Rn vs IJN (1 Viewer)

[Thumpalumpacus]

Without the European war, you're probably going to see slower development of shipboard radar, which will impact the RN's chances.

 

[RCAFson]

The British were developing their boats almost continuously and while a late 1941 boat was different than a 1938 boat a 1944 boat was also different than a 1941 boat.
The British changed form riveted hulls to welded, which allowed for the use of the ballast tanks for fuel to be brought back, the riveted construction allowed too much leakage.
The welding was stronger and allowed deeper diving and stood up better to depth charging. Additions to radar and sonar and new radios was also done within existing space, no small trick on a small submarine.

Kemp's T-Class Submarines states that partially welded boats had extra fuel added by converting ballast tanks, and that the formerly riveted ballast tanks were then welded to prevent leaks. This implies that it wasn't just all welded boats that were used in the far east.

 

[MikeMeech]

The US would probably provide some help to the UK but was often not eager (somewhat cynically) to uphold what they saw as European colonialism in (any part of) the Pacific or anywhere else in the world (even though the US was basically doing the same thing in China and the Philippines), and there were many isolationist factions in the US. So that might be enough of reason to make it to the ballpark of plausible.

Ultimately though it doesn't have to be really plausible - it's a "What If". All we have to do is define the parameters.

So as the OP, I say, give the RN whatever they actually had. Assume some assets have to stay in the Atlantic, Med or home islands, but a lot of what is available can be sent east. Since we do have some RN plans for this we can use that as a starting point. You can also ignore RN losses to the Germans if that makes the whole thing work better.

Hi

For the USA not to be involved their inter-policy on China would need to be totally changed, the USA by its military supplies and other support for the Nationalist Chinese made them a greater enemy to Japan than the European Empires. This would also have meant that they would not be using Burma to send the supplies to China ending one of the main reasons for Japan to attack the British and making it easier for the 'British' to try to reduce tensions with Japan by not having to keep in line with a US policy. However, that would mean that the USSR would become the major supporter of China, making them more of an enemy?
If there was no war in the ETO and MTO, it would probably be more likely that the huge British investments in buying, for example, US aircraft and enlarging US factories to supply the same would not happen (eg. no P-51). There would also not be any Tizard mission and the associated technology and operational knowledge transfer to the USA which would also had consequences for the US military.

Mike

 

[RCAFson]

Without the European war, you're probably going to see slower development of shipboard radar, which will impact the RN's chances.

The RN's radar development began prewar and both the metre wave ASV/AW radars and Type 280 AW/AAFC radar were prewar developments. The 50cm FC radars were also developed prewar with trials in late 1939. Design studies on centimetric radar were prewar as well, with the RN pushing for it. (Howse) However, this creates another set of variables because the effect of war was to speed up some developments, but slowed down others because of competing demands, especially after defeat of France.

OTOH, Japan also studied the course of the ETO/MTO war and incorporated lessons accordingly; this creates an almost endless set of variables.

 

[RCAFson]

The historical timeline here is:-

July 1940 - US embargo of war materials, scrap metal & high octane aviation fuel and closes the Panama Canal to Japanese ships.

Sept 1940 - Japan occupies Northern French Indochina to stop US supplies flowing to China via the port of Haiphong near Hanoi (Japanese occupation of Chinese ports had already eliminated supply through those). Under pressure from Japanese, and given the situation back home (middle of BoB, threat of invasion etc), Britain closes the Burma Road the last available route for US supplies to China. Under US pressure it reopens the Burma Road a few months later.

July 1941 - Japan occupies southern French Indochina.

26 July 1941 - USA freezes Japanese assets in the USA and embargoes the supply of all oil to Japan. About 75-80% of Japan's oil came from Californian oil wells and was largely shipped in US registered / controlled (e.g. Panama) tankers. Britain and the Dutch follow.

Previous Japanese attempts in 1941 to secure alternative sources of oil from the DEI had been rebuffed by the Dutch. IIRC they wanted about 40% of DEI production (can't locate the source for that just now).

So from the beginning of Aug 1941 the Japanese options are:-
1. Back down and lose face
2. Go to war to secure what it needs.

But for Britain it doesn't leave a lot of time, even under peacetime conditions, to carry out the necessary reinforcement of the Far East by Dec 1941.

Britain had a highly developed intelligence resource in the Far Eastern Combined Bureau. Set up in 1936 and based in Hong Kong combining personnel from all three services, but with a Naval bias due to the RN being the main weapon in any war with Japan. Heavily involved in SIGINT (radio intercept, direction finding traffic analysis etc) and with links to code breakers at the Government Code and Cypher School (Bletchley Park). For example monitored the build up in FIC. Withdrawn to Singapore before war with Japan (mid-1941 IIRC).

