What if Japan's attempt at a decisive June 1942 'Midway' battle, had been at Ceylon instead?

Another amusing 'what if' that came out of the current series of 'what if' articles. Enjoy.

What if Japan had made a serious effort to finish off the USN first? Rather than shifting most of their attention back to Malaya, the East Indies, Darwin, and the Indian Ocean for 5 or 6 months, and allowing the USN so much time to recover?

And by that, I mean what if Japan had at least followed through with at least a third strike on Pearl Harbour, or, better, with an actual invasion of Hawaii. 

(See my previous post on the debate over Japanese plans for such an invasion of Hawaii. Yamamoto and Nimitz both stated categorically that not following through was the greatest mistake the Japanese ever made.)

What if the Japanese had pro-actively concentrated on a 'USN first' strategy, and left the 'clean up' against their other flank until they were completely sure the USN threat was properly undermined?

What if they had concentrated most of their resources from December 1941 until May 1942 on completing the destruction of the USN – rather than wandering backwards and forwards to raid Darwin and the Indian Ocean – before trying to force a Midway style conclusive battle? 

If they had substantially reduced the USN in that way, then the Midway style 'decisive battle' plan would have been aimed at the British Eastern Fleet at Ceylon instead.

The two front trap...

Trying to solve the two front trap was the defining issue for aggressors in both World War's. The Schlieffen Plan of WW1, and the Pearl Harbour/Indian Ocean raids of WWII: were both samples of how failing to solve this issue guaranteed losing the war.

Japan's problem was that they couldn't risk seizing British and Dutch possessions without dealing with their vulnerable flank against the US.

Equally, they couldn't risk dealing with the US without opening their vulnerable flank against potential British/Dutch counter operations. (It's not just the 'possible', 'eventual', threat of a British fleet strong enough to mount an actual offensive they had to fear. Don't underestimate the immediate threat of those dozens of Dutch submarines based in Java against vital Japanese communications in the South China Sea between their homeland and their forces in China and Indochina.)

However it is interesting to speculate on whether it would have been more sensible for the Japanese to concentrate their first few months on the Americans, just assuming the British would not be in any position to mount a major counter threat for many months? (A pretty realistic assumption in early 1942.)

Could that have been more effective than splitting Japanese forces between operations against everyone simultaneously?

In reality of course, we know that the impressive looking efforts careening all over 1/3 of the globe trying to take out the USN at one end and the RN at the other end: just meant that neither was really defeated badly enough to be driven from the field more than temporarily. Despite the Allies slower battleship units sometimes being pushed back as far as the African or US West Coasts, worryingly strong Allied mobile forces always remained hovered around the Indian Ocean and Central and South Pacific. Forces quite capable of mounting Doolittle raids; invasions of Madagascar; spoiling attacks on the Andaman's; or around New Guinea; or at Guadalcanal. 

But instead of concentrating on finishing off one opponent or the other, the IJN just rushed backwards and forwards to more and more frantic attempts to achieve 'decisive' results here or there, usually with ever decreasing numbers of planes operating from less and less carriers each time.

What could they have achieved by concentrating on one opponent at a time?

Properly taking out one ally at a time?

I think we have to accept that the IJN simply couldn't take its whole navy to deal with the RN in the Indian Ocean in December 1941with an undamaged USN 'at peace' on its flank.  Their logic in thinking they had to reduce the threat from the USN even just temporarily if they were going to attack the British Commonwealth, is pretty unassailable.

But should we write off the idea that they might have concentrated practically their whole navy on the USN for the first 4 or 5 months, before worrying about cleaning up Malaya and the Netherlands East Indies? Decisive victory on one front should automatically allow for a much better attempt at decisive victory on the other front. Particularly as the RN needed at least 5 or 6 months to gather a reasonable force for even defensive operations, let alone for offensive ones.

But in this scenario, it would be far easier to completely finish off the threat from the USN (at least for several years), while reversing the 'final battle' strategy for use against the RN instead!

With the USN reduced to impotence, and the main Japanese fleet based at Singapore (which it actually was sometimes, even under the two front threat), then the IJN had a real chance of enticing the British into a decisive 'Battle of Tsushima' in mid to late 1942. 

