Efficiency of the U-boat fleet

[Stuart]

MPA: Something Patrol Aircraft?

Sorry, MPA. Maritime Patrol Aircraft.

Stuart, would you then say that the Klasse XXI was a step down in commerce raiding effectiveness compared to the VII and IX, with that sacrifice being accepted for greater evasive ability?

That's a bit black and white. It's important to remember that the Klasse XXI was quite a bit bigger than the VII and IX and size has its virtues. However, under ideal circumstances, the especial characteristics of the Klasse XXI (underwater speed and endurance) weren't worth very much so ton-for-ton under ideal circumstances, the VI and IX were better commerce destroyers. However, under the circumstances that prevailed in 1944-45, the Klasse XXI was the better commerce destroyer because it could survive (not would survive) while the VII and IX could not.

The best way to think about it is that to survive in 1944/45 meant paying a price and that price came out of commerce destroyer capability. If that price wasn't paid, the submarine didn't survive.

[Blayne]

On the other hand NOT having the uboats would've vastly eased the strain on the allies.

How much better would have say German technology and better numbers have helped the Japanese hypothetically?

[Vehrec]

I believe, although this may just be my incorrect opinion, that the main problem with the Japanese submarine forces was not equipment or numbers but tactics. That is, they persued the wrong targets for a fleet of WW2 subs, going out to hunt for warships instead of things they could actually catch like transports and tankers. Their doctrine was in in fact, hugely deficent in many areas when it came to submarines.

The (Submarine) force often operated helter-skelter during the war, being constantly obligated to commit submarines in unanticipated and ever increasing and dangerous crises. Submarines undertook a wide variety of assignments; for example, they were deployed along picket lines in an attempt to ambush and pursue enemy naval forces, only to be ordered and sometimes reordered to dash elsewhere when enemy forces were discovered beyond the original picket lines. Submarines were assigned to reconnoiter heavily guarded enemy ports and advance anchorages. There they sometimes launched midget submarines, human-piloted torpedoes, and aircraft, with minimal results. Submarine aircraft also dropped a few incendiary bombs on Oregon forests, and submarine deck guns fired on other minor targets on the American mainland and various islands. In addition to supply and evacuation operations with bypassed Japanese island garrisons, submarines transported highly explosive gasoline for refueling seaplanes. Moreover, the Japanese undertook other dangerous submarine transport operations with their German allies on the other side of the globe, with whom they exchanged personnel and small amounts of strategic goods, such as quinine and tungsten, and blueprints and prototypes of war machinery. There were also various forays into the Indian Ocean, but crises in the Pacific often forced the boats to concentrate there against strong and rapidly advancing Allied forces. These highly dispersed operations characterized much of Japanese submarine strategic and operational activity throughout the war. The occasional entreaty advocating concentration against enemy sea communications and extended U.S. supply lines, particularly to the South Pacific and Australia, was always played down and usually rejected.

Further explanation for the failure of the submarine force has its roots in the shortcomings of Japanese naval doctrine. The Imperial Navy's neglect of antisubmarine warfare (ASW) before the war proved deadly to the wartime Japanese merchant marine, but the Japanese submarine force was also adversely affected. Japanese submarines were poorly prepared to cope with U.S. Navy ASW operations.

During months of work against German U-boats in the Atlantic before the attack on Pearl Harbor, the U.S. Navy had the experience of escorting convoys, experience that sharpened ASW skills. The Japanese navy had no such wartime experience. When war came, Japanese submariners were unaware that they could be so effectively and systematically pursued on the surface by enemy radar and beneath the sea by sonar. Japanese submarines made little deliberate effort to avoid detection by such sophisticated sensors; moreover, Japanese submarine-borne radar and active sonar used later in the war were primitive by U.S. Navy standards and of little consequence. With no significant ASW doctrine, Japanese submariners, unlike their American and German counterparts, had little understanding of the theories of sound promulgation in relation to temperature layers or water stratification. Careful maneuvering while submerged could reduce the chance of detection, but deeply submerged Japanese submarines usually ascended directly to periscope depth to reconnoiter in a quick 360-degree sweep and then surfaced, fearing only the possibility of being spotted directly and visually by an enemy patrol. Japanese submarines were usually large, powerfully armed, and fast on the surface, but once detected they made good targets because of their slow submerged speed, poor maneuverability, and limited diving depth. Finally, a lack of concern about ASW manifested itself in submarine designs that failed until late in the war to emphasize noise-reduction features.