No war in the ETO means that IJ occupation of FIC is very unlikely.

However, we have to postulate a steady increase in tensions between the BEC and IJ for a war to happen at all. From ~1936 onward there was no 'peacetime conditions' for the UK as it had embarked on a massive rearmament program and was rebuilding the RN to match the combined naval strength of all the Axis powers.

 

[Thumpalumpacus]

The RN's radar development began prewar and both the metre wave ASV/AW radars and Type 280 AW/AAFC radar were prewar developments. The 50cm FC radars were also developed prewar with trials in late 1939. Design studies on centimetric radar were prewar as well, with the RN pushing for it. (Howse) However, this creates another set of variables because the effect of war was to speed up some developments, but slowed down others because of competing demands, especially after defeat of France.

Yes, I'm well aware of this, thanks.

OTOH, Japan also studied the course of the ETO/MTO war and incorporated lessons accordingly; this creates an almost endless set of variables.

Right. That's why deciding the outer circumstances do matter. Does this war start in Dec 41, or earlier, or later?

 

[SaparotRob]

Is there an embargo?

 

[Wild_Bill_Kelso]

Hi

For the USA not to be involved their inter-policy on China would need to be totally changed, the USA by its military supplies and other support for the Nationalist Chinese made them a greater enemy to Japan than the European Empires. This would also have meant that they would not be using Burma to send the supplies to China ending one of the main reasons for Japan to attack the British and making it easier for the 'British' to try to reduce tensions with Japan by not having to keep in line with a US policy. However, that would mean that the USSR would become the major supporter of China, making them more of an enemy?

One major reason for war in the Pacific with England - and the Netherlands, would be oil in Indonesia and Brunei. US could easily support China without getting directly involved, much as it's doing in Ukraine right now (at least, so far)

If there was no war in the ETO and MTO, it would probably be more likely that the huge British investments in buying, for example, US aircraft and enlarging US factories to supply the same would not happen (eg. no P-51). There would also not be any Tizard mission and the associated technology and operational knowledge transfer to the USA which would also had consequences for the US military.

Mike

Again, I think you are overthinking it. The point is not to engineer the creation of an AI simulation, it's just to compare what each side actually had. To cut through the bullshit, which keeps sprouting up regardless. Which is understandable since the facts make the situation look pretty damn bad for the RN even if they didn't have to worry about the Germans.

 

[Wild_Bill_Kelso]

Yes, I'm well aware of this, thanks.



Right. That's why deciding the outer circumstances do matter. Does this war start in Dec 41, or earlier, or later?

I'm ok with any time in 1941. Whichever works best for the British, as they need all the help they can get.

 

[RCAFson]

Right. That's why deciding the outer circumstances do matter. Does this war start in Dec 41, or earlier, or later?

Historically IJ waited until the KB was at maximum strength with the Zuikaku class and full development and deployment of new aircraft. OTOH, with no ETO war then there's a number of trip wires that could trigger war before then, especially if the UK and the other western powers decide to issue ultimatums to IJ, similar to that issued to Germany. One plausible scenario is that the German Army successfully removes Hitler and the Nazis and conducts a rapprochement with the UK and France. Mussolini is then deposed, and tensions ease in the ETO by Oct 1939 with Germany and Italy cancelling further naval expansion.

The BEC then decides that it's time to bring a now isolated IJ to heel and begins to increase pressure on Japan by strengthening BEC forces in the far east and basically dares IJ to start a war. There's a whole number of ways this could play out but to simplify things we could assume a start date of 7 Dec 1941, but with FIC neutral territory. I think we have to assume FAA aircraft production and development as per historical, (although there would have been time to allow the Fulmar II to have DTs and to be cleared to carry a 500lb bomb, since historically this was delayed due to wartime pressures) along with radar etc.

 

[Wild_Bill_Kelso]

Is there an embargo?

The Japanese had apparently hoarded enough fuel prior to war in the real world.

I know a lot of people around here have trouble with any kind of "what if" scenario. That's why a special area was made for them. But the point is simply a mental exercise to again, push aside the fluffy bullshit and expose the realities beneath - as in biplane torpedo bombers and two seat lumbering naval 'fighters'.

The origin of this was the premise which has been debated in two other threads recently (and many others prior to that) that the Japanese were inferior in technology in WW2.

Which is clearly B.S. and little more than a very persistent myth.