Consider a Midway style operation, but aimed at Ceylon, and with no effective USN to threaten its flank? If the Japanese had garrisoned Hawaii and Midway already, and done a couple of Darwin/Indian Ocean style raids on the US West Coast (hopefully reducing the USN to only one active carrier the way they actually did in late 1942 anyway): then such a Midway style operation might not even lack Shokaku and Zuikaku? (Admittedly the attrition rates of such a series of attacks would still see much reduced squadron numbers, and a lot of less skilled pilots, in the Japanese carriers. But it is still a sobering thought.)

Should the IJN have had its own 'Germany First' policy, on the same logic basis of knocking out the greatest threat, and dealing with the less  immediately capable foe later? 

Should Japan have gone full 'USN first'?

Most sensible strategists would probably say yes. If you are going to throw the dice in taking on too many enemies, then concentrating on a decisive blow against one of them before spreading your forces against several is pretty much Strategy 101.

But would it have made a difference?

In reality all the wandering back and forth for 6 months prevented the IJN from concentrating a strong enough strike to win at Midway. (Though there was still a lot of luck involved in the US victory.)

But frankly their situation might have been in no way improved had they spent those 3 or 4 months decisively defeating the USN, and given the RN the breather it needed to get a proper force in place in time to face whatever the much reduced IJN could throw at them after occupying Hawaii and bombing US West Coast bases.

In fact it might come down to whether they IJN could get the USN out of the way and re-concentrate against the RN by April 1 (when the Indian Ocean raid actually happened... probably the last time they had a really good chance), or if it still would have had to wait until at least May (Coral Sea), or June (Midway itself).

The delay until at least May, and very probably until June, might have been enough to change everything...

A June 1942 'decisive battle'... of Ceylon?

The actual Indian Ocean Raid in April 1942 saw 5 IJN carriers and the 4 Kongo class battlecruisers deployed; while the Kaga went home for service and repair, and the main IJN battle-fleet stayed defensively 'closer to home'. The Japanese faced a hastily gathered and still incomplete force of 3 British carriers – the modern armoured carriers Formidable and Indomitable, and the smaller, slower Hermes – and 5 battleships – the modernised Warspite, and 4 older and slower Revenge class.

But what if the IJN didn't arrive until the time of real Midway? What would they have faced then?

In this scenario lets assume the actual forces Japan used at Midway. 

7 Japanese carriers and 7 battleships, in 3 separate forces, against the ships Britain would have available by then, 5 carriers and 9 battleships.

For Japan, the carriers - Kaga, Akagi, Horyu and Siryu - plus the battlecruisers Haruna and Kirishima in the Striking Force; and the 3 battleships from Yamamoto's Main Body - Yamato, Nagato and Mutsu - plus their escort carrier Hosho. Plus the battlecruisers Kongo and Hiei and carrier Zuiho with the invasion force,  and a couple of seaplane carriers, up to a dozen cruisers and 30 odd destroyers split between the 3 forces. Operating perhaps 240 carrier aircraft.

[Another 4 slower Japanese battleships and 2 light carriers were feinting against the Aleutians, but even though Yamamoto's immediate response to the loss of 3 carriers was to call those two south at speed, there was no way that they would have got there in time to be of use. So we will discount that force, and assume that in a major Indian Ocean operation, those units at least would have stayed 'closer to home', defending Japan an its vital communications in the South China Sea.]

For Britain the armoured carriers Illustrious, Formidable and Indomitable, the older fleet carrier Eagle, and the light carrier Hermes (the equivalent of the Hosho). With about 160 carrier borne aircraft, plus a similar number in land based support on Ceylon, meaning perhaps 340+ aircraft.

[Roughly similar to US numbers at real Midway, but with 5 flight decks rather than 3 for the Japanese to have to find and sink... 3 of them the sort of armoured decks that easily shrugged off Japanese bombs and kamikaze strikes later in the war and continued operating! As one US observer noted in 1945, "A hit that would put an American carrier in dry-dock for six months, in the RN is just 'sweepers man your brooms'."]