[Stuart]

On the other hand NOT having the uboats would've vastly eased the strain on the allies.

Actually, that's an interesting argument but not quite the way you intend it. Let's imagine a timeline (impossible I know but bear with me) in which the German Navy doesn't build any submarines at all. Zilch, nada. Instead they put all their energy into building up a surface fleet (the building slips and infrastructure required magically materializing when needed). Doing some quick mathematics based on the 1939 issue of Janes Fighting Ships the German navy can build two additional Bismarck Class battleships plus some supporting ships. That means they have roughly double the fleet they had in reality (again, I know that's impossible but let's just see where this goes).

So the British respond. They have no submarine threat to worry about but they do have a more powerful surface fleet as an enemy. So, they build the Lion class battleships and keep Vanguard building at top speed. They don't build the sloops and corvettes, at least not in the same numbers (remember, they can't know that the Germans will not be building submarines at some time). Given that the Germans are building a surface fleet, the British have to take the Z-plan seriously and design (and build) follow-ons to the Lions.

All that requires a lot of resources. Now, we know that the German submarine offensive was actually pretty ineffectual except for a few special circumstances (drumbeat being one) so the question is, will the resources absorbed by building up an enhanced battlefleet be greater than the resources freed by not building the corvette fleet and not suffering the U-boat losses. I'd suggest that is an issue over which a long debate could be held and I wouldn't like to argue it either way.

How much better would have say German technology and better numbers have helped the Japanese hypothetically?

To some extent, the Germans did but as Vehrec pointed out, the issues with the Japanese submarine fleet were conceptual and operational rather than technical. The Germans could make a difference in things like messing standards and deployment but the truth is the operational conditions in the Pacific were such that German experiences weren't really transferable. In technical terms, the Japanese certainly weren't behind the Germans, arguably they were ahead of them in some areas. One hears a lot about the Klasse XXI and Klasse XXIII U-boats but the fact that the equivalent Japanese designs (the I-201 and Ha-201) were more effective boats goes unnoticed. They weren't German y'see.

So, all in all, probably no difference.

[K. A. Pital]

I don't think the surface fleet strategy you describe is all that impossible, Stuart. If the Germans reoriented their submarine resources to building more battleships and finishing their real carrier and a few converts, their Navy might have been a far more formidable threat in a surface engagement. And then yeah, the British would have to take the Z-plan more seriously. Whether that would have actually forced their hand to answer with a similar naval buildup, that's not a given though. Action-reaction does not always work.

[Stuart]

I don't think the surface fleet strategy you describe is all that impossible, Stuart. If the Germans reoriented their submarine resources to building more battleships and finishing their real carrier and a few converts, their Navy might have been a far more formidable threat in a surface engagement. And then yeah, the British would have to take the Z-plan more seriously. Whether that would have actually forced their hand to answer with a similar naval buildup, that's not a given though. Action-reaction does not always work.

Actually, action-reaction very rarely works. The idea has caused more trouble than most things I can think of. However. . . .

It's a good question what the British would have done if they had seen a serious German surface fleet build-up. We know the Lions would have been built; the primary reason for their cancellation was to clear the slips for ASW work - the cruiser fleet took a big hit for the same reason as did the carriers. So, absent the German submarines, we can assume that the pre-war package of battleships, armored carriers, cruisers and destroyers goes through. However, where we go from there could be a very good question. I can see Sir Arthur Harris claiming his bombers could destroy the German ships in port (well, actually, knowing Sir Arthur, he would claim that the ships would be sunk while he was burning the ports down). The submarine community would claim they could keep the German ships bottled up using mines and torpedo attacks and the carrier fraternity would claim their carriers were the ideal way of nailing the German battleships. So, the actual course the British would have adopted post-Lion class is up in the air. However, all of the options would involve heavy resource expenditure one way or another.