What I see so far is the Japanese have a technologically and organizationally vastly superior naval air arm than the British.

They have better aircraft carriers.

They have bigger and more deadly battleships.

They have much better torpedoes.

They have better optics on their ships.

They also have flashless (or 'less flash') powder not that it's anywhere near as important as some have been claiming.

About all the British had to contend with this was radar, good cryptography, and some good land based interceptors. None of which are decisive or any kind of guarantee of victory or superiority. I don't think that shows Japan was behind Europe in any way. Very much to the contrary.

 

[SaparotRob]

If and when an embargo occurs will affect the start of the conflict.

 

[ThomasP]

I think we have to assume the embargo still takes place or there is no reason for Japan to go to war (at least not for a few years). If Japan goes to war (due to the embargo of oil products) then per the OP we have to assume they do not attack the US territories (ie the Philippines or the other US held islands). This means the British and Dutch oil rich areas are among the primary targets.

The only way for the UK to have a chance of stopping or defeating the Japanese in the 1941-1944 time frame is if the UK begins gearing up for the war in the Far East in the mid-1930s (or earlier). This means moving the majority of their fleet and ground forces to the Far East, along with the supply train necessary to support the operation - before the Japanese attack - which they did not do historically. AND/OR make significant investments in defensive capabilities and ground forces for the colonies (far beyond what they actually did historically) - before the Japanese attack - hopefully giving the UK time to move the fleet and army after the Japanese attack. Otherwise you just end up with what happened in real life, except the Japanese have more IJA and IJN resources to apply since they are not needed vs the US.

If the UK already has the fleet in the Far East then they can hopefully do a dance with the Japanese fleet, using the choke points to contain the Japanese, attacking ports and supply chains at night and in bad weather as circumstances and planning allows. All the while building up the new Far East fleet (the fleet necessary to defeat the IJN in the open ocean) through new construction, plus creating the ground and amphibious forces necessary to take back whatever the Japanese manage to grab.

Even if we assume Singapore is built up and defensible in 1941, the UK supply chain is about 10,000 miles for most of the heavy stuff. If the UK fleet and army are not there at the start, the action on the ground will happen more or less as it did historically, and the UK will have to develop manufacturing and major sources of supply points closer to the theater, and fight a war of attrition - or wait until they get the A-bomb in 1946.

And do not forget, without the US involvement in the hot war the Japanese will have the chance to significantly build up and improve their forces as well.

 

[MikeMeech]

Hi
We should also take into account RN Submarines, they were already sailing undetected into Japanese waters in late 1939 on intelligence missions, see extract from Boyd's 'British Naval Intelligence', page 310:

In a shooting war those carriers may well have been sunk or damaged.
Alastair Mars in 'British Submarines at War 1939-1945' discusses the pre-war plan for submarine action in the Far East, extract from pages 53-54:

If no war in Europe the RN could deploy a lot more submarines. As an aside the Japanese cruiser ASHIGARA is mentioned, this was actually sunk by HM Submarine TRENCHANT on 8th June 1945. We should also look at the geography, this was not the Pacific it would be harder to hide from reconnaissance, especially with no war in Europe which would mean Britain could send many more Fighters, Bombers, Reconnaissance aircraft etc, as well as larger ground forces with tanks etc. as there would have been no Battle of France or North Africa. The French and Dutch would have strengthened their possessions as well.

The USA could not help China without the European colonies, how would they get the equipment in? The choices would be through Burma or FIC (in the new time line). The USA could not say let us send stuff to China, which will annoy the Japanese, if it does we are not going to help. The European powers would just tell the US Government, politely, well NO then.

Mike

 

[Shortround6]

HMS Regulus, one of 4.

These oldish boats (1930) were sizable craft at around 1700 tons. (?)
Wiki "They could reach 17.5 knots (32.4 km/h; 20.1 mph) on the surface and 9 knots (17 km/h; 10 mph) underwater. On the surface, the boats had a range of 7,050 nautical miles (13,060 km; 8,110 mi) at 9.2 knots (17.0 km/h; 10.6 mph) and 62 nmi (115 km; 71 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged"

They carried 14 torpedoes. The British built about 9 more big boats until 1938 finally going over to the smaller S class and the U and T classes. They had built 12 of the previous "O" and "P" classes.
The Med was not kind to these big boats and 10 of them were sunk in 1940 alone. 6 (?) by Italian destroyers and TBs.
4 of the Prewar "T" class were sunk in 1940.


The Oil Embargo was the final straw.

