1930's Japanese Navy - What would you have done differently?

[Garyt]

Most of you examples of ships being lost to their own torpedoes are from aircraft bombs which weren't anywhere near the threat in the late 20s/early 30s when the Japanese Cruisers were designed and built.

Indeed. But it's not extremely difficult to retool once you realize the threat that aircraft poses by about 1940. Get rid of some torpedo tubes, add some AA.

Shortround, what I am trying to point out is that Japan geared it's navy almost entirely to fight that decisive surface battle which never materialized, certainly not in the way envisioned by the Japanese. By building their navy with such single minded purpose, they made it less effective and/or versatile for engagements that did not take place in the way the decisive battle was envisioned.

 

[parsifal]

Parsifal, I am not by any means stating the Japanese should have given up on or not researched or not equipped their ships with the long lance. BUT what I am questioning is whether they should have been deployed on cruisers, particularly heavy cruisers. If you look at kills vs. being killed, the use of long lances on Heavy cruisers did not seem to make much sense. On Destroyers and light cruisers - absolutely. I just question the idea of arming your heavy cruisers that way.

I understand the why - the decisive battle launch of 100's upon hundreds of torpedoes, at night I think the plan was, by cruisers and destroyers to weaken the american battle line for a daylight gun engagement. But perhaps the Japanese would have fared better by following the American plan of no torpedoes aboard heavy cruisers.

The trouble is your not understanding the why. The decisive battle did not play out as a single decisive event, but rather it played out as a series of drawn out affairs, which in the end favoured the Americans and their vastly superior resources. But at a tactical level, the Japanese got the best of most of the surface actions until well into 1943, with one or two exceptions. Its just that the US could afford to take their losses and step right back up for more, the japanese could not. Therein lies the reasons for the Japanese defeat...simple sheer attrition. it had nothing to do with their cruisers carrying torps. if anything the carrying of TTs by all capital ships was part of the secret to Japanese success.

Why was it that the Japanese could achieve victory in most of the surface actions they fought. Consistently they were outnumbered, they were certainly behind the USN in terms of major technologies like radar, Japanese gunnery was patchy at best, and their torpedoes missed more often than they hit. Given all that, one wonders how they survived even the first year of the war, let alone emerge as the tactical victors. The answer lies in one word....flexibility.

For the Americans with certain ships only equipped to do certain things seems like a dreadnoughtish (with its all or nothing principals considered) thing to do, but in the confusion of a night battle this was a massive handicap. In night battles it always was the Torps that delivered the fatal blows, or almost always. Separate the US cruisers from their escort and they are vulnerable. And separate they did....often. This made them far less capable than their japanese counterparts. The Japanese cruisers, by camparison were packing their own heat and this always meant they were dangerous, with or without their destroyer escorts. It meant japanese DDs could detach from protecting their gunlines and move in for close range attacks, sometthing the US could only do if they accepted massive risks to their gunlines.

So it was absolutely essential that Japanese cruisers carry torpedo armament, to maximise the flexibility of the force of cruisers and destroyers. Their equipment with flashless powder, their disdain in using TBS, whilst the US ships chattered incessantly, the ability to react immediately without orders, or trying to worry about "co-ordination" like the Americans always had to do, made them very dangerous at night. For the light cruisers in particular, their ability to fire torpedoes and outrange the US DDs gave their destroyers a massive advantage in firepower over the US light forces. US CLs were completely unable to undertake the same mission, though they did try. Mostly US cruisers acted as targets that the japanese shot at , whilst the US destroyers did their best to work into position and do some real damage with their vastly inferior torpedoes. Post Guadacanal, the USN did a study into its cruiser fire capabilities and found them to be very nearly useless in the close range brawls that were the night fights in the Solomons. ROF for the cruisers were too slow to track and hit fast moving targets , their radar could not track quick enough and was frequently inneffective. Procedures too slow and cumbersome. It took another year for the USN to finally work out procedures that could get the better of the japanese in a one on one fight for their cruisers.

You have a vastly over-inflated view of US effectiveness in surface actions in 1942. They had one or two very significant wins, and full credit needs to be given for that, but to argue that the Japanese should abandon a very successful formula and adopt a known less effective formula makes no sense to me at all.

 

[Garyt]

Parsifal, are you familiar wit this article? Were the Best Good Enough?

It goes into depth battle by battle, how many torpedoes were launched, what the effects were, etc.

