Japanese logistics, purchase programs and war booty, reality and alternatives 1936-44

z42 said:

They would have needed to remove some main armament turrets, or something like that, on many ships in order to make room for more AA and radars

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This is very true and it is true for most (all?) destroyers before the late 1930s.
Some of the Japanese DDs from WW I and the early 20s had a pair of 6.5mm machine guns, replaced by a pair of 7.7mm guns. Even swapping for or adding a twin 13.2mm Hotchkiss mount is starting to push things

What is a little weird is that the Japanese had 100-200 British pdr Pom-Pom guns in the 1920s. They were not happy with them and they tended to get replaced by the 25mm Hotchkiss.
The British put time/effort into the WW I 2pdr to get the guns/ammo used in WW II so it is hard to say.

Most (all?) Navies biased their destroyers to torpedo and surface action in the 1920s/30s.
British and Americans had large numbers of WW I destroyers they could down grade to escorts (not enough but a lot more than anybody else had).

But Japan had considerations that other countries (except for England) did not have. Their trade routes were much longer than WW I destroyers could really deal with.
The planned attack on the DEI really shows the problem, It is over 1300 miles from the North of Borneo to just north of Taiwan, let alone getting to Japan.
Much of the raw materials that Japan wanted to seize were hundreds of miles further than their 'normal' trade routes.

Several things happened the first year of the Pacific war to help lull the Japanese into a false sense of security. The British had withdrawn their subs from Singapore. Holland had been over run and the DEI was trying to hang on pretty much by it self. Parts/supplies for the Dutch subs in the DEI were not as plentiful as they might have been. The rapid collapse of the Philippines took out the US Navy sub base, moving operations to either Australia or Pearl Harbor. The US torpedoes sucked so the US subs were not very effective (and for a few other reasons) so the expected losses due to subs in 1942 were within the expected losses the Japanese high command had anticipated. Perhaps they goofed here, They could absorb losses during a short war. But the losses are cumulative and they could not replace the early losses and as the war went on and the loss of transport only got steadily worse. even 20-30% fewer losses in 1942 might have been worthwhile.
On the flip side, while the US was not inflicted a lot of losses on Japanese merchant ships, the Japanese were not sinking very many US subs. The US sub commanders, unlike some of the admirals had a good idea where the problems were were even if they didn't know how to fix them. The US was not getting the results they wanted but they were not loosing very subs either. The US could afford to wait to see if things changed (fix the torpedoes). Had the Japanese been sinking more subs and the US subs been getting even few kills perhaps the US might have changed/modified their strategy?
But escorting merchant ships was not in the mindset of the Japanese navy. In fact even later in the war one account claims that many of the escort commanders had graduated from the merchant fleet academy and not from actual naval academy. Granted many British and US officers were reserve officers and while there were class distinctions it may not have been as bad as in Japan? There were no AS training schools.

The Japanese didn't really need more Emily's.
What they needed were planes closer to the Catalina or perhaps a twin closer to the Martin Mariner.
Something they could built two of instead of one Emily.

Shortround6 said:

The Japanese didn't really need more Emily's.
What they needed were planes closer to the Catalina or perhaps a twin closer to the Martin Mariner.
Something they could built two of instead of one Emily.

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Good point about the Japanese making the Catalina equivalent.
Emily was a great design, but it was one of the biggest and most expensive flying boats made, with 1800+ HP engines and heavy & big airframe that will be using fuel like there is no tomorrow.
Catalina used the engines that were perhaps 3rd tier US engines (meaning there was a lot of them), of the modest power, and just two of these - all the factors contributing to the quick ramp-up of the production, and that production was of the American type
Making the Japanese Catalinas around the Sakae or Zuisei would've perhaps meant 5 of these vs. two of Emilys? But even the 2:1 ratio equals to another ~170 flying boats, that will go a long way to plug the gaps in the aerial coverage.

The same math can be applied to the H6M Mavis, that was made in 216 copies.

Here is the Japanese 'baby Catalina', the Aichi H9A.

Well, I would say, even though I'm nowhere near an expert, that the problem is twofold.

The first is the military mindset, and the second is the possibility to design (copy/license) something and then produce it.

Technologically, Japan was certainly not behind in the 1930s and 1940s. Well Japan had cavity magnetron radar technology before the UK (and they offered it to the Germans who were not interested), Long Lance and keel breaking torpedo (Indianapolis), multiple types of jet engines, rockets, radar....but no the ability to produce them in quantities for total war.
Especially not sophisticated electronic equipment.

