Rn vs IJN

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I don't think that even if peace miraculously is assured out in Europe in 1938-39 that by 1941 the RN could send a force to the Pacific that could match an otherwise unopposed IJN. Even a force made of the most modern and fastest ships then available: HMS KGV, POW, Hood, Repulse, Renown, Ark Royal, Illustrious, Victorious, Formidable, plus the best 8x8" County class CAs and latest Town and Fiji class CLs, latest Tribal and Jervis class DDs and large T-class submarines, plus with DOY and Indomitable joining in early 1942, would still struggle against the IJN on its homefront, with its six fleet carriers (Akagi, Kaga, Sōryū, Hiryū, Shōkaku, and Zuikaku) plus CVLs, and the IJN's formidable battleships, cruisers, destroyers and the IJNS' A6M-escorted land-based torpedo bombers. If France hasn't fallen, then at least FIC isn't used as a Japanese base.
 
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I think that your being a little harsh on the RN. That said that Japanese clearly have an overriding advantage in the quality of the naval aircraft, to pretend otherwise would be foolish.

To the RN vessels mentioned I believe that you should add the QE class, which would be a good match for the Japanese Fuso and Ise, plus the Nelson and Rodney who would match the Nagato.

The Courageous and Glorious plus the Furious are useful light carriers, but I repeat the comments about the aircraft carried.

RN Cruisers are at least as good as the Japanese cruisers and the lighter cruisers Leander and Arethusa are a whole different level above the Japanese lighter cruisers

RN modern destroyers were a good match against the Japanese destroyers but the A-I class could more than hold their own

All the RN vessels were far better equipped with Radar and AA weapons plus the cruiser and above had more modern fire control. What shouldn't be forgotten is the humble escorts of which the RN had a good number of very capable craft. Some of which could take on any destroyer.

If you include land based aircraft then the Beaufort and Beaufighter could be a real danger
 
And ...

The Japanese had Yamato and Musashi

The Japanese torpedoes and night vision capability gave them an edge in surface combat (significantly increasing the threat posed by their DDs and CLs)

The Japanese carriers not only carried better planes, they carried half again as many.

Their naval aircraft strike capability was also at two or three times the range.

If you include land based aircraft, the Japanese G3M and G4M had a demonstrated capability of sinking ships, whereas the Beaufort really didn't. Beaufighter did but it wasn't carrying torpedoes until fairly late in the war.

The British did also have the Wellington which had some substantial torpedo carrying (and demonstrable ship-killing) capability.

The British advantage is radar was not necessarily decisive in a night action, but it would help during bad weather, which was frequent in the Pacific. This would apply to their strike aircraft as well.

The British had an advantage in submarine warfare, if they had bases to use them from. Presumably they could use northern Australia at the very least.
 
The Japanese had Yamato and Musashi
A lot depends on timing (when the conflict breaks out) The Yamato wasn't ready until early summer of 1942 and the Musashi wasn't ready until about Jan 1943.
Edit, the Matsu didn't blow herself up until June of 1943. So in the first 5-7 months The Japanese have two 16in ships that are about 2kts (at best) faster than the QEs.
trouble is they are throwing 1000kg shells vs the British 870kg shells, advantage to the Japanese but the British have how many ships with 15in guns?
The Japanese torpedoes and night vision capability gave them an edge in surface combat (significantly increasing the threat posed by their DDs and CLs)
They do have an edge but no where near the advantage they had over the Americans. Most of the actual night combats took place at 15-20,000yds and under. British torps may have been slow but they could reach to 14-15,000 yds.
If you include land based aircraft, the Japanese G3M and G4M had a demonstrated capability of sinking ships, whereas the Beaufort really didn't. Beaufighter did but it wasn't carrying torpedoes until fairly late in the war.
Again lot depends on where they are fighting. The British have no real need to go Island hopping to begin with. What the British need to do is stop the Japanese from gaining their historic advances or a substantial part of them. This would allow the British to operate in area with land based air support, Which would help negate the Japanese carrier advantage.
The British advantage is radar was not necessarily decisive in a night action, but it would help during bad weather,
The radar is not a cure all, but neither are Japanese optics. In some battles radar may do no good, in some it may help somewhat, in others it will be decisive.
Since the Japanese don't have radar or don't get in until very late, on average, the advantage goes to the British.
The British had an advantage in submarine warfare, if they had bases to use them from.
Again it depends on what the British are trying to do. If they keep Singapore and some of the DEI, the game becomes holding on to the rest of the DEI and keeping the Japanese from exploiting the DEI/SE Asia.
A tanker sunk 300 miles north of Borneo is just as sunk as one sunk 300 miles south of the Bungo channel.

