AHC/WI: Better IJN anti-submarine warfare in WW2

[Anime Ninja]

The best way to have the IJN to be better at ASW would be starting in WWI.

At the time the IJN and RN were allies, the RN starts to teach IJN destroyer captains the best ways to protect valuable shipping. The ASW captains and crews start seeing themselves as noble yojimbo that make it their duty to protect their charges, the merchant fleet. A couple of the captains get enough rank to be able to do some minor direction on what ships need to be designed and built. They suggest a quick to build escort that is designed around hunting and killing subs. They use the idea that is the main fleet can't have food or fuel what use are they in any great battles.

 

[Kantai Kessen]

No. IJN radar tech was at least a generation behind any of the other major players. The U.S. ASB, to use just one example, which was deployed in early 1942, was superior to anything the IJA/IJN deployed during the entire war, it was small and light enough to be deployed on carrier capable aircraft, while even late into the war the Japanese sets were so heavy and bulky that they were largely limited to Heavy bombers and didn't make their first appearance until mid 1944.

But the H8K did carry ASV radar, and it is certainly large enough to do so.

Also, regarding the earlier point on escort carriers, the IJN did operate some during WW2. These were too large and, surprisingly, a bit too fast to be useful as conventional CVEs. However, do you think Japanese industry could produce some small ships along the lines of the Sangamon-class for hunter-killer operations? They could use the B5N as a patrol aircraft - it was used in the ASW role anyway. Carry some A5Ms if you're worried about the CAP role.

 

[Kantai Kessen]

The best way to have the IJN to be better at ASW would be starting in WWI.

At the time the IJN and RN were allies, the RN starts to teach IJN destroyer captains the best ways to protect valuable shipping. The ASW captains and crews start seeing themselves as noble yojimbo that make it their duty to protect their charges, the merchant fleet. A couple of the captains get enough rank to be able to do some minor direction on what ships need to be designed and built. They suggest a quick to build escort that is designed around hunting and killing subs. They use the idea that is the main fleet can't have food or fuel what use are they in any great battles.

I like that train of thought. If we really want the IJN to get first-hand top-notch ASW experience, though, I think they're going to have to help out in the Western Approaches in 1917. Which is problematic because the Americans are also there, and they are racist.

Actually, hang on - what if the Japanese army is sent to the Med like the navy, and the troops are sent to fight the Ottomans in place of the British/French troops that would normally be doing the job? Then we could get the sunk-transport situation and a potential outcry.

Were the IJA capable of desert warfare?

 

[Kantai Kessen]

Major issue with this sort of strategy is that, well, the technology didn't exist. What you are describing is similar to late Cold War NATO doctrine, specifically the use of SURTASS trawlers with attendant ASW air assets. That requires not just excellent passive sonar (which was simply hydrophones in the 1930s-40s) with the ability to detect contacts one or two hundred kilometers away (hydrophone might get five miles in excellent conditions) and a method to process millions of data point so that patch of krill 20 miles west can be sifted out from the submarine cruising along five miles behind it

Another method is to create Hunter-Killer groups centered on a escort carrier (a real one, not the IJA version that was meant to handle one or two liason aircraft or autogyros) with three or four escort ships (what the RN called corvettes and the USN called destroyer escorts). These, however require air superiority, actually close to air supremacy given that if they run into even a well armed patrol bomber there is a very real chance that the CVE will become a statistic and are only effective while hunting along a convoy route (which actually makes them a negative asset if used as a forward screen since the presence of the HK Group means that there is a significant enemy formation nearby.

Not sure what putting a couple more underarmed BB would accomplish since they will count against WNT/LNT gross tonnage limits. You can butterfly away the Treaties, but all that really accomplishes is bankrupting the Japanese Empire. The whole reason the WNT and the successor LNT came about was the horrifying reality in both Tokyo and London that the United States had all the money it needed to sink their fleets by piling up bags of quarters on them until they capsized (or, put another way, the U.S. had six South Dakota (1920) class battleships AND six Lexington class battlecruisers under construction AT THE SAME TIME while both the Japanese and British were trying to assemble the funding for a building program to construct four BB and four BC each over the space of 5-7 years). The U.S. Congress was also seriously considering authorizing some variant of the "Maximum Battleship" i.e. Tillmans if necessary as a follow up. You will sometimes see comments regarding the "danger of an arms race" for the reason the WNT happened. There was not going to be an arms race. The U.S. had already won it, and had terrifying amounts of funding available to simply bury any other player, the WNT was an spending moderator. The Japanese couldn't have completed their 8/8 programs in 15 years, especially after the 1923 Tokyo Earthquake, and the British would have literally been trying to outspend the bankers loaning them the money to spend. The irony, of course, is that the only ships that actually were of serious utility by the time of WW II were the battlecruiser conversions that resulted from the implementation of the WNT.