Let's add to that the duplication of development programs (army - navy). So there is a shortage of production capacity.
And if the kinsei Zero (yes - should have had it instead of the sakae at least with A6M3 model) was so overpowered that it wiped out all the American planes over Midway in round two within year or less with 5 or 15 to one they wouldn't have stood a chance.

And military philosophy ... since it's a lazy Sunday morning, I won't look for a source but ...

Someone wrote nicely that Japan waged war on the principle of the 18th century. That is, two warring armies met, clashed, the better/stronger/smarter/better equipped was won. After the battle, the winner and loser sat down at the table, agreed on a peace/truce and moved on. They missed the lessons of World War I (they didn't really have a Western Front) and Japan didn't realize that wars had changed and become total. They went to war like let's give a strong slap to the opponent and then agree on what we will keep.

And that's why the army (and especially the pilots) was still based on samurai. So the emphasis in the planes themselves (and tactics) was placed on individual superiority (maneuvering abilities and pilot training ).
I (can) understand the kamikaze tactic, the hard military logic of numbers speaks in its favor, besides, if my burned cities are behind me, then there is also the motivation of all those pilots.
Pointless banzai charges and seppuku suicides for emperor and pride - not really.
And the cynical component that the kamikazes had is also missing - we can say that a couple of thousand planes are for the sunk 30 or so ships not in favor calculation, but that's not the whole story. The USN was pretty shaken up after Okinawa.

And there is a general strategic mistake - I would say (again) Yamamoto. The Navy planned 'one' decisive battle in its waters (along with the fleet AND AVIATION), and they carried out the PH. And if we can say - then the battleship was the king and the basis of the fleet ... but Pearl was attacked from the air and not bombarded by the guns of the fleet. And yes - they were sure that aviation would sink the battleships (Taranto).

So even the best equipment and training cannot correct strategic mistakes and arrogance. Like when, when planning the attack on Midway, they brought back two "sunken" carriers because who would care about junior officers playing the enemy.

Although I find the intellectual experience (and there is a lot to learn and broaden one's perspective) in such discussions - I'm afraid that not even a 'super maxi' Zero would fix the situation in which Japan was found itself.

And now I have to stop, so not to become a thread killer .

Zmauky said:

So even the best equipment and training cannot correct strategic mistakes and arrogance. Like when, when planning the attack on Midway, they brought back two "sunken" carriers because who would care about junior officers playing the enemy.

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One wonders how much of a change of a mindset is required for the roles to be reversed - have the top brass 'play' the enemy side (USA, mostly) in the war games, and junior officers 'play' the Japanese forces.

Big stick and juicy carrot. .

Not the first and last time that self-confidence and/or ignorance results in disaster.
For example, land a helicopter landing party at an airport and don't think that the opponent has rocket launchers nearby (and that they won't run away in fear).
Or plan a fleet attack from three (4?) directions and when you (accidentally) manage to reach the strategic objective (transport ships full of un-landed troops) retreat due to possible losses. True there are more than a few naval battles where the Japanese Navy could (should) have had a little more banzai mentality.
The Japanese army did have its enlightenment in Khalkhin Gol, the navy remembered Tsushima.

Unfortunately, Japanese politics is not my strong point, but maybe some incentive for the seppuku of selected individuals from the divine Emperor?

The Japanese did have an amphibious type similar to the PBY, but never took advantage of it. It was the Aichi H9A, used mostly.for training.

Another asset Japan had, but did not use to it's full extent, was their submarine force. Their tactics and doctrine were nowhere near as aggressive as the USN and Kreigsmarine, even though their subs were comparable.

Zmauky said:

Well, I would say, even though I'm nowhere near an expert, that the problem is twofold.

The first is the military mindset, and the second is the possibility to design (copy/license) something and then produce it.

Technologically, Japan was certainly not behind in the 1930s and 1940s. Well Japan had cavity magnetron radar technology before the UK (and they offered it to the Germans who were not interested), Long Lance and keel breaking torpedo (Indianapolis), multiple types of jet engines, rockets, radar....but no the ability to produce them in quantities for total war.
Especially not sophisticated electronic equipment.

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The US, Britain & Germany all had magnetic pistols for their torpedoes on the outbreak of war, so that hardly puts Japan ahead technologically. All experienced difficulties with them in practice. But having a magnetic exploder did not prevent them being triggered bycontact with the ships side.