Also 9 battleships: Nelson, Rodney, Warspite, Valiant, Malaya, Revenge, Resolution, Ramillies and Royal Sovereign. (Compared to NO US battleships available for the USN at Midway...) 

And as a bonus the RN would have considerably more cruisers, destroyers, and possibly even submarines than the USN had available for Midway. Midway 8 cruisers, 15 or so destroyers. Ceylon a bit harder to say, but back in March they had had 7 cruisers, 15 destroyers, and the numbers planned for redeployment should have at least doubled that by June. Only in submarines did the 19 the USN had at Midway probably outnumber the total the RN would have had at Ceylon. 7 were available in March, and the number would have more than doubled by June, but perhaps not tripled...

[Note - for the curious and for pedants – the deployment dates of RN capital ships are from British Cabinets Principal War Telegrams (B). 9. no 189; and (E). 1. no.334.]

In reality of course, at Midway the Japan didn't have their 7 carriers and 7 battleships close enough to support each other. The strike force of 4 carriers and 2 battlecruisers was defeated long before the Main Body or the Invasion Force could add their 5 extra battleships/battlecruisers and 2 light carriers to the mix. And way way before any call the other 2 light carriers and 4 battleships 'trailing their coats' in the Aleutians would have helped. (The IJN's fabulously overcomplicated plans, and constant dispersion of forces that would have done better concentrated repeatedly saved the Allied cause. Imagine if the IJN Strike Group had actually included all 9 available carriers supported by even just the 7 27+knot – of the 11 available – battleships! Game over.)

Frankly it would be a far more even fight between the RN and IJN at Ceylon, than the fight between the USN and IJN at Midway actually was. With the RN actually having superior numbers in both carriers and battleships (as well as aircraft) by the time of Midway, and able to slug it out in a way that the 3 US carriers with no battleship and very little cruiser support simply could not have risked. The USN could only 'ambush and run'. The RN would have been able to stand and fight, and perhaps even pursue.

Some qualifications on the dangers to the worldwide strategic situation

Just to note the effects of such a concentration of British ships, and the probable effects on other theatres...

Present in the Indian Ocean by April 1 were the carriers Formidable, Indomitable and Hermes, and battleships Warspite, Revenge Resolution, Royal Sovereign and Ramillies. This was already the biggest concentration of allied capital ships anywhere in the world at the time.

Reinforcements targeted for arrival during April and May were the carriers Illustrious and Eagle, and battleships Valiant, Malaya, Nelson and Rodney. The planned total of 5 carriers and 9 battleships in one fleet being by far the largest concentration of capital ships that any nation could field so far from home prior to the USN's 'luxury of new and rebuilt shipping' available much later in the war. 

[In fact, at that point, the only way any other navy on earth could field a bigger fleet in one place, was if Japan could take the risk of moving practically her entire navy 10,000km – that's a quarter of the globe – away from home waters... That's between 4 and 5 times the distance from home of even the furthest Japanese deployments for the Midway operation... Frankly taking that sort of risk is fantasy stuff, even if the entire USN has been practically eliminated as a threat. Imagine what fun the USN could have with some 'Doolittle raids' if they were absolutely certain that the nearest IJN battleship or carrier was 10,000k away!]

But, to be honest, I think that if the RN had had to concentrate this much in the Indian Ocean for most of 1942, then Malta would have fallen, and the North African campaign would have dragged on for even more years. So we can't pretend there would not be problems in the RN making such deployments. (And Churchill queried Roosevelt about adding the two US ships currently assisting the RN in the Atlantic - the brand new battleship Washington and the light carrier Ranger - to that total, which would have made the Mediterranean situation even worse... But King was, unsurprisingly, totally opposed.)

However too many people overlook the fact that Rommels last great surge forward in North Africa, that lead to the battles of Al-Alamein, were precisely because the RN did re-deploy most of these ships to the Indian Ocean when needed in early 1942. Effectively reducing their Eastern Mediterranean deployments to only a half dozen cruisers and a couple of dozen destroyers, thus allowing Rommel the supplies and freedom of action he had previously lacked. 

(Thus also keeping the interwar 'main fleet to Far East' promise to effectively abandon the Mediterranean if Australia or India were actually under threat. Too many people – particularly British and Australian 'historians' – fail to notice that minor detail...) 

