggressive/creative with its use of subs. Blockading the Canal from one or both sides would have paid dividends, I believe.

 

[SaparotRob]

That certainly would have been a much more effective attack. As to coordinating it all, I don't know.
1). Of course. I can't remember which officers on Adm. Nagumo's staff called for the third strike against the tank farms and infrastructure. Somehow Adm. Yamamoto replaces him with Ozawa? (psst, psst, don't forget the submarines docked there)
2) Agree. Detail Shoho and the other guy to strike Midway and Wake. They join up with KB on the return. Easier to coordinate.
3) Disagree. The plan says the Yankee carriers will be there so this step isn't needed.
4) Brilliant.
5) See above.
6) This may be too ambitious and possibly too many chances of discovery.


Edit: I meant replace Adm. Nagumo with Adm. Ozawa.

 

[SaparotRob]

As to the 2 lighter CVs, they might just run into CV-2 or CV-6 during the latter's reinforcement runs if Midway or Wake was hit. Timing is everything.

 

[Thumpalumpacus]

I can't remember which officers on Adm. Nagumo's staff called for the third strike against the tank farms and infrastructure. [...]

IIRC that was Minuro Genda.

 

[SaparotRob]

Thanks. I thought so. Memory is the....what were we talking about?

 

[Thumpalumpacus]

As to the 2 lighter CVs, they might just run into CV-2 or CV-6 during the latter's reinforcement runs if Midway or Wake was hit. Timing is everything.

That could turn out to be a shitshow.

 

[SaparotRob]

Except the IJN units know they're going to a fight.

 

[Thumpalumpacus]

Except the IJN units know they're going to a fight.

I guess it'd depend upon whether or not the American CVs had received news of the attack at the time of the encounter at sea with the IJN CVEs/CVLs.

 

[SaparotRob]

Timing is everything.
I'm thinking that if the US CVs are transporting aircraft, they would be even less ready on a quiet Sunday morning. Unloaded, they'd put up a better fight. I know that U.S.N. aviators were well trained but I have no idea how good the aircrews of the IJN's "B" squad were. I'm too lazy to look up what ship was where.

 

[Thumpalumpacus]

I know that U.S.N. aviators were well trained but I have no idea how good the aircrews of the IJN's "B" squad were. I'm too lazy to look up what ship was where.

I'd be willing to bet they had some decent skills too, if for no other reason than the difficulty of landing on a smaller-than-normal postage stamp. Their big problem would likely be equipment, because the big flattops got the best planes, for the most part. I think when Shoho was sunk in May 42, it still had some A5Ms in its air group. And didn't one of the CVEs sail in support of the Main Body at Midway with B4Y biplanes aboard?

 

[GrauGeist]

Timing is everything.
The Enterprise was less than two hundred miles from Pearl that morning and was on alert as she approached.

As for the Japanese, they were too cautious - they were planning on the element of surprise and the reports coming in from the first attack wave confirmed success.
There should have been a contingency plan in place to bring the fleet in close in such a situation and bring the battleships/cruisers guns to bear on targets while the carriers provided air cover, in order to maximize damage done by the air strikes.

 

[Admiral Beez]

There should have been a contingency plan in place to bring the fleet in close in such a situation and bring the battleships/cruisers guns to bear on targets while the carriers provided air cover, in order to maximize damage done by the air strikes.

Battleships sitting 20 km offshore bombarding PH and Honolulu (presumably with spotting aircraft) along with bombers lighting up the fuel farms would have brought panic to the population.

I definitely agree that the IJN could and perhaps should have been more aggressive/creative with its use of subs. Blockading the Canal from one or both sides would have paid dividends, I believe.

It does perplex me. By Nov 1941 Japan one of the largest fleets of long distance fleet submarines. Use them to torpedo and mine anything that leaves a US mainland port.

 

[GrauGeist]

Battleships sitting 20 km offshore bombarding PH and Honolulu (presumably with spotting aircraft) along with bombers lighting up the fuel farms would have brought panic to the population.

They had two battleships and two heavy cruisers in the taskforce that accompanied the six carriers, they could have easily circumvented Oahu and come in close to Pearl to deliver the Coupe de Gras after the initial air attack.

They knew from extensive aerial recon, where strategic targets were. Not only the oil and gas tank farms, but more importantly, the drydocks and support facilities. Taking those out or severely damaging them would have been a massive setback for the USN.

 

[Greg Boeser]

I guess it'd depend upon whether or not the American CVs had received news of the attack at the time of the encounter at sea with the IJN CVEs/CVLs.

CV-6 was on a war footing from the time it left Pearl Harbor to ferry VMF-211 to Wake. Scout aircraft were armed and instructed to attack potential enemy vessels.

 

[ThomasP]

re submarine attacks and/or blockade of the west side of the Panama Canal.