Equally, on the German side, it's interesting to argue what might have happened if the Germans had scrubbed submarine construction AND surface ship production. A lot of those resources could have been transferred to Army use giving them a lot more really heavy artillery and a substantive improvement in their vehicle production (and optics; the U-boats were a massive sink-hole for first-line optical equipment. Give that kit to German tank destroyers and things might have gotten tricky. A German navy consisting entirely of S-boats and minesweepers wouldn't have done any worse than the German Navy did historically and it would have freed up a lot of resources.

On the other hand, a non-Navy Germany wouldn't help the allies that much. Both the British and Americans needed their navies for duties other than a war with Germany so they'd still have massive naval construction programs. just the balance within those programs would change.

[Thanas]

^However, without a surface fleet, what is to prevent the British from taking Norway and cutting off ore transports?

EDIT: Stuart, did you get my PM?

[Stuart]

Stuart, did you get my PM?

I did indeed and I'm thinking about it now. I'll get an answer back to you in a day or so ( I like to think these things over carefully).

[Simon_Jester]

I believe, although this may just be my incorrect opinion, that the main problem with the Japanese submarine forces was not equipment or numbers but tactics. That is, they persued the wrong targets for a fleet of WW2 subs, going out to hunt for warships instead of things they could actually catch like transports and tankers. Their doctrine was in in fact, hugely deficent in many areas when it came to submarines.

(extended doctrine quote)

To be fair, some of this probably made sense: such as using submarines to ship extremely valuable strategic resources and blueprints between allies who had no other way of reaching each other. But the rest of it... yeah. Lobbing a few shells or a scattering of incendiaries at the enemy coast isn't a cost-effective use of a submarine's time, not when the enemy coast is ten thousand miles from home. Likewise ordering them to run around in circles chasing fast warships.

Actually, action-reaction very rarely works. The idea has caused more trouble than most things I can think of.

Would you mind expanding on that for people who've read less strategy literature? I'm curious.

On the other hand, a non-Navy Germany wouldn't help the allies that much. Both the British and Americans needed their navies for duties other than a war with Germany so they'd still have massive naval construction programs. just the balance within those programs would change.

Yes. The only catch I see is that the Allies would be able to move stuff across the Atlantic with much less fear of submarine attacks- fewer time-consuming evasive routings, less need to restrict the available convoys to what could be escorted against the sudden attack of a German battleship. Would that not make a difference?

[Sea Skimmer]

^However, without a surface fleet, what is to prevent the British from taking Norway and cutting off ore transports?

The invasion could have been done with only cruisers and destroyers. No surface fleet at all is not realistic because of the threat of the Soviets and even the lesser fleets in the Baltic.

[Blayne]

Hrrm but the Germans have easier air access there though.

[JBG]

I don't think the surface fleet strategy you describe is all that impossible, Stuart. If the Germans reoriented their submarine resources to building more battleships and finishing their real carrier and a few converts, their Navy might have been a far more formidable threat in a surface engagement. And then yeah, the British would have to take the Z-plan more seriously. Whether that would have actually forced their hand to answer with a similar naval buildup, that's not a given though. Action-reaction does not always work.

Actually, action-reaction very rarely works. The idea has caused more trouble than most things I can think of. However. . . .

It's a good question what the British would have done if they had seen a serious German surface fleet build-up. We know the Lions would have been built; the primary reason for their cancellation was to clear the slips for ASW work - the cruiser fleet took a big hit for the same reason as did the carriers. So, absent the German submarines, we can assume that the pre-war package of battleships, armored carriers, cruisers and destroyers goes through. However, where we go from there could be a very good question. I can see Sir Arthur Harris claiming his bombers could destroy the German ships in port (well, actually, knowing Sir Arthur, he would claim that the ships would be sunk while he was burning the ports down). The submarine community would claim they could keep the German ships bottled up using mines and torpedo attacks and the carrier fraternity would claim their carriers were the ideal way of nailing the German battleships. So, the actual course the British would have adopted post-Lion class is up in the air. However, all of the options would involve heavy resource expenditure one way or another.

Equally, on the German side, it's interesting to argue what might have happened if the Germans had scrubbed submarine construction AND surface ship production. A lot of those resources could have been transferred to Army use giving them a lot more really heavy artillery and a substantive improvement in their vehicle production (and optics; the U-boats were a massive sink-hole for first-line optical equipment. Give that kit to German tank destroyers and things might have gotten tricky. A German navy consisting entirely of S-boats and minesweepers wouldn't have done any worse than the German Navy did historically and it would have freed up a lot of resources.