The I58 fired a spread of 6 torpedoes at the Indianapolis set to a depth of 4m (13ft) per her CO during the USN enquiry into the loss of the ship. Five of these had magnetic exploders fitted. But given the running depth v the draught of the ship, the magnetic exploder clearly played no part. Whitley gives her mean draft as 21ft and she was probably a bit deeper in the water than that in 1945. 2 or 3 hits were obtained.

The 24" Long Lance fitted to IJN surface ships, not submarines, was a nasty shock for the Allies. This weapon was part of Japan's plan to degrade the power of the US fleet as it crossed the Pacific before engaging in the "Decisive Battle". But in 1942 they proved unreliable as the crews were found to be adjusting the sensitivity of the exploders thus making them too sensitive and liable to premature detonation.

Incidentally the RN developed a 24.5in torpedo designed around 1923 for the Nelson class battleships (its only use). Range was 15,000 / 20,000 yards at 35 / 30 knots with a 743lb warhead powered by oxygen enriched air. Long Lance developed in 1933, was 21,900 / 35,000 / 43,700 yards at 48-50 / 40-42 / 36-38 knots with a 1,080lb warhead powered by a kerosene-oxygen wet heater.

As for "sophisticated electronic equipment" or the lack of it, that does not do the Japanese justice. It is true that they failed to exploit radar and in particular to develop the command and control facilities to direct aircraft using it. On the other hand they did succeed in understanding virtually all the Allied shipborne radars thus allowing them to plan their attacks to exploit weaknesses. That proved particularly effective with the kamikaze attacks off Okinawa.

Japanese subs were a weird bunch. They had capabilities that the Germans and US did not have. They also had liabilities that the the Germans and US did not have.
Many/most of the Japanese subs were long ranged and had high surface speeds.
This also meant they were large which made them better visual targets, better radar targets and better sonar targets.
They also did not turn well, at least compared to many other subs so making sharp turns wasn't quite as good at dodging a depth charge attack.
The large subs also took longer to dive, which gave aircraft more time to get into bomb range.
They also were not (usually) designed for deep diving. They could not use the 3rd dimension very well.

This trade off between size and different capabilities were well known to both the British and the Germans. The US didn't have a much choice as those two as their main opponent required long range (size) to get into Japanese waters. But the Japanese ASW capabilities sucked which means that the US lost comparatively few boats.
The British lost 75 boats during WW II. The British also had the 2nd highest kill to loss ratio after the US subs.

Japanese subs were large and very, very expensive. A small Japanese sub was the size and power of a German MK IX.

The three classes of USN subs used during the war, were a little over 310 feet long or roughly 50 feet shorter than the USN's Gleaves and Fletcher class destroyers.

By the way, here's the wiki page that has info (and pics) for Aichi's H9A.


This could have had potential to be Japan's PBY equivalent.

The H6K was a great aircraft (as was the H8K), but the H9A would have been more practical and required less strategic materials for production.

Another dedicated ASW aircraft, but one that came along too late to influence anything.

The B5N Kate and B6N Jill were also used in the ASW role late in the war, gaining ASV radar to help theceearch process.

The Aichi H9A was pretty but it was too small. It was slightly larger than a Grumman Mallard.
While the Japanese needed a lot of AS planes it needed them in 1943 (or 1942 for experience). The 1944 is too late.
They needed planes with two 1100-1300hp engines, not 700hp engines. And not 1500-1800hp engines out of their first line aircraft.

Ok, let's keep in mind that we're going over what Japan could have done to improve their position at the onset of the Pacific War.

Their recon abilities had sufficient coverage in short and long range aircraft, but no intermediate recon utility aircraft like the PBY.

This is where a type like the H9A could have been built on.

Yes, was a bit smaller (but not by much) than the PBY, however, it was amphibious and held potential to fill that gap.
As an advanced trainer, it didn't need more powerful engines or nessecary electronics, so of course it's historical performance isn't all that impressive.

Nakajima engines producion, 1941-44, with (average?) prices for that year. Why was the Sakae for the Navy more expensive than it's sibling for the Army is anyone's guess. Over-charging for the navalization? Note the steep decline in the price of the Ha 109 engines; granted, Nakajima was charging a lot for the Ha-5 and -41.
Mamori was probably the only Japanese engine that was a lemon.

It is worth going back to the immediate post WW1 period and reminding ourselves of how the various Pacific Islands, many of which had been German territory were divided up. Because that is what the various strategies were based around.



That map is expndable here:-

The problem with the recent part of thie discussion is that it is focussing on a helping Japan fight a war that it never envisaged until they actually got involved in it. And it never envisaged it because until mid-1941 it had no intention of attacking the DEI, which was what generated the need to convoy war materials back to the homeland.