If we look at it as a strict scorecard, Japanese CA's lost due to their torpedoes exploding, and factor in how many allied vesseld were sunk by cruiser torpedoes (this would be rough, all we could do is take total torps fired vs. those fired by cruisers and apply that percentage to american losses by Japanes torpedoes), and I think the results would be more Japanese CA's were sunk because of their torpedoes than by their torpedoes.

And to be fair, we should throw out sinking of vessels that were ready to be scuttled, as well as heavy cruisers which were heavily damaged prior to their torpedoes going off.

Now perhaps you believe that there are reason beyond the results that justify Japanese CA's carrying torpedoes. Possibly, but I still think it should show in the results.

 

[tomo pauk]

Hmm - how many Allied ships were sunk by gunfire vs. how much by the torpedoes, by the Japanese surface units (minus CV)?

 

[Garyt]

Gambier Bay 25 October 1944 Sunk by Japanese naval gunfire
Heavy cruisers[edit]
Name Date Cause
Astoria
9 August 1942 Sunk by naval gunfire
Houston
1 March 1942 Sunk by naval gunfire and torpedoes
Northampton
30 November 1942 Sunk by naval torpedoes
Quincy
9 August 1942 Sunk by naval gunfire and torpedoes
Vincennes
9 August 1942 Sunk by naval gunfire and torpedoes
Light cruisers[edit]
Name Date Cause
Atlanta
13 November 1942 Sunk by naval gunfire
Helena
6 July 1943 Sunk by naval gunfire (torpedoes)
Destroyers[edit]
Name Date Cause
Barton
13 November 1942 Torpedoed by Japanese destroyer Amatsukaze

Benham
15 November 1942 Scuttled after being severely damaged by Japanese torpedo
Blue
22 August 1942 Torpedoed by Japanese destroyer Kawakaze

Chevalier
6 October 1943 Scuttled after being severely damaged by Japanese torpedo
Cooper
3 December 1944 Torpedoed by the Japanese destroyer Take

Cushing
13 November 1942 Sunk by naval gunfire
Duncan
12 October 1942 Sunk by naval gunfire
Edsall
1 March 1942 Sunk by naval gunfire and carrier-based aircraft bombs
Gwin
13 July 1943 Sunk by Japanese torpedoes
Henley
3 October 1943 Sunk by torpedoes
Hoel
25 October 1944 Sunk by naval gunfire
Johnston
25 October 1944 Sunk by naval gunfire
Laffey
13 November 1942 Sunk by naval gunfire
Monssen
13 November 1942 Sunk by naval gunfire
Pillsbury
1 March 1942 Sank in surface action with Japanese cruisers Takao and Atago

Preston
15 November 1942 Sunk by naval gunfire by Japanese cruiser Nagara

Walke
15 November 1942 Sunk by naval gunfire


From the above list, looks like 14 by gunfire, 4 by a combination of gunfire and torpedoes, and 8 by torpedo. I've counted destroyers and larger, combatants only, and tried to remove any that were sunk by airpower, subs, or not in the Pacific theatre. The only thing I'm not sure of, and you would have to research this vessel by vessel, is if any of these destroyed by gunfire and torpedo were given the coup-de-grace by a torpedo, the real damage coming from gunfire. There may not be any.

Next question would be how many were destroyed by torpedoes from heavy cruisers? Not sure, but it would be in the minority for certain. It seems when a ship is listed as doing the sinking, it is almost always a destroyer.

 

[gjs238]

Some of this may be difficult to quantify if the Wikipedia article on the Type 93 "Long Lance" torpedo is correct:

https://en.wikipedia.org/wiki/Type_93_torpedo

In the early surface battles of 1942–43, Japanese destroyers and cruisers were able to launch their torpedoes from about 20 km (11 nmi; 12 mi) at the unsuspecting Allied warships attempting to close to gun range. Allied warships expected that, if torpedoes were used, they would be fired from not more than 10 km (5.4 nmi; 6.2 mi), their own typical torpedo range. The many torpedo hits suffered by Allied warships in such engagements led their officers to believe torpedoes had been fired by undetected Japanese submarines operating in concert with the surface warships. On rare occasions stray very long-range Type 93s struck ships much further range than their intended targets, leading the Allies on occasion to suspect their ships had been mined. The capabilities of the Type 93 went mostly unrecognized by the Allies until examples were captured intact in 1943.