Most of the RN ships named above were either already already deployed, or still on their way, when the USN's Coral Sea victory in May reduced the pressure. The Midway victory reduced pressure even further, and actually allowed more than half the Eastern Fleet deployments to turn back to the Mediterranean and spend the middle of 1942 saving Malta instead. (The vital Pedestal Convoy in August 1942 - escorted by 4 carriers, 2 battleships, 7 cruisers, 32 destroyers and 7 submarines – was only possible because the remaining Mediterranean carriers – Victorious an Argus – could be reinforced by elements withdrawn from the Eastern Fleet after Midway. Specifically the battleships Nelson and Rodney, and the carriers Indomitable and Eagle.) 

However there is no doubt that had the USN continued to suffer defeats at Coral Sea and Midway, the RN's increased deployments to the Indian Ocean would have had to go ahead. As it would have anyway  had Pearl Harbour been occupied, or had the remnants of the USN been pushed back to California bases. So saving the situation in Asia would have been at dreadful cost in the Mediterranean. The war in Europe might have been extended by another year or more.

Tactical Perspectives of a 'Battle of Ceylon' (on 4-7 June 1942, time of Midway battle)

1. Surprise

Much is made of the fact that intelligence intercepts meant that the USN knew the Japs were coming at Midway on June 4. Most people don't remember that the British Eastern Fleet also had intelligence intercepts for the April 4 Indian Ocean Raid. Admiral Somerville had positioned his fleet perfectly for a night ambush on the day intelligence expected them, April 1... (Only for the Japanese to be delayed by 3 days by oiling issues). If the IJN had turned up at Ceylon in June, you can bet the farm that the RN would have had adequate intelligence to mount another ambush.

But instead of Nagumo's 4 carriers and 2 battlecruisers facing only the 3 USN carriers and no battleships they faced at Midway; or facing the 3 RN carriers and 5 battleships they would have faced in April; by June the IJN would face 5 RN carriers and 9 battleships... the 4 RN carriers and 5 battleships of the Fast Force, with the other 4 battleships and their support carrier of the Slow Force perhaps 50/50 chances of being close enough to support. 

Given it's intelligence and radar superiority, the element of surprise - both strategic and tactical – would almost certainly go to the RN. 

[As it did in April, but unfortunately only after Somerville had spent 3 fruitless nights in ambush position for the expected April 1 arrival, and then returned to his secret base at Addu Atoll to refuel... Catalina recce planes spotted the Japanese fleet just as his slow force was entering harbour, which meant his fast force could sail again within a few hours to reposition for ambush, but the slow support force not until much later. See Wikipedia and Armoured Carrier. Nonetheless by the evening of the 5th Somerville was again in position to ambush, and as darkness approached on April 5 – when his scouts found Nagumo's fleet late afternoon only 180 odd miles away – and he positioned for a night strike... only to have Nagumo serendipitously reverse course just in time.]

2. Air strikes

The IJN would still have a considerable advantage in purely carrier versus carrier planes... in daylight. At least 50% more carrier borne aircraft, and the RN's strike aircraft were far more effective at night, and far too vulnerable to use during the day. (They would almost certainly have been as easy to swat out of the sky had they been risked in a daylight attack, as the Devastators were at Midway.)

Though probably this number advantage would not be enough of to overcome the radar guided fighter intercepts that had seen British multi-carrier forces hold off literally hundreds of combined German and Italian fighters and bombers in the Mediterranean.  (See the Malta Convoys in general, and the particularly good descriptions of the aircraft carriers fighting off 456 German and 358 Italian land based aircraft on August 12 in Operation Pedestal... An operation that simply would not have happened unless the IJN had been smashed at Midway or Ceylon). 