In July 1939 The US had announced that it intended to revoke Japan's "most favored nation" trade status (which required 6 months notice) and in 1940 followed through ending a 1911 trade treaty. This would permit the implementation of an embargo.
"The embargo, which halted the shipment of material such as airplanes, parts, machine tools, and aviation gasoline, was designed to be an unfriendly act."
No oil embargo yet.
Sept 1940 saw expansion to . include iron and steel scrap. 74.1% of Japan's scrap iron came from the United States in 1938, and 93% of Japan's copper in 1939 came from the United States. The Panama Canal was also closed to Japanese shipping.
In early 1941 Japan moved into Southern Indochina. On July 24th they occupied key airfields in Indochina. On the 26th the US froze Japanese assets in the US and on Oct 4th instituted the Oil Embargo.

 

[Thumpalumpacus]

I'm ok with any time in 1941. Whichever works best for the British, as they need all the help they can get.

My own opinion is that the earlier this war, the more difficult it is for the Brits. Rearmament may not be pumping full spate. Lion class are still in build. Without war in Europe, the Commonwealth probably isn't mobilized, too. But the Brits have significant edges in radar tech, basing options, and what will likely be a friendly neutral USA still acting as an "arsenal" as well as oil/food source that, because of China (and let's be honest, race), will not be grace extended to Japan. Those advantages, except perhaps basing options, are likely to grow as the years go on. The Brits will almost certainly use subs smarter, too -- they will see the vulnerability of an island nation's trade better than anyone else.

On the other hand, Shinano is completed as a battlewagon, with all that implies for the Eastern Fleet -- they may be facing 3 Yamatos by 1943. Between 1939 and 1943-44, Japanese carriers have more and better planes on each flight deck, and torpedoes far superior throughout the war. Both the IJA and IJN have more experience from fighting in China, too.

As this hypothetical war goes on, the advantages start shifting from the Japanese to the Brits. So the Japanese need to attain a fast victory, imo. The longer the war goes on, the more the UK can exercise advantage.

 

[Wild_Bill_Kelso]

That's a very good point about knowing how to exploit the vulnerabilities of an island nation.

I had a semi-random thought as well, getting ready to build a PBY. The US and the Aussies used several squadrons of these as 'black cat' night intruders and bombers (and increasingly, torpedo attacks). They sunk a fair number of ships with them. That would probably a pretty close analogue for the Wellington in a similar role, probably. You could use the 'black cat' as a kind of baseline.

 

[Thumpalumpacus]

That's a very good point about knowing how to exploit the vulnerabilities of an island nation.

I had a semi-random thought as well, getting ready to build a PBY. The US and the Aussies used several squadrons of these as 'black cat' night intruders and bombers (and increasingly, torpedo attacks). They sunk a fair number of ships with them. That would probably a pretty close analogue for the Wellington in a similar role, probably. You could use the 'black cat' as a kind of baseline.

Yeah, Wimpeys could do that in SEA, I bet.

 

[don4331]

I'm not sure they will use the submarines "smarter".
USN could and did implement USW from practically 8/Dec/'41, but the last thing the UK wants is any current or future implementing that on them. (I recognize the KM was treading very thin line, but they weren't going all out at USW right out of the blocks)

Same goes for RADAR and by extension homing beacons/radio communications/IFF: From posts here and on the navweaps site, it appears RN was so concerned with their enemy using SIGINT, that they didn't use the advantages that they had.
While PoW did have legit issues with her RADAR operating in tropical conditions, it is looking more and more to me that it was also a conscientious decision to leave it turned off to prevent IJN forces from homing on it. If it isn't turned on, it isn't providing an advantage.
RN had Catalina fly over Bismarck to "relocate" her rather than provide Germany with inkling that their RDF was what gave Lütjens away. While if you're maintaining silence you're not giving your location away, you're also not providing your forces updates on your situation.
Without homing beacons allowing FAA aircraft to locate the carrier, a navigator is a critical to RN requirements.*
Up until the end of the Anglo-Japanese Alliance, IJN is partial to all the RN development in these area, so RN has legit concern.

Without ETO/MTO experience, will FAA be operating Blackburn Rocs as its primary fighter? Will the follow on even be the Fulmar, but rather a next generation turret fighter - there were enough spec being floated for one. Does the Spitfire end after initial production as Hawker has Tornado/Typhoon as the RAF primary fighter.

On other hand, Commonwealth forces fight such a different war that its hard to control all the butterflies.

 

[Shortround6]

its hard to control all the butterflies.

Yeah, we are trying to herd butterflies using cats.