The IJN, though, needs to have new battleships if everybody else is getting new battleships, if only to save face. They'll be playing a smarter card in real life, since the Yamato-class would not work in WW2. That's why I think using the Tosa-class turrets to build a pair of fast battleships would be useful. HUGE amounts of resources could be saved, of which some could definitely be used for ASW.

I think hunter-killer groups will work, given the IJN's aggressive mentality.

 

[Kantai Kessen]

Actually closer to saying that after IJN and RN squadrons had wiped out German raiders the Japanese sent three obsolete cruisers and a significant fraction of their destroyer complement to the Med. the result was one heavily damaged IJN destroyer resulting in the death of 2/3 of the ship's company, rescue of roughly a brigade of troops from a previously sunk British transport and zero submarines sunk. Overall, a nice piece of seamanship and excellent force projection in support of an ally, but of limited effectiveness.

But definitely worth learning from.

 

[CalBear]

But the H8K did carry ASV radar, and it is certainly large enough to do so.

Also, regarding the earlier point on escort carriers, the IJN did operate some during WW2. These were too large and, surprisingly, a bit too fast to be useful as conventional CVEs. However, do you think Japanese industry could produce some small ships along the lines of the Sangamon-class for hunter-killer operations? They could use the B5N as a patrol aircraft - it was used in the ASW role anyway. Carry some A5Ms if you're worried about the CAP role.

The Emily did carry the Type 6 radar, but it was quite rare until the Mark3 Mod 4 variant (which was the production version of the set) was introduced in April of 1944. Previous Marks of the radar were effectively "beta" prototypes that were mainly for testing.

But definitely worth learning from.

By who?

The RN was far more effective. The total of U-Boats (both German and AH) sunk in WW I was ~200 (the total loss figures vary slightly, as does the account for reason for loss, some boats just never returned from patrol) with virtually all of those collected by the RN (the French Italian and U.S. each picked up a few kills, but it was the RN tht did the dirty work). If fact of all the Entente navies only the Japanese ended the war with a bagel.

The IJN, though, needs to have new battleships if everybody else is getting new battleships, if only to save face. They'll be playing a smarter card in real life, since the Yamato-class would not work in WW2. That's why I think using the Tosa-class turrets to build a pair of fast battleships would be useful. HUGE amounts of resources could be saved, of which some could definitely be used for ASW.

I think hunter-killer groups will work, given the IJN's aggressive mentality.

It does, however, and this is a critical element, it is limited to tonnage. Since it was limited to 60% of the RN or USN's tonnage the Japanese, unsurprisingly, decided that they would need to construct ships that were qualitatively superior so three IJN capital ships could successfully engage and defeat an enemy flotilla with five capital ships. That was why the Japanese walked away from LNT 2 and began construction of the enormous Yamato class. It is worth mentioning that the Yamato class would absolutely have been capable of taking on five of the legacy RN or USN battleships and dispatching them, probably with no loss to themselves since they were far faster, much more heavily armed and armored, and would have fought under a well considered tactical doctrine (imagine five American "Standard" class BB, say the four Colorado class ships and a Tennessee class, or or the RN's Nelson class, Hood, and two Queen Elizabeth class, it would have been a massacre, arguably even if the Anglo-American fleets was combined and it was 10-3, the Yamatos would have stood a reasonable chance of at least inflicting a draw).