 

[Garyt]

I think the range of the Long Lance was a bit overrated as far as it's sucess. It could give you the rare hit at extreme range, which would be a suprise to allied forces in the early part of the war, put I believe other factors, speed and reliability were more important.

In an excerpt from an article by Joseph Czarnecki regarding the type 93 torpedo:

The first is a review of the Type 93 torpedo by range fired, and speed setting employed. The dismal performance in such long-range actions as Java Sea and Komandorski Islands, and the relative success in the close-range actions of the Solomons Campaign, imply that the weapon's speed was a greater asset than its range. It may be that the Japanese misappreciated their own weapon and would have been better served by a plan which eschewed "long-range concealed firing" in favor of short-range attacks that offered the enemy less time to evade.

 

[tomo pauk]

...

From the above list, looks like 14 by gunfire, 4 by a combination of gunfire and torpedoes, and 8 by torpedo. I've counted destroyers and larger, combatants only, and tried to remove any that were sunk by airpower, subs, or not in the Pacific theatre. The only thing I'm not sure of, and you would have to research this vessel by vessel, is if any of these destroyed by gunfire and torpedo were given the coup-de-grace by a torpedo, the real damage coming from gunfire. There may not be any.

Next question would be how many were destroyed by torpedoes from heavy cruisers? Not sure, but it would be in the minority for certain. It seems when a ship is listed as doing the sinking, it is almost always a destroyer.

Thanks for the effort to type down the list. The link you kindly provided lists 18 Allied ships sunk by a torpedo, though. More Allied ships were also lost by gunfire, too, ie. not just USN ships.

 

[Garyt]

The link you kindly provided lists 18 Allied ships sunk by a torpedo, though

That's why I only included combatant types. I mean an LST may carry some light AA, but it's not a combat vessel.

Parsifal's thoughts seemed to be by putting type 93's on a CA you are making them more effective in a battle setting, so I look to combat vessels sunk.

Against a slower badly armed and armored non-combatant vessel, you can really sink it with anything, it's your choice. That's one major reason why subs carried deck guns, they could sink weaker opponents without wasting valuable torpedoes.

As far as coming up with a list of all allied ships sunk, it would have taken a heck lot more work. And the US vessels sunk should provide a decent enough sized sample base to get an idea.

Also, I did not count aerial launched torpedoes in the equation - it's apples and oranges.

 

[Glider]

I am more or less out of the loop at the moment due to work but I am surprised that no one seems to have suggested buying the 40mm AA gun, being up to speed on radar development and deployment, plus developing a larger and more modern anti submarine capability. These to a larger degree, were what killed the Japanese forces. As with the Luftwaffe the Japanese air forces should have put more effort into getting their training programs into full gear earlier.

There was nothing wrong with the aircraft of the IJN apart from being a little slow on introducing a follow on to the Zero and the ships were very capable.

Had the IJN carriers been fitted with Radar then the Battle of Midway would almost certainly been won by the Japanese and the impact of that would have been huge. The 25mm wasn't as bad as most people think but there is no doubt that the 40mm would have made their AA defences far more dangerous.

As for the need for better A/S defences need I say anything as its so obvious. Japan is an island as is the UK and they should have put as much effort into A/S equipment, training and infrastructure as the RN did.

 

[parsifal]

This is a very suspect way of assessing the effect of Long lance on the battler. A better way would be to look at one battle where Japanese cruisers were alone or nearly alone, and assess the performance in that situation. A near perfect battle exists for that very purpose

Savo Island

Admittedly there were a lot of other factors at work that caused the allies to get themselves defeated, but its significant to note that the Japanese cruisers of which there were 5 CAs and 2 CLs were escorted by a single DD. An allied force in that situation could not have operated. as it was the Allied force, some 9 cruisers (in the total force, with 6 actually engaged) and 15 DDs failed to co-ordinate. The Japanese were completely impervious to the allied destroyers, who fired salvo after salvo of torpedoes at them but at long range. The US DDs milled around aimlessly a lot, but also, they could not risk getting close to the Japanese because they feared the torpedo broadsides carried by the Japanese cruisers. Not so the Japanese cruisers, who closed on the US and Australian cruisers to point blank range and then tore them to pieces with guns and torps. The torps made all the difference. The Allies lost 3 cruisers on the night, plus two DDs heavily damaged, and a further cruiser scuttled the next day. all of the cruisers had suffered damage either directly or indirectly because of the Long Lances on the cruisers, and could not reciprocate, at least partly, because they could not co-ordinate with their own DDs and could not risk getting too close to the IJN because of the fear of the IJN torpedo broadsides. Not that they knew exactly what was going on. Not all of these losses can be attributed solely to Japanese topedoes, but the torpedoes were part of a weapon system, and that weapon system delivered repeated tactical victories for the japanese, and made the achievement of a strategic victory at guadacanal much more difficult. After Savo, the USN avoided resupply of the island except by day, and that strung the campaign out by many months, because the control of the seas, the key to everything, was passed to the IJN at night....all because of the fear of the torpedoes the Japanese ships carried, which included their heavy ships. . The same situation arose at New Georgia. At bougainville the USN were at last able to hit back on better than even terms. All this fuss was largely due to to the Long lance effect. Without it, the Japanese would have been far more manageable at night, and a big part of that threat arose because their cruisers were torpedo armed and the Allied cruisers were not.