On the other hand, a non-Navy Germany wouldn't help the allies that much. Both the British and Americans needed their navies for duties other than a war with Germany so they'd still have massive naval construction programs. just the balance within those programs would change.

The Lions would certainly be built as they are adequate to deal with Bismark klasse vessels but I'm not so sure that Vanguard would get any priority in that situation. The KGVs of course would deal with the twins and a properly sorted KGV would be an enemy worthy of respect to the Bismarks. Particularly with more Tribals and Colonies for escort.

Maybe there would also be a more universal program of modernisation so you don't end up with the contrast, for example, between Repulse and Reknown or between Barham and Warspite.

[Marcus Aurelius]

Hrrm but the Germans have easier air access there though.

The Soviets had a substantial submarine force on the Baltic Sea, so minimally the Germans would have needed ships capable of convoy escort. The S-boote (E-boats) or the traditional torpedo boats don't cut it, but so called fleet torpedo boats (Flottentorpedoboote) might. However, despite the name they were actually small multi-role destroyers rather than torpedo boats. Many people also think that they were the best destroyers developed for the Kriegsmarine.

[Stuart]

Would you mind expanding on that for people who've read less strategy literature? I'm curious.

Action-reaction is a theory about the dynamics of international relations in which the process is driven by actions and the reactions of others to those actions. Each reaction, in turn, becomes an action that generates its own set of reactions and so on ad infinitum. So, as a supposed example, pre-WW1, the British switch from 13.5 inch guns to 15 inch guns for their battleships so the Germans react by shifting from 12.2 inch to 15 inch while the US shifts from 14 inch to 16 inch. The British see the Germans and Americans shifting to 15/16 inch so they then plan a shift to 18 inch. Another example is supposed to be people, especially the U.S. are developing anti-ballistic missile systems so that decision drives people to install MIRVs on their missiles so that they can swamp the ABM system with warheads. There's a lot more examples we can give here and they affect nearly every area of military technology.

So far, that all sounds very good but, as always, the devil is in the details. Taking the battleship example first; when the archives were studied, it became apparent that the German decision to shift from 12.2 inch to 15 inch was nothing whatseoever to do with the British decision and that the British decisions were nothing to do with anybody elses. In each case, all the nations involved were following a strategic logic of their own that had very little to do with waht other nations were doing. There was a "battleship environment" certainly but it determined things in only a very simple, generic sense. Each nation was really committed to building the most powerful battleships they could for the requirements of their own national strategies and that was what determined gun caliber. Nobody was responding to anybody else.

The ABM/MIRV case was even more emphatic on the issue. MIRV was introduced for reasons that had nothing to do with ABM. Put briefly, what drove ABM was the realization that a land-based missile force is a very expensive way of deploying a strategic nuclear deterrent. It doesn't look it at first, but it is because the missile is actually the least expensive part of the system. Typically, the missile itself costs around 10 percent of the cost of the system built around it. So, if we want to double the number of nuclear warheads delivered to the target, sticking to one warhead per missile means we have to double the number of missiles in the whole system and that doubles the cost of the whole system. If, however, we double the number of warheads on the same missile, we only have to buy the new missiles and we can put them in the same silos. That means we only have to spend 10 percent of the cost needed to double the number of missiles. There was a problem of course; a MIRV system with multiple warheads per missile can be easily countered by shooting down the MIRV bus before it discharges its missiles. 20 single-warhead missiles are actually significantly more "penetrative" than 10 double-warhead missiles. Taking it to extremes, 20 single-warhead missiles are vastly more penetrative than two ten-warhead missiles. Only, two ten-warhead missiles are vastly less expensive than twenty single-warhead missiles. So, people wanted to go to MIRV to reduce costs, MIRV was only viable in the absence of ABM and that's why there was such pressure to destroy ABM in the 1970s.