On the Pedestal convoy, Victorious, Indomitable and Eagle, used only 72 fighters on rotating patrols  to fight off 714 enemy aircraft. Assuming Indomitable and Eagle had slightly smaller loads at Ceylon in June, and Victorious' sisters Illustrious and Formidable also had a slightly smaller loads: that would give the RN about 80-85 fighters for this 'Midway' battle. But instead of facing 714 land based planes that knew exactly where the convoy was all day long, (and didn't have to protect their airfields in the process); they would only face 240 Japanese aircraft, (some of which had to stay and protect their own carriers). And the Japanese would have no accurate intelligence about where the British fleet might be, and would have to mount Coral Sea/Midway type sweeps to find them... (Note, at Midway the 3 USN carriers also had about 80 fighters, but unfortunately lacked the experience with radar intercepts to use them anywhere near as effectively.)

The IJN's best bet obviously remained a surprise day attack by this experienced and skilled air strike arm. But whether they would get it is very doubtful. They still had to find the enemy, and then co-ordinate strikes; and then not get lost en-route; and then fight past the radar guided CAP; and the vast RN AA. (Again, while the USN still followed interwar doctrine and separated it's carrier task groups, the IJN and RN concentrated them for maximum AA and AS protection. See more on AA below.)

Frankly by this stage the RN had so much experience with radar interception and holding off much larger German and Italian air strikes with relatively small CAP's, that it seems highly unlikely that the sorts of attacks the Japanese succeeded with at Midway would have had much chance getting similar results against the British fleet. 

[In fact even the IJN having 6 carriers rather than 4 probably wouldn't be enough to balance the technical odds. Even if we reversed the starting premise of the same forces as were used at Midway, and said Shokaku and Zuikaku were still undamaged after finishing off the USN; and still had enough functional air group to be able to support the other 4 carriers: the technical odds against the Japanese would still require considerable luck to overcome RN technology and experience. 2 Extra flight decks and a 50% increase of 100 to 120 extra planes would certainly help the odds a bit, but the IJN would still need the series of multiple lucky breaks the USN had at real Midway to gain a victory.]

Nor would any RN strikes led by radar equipped torpedo bombers suffer from the hopeless/helpless wandering around and getting lost that both the IJN and USN air strikes suffered from at Coral Sea and Midway. (That saw dozens of planes run out of fuel before finding anything, or simply fail to get back before getting lost in the dark, or even trying to land on each others carriers!) Day or night, RN strikes could find their targets, and usually had a very good percentage of hits if they did get through. (Plus, their torpedoes actually worked... unlike those of the poor Devastator pilots who survived the slaughter at Midway long enough to actually launch against Japanese carriers!)

But note that Somerville definitely didn't want to risk his slow and vulnerable torpedo bombers by day... He wanted to be in position to do an ambush strike at night. 

3. AA defenses...

The combined AA of the 4 Jap carriers and the 2 escorting battlecruisers was probably less powerful, and certainly less effective, than that of a single Illustrious class carrier, or of the modernised battleship Valiant. To be blunt, Jap AA sucked. (In fact the main IJN 25mm AA gun was a practically useless waste of space compared to the far superior 40mm and 20mm medium and short range weapons of the Allies, and certainly couldn't defend either ranges adequately, let alone try and manage both ranges. Only the equivalent USN 1.1" – which still made up the majority of USN capital ship and cruiser weight AA at Midway – was a worse AA gun than the 25mm.)

By contrast for the RN the modern AA batteries of the 3 British carriers, and the Valiant, amounted to 68 4.5" guns and there were more than 50 odd almost as effective 4" guns (both models having approximately equivalent rate of fire, and considerably better range, than the quite excellent 5"/38 on the newer USN ships). Let alone over 100 less effective 4.7" and over 300 2 pounder pom-poms and hundreds more 20mm and .50 MG's on the other RN ships in the fleet. (Particularly note the specialist Dutch AA cruiser Jacob van Heemskerk). 2 years of quite painful war experience had paid off for the RN. There was much more, much better, and much better directed, AA firepower on just the capital ships and cruisers of the Eastern Fleet, than in the entire Japanese navy put together at that time. 

But keep in mind, Somerville – with superior intel and the advantage of radar – was trying to avoid this sort of day action... His AA capabilities were really only a safeguard part of the backup plan, and preferably not even relevant to his ambush plan. However, given the – still unrecognised – range advantage of Japanese carrier aircraft, it was a very useful backup. Even if his night attack had taken 3 carriers as happened at Midway, that would still leave Hiryu's counter attack to deal with in the morning. And if the night attack hadn't managed to damage all 3 carriers, perhaps only getting one or two of them: then even if he fell back on the support force in daylight, they very probably wouldn't be out of range of some sort of counter-attack.