 

[tomo pauk]

Broadly related to the thread - a historical research of the USN in ww2, so it would include the INJ assets actions: link.

 

[Shortround6]

I would note that the Americans were about the ONLY navy not to put torpedoes on heavy or large cruisers. Now maybe the US was right and everybody else wrong but the Japanese were not following a path all on their own.

FEAR of the torpedo has often exceeded it's combat results in surface actions.

And HOPES of results from the torpedo have often exceeded it's actual results/effects.

Japanese faith/hope in the Torpedo got back the Russo-Japanese War of 1904 when they achieved some spectacular success with the primitive torpedoes of the day and in the 1920s/30s when the Japanese cruisers were built those successes were only 25-30 years old.

 

[Garyt]

FEAR of the torpedo has often exceeded it's combat results in surface actions.

And HOPES of results from the torpedo have often exceeded it's actual results/effects

Definitely.

Parsifal, you bring up some good points about Savo, most notably that I see a force of mostly cruisers was able to do some damage with torpedoes.

As far as the fear of torpedoes keeping US destroyers at bay - I don't think this was the case. I think the US destroyers milling about has much to do with surprise, a lack of co-ordination, and that the US was not trained to night operations nearly as well as the Japanese, which is the reason for the first two issues in this sentence.

I'd say Savo did however show the superiority of the Japanese torpedo over the US torpedo at this stage of the war, but in general I'd say the sucess in night battles had more to do with two factors, the superiority of the Japanese torpedoes and better Japanese night training than it did Japanese heavy cruisers being torpedo armed. Radar assisted fire control helped turn the tide for certain later on.

I'd also not try to put hindsight in the hands of US destroyer captains - the US sailor was not fully or even close to fully aware of the specifics of the type 93, or the inadequacies of their own torpedoes by comparison. Some of the long range early war strikes by type 93's were often thought to be submarine torpedoes or even mines. The boat captains in WW2 did not have our advantages of post war knowledge of weapon systems. It would be a confusing situation for them at best at night, and knowing where the torpedo came from that it them was very much a guesstimate.

Shortround, It does indeed look like many heavy cruisers of other navies carried torpedoes as well. Looks like the Zara class, the most modern Italian class bythe start of Ww2 was not torpedo equipped. The British have some with and some without, and all German Heavy cruisers carried torpedoes. What does seem to be the trend though is that the newer the cruiser, the more likely the torps are not carried.

The difference though is these nations torpedoes were not nearly as dangerous for the user as the type 93. Chokai was hit by a single 5 inch shell which set of it's torpedoes. This type of shell should not have done much damage, and with less volatile torpedoes, it would have been OK as well. Destroyers really have no armor, which means their magazines are not protected, to the torpedo provides no more threat really than it's existing magazines already do. With a cruiser, with a few inches of belt and deck armor, you are somewhat impervious to 5" shells, HE rounds are not a huge threat, you even have protection from 6" rounds at a portion of distances.

With torpedoes on deck, you in essence have brought some of your magazines up above the armor protection, making you vulnerable to rounds which would not normally penetrate your armor. I also makes you vulnerable to GP bombs, the type most carried by aircraft. A GP bomb may still cause damage, but is not going to generally penetrate the armor of many cruisers, keeping it away from the magazines. Again, with torpedoes on deck, it's like having your magazines on deck.