Northern Australia is out, you have to pretty much build the base/s from scratch.
The trick is to hold much of Malaya, Sumatra, Java, and as much of the Lesser Sunda Islands as possible. Keeping Borneo in contention would be a real bonus.

This turns the whole thing into a super Guadalcanal campaign instead of a mid pacific Battle.
A jungle version of North Africa with battles for the land air fields actually dominating.

The British need to turn it into a war of attrition where the British Commonwealth's greater Industrial capacity will win in the end.
Concentrating on oil sooner will help.
 
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The Courageous and Glorious plus the Furious are useful light carriers, but I repeat the comments about the aircraft carried.
With no European War there is likely reduced funding and no to limited conscription. So, I expect the three Outrageous class, along with all five Revenge class battleships are put into the reserve fleet.
 
With no European War there is likely reduced funding and no to limited conscription. So, I expect the three Outrageous class, along with all five Revenge class battleships are put into the reserve fleet.
OTOH with no European war the UK could afford to concentrate more forces to the Far East when Japan starts saber rattling. If the Allies had managed to hold on to or more thoroughly destroyed the DEI and Borneo oil fields, Japan's war plans could have been in serious trouble.
 
With no European War there is likely reduced funding and no to limited conscription. So, I expect the three Outrageous class, along with all five Revenge class battleships are put into the reserve fleet.
With no European war the Japanese would not have been dumb enough to start anything.
Even if the US stays out of it what started the oil Embargo was Japan advancing into French Indo china under the assumption that the Vichy French either could or would do nothing.
A France was that was not fighting or had not been defeated by Germany would certainly send forces to South East Asia,
The British would have had a much stronger presence in the Far East. They had been planning against the Japanese since 1921 as a worst case. They could not do what they wanted due to finances and conditions in Europe.

The Rs might have been scrapped but only in ones and twos as the KGV and later ships commissioned. Much of the British build plan was with Japan in mind, not Germany, the German fleet was just a blip. What screwed up everything was Italians joining the Germans with the Italians having either the 4 or 5th biggest fleet in the world and then the French surrendering which took the 5th or 4th biggest fleet out of play.
The British were planning on taking on the Japanese PLUS whoever was left aside from the US while France and Italy canceled each other.
 
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I put my money on the IJN battleships, personally, though I grant you that is debatable

They do have an edge but no where near the advantage they had over the Americans. Most of the actual night combats took place at 15-20,000yds and under. British torps may have been slow but they could reach to 14-15,000 yds.

I'll grant you most of that, but the Japanese torpedoes are both longer-ranged and faster (especially if shooting for shorter ranged targets) and I think they carried more of them. How well trained was the RN for night surface combat? They seemed to have some trouble in the engagements I know of.

I think the real RN advantage, during the window when the RN have radar and the IJN don't, is to attack during bad weather, during day or night. The IJN did have radar showing up on some ships already in late 1942, and it was widespread by mid 1943, including on aircraft.

On a clear night I give the advantage to the IJN, personally. In a storm or maybe new moon or night with heavy cloud cover, maybe the RN has a chance.


Plausible and interesting scenario you have come up with there.
 
The RN had excellent night battle doctrine along with flashless propellant; this gave them an major advantage over the USN, in night combat.
 
I put my money on the IJN battleships, personally, though I grant you that is debatable
It is close, that is certain, but I go with the RN. Radar is the big difference between the two forces so where you actually draw the line is a major influence.
If we go for 1941 then the radars are less effective, less reliable, there are fewer of them, and the knowledge of how best to use them is still being learnt.
Go for mid 42 and the lessons have largely been learnt, they are far more common, performance is still average and the lessons are better understood. The combat in the Med are a good example.
Go for 1943 and the situation is good to go, performance is good and the lessons have been learnt and pretty well mastered. Think the sinking of the Scharnhorst, terrible weather, at night against a fast modern capital vessel
There will be some but a lot of RN combat was at night and generally they did well, at every stage of the war. The vast majority of the convoy battles and those in the Channel were at night and generally the RN was well trained and equipped to fight at night. The type 284 was a widely used fire control radar from around early 1942 so again where you draw the line has a major impact on capability. I am not aware of any meaningful Japanese Fire Control systems available in any numbers until the latter stages of the war
 
The RN had excellent night battle doctrine along with flashless propellant; this gave them an major advantage over the USN, in night combat.