The lesson here is that things are always much more complex than they seem and the very simplistic action-reaction theory falls apart once we start to look deeply at what was going on. This phenomenum where what appears to be a reaction to something in reality turns out not to be is almost universal to the point where it is very hard to find an example of action-reaction actually taking place. They do exist but they are very rare indeed (this isn't helped by the fact that sometimes X is described as being "an answer to Y" for public consumption whereas in fact the truth is "nevertheless, we were going to do X anyway".)

It gets even worse because the naive and innocent (or evil and malicious) then use action-reaction to try and kill off things they don't like - which is usually everything. Their argument goes "if we do X, they will do Y. We don't want them to do Y so we mustn't do X." This argument gets used against every defense program; "if we build a new fighter, the other side will build a better one. We don't want them to do that so we mustn't buy a new fighter."

The truth is that all nations have their own strategic outlook and build the weapons and systems needed to execute the strategies determined by that outlook. What other nations are doing only figures into that in a very general sense.

[Stuart]

The Lions would certainly be built as they are adequate to deal with Bismark klasse vessels but I'm not so sure that Vanguard would get any priority in that situation. The KGVs of course would deal with the twins and a properly sorted KGV would be an enemy worthy of respect to the Bismarks. Particularly with more Tribals and Colonies for escort. Maybe there would also be a more universal program of modernisation so you don't end up with the contrast, for example, between Repulse and Reknown or between Barham and Warspite.

A KGV in good working condition was perfectly adequate to blow seven kinds of hell out of the Bismarck and the RN knew it. The problem really was that it took a long time to get the KGVs up to full working condition. The Lions were an example of British strategic considerations in view and really were what the Royal Navy wanted to build. Vanguard was a curious ship; she was originally intended as a sort of battlecruiser for the Far east fleet and if built as intended she would probably have spent most of her life in Singapore. She was actually additional to the fleet plan in that she didn't use battleship bottlenecks (which was why she kept being built while all the other heavies were cancelled). The intriguing question is whether, as Lions replaced the Rs, would the guns from the Rs be used to build more Vanguards? One suspects they might well have been. That gives rise to another intriguing question, what would the effect have been if the UK had a pair of Vanguards in Singapore instead of PoW and Repulse? Wouldn't have stopped the Japanese trying something of course, but might have given them a much harder fight in Malaya.

Another intriguing question; what would have happened once the Lions were under way. They were basically (IIRC) 38 and 39 programs. That leaves us with the 1940 and 41 battleship programs. One might suspect a repeat Lion with perhaps a bit more armor.

I suspect we would have seen a British building program that went like this (36, 37 and 38 all historical except completions were delayed in OTL)

1936 program 3 KGVs commissioning 1940
1937 program 2 KGVs commissioning 1941
1938 program 2 Lions, one Vanguard, commissioning 1942 (Lions), 1941 (Vanguard)
1939 program 2 Lions (completing 1943)
1940 program 2 repeat Lions, one repeat Vanguard, completing 1944 (Lions), 1943 (Repeat Vanguard)
1941 program 3 repeat Lions, completing 1945

So, if the Z-plan had been completed (made possible by not building submarines), teh German battleline would ahve been

6 H class
2 Bismarck
2 Scharnhorst (with 15 inch guns)

for 48 16 inch guns and 28 15 inch

And the British battle line (assuming the Vanguards are out in Singapore)

10 Lions
5 KGV
2 Nelson
3 modernized QE
1 Hood
2 Renown

for 108 16 inch guns, 44 15 inch guns and 50 14 inch guns.

I'd also guess that Hood and Repulse would be modernized to Renown standards.

[Elfdart]

Wouldn't a buildup of a German surface fleet be a waste anyway? Without carriers and bases across the Atlantic for aircraft, those ships would be fat, juicy targets for British (and later, American) planes would they not?

[Marcus Aurelius]

[ That gives rise to another intriguing question, what would the effect have been if the UK had a pair of Vanguards in Singapore instead of PoW and Repulse? Wouldn't have stopped the Japanese trying something of course, but might have given them a much harder fight in Malaya.

I guess this counterfactual boils down to AA armament. Vanguard certainly had a much better AA suite than PoW and Repulse, but much of the equipment she had would not have been available in 1941. The 5.25" dual purpose guns themselves would have been a major advantage, of course, but the light AA gun suite probably would not have been nearly as impressive in 1941. Do you have access to sources which would give an idea of the original planned AA armament of Vanguard?