Of course, in hindsight the Yamato class was worse than useless, but as late as early 1942 it was an accepted fact by all naval professionals that battleships were still the critical element of any major fleet, with carriers considered to be part of the scouting forces (when reading the limitation of the WNT/LNT this is amply illustrated since carriers were limited to tonnages well below that of battleships and were also limited to, at maximum 8"/203mm guns) not the primary striking force of a navy. The irony, of course, is that it was the Japanese who demonstrated that the time of the Battleship had passed with their sinking of the PoW and Repulse. Yet, despite that proof, the Japanese, more than any other navy, persisted in believing that its Battle Line was still preeminent and kept their heavies, excepting the Kongo class, which were actually battlecruisers with delusions of grandeur) out of the knife-fighting that marked the otherwise "all in" Solomons campaign . When the critical November 1942 Naval Battles that decided the fight for Guadalcanal too place Yamato and Mitsu were riding at anchor in Truk lagoon. Their sum total impact on the campaign that some consider to be the decisive engagement of the Pacific War was to have transferred some rice rations to replenish Kondo's "Advance Force" stores before Kondo left to fight it out in The Slot.

Regarding the Hunter-Killer concept, I believe that my position regarding the fatal flaws in the concept (in the scenario under discussion) stated previously can stand with out further elaboration.

 

[Kantai Kessen]

The Emily did carry the Type 6 radar, but it was quite rare until the Mark3 Mod 4 variant (which was the production version of the set) was introduced in April of 1944. Previous Marks of the radar were effectively "beta" prototypes that were mainly for testing.


By who?

The RN was far more effective. The total of U-Boats (both German and AH) sunk in WW I was ~200 (the total loss figures vary slightly, as does the account for reason for loss, some boats just never returned from patrol) with virtually all of those collected by the RN (the French Italian and U.S. each picked up a few kills, but it was the RN tht did the dirty work). If fact of all the Entente navies only the Japanese ended the war with a bagel.


It does, however, and this is a critical element, it is limited to tonnage. Since it was limited to 60% of the RN or USN's tonnage the Japanese, unsurprisingly, decided that they would need to construct ships that were qualitatively superior so three IJN capital ships could successfully engage and defeat an enemy flotilla with five capital ships. That was why the Japanese walked away from LNT 2 and began construction of the enormous Yamato class. It is worth mentioning that the Yamato class would absolutely have been capable of taking on five of the legacy RN or USN battleships and dispatching them, probably with no loss to themselves since they were far faster, much more heavily armed and armored, and would have fought under a well considered tactical doctrine (imagine five American "Standard" class BB, say the four Colorado class ships and a Tennessee class, or or the RN's Nelson class, Hood, and two Queen Elizabeth class, it would have been a massacre, arguably even if the Anglo-American fleets was combined and it was 10-3, the Yamatos would have stood a reasonable chance of at least inflicting a draw).

Of course, in hindsight the Yamato class was worse than useless, but as late as early 1942 it was an accepted fact by all naval professionals that battleships were still the critical element of any major fleet, with carriers considered to be part of the scouting forces (when reading the limitation of the WNT/LNT this is amply illustrated since carriers were limited to tonnages well below that of battleships and were also limited to, at maximum 8"/203mm guns) not the primary striking force of a navy. The irony, of course, is that it was the Japanese who demonstrated that the time of the Battleship had passed with their sinking of the PoW and Repulse. Yet, despite that proof, the Japanese, more than any other navy, persisted in believing that its Battle Line was still preeminent and kept their heavies, excepting the Kongo class, which were actually battlecruisers with delusions of grandeur) out of the knife-fighting that marked the otherwise "all in" Solomons campaign . When the critical November 1942 Naval Battles that decided the fight for Guadalcanal too place Yamato and Mitsu were riding at anchor in Truk lagoon. Their sum total impact on the campaign that some consider to be the decisive engagement of the Pacific War was to have transferred some rice rations to replenish Kondo's "Advance Force" stores before Kondo left to fight it out in The Slot.

Regarding the Hunter-Killer concept, I believe that my position regarding the fatal flaws in the concept (in the scenario under discussion) stated previously can stand with out further elaboration.

Good to hear about the radar. I guess that kind of shoots active hunting of submarines in the foot.

Apologies for not clarifying: I meant that the Japanese could learn from their own experiences, and from the British, which could help them later on.

And it seems the Japanese are doomed to build big battleships no matter what...

 

[tigercat]

What would the Japanese make of the MAC ship ? If operated by civilian crews like the British Version would that avoid the defense is dishonourable trope as for merchant crews it would be a chance to gain more honour .

Air crews might not be happy...

 

[Kantai Kessen]

What would the Japanese make of the MAC ship ? If operated by civilian crews like the British Version would that avoid the defense is dishonourable trope as for merchant crews it would be a chance to gain more honour .