And there is the terms of the 1922 WNT to take into account regarding these territories:-




In the event of war with Japan what the US envisaged happening was laid out in War Plan Orange. An advance across the Pacific to relieve / recapture the Philippines. i.e. to move across that area of Japanese Mandate terrritory that separated Hawaii in the east from the Philippines in the west.



Japan intended to counter that with a series of actions to attrite the US fleet on its long journey west through the Marshalls and Caroline Island chains, through use of submarines (aided by air recce for cruisers culminating in the Oyodo class), land based aircraft on its island bases on these island chains (when it finally hurriedly build the necessary air bases) carrier based aircraft (aided by cruiser borne recce aircraft), as well as destroyer and cruiser attacks with Long Lance torpedoes backed up by the battlecruisers. There would then be a Decisive Battle between their battlefleet and what survived of the US Fleet somewhere near Japan (exactly where they never seem to have specified).

Britain meanwhile built up a strong submarine force at Hong Kong (it built up to around 14 O/P/R plus 2 minelayers between 1929 & 1937) along with a cruiser squadron based around the 5 Kent class from the late 1920s and a destroyer flotilla plus another cruiser squadron from the East Indies Station that could be quickly drawn on as well as a local flotilla of 4 old ships at Hong Kong after 1935 for local defence duties. The plan was to blunt any IJN thrust in the direction of the South China Sea in the area to the south of Formosa, delaying the Japanese fleet until such times as a fleet could arrive from Europe / Med to be based at Singapore, initially planned to take 3 months.. That fleet would then move forward through the South China Sea to blockade Japan.

1931 Japan engineers a crisis and occupies Manchuria which yields a large amount of resource that it needed - coal and iron ore for example. But the routes for these are relatively secure being either well away from British and US submarines or within the Sea of Japan, easily secured by minefields at a small number of choke points.

1937 Japan invades north-east China. 1938 it siezes enclaves around the major Chinese ports further south, but does not seek to push far inland to exploit them. 1939 it takes Hainan Island. The objective is to cut China off from the outside world and in particular limit supplies of arms to Chiang Kai-shek. Taking the northern part of Indochina was an opportnistic continuation of that policy, this time against a weakened France in Sept 1940, eliminating Haiphong as a port of entry to supplies to southern China. At the same time Britain was persuaded to close the Burma Road until the US persuaded it to reopen the route about 3 months later.





Only in June 1941 do the Japanese begin to look to the south to satisfy it resource needs. It starts with occupying the rest of Indochina in July. The US oil embargo (followed by Britain and the DEI) kicks in on 1 August 1941, and ultimately leads to war on 7/8 Dec 1941. That in the longer term produces the need to convoy merchant ships back to the Japanese Homeland, driving the need for many more escort vessels and ASW aircraft than previously considered necessary.

In naval terms you need to look at the Japanese Rapid Naval Armaments Supplement Programme agreed in Aug 1941. Amongst the smaller warships were:-

30 Etorofu class Kaibokan (Escort Ship Type A)
16 Mikura / Hiburi / Ukuru Kaibokan (Escort Ship Type B) laid down Oct 1942 to June 1944

30 (28 completed) more of the latter were ordered in later programmes with completions running right to the end of the war. But the main problem is the capacity of Japanese industry to build enough of these types of vessel quickly enough to meet the demand. The simplified ships (Escort Ships Type C & D) began to be laid down in Sept 1943

So basically Japan has 3 possible (not probable) time periods in which to start figuring out greater need for convoy escorts.

The Oct 1938 attack/invasion of Canton and the other southern Chinese ports. Putting Japanese troop convoys/supplies at greater risk of possible attacks by British/American forces.
Not sure if the Japanese get much in the way of resources back out.
The Feb 1939 invasion of Hainan Island which was much more for cutting off Chinese access to supplies and provide Japan with air bases and bases of operation for further attacks on China than getting any resources. It does expose Japanese military supplies to interdiction from British, French, US forces if any/all of those countries decide on greater intervention. At some point iron and copper resources were exploited but they were not the primary reason for the operation.
The Summer of 1940 Fall of France give Japan the opportunity to occupy northern Indochina, again much more to seal off the Nationalists from supplies rather than for resources for Japan.
The Japanese had planned for some escort ships. The Shimushu class

of 1938-39, completed in 1940-41 but the design was both more expensive than planned and as things worked out, not as capable as was needed.
No torpedoes but the three 12cm guns were a little heavy on the surface warfare side and the two twin 25mm AA guns were not bad compared to everybody else in 1939/40 but everybody else was pretty much stuck in sucky AA Armament land also.
They planned 16 but only built 4, in part due to the higher than anticipated costs. They were good for just 20kts and had long range, in part due to their diesels engines. We can argue back and forth the diesels. Cost, long range, and so on.
The Real failing was they only carried 18 depth charges to start and were equipped for minesweeping. They also did not get Sonar until May (?) of 1942 which really reflects the low AS priority of the Japanese Navy.