[Raesene]

[ That gives rise to another intriguing question, what would the effect have been if the UK had a pair of Vanguards in Singapore instead of PoW and Repulse? Wouldn't have stopped the Japanese trying something of course, but might have given them a much harder fight in Malaya.

I guess this counterfactual boils down to AA armament. Vanguard certainly had a much better AA suite than PoW and Repulse, but much of the equipment she had would not have been available in 1941. The 5.25" dual purpose guns themselves would have been a major advantage, of course, but the light AA gun suite probably would not have been nearly as impressive in 1941. Do you have access to sources which would give an idea of the original planned AA armament of Vanguard?

PoW had the same number of 5.25'' guns, Vanguard had the advantage of an improved mount (roomier and stronger turning motors?) that might not have been available had she been finished before the war. Design 15E (the final one) had an AA-armament of 16 5.25'' guns, 6x 2-pdr mk VI (octuples) and 4 UP-launchers, comparable to what was present on a KGV as built (December 1940: four Mk VI and four UP-launchers, the four 12.7mm MG originally specified were never fitted). All based on Raven/Roberts British battleships of WWII, german edition

[Sea Skimmer]

The difference wouldn’t come from the different anti aircraft armaments as much as two Vanguards are simply bigger ships, better protected and with homogenous ship handling characteristics in speed and turning circles. That means they can maneuver together rather then being split apart under an air attack. They also had better detail design with actual emergency generators, and while that was the result of war experience, other navies had realized the need for such generators prewar anyway.

[Marcus Aurelius]

The difference wouldn’t come from the different anti aircraft armaments as much as two Vanguards are simply bigger ships, better protected and with homogenous ship handling characteristics in speed and turning circles. That means they can maneuver together rather then being split apart under an air attack. They also had better detail design with actual emergency generators, and while that was the result of war experience, other navies had realized the need for such generators prewar anyway.

I suppose the better torpedo protection would help, although how much it would help would depend mostly on sheer luck (i.e. the actual location of torpedo hits). Emergency generators certainly would, but I don't know about the maneuvering. The Japanese torpedo bomber crews were very well trained and conducted a nearly text book attacks historically, which were spesifically designed to minimize the efficiency of evasive maneuvers.

All in all I estimate that without significant improvement to AA armament the effective results would be the same. Perhaps only one ship is sunk or both even manage to stay afloat, but probably so badly damaged that they would not be able to carry on with their mission to seek out Japanese invasion forces. Not that the mission made much sense anyway, since two capital ships with a small number of destroyers was clearly not enough for the task.

[Simon_Jester]

Maneuver can still help against a torpedo attack. As I recall, Repulse managed to dodge... somewhere between 15 and 20 torpedoes before the Japanese managed to get a synchronized attack in and nail her. It's not enough, but it can help improve the effectiveness of other features like AA defenses and torpedo protection.

[Stuart]

PoW had the same number of 5.25'' guns, Vanguard had the advantage of an improved mount (roomier and stronger turning motors?) that might not have been available had she been finished before the war. Design 15E (the final one) had an AA-armament of 16 5.25'' guns, 6x 2-pdr mk VI (octuples) and 4 UP-launchers, comparable to what was present on a KGV as built (December 1940: four Mk VI and four UP-launchers, the four 12.7mm MG originally specified were never fitted). All based on Raven/Roberts British battleships of WWII, german edition

I think its reasonable that a non-slowed-down Vanguard would have had the same AA armament as a KGV; the improved turrets wouldn't have shown up until later (probably on the Repeat Lions). That still gives the two battleships a lot more AA firepower than they had historically though; Repulse's AA firepower was very weak.

The real problem is that none of this will save one of the battleships if they take a hit in the same place as did for PoW. Statistically, that isn't unlikely. There's one chance in six that a torpedo will go into the screws and shafting. That'll do for any battleship.

The impact of two Vanguards in Singapore would be more political than anything else. They are a demonstration of a serious attempt to defend the place.

[Lonestar]

The impact of two Vanguards in Singapore would be more political than anything else. They are a demonstration of a serious attempt to defend the place.