Air crews might not be happy...

The Japanese would need a Swordfish equivalent, since the B5N can be used but should be retained for front-line duty. If there aren't enough to go around, perhaps some spare Yokosuka B4Y biplanes?

Yokosuka B4Y - Wikipedia

en.wikipedia.org

They were still in use to 1943, so should be available. Perhaps 9 each for half a dozen MAC ships. They are second-rate planes anyway so we don't need to use elite attack pilots for them, and so there is less cause for complaint.

 

[Peg Leg Pom]

This may be ASB but the IJN could listen to the IJA who actually cared about supply ships getting through and were quite innovative about ASW.

 

[Kantai Kessen]

This may be ASB but the IJN could listen to the IJA who actually cared about supply ships getting through and were quite innovative about ASW.

See above in the thread; this has been discussed. Given the frequency with which it has appeared, though, it is definitely worth continuing. Not totally ASB.

 

[phx1138]

requires a wholesale removal of every Eta Jima graduating class since 1900

I'm not so sure it does. It does need a deep & fundamental re-assessment of the IJN training curriculum. IJN produced SOs incapable of knowing the difference between tactical & strategic victory, who fell into the grip of Mahan with the blind allegiance of apostles. IMO, you also need a change in basic training, which appears to produce inflexible officers rather than ones well-trained in initiative & adaptability. If you can get at that, you might be able to avoid a wholesale, generational massacre.

That said, you probably do need to shoot at least one whole class, to break their grip on the senior positions responsible for creating the mess to begin with...

Your closing point is still correct, tho. IJN is fighting both of the top blue-water navies in the world with a glorified brown-water fleet & thinking. The surprise is, it took as long as it did.

With my IJAN, there wouldn't be the vast strike across to Pearl Harbor, wouldn't have the gear or attitude for that.
But they could still take the Phillipines and DEI, and play defense while victory in China was always just one more campaign season away.

The problem with that proposition is, the Army is likely even less interested in ASW than the Navy (if that's possible ). IJA wants to win ashore, not fight at sea. You'd have to create a kind of Marine Corps, & develop a dedicated ASW doctrine, but do it with no history or tradition or training in naval operations at all.

The barrier strategy depended on controlling SLOCs & having strike forces to counterattack. How a force with even less preparation, & equipment, for either than OTL IJN is going to manage isn't clear to me. IJA leadership was even less capable of distinguishing tactical from strategic, & of telling wisdom from folly. You're trying to decide if you'd rather have your naval ops run by Abbott & Costello or the Three Stooges (more or less). Take the less incompetent, OTL's IJN.

You can butterfly away the Treaties, but all that really accomplishes is bankrupting the Japanese Empire.

Word. And the Japanese militarists couldn't see the cap was really a safety net against them jumping off that cliff & ending up a coyote-shaped hole in the ground.

Can you have large flying boat based ASW?

That might actually work. The trouble is, beside being resource intensive to build the aircraft, they'd be insanely costly of fuel, of a grade Japan has enough trouble producing without spiking the demand through the stratosphere. Bear in mind, it was lack of bunker that crippled movement of the heavies. Hang your ASW on avgas production, even the dismal Sub Force efforts are going to be stepping on your neck in pretty short order--& if Nimitz &/or English get a clue about tanker priorities...

There's also the matter of wastage: most of the notional ASW patrols are going to be "dry", & as costly as the fuel is, Japan can't afford that. She was actually really (surprisingly) good at collecting sub position data. She was abysmal at disseminating it: ASW command could tell you with fine accuracy where U.S. boats had been two or three days ago, but had no damn idea (really) where they were now.

I think hunter-killer groups will work, given the IJN's aggressive mentality.

They won't, for the above two reasons. Never forget, Japan is fuel critical for everything. The Tokyo Express was an insane waste of bunker. HK groups need fuel & good intel in abundance. Japan could provide neither. Even allowing you solve the intel dissemination problem, supply of bunker is going to bite you, even if Nimitz &/or English don't put tankers at top priority when they realize what you're up to--& they will realize, & will change the priority, & will do it sooner than OTL, all of which is lethal for HK groups & Japan's war effort.

the United States had all the money it needed to sink their fleets by piling up bags of quarters on them until they capsized

Damn, I wish I'd said that.