1. Unlike the US, the Japanese had adopted the Geneva Convention prohibition against unlimited submarine warfare. They could therefore only attack military ships, or non-military ships carrying military supplies or personnel. In the early actions in the western Pacific the Japanese sub commanders actively ignored ships at sea that they could not effectively ID as valid targets under the treaty, even though they could easily have sunk them. The IJN stuck to the treaty for most of the war. Post-war intel debriefs revealed the few non-military ship targets attacked by IJN submarines were by mistake. At least until it was clear that the US was willingly attacking Japanese non-military ships, at which point the Japanese were not longer obliged to follow the treaty where such attacks were concerned. Even then, the IJN sub commanders displayed an unwillingness to engage non-military ships.

Aside from warships and tankers, it would be very difficult for the IJN sub commanders to ID valid targets off the US or Panama Canal coast.

2. Although the long range subs of the IJN could reach the Panama Canal zone, they would have had relatively short on-station times without forward resupply. Also, when should they take up stations? D+1, +10, +30 . . . ? Unlike the Germans on the East Coast, the Japanese did not have a surfeit of spies in the Panama Canal area to give regular reports usable for planning such operations.

I am not saying that nothing along the suggested line could be done, just that it would be very difficult.

A submarine launched air attack might have had serious effect, if they could use torpedo bombers to take out a couple of the locks. Maybe? My question is how much effect would it have aside from increased transit times from the Atlantic coast to the Pacific coast.


re the IJN battleships moving in close and bombarding the islands. Never going to happen.

The IJN would not be willing to remain in the area long enough, not just because of the possibility of the US carriers finding them, but also because of the (and possibly more worrying) possibility of USN submarines finding the IJN battleships and/or carriers. Somewhere in all the intelligence reports and historical record it is mentioned that part of the reason Nagumo did not plan on hanging around was due to the worry of US submarines.

 

[Thumpalumpacus]

CV-6 was on a war footing from the time it left Pearl Harbor to ferry VMF-211 to Wake. Scout aircraft were armed and instructed to attack potential enemy vessels.

I had no idea they had these sorts of "shoot-on-sight" orders like the Atlantic Fleet subs did. Thanks for giving me something more to look into!

A submarine launched air attack might have had serious effect, if they could use torpedo bombers to take out a couple of the locks. Maybe? My question is how much effect would it have aside from increased transit times from the Atlantic coast to the Pacific coast.

Did any IJN submarines have mine-laying capability? That could prove useful against the Canal as well.

 

[Shortround6]

Japanese submarines had some problems operating off the US coast. A few did operate in 1941 but they didn't achieve much.
The Japanese boats were slower to dive than German and Allied boats.
The US forces were operating in the Atlantic, both air and sea, against the German boats as part of the "Neutrality patrol"
How much training, information was used by the Pacific Fleet I don't know.
The Japanese subs using aircraft in 1941/42/43 were using small recon aircraft.

The most common Japanese plane used Submarines used a 300-340hp engine.
A lot of the Japanese boats also had a diving depth of 220-330ft (in some cases the 330ft depth was the test depth and not the operational depth).

The Japanese had a large number of boats but they may have been constrained by the need to keep losses down. Submarines are much more expensive to build per ton than most other types of naval aircraft. Trying to use submarines as a weapon of attrition might not have worked well for the Japanese.

A more aggressive stance by the Japanese Subs in 1941/42 might well have tied up US forces on the US Pacific coast and delayed reinforcements to the Pacific. But it might have been a close run thing as the Japanese can't afford many losses off the coast. It also takes weeks to a Sub from the Japanese bases to the US west coast and weeks back so the number of subs on station at any one time (after the 1st couple weeks) is going to be very low.

 

[GrauGeist]

There were several instances of Japanese sub attacks on the west coast of the U.S., conducted by subs of the 6th fleet.

They sank two tankers and damaged a freighter.

After physically landing at Point Loma for recon, I-17 shelled the refinery area at Ellwood (near Santa Barbara), California on 23 February '42 resulting in little damage, but was quite effective at launching an invasion scare.

In 21 June '42, I-25 shelled Fort Stevens (Oregon), with little damage as a result of their effort.

And finally, on 9 September '42 near Brookings (Oregon), I-25 launched it's E14Y armed with two 76kg incendiary bombs, targeting the forest with the intention of starting a forest fire.
While it may have been a good idea, the coastal forests are typically damp and rarely catch fire, so nothing came of the effort.

All in all, this was a weak effort by the IJN's subs and could have produced much better results if there had been better planning/coordination.

 

[Shortround6]

The I-25's effort by the E14Y required the pilot to fly the plane as a single seater as the bomb load used was more than doubled the "normal" bomb load.

Max speed clean was 153mph at sea level, the Cruising speed was 104mph at 3280ft.

The I-25 was an audacious effort but obviously the plane offered very little scope for any improvement in attack profile.

The I-25 was part of the largest class of I subs built (20?) and it took Japan from Sep 1940 till April 1943 to complete the 20 boats (they were building other class at the same time) of this class.
The B1 class boats were about 50% larger than the America Gato class sub and used diesels engines over twice as powerful.
The Japanese tactics may have been too cautious but the big boats may not have been suited for operating in Pacific coastal waters. There weren't a lot of ports on the US Pacific coast. and some of them are 400 miles or more apart (2-3 days by sub?) There are a lot of places to "hide" like being 100-200 miles from the major shipping lanes.