I'd think even putting less volatile torpedoes on deck would be a more viable option. The Japanese had a type 96 torpedo used in subs that seemed to perform pretty well, and was a 36% oxygen mixture, not pure oxygen. I would think this would be a fair amount less volatile than the 100% oxygen used in the type 93. I think what is important there were a few aspects of the type 93 that made it better than the US torps, perhaps most importantly was that it had a much more reliable detonation system.

 

[parsifal]

Ah no, the USN by August 1942 had had at least several scraps with Long Lance, and had a good understanding of its capabilities. The first big scrap had occurred at java sea, in which US DDs and a cruiser had participated. They again were subjected to its capabilities on several of the subsequent engagements, including Sunda Strait, where they lost a cruiser.

USN DDs did fail to react adequately at Savo, and a lot of that was to do with their inability to co-ordinate . This happened repeatedly in the coming night battles. A lot of it was to do with the lack of training and faulty procedures. USN reactions in night battles was a confusing array of chatter across TBS, blinding flashes and confused situational awareness, that inevitably led to fatal hesitation. US procedures might not have meant to do this, but in practice it did.....they confused the hell out of themselves and paid heavily repeatedly. Until USN DDs detached themselves from protecting the US cruisers, they were doomed to that sort of second rate response. Invariably they were tied to protecting cruisers and never got the chance to shine in their own right until much later. The lack of torpedo armament in the US cruisers undoubtedly was a factor in this lacklustre performance for its destroyers...the cruisers were chained to them like a dead albatross around their necks. Inevitably the Destroyers were always confused, because they had to watch two games at the same time....what their own cruisers were doing and what the opponents were doing. inevitably they got lost and confused and they hesitated too often, sometimes because they were forced to remain too close to their own cruisers and coulod determine who they were firing at.

Eventually some people in the USN began to realize that the cruisers they were chained to were not worth the trouble. It is significant that the real turn for the USN in these battles came with a man called Arleigh Burke. Ive often said that Burke was in the wrong navy, because he sure acted like a Japanese Admiral. After one of the 30 or so battles fought near Bougainville, he once stated that the difference between a bad admiral and a good admiral in a battle at night was about 10 seconds...referring to his now standing orders to immediately attack, with both guns and torpedoes, and use maximum speed. He was given the nickname 31 knot Burke, because he was unhappy with that speed....his usual; attack speed was 35 knots...flat out and not waiting for any torpedo-less cruiser to confuse the hell out of him and more to the point, not having to wait for orders to engage, which was invariably the case when a mixed force of cruisers being protected by Destroyers was involved. Most of Burkes battles were fought without cruisers to "support" him. The Americans were finally learning, and I bet they wished all their ships had torpedoes by that stage. They eventually learned to do without them, by very intensive training, a change in tactics and heavy use of radar guided control. They had the numbers by then, but could have been a whole lot easier if they had equipped their ships at the outset with torpedoes that worked and fitted them to all ships they intended to use at night

 

[Garyt]

Ah no, the USN by August 1942 had had at least several scraps with Long Lance, and had a good understanding of its capabilities.

Having good ideas of the capabilities of the long Lance runs contrary to most of what I have read. Indeed they fought of Java Sea, but as I mentioned they were not even sure what hit them, attributing some of the long range hits to a submarine or even a mine.

From the Pacific War online Encyclodedia:

Because of the long range and nearly invisible wake of the Long Lance, its existence remained a secret well into the war. Hits from the Long Lance were often attributed to mines or an undiscovered submarine. It took the capture of Japanese documents to convince Allied naval leaders that the Japanese had come up with such a capable weapon. An intelligence bulletin accurately describing its performance was not issued until March 1944.

I'm not sure of the quality of the Pacific War Encyclopedia, but I must say it meshes with most of what else I have read of the type 93 torpedo. And the intelligence bulletin regarding it not coming out until 3/44 would seem to coincide with this as well.

 

[Shortround6]

Shortround, It does indeed look like many heavy cruisers of other navies carried torpedoes as well. Looks like the Zara class, the most modern Italian class bythe start of Ww2 was not torpedo equipped. The British have some with and some without, and all German Heavy cruisers carried torpedoes. What does seem to be the trend though is that the newer the cruiser, the more likely the torps are not carried.

In many cases the torpedoes were there in the initial planes but dropped due to weight problems. It is a lot easier to NOT install the tubes than it is to change the thickness of deck armor or redesign turrets or whatever else they thought they needed to do to get the weights in line. Most 8in gun cruisers built between the wars were very tight ships from a weight standpoint. And weight high up causes problems that magnify. Most countries cheated to a greater or lesser extent on the weight and still couldn't get everything wanted in one ship. Once you had built the hull (even if not launched yet) major changes in armament (like more AA guns) have to be compensated for by taking something else off the ship.