The Eastern Fleets AA firepower would have been an excellent security blanket.

4. Night Fighting

Although the IJN surface fleet had trained extensively for night fighting, the IJN's carrier arm was not capable of night operations. And of course, the IJN had virtually no radar (though Kaga for one had received a very simple set during her April refit that caused her to miss the Indian Ocean raid, not that it helped at Midway). The IJN also had absolutely no practical experience of using radar in combat. 

[The USN, still amateurs at radar in combat, weren't really trained to fight at night full stop at the time of Midway. See Savo Island for a good discussion of that issue...]

The RN of course, had extensive combat experience day or night, and lots of that combat experience had involved radar directed operations of all sorts. From night ambushes by surface units like Cape Matapan and Force K (particularly the Duisburg convoy battle); and night strikes by aircraft like at Taranto and the Bismarck. And the Japanese had no answer at all to the British radar guided torpedo bombers at night. (They might be old fashioned looking biplanes, but if they can find and sink you when you can't even see them coming, you are at a considerable disadvantage.)

Which is why Somerville planned his April ambush around his fast force making a night strike, and retiring on the slow force in daylight.

The difference is that by June he would probably not even need to retire on his Slow Force. The Fast Force alone could handle anything Nagumo's Strike Force could offer, and only the arrival of Yamamoto's Main Force might require support from the Slow Force to deal with.

5. Surface Action?

Well it did happen quite a bit during the war, from Narvik to the Bismarck action to the North Cape: from Calabria to Cape Matapan; and from Guadalcanal to Surigao Strait to Malacca Strait. So let's assume it could happen here.

If the IJN Strike Force had only the 2 Kongo class battlecruisers they actually had at Midway, then they simply could not take on either the British Fast Force or Slow Force separately with any real chance of winning. Certainly not if they happened to be in company.

Frankly I would like to think that Japanese dispositions would be more sensible for an attack on Ceylon than the 3 (or 4 if you include the Aleutians group),widely dispersed forces at Midway. Given that at Midway the Strike and Main forces both come roughy from Japan, whereas the invasion force comes from much further south, it is quite reasonable that two of the Japanese battlecruisers and 2 light carriers were diverted for protecting and supporting the invasion force. But for a Ceylon battle all the forces would all be coming pretty much from the same direction, so why not a bit more concentration?

Let's say the 27 knot Yamato, Nagato and Mutsu with their 2 covering/invasion supporting light carriers cover the actual invasion force (if there is one... maybe they are out of resources for land ops if they have occupied Hawaii etc). Or at least form the traditional Japanese Support Force/covering force/ Main body/whatever coming along behind the Strike Force. That allows all 4 of the 30+ knot Kongo class battlecruisers to be with Nagumo's fast carrier strike fleet, the way they actually were in the April Raid. In theory those 4 working together might be willing to take on one of the RN forces. (And their speed would give them the option to run from superior numbers anyway.)

Unfortunately the IJN's extremely vulnerable Kongo class battlecruisers (with only 8" belts - inferior to even the WW1 battlecruisers lost at Jutland) could simply not risk facing real battleships in slugging matches. Re-naming them 'fast battleships' during the 1930's could not disguise their lack of armour. And even the IJN's vaunted night fighting training probably couldn't have saved if they came anywhere near the radar guided British battleship guns. (Frankly it would take Kamikaze runs by IJN destroyers armed with the lethal Long Lance torpedoes to try and even the odds... and too many of the British cruisers and destroyers tasked with stopping such attacks had radar too...)

A surface action between the 4 Kongo's and the 2 Nelsons supported by 3 Queen Elizabeths could only have one outcome... even without the 4 Revenge class being close enough to be in support.

Fantasy Stuff, for the fun of it...

But what if the Japanese had actually really concentrated for once? If they abandoned the 'multiple forces converging from multiple directions' approach they used at Coral Sea, Midway, Philippines Sea, Leyte Gulf, and almost every battle in between: and actually sent Yamamoto's main body in as a close support force for Nagumo's strike fleet? Then you would have both sides using fast forces supported by slow forces, both of which contained both carriers and battleships/battlecruisers.