As EwenS has noted the next class were the somewhat simplified Etorofu class Kaibokan of essentially the same size/power/speed/armament but the delay means they are not completed and starting to enter service until March and the Spring of 1943, right in time for the Americans to really get into their submarine offensive with working torpedoes.
This 2nd class was initially completed with 36 depth charges and one launcher. Both classes, those the survived, wound up with 60 depth charges and up to 6 launchers. But that is in late 1943 or 1944 which is way, way behind British and American escorts operating in the Atlantic. There were later classes but way to late to really change things.

But remember the IJN began WW2 with some 56 old destroyers of the Momi (13), Minekaze (15), Wakatake (7), Kamikaze (9) and Mutsuki (12) classes built between 1919 and 1927 (some reclassed as patrol boats) plus 12 Tomozuri & Otori classes that had been reduced to second line escort duties. That was everything before the Fubuki class destroyers.

A bit like RN use of the old WW1 R/S/V/W/Leaders and the USN 4 stackers (Town class in RN/RCN hands)

On the subject of the Catalina, perhaps before the war, Japan can acquire a licence to build it, like the Russians did? They bought a licence to build the DC-3. A Japanese made Bofors gun I encountered recently.

_ADP9784

Unfortunately, as has been pointed out by Zmauky, the Amry and Navy did not talk to each other; this self-centred world view scarpered the Japanese and the strategy of working together toward the same end as the Allies enacted during the war simply didn't exist between the two. That has to end before Japan has a hope of moving forward effectively.

EwenS said:

But remember the IJN began WW2 with some 56 old destroyers of the Momi (13), Minekaze (15), Wakatake (7), Kamikaze (9) and Mutsuki (12) classes built between 1919 and 1927 (some reclassed as patrol boats) plus 12 Tomozuri & Otori classes that had been reduced to second line escort duties. That was everything before the Fubuki class destroyers.

A bit like RN use of the old WW1 R/S/V/W/Leaders and the USN 4 stackers (Town class in RN/RCN hands)

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Much like the RN and the USN, the Japanese did not have enough new destroyers to handle all the fleet needs and the 21 ships of the Kamikaze & Mutsuki classes were in destroyer flotillas at the start of the war and for a while after.
The 12 Tomozuri & Otori class were 600-840 ton torpedo boats and while the Otori's provided escorts for the invasion fleets they didn't see a lot of changes for escort work early in the war.
There were more significant changes later in late 1943 and/or 1944.

The more modified Momi & and Wakatake classes were 2nd class destroyers of around 800-900 tons.

There had been 21 of the Momi's built but by the start of the war only 12 were assigned to combat duty. 4 retired and 5 were tenders so numbers get confusing. 3 were still DDs and 9 had under gone an extensive conversion to escort. One boiler taken out dropping speed to 18kts. both torpedo mounts removed, the midships 4.7in gun replaced by a twin 25mm. they got 3 depth charge launchers and 36 depth charges. However in 1941-42 they were converted to amphibious transports for 150 men and one landing craft. The 3 DDs were used as escorts and were slowly adapted by the removal of mine sweeping gear and the addition of depth charge launchers and 36-38 depth charges. One of the 4.7in guns was swapped for two triple 25mms but this was in 1943-44 (?).
The slightly newer/repeat Wakatake's mostly stayed as small destroyers although assigned to escort duties. One got the conversion that pulled out one boiler.
The Wakatake class as a whole scored no kills against US subs but 4 were sunk by US subs.
12 ships of the Minekaze class (1370 tons) were modified as escorts either prior to the war or just after(?). Powerplant stayed the same but the two aft torpedo mounts were removed (leaving the one forward of the bridge) and two midship 4.7in guns taken out and replaced by a few 25mm guns and four depth charge launchers and 36 depth charges. Time added more 25mm AA guns.

The depth charge load out for most Japanese ships was low until late in the war. They rarely got near the numbers that some of the Allied escorts carried (sometimes around 80) and they never got much in the way of ahead throwing weapons (and single army 8cm mortar was not effective).

But if the IJN could turn Godzilla AND Mothra, we'd be talking a different story here.