With torpedoes on deck, you in essence have brought some of your magazines up above the armor protection, making you vulnerable to rounds which would not normally penetrate your armor. I also makes you vulnerable to GP bombs, the type most carried by aircraft. A GP bomb may still cause damage, but is not going to generally penetrate the armor of many cruisers, keeping it away from the magazines. Again, with torpedoes on deck, it's like having your magazines on deck.

While the GP bombs might not kill/sink a cruiser (and many cruisers had fairly thin deck armor over large parts of the hull.) depending on where they hit they it might only take one "mission" kill a cruiser, make it unable to continue on its mission. Fire control and some other systems being more vulnerable to damage than is generally thought. Bombs have taken out condensers, and boiler rooms without actual penetration of the space.

Naval damage is very hard to "model" or war game because so much depended on "luck". Where do the first few hits happen and what effect do they have. If one ship looses it's fire control in the first 2-3 hits that skews the rest of the battle, but another ship might take many hits before it's fire control is taken out.

 

[Garyt]

depending on where they hit they it might only take one "mission" kill a cruiser, make it unable to continue on its mission.

I agree. But something like taking out fire control requires a very lucky hit - with the area occupied by torpedoes a bomb hit would not have to be that "lucky", as anything amid ships stood a good chance of getting to the torpedoes, even more so if as volatile as the type 93. And secondary fire control systems were usually available, so it usually would not "mission kill" a capital ship wit one director being taken out, though the using the secondaries usually meant a bit less accuracy. Heck, you could even uselocal control but then accuracy would indeed be compromised, unless at very short range.

(and many cruisers had fairly thin deck armor over large parts of the hull.)

Indeed. And some, including many Japanese cruisers had rather thin armor over the turrets. But about all US and Japanese Heavy Cruisers had at least 2 inches or more over the magazines, which would certainly be enough to stop penetration. And even those with thin turret armor (only an inch or so on some Japanese CA's) still had the 2"+ deck armor, which had to be penetrated to reach the magazines.

Bombs have taken out condensers, and boiler rooms without actual penetration of the space.

Yep, even the Musahi had a boiler room taken out by a bomb, and no bomb used on her was capable of penetrating her massive deck armor. Had to be scaling or something similar. Maybe even a luck hit at a joint or even down the smokestack, though nothing indicates that. I guess if you hit a ship with 27 bombs, a few will be lucky hits

But still, a non penetrating hit was far far less likely to cause damage beneath a layer of armor as opposed to a penetrating hit.

 

[parsifal]

Having good ideas of the capabilities of the long Lance runs contrary to most of what I have read. Indeed they fought of Java Sea, but as I mentioned they were not even sure what hit them, attributing some of the long range hits to a submarine or even a mine.

From the Pacific War online Encyclodedia:



I'm not sure of the quality of the Pacific War Encyclopedia, but I must say it meshes with most of what else I have read of the type 93 torpedo. And the intelligence bulletin regarding it not coming out until 3/44 would seem to coincide with this as well.

The USN had knowledge about Long lance from at least 1935. I refer you to the USN Intel report referenced DOD.DIR.5200.IO. This was an open file on Japanese torpedo technologies, begun in 1935 and updated periodically (and regualalry) thereafter until the final report in early 1946. The final report is dated january 1946, but it was a living document, showing that the USN had an interest in this technology from at least 1935, and documents LL development from around 1920. Both the USN and the RN tried to develop oxygen fuelled torpedo engines but abandoned them over safety concerns. They also believed prewar that the weight and reduced torpedo broadsides were an overall liability, along with the notion that the oxygen propellant was a liability. This argument is far from a new idea. After March 1942, that line of argument completely disappear from the intelligence assessments...the USN knew these weapons were lethal additions to the Japanese inventory, and those intelligence summaries tells it all.

So the intelligence was there....it just wasnt acted upon. USN surface admirals were amongst the most reactionary in the world, almost impervious to any sort of change that might challenge their view on how a naval battle ought to be fought. So in a sense what you are claiming (that the USN was unaware of the LL lethality) is true. Not because they didnt know about it, but because they chose not to know....the official record shows that they clearly had access to such information as was needed....., put most simply they didnt act on this information because their concepts were so entrenched and they (the US surface admirals) so unmovable to change that they simply ignored the threat. The result was that their surface fleet , despite the knowledge being there, chose to ride into battle unprepared for the carnage about to be unleashed on them.