Yeah we investigated, discussed, and debated that one. Methinks you are overselling that factor, a lot. Though I'll grant you it's probably worth something.
 
Yeah we investigated, discussed, and debated that one. Methinks you are overselling that factor, a lot. Though I'll grant you it's probably worth something.
The IJN was able to make use of their optics because of their night battle doctrine and their use of flashless propellant; doctrine and tech go hand in hand.
 

Ok but it looks like in 1942 the Japanese already got radar on a few ships, Battleship Ise for example had air search radar by mid 1942, and by mid 1943 they had surface search radar on many several battleships and light cruisers. They were also putting radar on H8K, G4M and G3M by that time. The IJN also had radar detectors which could kind of use your radar against you, at least for early warning purposes.

Japanese radar did seem to have pretty short range though. And they did not have Combat Information Centers like the US ships did, not sure if RN had those.


It's kind of hard to figure out but it looks like some kind of 'fire assisting' radar (21-Go and 22-go) was available in some ships in early 1943, and most battleships, cruisers and carriers mid to late 1943. Looks like the true fire control radar, type 32, was available in 1944.

The window for the British to have maximum advantage here may have been mainly in 1942 and early 1943.
 
The IJN was able to make use of their optics because of their night battle doctrine and their use of flashless propellant; doctrine and tech go hand in hand.

Again, we got deep into this. "Flashless" propellant only works to a point, you overstate it's decisiveness. Once the first ships are burning and being hit, it's limited in value.
 
A lot of the radar depends on date and type.
British had radar in the summer of 1940 on some ships in the Med, Both the radar and the technique of using it changed.
Japanese Radar of 1942 was unlikely to be equal to British Radar of 1942. British Radar was not instantly upgraded to latest versions. Much like the US had "flag" ships with older generation radar than some of their escorts.
The British was the first navy to set up "plotting" tables/stations in the bridge area of some of their ships, this was in WW I. It was a way for commander to keep track of the movements of his own ships and the enemy's reported positions or bearings. This was especially useful at night well before radar. Just look at some of both the US and Japanese mistakes of identifying enemy ships as friendlies and vice versa. They would loose sight of a friendly and a number of minutes later pick up a ship in roughly the same direction and think it was the friendly reappearing. Plotting last known courses and speeds helps but does not eliminate such confusion. In a night battle it is too much for commander to keep it in his head.
This is part of the night battle "doctrine". Not saying the RN was perfect, but they had been thinking about night battles for over 20 years and practicing from them. There is practice and there is Practice. Conducting an annual night battle practice so they can check off a box on a form doesn't actually do much. Analyzing and changing things that go wrong does.
The Ajax did not have flashless propellent in the Fall of 1940, there is some debate about radar, she may have had air waring radar only. There was light fog/haze. Italians did not concentrate their forces (trying to "scout" at night limits options.) The Ajax got lucky, dodging (by luck or on purpose) numerous torpedoes from the 7 Italian ships involved, She sank two of the three torpedo boats (800 tons, three 3.9in guns, four 18in TT) and crippled the destroyer Artigliere (1850 tons, four 4.7in guns, six 21 in TT) latter sunk by the HMS York. Ranges at times got down to machine gun range. Ajax was operating without any support.
British ships fought many night actions across the North Sea and Channel and many actions in the Med. Not always successful but they probably had more experience than any other navy by the end of 1941.
By 1943-44 some British ships had 3-4 different radar sets doing different jobs. A Japanese ship with 1-2 radar sets is still behind.
Maybe the Japanese in 1941-42 were close in many aspects to the British (radar excepted and that is a big one) but the RN was a long way ahead of the USN in 1942 and 43. Not just in the radar it self but in how to use it (like plotting all available radar contacts at all times to help sort out new from existing) and how to maneuver formations.

Again radar is not infallible or all seeing/all knowing but a number of the early USN disasters might not have occurred to the British. The HMAS Hobart At the Battle of Savo with the transports (miles away form the action) had picked up the Japanese attackers before they opened fire as an indication of the difference between British radar and American radar at the time. One of the 8in gun Australian cruisers also had a better idea of what was going on but the US practice of putting the force commander on the most prestigious ship instead of the one with the best sensors and command facilities played a big part in the outcome.
 
Very interesting analysis. And I think it is indeed worth thinking about the differing capabilities of different types of radar.

Air Search obviously will help against aircraft, if only to provide early warning, and that could be quite important for the IJN against the RN / FAA, since one of the RN's biggest advantages would be night attacks with Swordfish.