Assuming that the Japanese even know they are there. Didn't the local commanders express surprise at the arrival of two RN Capital ships off of the Malay Peninsula, despite the very public arrival of the PoW and Repulse to Singapore in the press?

(I'm remembering the account from The Great Ships: British Battleships in WW2...the author is a very old school British Imperialist whose writing tone and style reminds me of you, Stuart)

[Sea Skimmer]

.

The real problem is that none of this will save one of the battleships if they take a hit in the same place as did for PoW. Statistically, that isn't unlikely. There's one chance in six that a torpedo will go into the screws and shafting. That'll do for any battleship.

The odds are a lot less then one in six that damage in that area would cause such catastrophic flooding and such extensive loss of power. A direct hit on the shaft bracket is more like a 1/200 chance. USS Intrepid took a deep running torpedo hit in-between her rudder and her screw, not a very large space, and this did not lead to the loss of use of any shaft for example. The rudder was ruined.

[JBG]

The Lions would certainly be built as they are adequate to deal with Bismark klasse vessels but I'm not so sure that Vanguard would get any priority in that situation. The KGVs of course would deal with the twins and a properly sorted KGV would be an enemy worthy of respect to the Bismarks. Particularly with more Tribals and Colonies for escort. Maybe there would also be a more universal program of modernisation so you don't end up with the contrast, for example, between Repulse and Reknown or between Barham and Warspite.

A KGV in good working condition was perfectly adequate to blow seven kinds of hell out of the Bismarck and the RN knew it. The problem really was that it took a long time to get the KGVs up to full working condition. The Lions were an example of British strategic considerations in view and really were what the Royal Navy wanted to build. Vanguard was a curious ship; she was originally intended as a sort of battlecruiser for the Far east fleet and if built as intended she would probably have spent most of her life in Singapore. She was actually additional to the fleet plan in that she didn't use battleship bottlenecks (which was why she kept being built while all the other heavies were cancelled). The intriguing question is whether, as Lions replaced the Rs, would the guns from the Rs be used to build more Vanguards? One suspects they might well have been. That gives rise to another intriguing question, what would the effect have been if the UK had a pair of Vanguards in Singapore instead of PoW and Repulse? Wouldn't have stopped the Japanese trying something of course, but might have given them a much harder fight in Malaya.

Another intriguing question; what would have happened once the Lions were under way. They were basically (IIRC) 38 and 39 programs. That leaves us with the 1940 and 41 battleship programs. One might suspect a repeat Lion with perhaps a bit more armor.

I suspect we would have seen a British building program that went like this (36, 37 and 38 all historical except completions were delayed in OTL)

1936 program 3 KGVs commissioning 1940
1937 program 2 KGVs commissioning 1941
1938 program 2 Lions, one Vanguard, commissioning 1942 (Lions), 1941 (Vanguard)
1939 program 2 Lions (completing 1943)
1940 program 2 repeat Lions, one repeat Vanguard, completing 1944 (Lions), 1943 (Repeat Vanguard)
1941 program 3 repeat Lions, completing 1945

So, if the Z-plan had been completed (made possible by not building submarines), teh German battleline would ahve been

6 H class
2 Bismarck
2 Scharnhorst (with 15 inch guns)

for 48 16 inch guns and 28 15 inch

And the British battle line (assuming the Vanguards are out in Singapore)

10 Lions
5 KGV
2 Nelson
3 modernized QE
1 Hood
2 Renown

for 108 16 inch guns, 44 15 inch guns and 50 14 inch guns.

I'd also guess that Hood and Repulse would be modernized to Renown standards.

Ah, the Z Plan. Assuming that the H klasse are the first H iteration with 16" guns. Later Hs were IMHO bloated monstrocities.

The problem is that Britain could have built up to or close to what you referred to, but Germany, a continental power at war, had no hope. Pipe dream of the wunderwaffe type.

Frankly I was not aware of far eastern intentions for the Vanguards. Given how poorly the RS class, for instance, performed around Ceylon (sever fresh water and ventilation issues), more modern ships might do better though PoW was uncomfortable in the Med prior to going to Singapore.

A modernised Reknown class with 4.5" AA as opposed to early 5.25" AA on KGVs would have been useful.