The result of that would effectively be the Battle of the Leyte Gulf, but in June 1942. What fun!

It is amusing, if unrealistic, to imagine a fleet action with the IJN's 7 battleships and battlecruisers in line against the RN's 9 battleships. The Japanese would have a clear speed advantage, but, even allowing for Yamato's 18" guns, the RN would have a substantial advantage in firepower and in weight of armour protection across the board. Only Yamato had armour at the levels of the British ships (see my pretty detailed discussion of armour quality versus quantity here), with even the Nagato's quite lightly protected by British standards. And the Kongo's were practically defenceless against heavy shells of any sort. 

Let alone the RN's considerable accuracy advantage based on their radar and superior gunnery in general. A post war USN report noted that the RN's 15" guns were the most reliable and accurate big guns of the war. Warspite for instance had achieved the longest range hits against another battleship in history - 25 miles - at Calabria, (and the Scharnhost got hits from a similar range against the carrier Glorious the same year.. with 11" guns!).. The longest range Japanese 'hits' ever recorded were some near misses in perfect daylight conditions, by the Yamato at 19 miles in 1944, that nevertheless sunk an escort carrier. (Though I'd be interested if someone can quote a longer range hit?)

Even in clear weather, and in daylight, the RN would have a significant advantage in a pounding match. In poor visibility conditions, or at night, with radar direction, the RN's advantage would be completely overwhelming. That would probably still be the case even if the 4 Revenge's were not within range, and the 5 British battleships of the Fast Force engaged the 3 IJN battleships and their 4 battlecruiser supporters simultaneously. 

But that is vanishingly unlikely.

In reality the two sides fast and slow squadrons would be manoeuvring around each other more like the various squadrons at Jutland, than the crashing lines at Trafalgar. And the problem with that is that even if the Japanese Strike Force's Kongo's accidentally got through to attack the Revenge's in the Slow Force, they would probably lose; and if they more realistically met the British Fast Force head on, they would definitely lose. Their only chance was to try and lure the Fast Force back into range of the Yamato and the Nagato's... where, excepting a striking bit of luck, they would still probably lose.

Even the vaunted Yamato supported by a couple of Nagato's, doesn't stand much of a chance against a pair of radar equipped Nelson's supported by 3 radar equipped Queen Elizabeths.

Re-emphasising that 'two front' dilemma

In reality the IJN tried to win just enough against the USN at Pearl Harbour to keep them unable to respond for a while; then rush over to try and beat the RN badly enough in the Indian Ocean to clear the threat to that flank; in time to rush back and finally defeat the USN at Midway. In reality all 3 attempts failed to achieve their goals.

To use a baseball term, "Three strikes and you're out"...

The alternative solution suggested here is that they should have just left a minimal screen against the RN for a few months; spent the time to properly eliminate any immediate threat from the USN; and then been able to turn their full resources to properly defeating the RN on the other flank.

Problem is, as the above makes clear, that probably wouldn't have worked either.

There can't be much doubt that by the time the USN had been comprehensively defeated, and the somewhat weakened IJN finally turned to face the RN, the British buildup would have been too great for the Japanese to have much chance of victory.

In other words, regardless of which allies absorbed the damage during the crucial 6 months in the process of preventing the Japanese claiming a decisive victory, the end result was always going to be allowing the other ally to build adequate strength to face the Japanese.

In reality it seems that the IJN's best result was what they actually did. Disabling the USN temporarily; then disrupting the British buildup before it was complete (with at least a chance of a decisive victory there); and then getting a better than even chance shot at the USN at Midway, (where a proper concentration of forces might still have given them a victory.)

By contrast if they had taken that few extra months to occupy Hawaii, attack the US West Coast, and seek and destroy any remaining USN in the Pacific: the RN would have been given the time it needed to build practically unassailable strength in the Indian Ocean.

Frankly, it seems likely that if the IJN had concentrated on the USN for months and left the RN relatively untroubled, it would actually have worked out worse for the IJN in the long run.