Surface Search or equivalent is again, arguably the most important for surface combat because it alerts your forces to the possible presence of enemy ships. The IJN would have the means to follow up on that by other methods - night time capable optics, seaplanes which can operate at night and drop flares, ships that can shoot flares (may not be needed or ideal in some circumstances) and (most perilously) searchlights.

Then you have actual gunnery radar which can be used to shoot more accurately. This proved to be a big advantage for example in the famous Battle off Samar in the Philippines in 1944, due not to night time, but to squalls, smoke from burning ships and smokescreens. The little US Destroyers and Destroyer Escorts were able to punch far above their weight, and outgunned some heavy cruisers etc. thanks to accurate radar directed gunfire, sometimes while hiding in squalls and smoke. I'm not sure at what point the RN had this capability but it could be telling, clearly. The gun accuracy for DDs pre-radar was pretty dismal.

That said, depending on the circumstances, IJN proved more than capable of engaging at 20km or greater distances and reacting intelligently at night, whenever they knew that the enemy was there. Their lookouts often spotted American ships, but not always. So the early warning aspect of radar could be enough.

One other possible advantage for RN that occurred to me, is that they had a lot of small vessels - sloops, frigates, corvettes, which were used for ASW / convoy escort, but in the "extended Guadalcanal campaign" in Malaya, the Indies etc. as you described, could probably act as pickets and be based around the coastlines and used to detect enemy fleets movement, much as the US PT boats did (which seems to have been their main contributions, as their torpedo attacks never seemed to work).

For that matter the British also had some MTB of their own, and with better torpedoes these might have been considerably more effective than the American ones were in and around coastlines and islands. Assuming they could get them to the Theater. I know they had some at Dunkirk.
 
seaplanes which can operate at night and drop flares, ships that can shoot flares (may not be needed or ideal in some circumstances) and (most perilously) searchlights.
Many navies planned for this, actual implementation was a bit more varied. Flares/star shell was fairly common in theory. Again implementation (scale of issue of ammunition and which guns got it) and drill/doctrine varied. Most countries wanted to fire the star shell behind the enemy to silhouette them. Which call for good initial range. Star shells going short should blind the enemy more than the firing ships but actual range, how short and height other star shell is at (descending by parachute so always getting lower) is going to hurt the firing ships some. Some ships

Italian Littorio here, used a few old (pre WW I) 120mm/4.7in guns for star shell guns, The two guns in the lower left hand corner of the picture. Some of the very late war British destroyers with twin 4.5in turrets on the bow used a single 4in or 4.5in gun just aft of the funnel that was referred to as the star shell gun.

The 40mm guns aft were given better arcs of fire at any rate.

Other navies just blended Star shells into the normal gun mix, but you needed at least a 4in shell to carry a decent size flare. Using large shells may have been too much of a good thing and a lot of large guns (8in and above) didn't have enough AP and HE to begin with. Not to mention that even with star shells engagement ranges were going to be shorter than daylight.
Also note that using float planes called for good coordination and planning. In one US operation they planned for it and launched the aircraft but also planned to have the planes land at/near Henderson field so they would not being trying to recover planes at night and/or when the gun battle was still going on.

Some navies had been using search lights since the 1880s (?) but actual combat practice was pretty much limited to WW I (Japanese in 1904?). People seemed to forget that without good discipline (very, very good discipline ) on both side, any ship that used search lights became a shell magnet for any gun on the opposing side.

That is actually a pretty crappy website for looking at British small craft as it is arranged by length and not date so things get jumbled up fairly quickly.

We are getting into some of the butterfly effects. The British pretty much relied on US engines for their small fast craft (and I am calling 18-20kts fast). If the US is "neutral" how much "stuff" do the British get in this scenario? Lots of Lend lease aircraft? tanks? thousands of engines for fast boats?
The British commonwealth built about 650 of these Fairmile B motor launches

At least two in Bermuda
88 in Canada
35 in Australia
12 in New Zealand
6 in South Africa
Many of them were built in 1942 and later.
ALL were powered by American Hall-Scott Defender engines. The Bs got two engines, the handful of A's got 3 engines, the 2 dozen C' gun boats got 3 supercharged Hall-Scotts.
The 228 (?) D's got 4 Packards.
The vast majority of the British motor TBs and MGBs were powered by Packards. Other engines were used but in on quantities of few dozen usually (except for Napier Lions but there was only so much you could do with 500-600hp engines).

If German makes peace in 1940-41 then the British have more options. If they don't, the British need the US to supply engines.
As a side note, the British MTBs are supposed to have had a better hit percentage per torpedo fired than British subs, aircraft or other surface ships.
 

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