 

[swampyankee]

The USN had knowledge about Long lance from at least 1935. I refer you to the USN Intel report referenced DOD.DIR.5200.IO. This was an open file on Japanese torpedo technologies, begun in 1935 and updated periodically (and regualalry) thereafter until the final report in early 1946. The final report is dated january 1946, but it was a living document, showing that the USN had an interest in this technology from at least 1935, and documents LL development from around 1920. Both the USN and the RN tried to develop oxygen fuelled torpedo engines but abandoned them over safety concerns. They also believed prewar that the weight and reduced torpedo broadsides were an overall liability, along with the notion that the oxygen propellant was a liability. This argument is far from a new idea. After March 1942, that line of argument completely disappear from the intelligence assessments...the USN knew these weapons were lethal additions to the Japanese inventory, and those intelligence summaries tells it all.

So the intelligence was there....it just wasnt acted upon. USN surface admirals were amongst the most reactionary in the world, almost impervious to any sort of change that might challenge their view on how a naval battle ought to be fought. So in a sense what you are claiming (that the USN was unaware of the LL lethality) is true. Not because they didnt know about it, but because they chose not to know....the official record shows that they clearly had access to such information as was needed....., put most simply they didnt act on this information because their concepts were so entrenched and they (the US surface admirals) so unmovable to change that they simply ignored the threat. The result was that their surface fleet , despite the knowledge being there, chose to ride into battle unprepared for the carnage about to be unleashed on them.

Everybody tends to fight the last war, at least the last one they didn't lose. It's a cliché, but it, like all clichés, has some truth behind it (other clichés have Shakespeare behind them ).

I suspect that one of the USN's problems was that its interwar doctrine heavily stressed line-of-battle tactics, even for its cruisers,with the idea of using its 8 in gun cruisers as more as mini-battleships than in the way the RN or IJN intended using their cruisers, which was, at least partly, to support destroyers in torpedo attacks against enemy forces, especially at night and in bad weather. I've speculated, with very little evidence, that part of the reason for this was that the USN considered the Pacific as its key operational area, and the weather around San Diego (the USN's primary Pacific Fleet base at the time) tends to be clear and sunny. Make the USN's primary Pacific base Seattle, and the admirals would have a somewhat different view of normal visibility.
Again, speculating with very little evidence, the fact that successful torpedo attacks are much more difficult in good visibility, the USN deprecated the idea of torpedo attacks, which reduced the amount of effort the USN placed on torpedo development and use (even for aircraft: I've seen posts that the USS Ranger was built without magazines for aircraft torpedoes). So, I speculate that the train of thought was something like this:

Normal visibility conditions are "good."
This means that torpedo attacks are not a viable tactic (even if the destroyer guys think so: their real job is to shoot up other destroyers)
This means that it's preferable for ships to have long range guns
This means that cruisers should have the largest guns practical. Since treaties say that's 8 in, that's what they'll get.
Since they've got long-range guns, they need to operate in strict lines so that they can engage the enemy ships which, because their admirals will have come to the same conclusions we've come to.

The trouble is, of course, that the other admirals came to different conclusions: the IJN decided its cruisers and destroyers existed to attack the USN battle line, which meant that they would have to do so in conditions of restricted visibilty. It's impossible to arm a cruiser (especially a treaty cruiser) with a gun large enough to hard-kill a battleship, but torpedoes will do so quite nicely.

After a few engagements, the USN's leaders changed their tactics to fit conditions. Their strategic concept, which was that navies existed to control the sea, didn't change. The IJN's leaders never really changed their strategic concept, which seems to have been the role of the navy was, pretty much exclusively, to sink battleships. They didn't seem to think about the ships that carried the food and fuel that their people needed to live or the ships carrying the raw materials that their factories needed to produce things like airplanes and ships.

As I've said before: the best thing the IJN could have done was to get rid of the ultra-nationalist loonies who wanted to take over Asia. Failing that, take some time studying what happened to US seaborne trade due to CSN raiders in the American Civil War and how Germany lost 800,000 due to starvation in WW1 as they could no longer import nitrates, and the government chose to produce munitions, not fertilizer, via the Haber process, so its people starved, one of the major factors in Germany's defeat.