Rn vs IJN

[RCAFson]

Some of it depends on the range but the British cruisers look like they had about 75% of the fire rate of the Americans, which is not bad compared to 8in guns
US guns had power ramming up to 20 degrees and the British used had ramming, since everybody had to lower the guns to load/ram elevation/range had an influence on rate of fire.

Japanese 5.5s depended on how far the crews had to lug the shells.
Agano may have been at 5-6 rpm and the Oyodo was lucky to hit 5 rpm.

I've seen claims of 10 rounds per minute for the USN 6in/47 triple turret and thus a 6 second firing cycle.

This is from Wikipedia regarding the Belfast and Fiji class 6in turrets:

"A RN gunnery officer on HMS Bermuda gave details of the loading cycle which could be attained in the Mk XXIII turret with a well trained crew: "...a loading cycle of four and a half to 5 seconds was attained at low elevation, another two to three seconds being required with the guns elevated for long range. The time would lengthen as fatigue set in, but was creditable..."[4 - Brook, Alarm Starboard]"

 

[mack8]

Here is a diagram i found elsewhere showing the major shipyards and the major RN ships built on them, from cruisers upwards. Not sure how accurate it is but it's very interesting nonetheless.

Note the greatly decreased number of major ships laid down after 1940, presumably in our ATL those slipways would mostly still continue to build major combatants such as BBs, cruisers and some CVs, at least until 1942, when i assume the war against Japan (which i expect to go quite badly at fiorst for UK) would compel different, more urgent, priorities.

As i expect that the RN carrier force will be very roughly handled by Kido Butai in 1942, probably carriers will be top priority for RN from 1942 onwards (sort-of like the japanese did after the Midway disaster). These could be repeat Implacables, or perhaps the 27,000 ton Irresistible design instead of the OTL Audacious and Malta, plus likely a large number of Colossus like ships, perhaps 16 like OTL. BUT, just like the japanese program, these ships won't be all ready until 1946-47 at best.

Really, this is a fascinating scenario, as i expect the japanese to respond with their own large carrier building program (especially if they lose some against RN in 1942), OTL it was something like 5 Taihos and 15 Unryus. Probably some conversions will still be done too, such as the CVEs, the Chitoses, probably Shinano etc. Wonder if UK will start doing CVE conversions too, iirc they only done 6 during the whole war, because they got dozens of CVEs from US. But in our scenario, the US is not involved, not yet anyway. Though there doesn't seem to be any incentive for such conversion before 1942 (when the ATL war with Japan is in full swing).

And as to the US, if no war in Europe, then perhaps there is no incentive for the Two Ocean Navy act, not in 1940 anyway (or if there is an increase, there might be something akin to the 11 percent act at most imo), and probably nothing as big even in 1941, since France and UK are still very much intact. Though i suspect there will be some kind of big program by 1942. Lots and lots and lots of butterflies to ponder.

 

[Thumpalumpacus]

I've seen claims of 10 rounds per minute for the USN 6in/47 triple turret and thus a 6 second firing cycle.

This is from Wikipedia regarding the Belfast and Fiji class 6in turrets:

"A RN gunnery officer on HMS Bermuda gave details of the loading cycle which could be attained in the Mk XXIII turret with a well trained crew: "...a loading cycle of four and a half to 5 seconds was attained at low elevation, another two to three seconds being required with the guns elevated for long range. The time would lengthen as fatigue set in, but was creditable..."[4 - Brook, Alarm Starboard]"

I've read those claims about the Brooklyns as well, but I think they might be a little overenthusiastic. And I'm sure I've read somewhere about Jamaicapulling off fire-rates nearly as fast, which is why I asked Ewen.

 

[RCAFson]

I've read those claims about the Brooklyns as well, but I think they might be a little overenthusiastic. And I'm sure I've read somewhere about Jamaicapulling off fire-rates nearly as fast, which is why I asked Ewen.

I managed to find the entire quote:

"Once confidence had been gained the stopwatch was produced to promote competition among the three crews. Eventually a loading cycle of four and a half to five seconds was attained at low elevation, another two to three seconds being required with the guns elevated for long range. The time would lengthen as fatigue set in but was creditable."

Brooke, Geoffrey. Alarm Starboard!: A Remarkable True Story of the War at Sea (p. 309). Pen & Sword Books. Kindle Edition.

 

[Shortround6]

Also, one can assume that most of the troops, shipping and planes OTL aimed at the Phillipines (and places like Guam and Wake) will in this ATL be aimed at the british/french/dutch etc.

We are into the Butterflies again

We do have to assume that the forces used to attack the Philippines and outliers would be directed to the British/French/Dutch etc.

However the difficulty level goes up a bit.
By passing the Philippines combat also bypasses the Philippines as a staging area.
Another butterfly, Reinforce Hong Kong a bit. Maybe it lasts another two weeks?
the whole Indochina thing.

Does Britain close the Burma road in July 1940 for 3 months if there is no European war?
If China is getting more supplies in the summer of 1940 what do the Japanese do (spend) to fight harder in China?
More butterflies.

Up until about April of 1940 Everybody assumed the French had the strongest army in Europe and even if the phony war continues into 1941 and France gets stronger what happens?
What Happens if Germany stops at Czechoslovakia and never attacks Poland? What does France send East in 1941?

Japan was the Bad Boy of the world from about 1933 on, Italy tried to be a bad boy over Abyssinia in 1935. Adolf doesn't really get into the Bad Boy club until 1938, He talks a lot, but hasn't committed any outright aggression. He is fooling around in Spain with "Volunteers" and German's industrial might and history is making people very nervous but Japan has been fighting in China for years. The USS Panay incident on December 12, 1938 sure didn't make anybody feel any better following about a year after the Rape of Nanking.

If Adolf and Benni hadn't been distracting the world the Japanese would have been very foolish to try to expand by force. Japan had been demoted to Bad Boy #3 over on the side by the end of summer of 1940.

 

[Shortround6]

Here is a diagram i found elsewhere showing the major shipyards and the major RN ships built on them, from cruisers upwards. Not sure how accurate it is but it's very interesting nonetheless.

I have checked two ships(PoW and Belfast) and it seems accurate for the length of time on slipway, laying down to launch. Fitting out can take another year or two.

 

[Wild_Bill_Kelso]

perhaps the French and Dutch would have been little more than speed bumps but the whole Japanese attack of Dec 1941-March of 1942 of hanging by shoe strings, frayed knotted shoe strings at that. A couple of weeks of delay might have broken one or more of the shoe strings.

Maybe, but as has been noted, taking the conquest of the Philippines out of the equation frees up more than enough resources for the Japanese to take the French, British and Dutch colonial assets, IMO.

Ki-43 Production in 1941 was 157 aircraft, 43 of them in Dec, they built another 113 in the first 3 months of 1942.

Zero Production totaled 507 by the end of 1941, the first 100 or so were being used as trainers (they had a few limitations) and they built another 152 in the first 3 month of 1942.

True, but Ki-27 (army fighters) seemed to do quite well against most of the Colonial aircraft in Malaya etc., and they had plenty of those. The A5Ms were also pretty capable though there weren't quite as many.

If the Japanese do NOT start in French Indo china and have to take it over? Yes they can do it, but how much longer to take Malaya and Singapore? A few weeks? a month?

Again, I think if they don't need to worry about the Philippines they have more than what they need here.

If the British had more equipment to give the Indian troops in Malaya? To heck with more troops, just give them 1/4 to 1/3 of the artillery and anti-tank and AA guns that an equivalent number of of Troops in NA had. The troops in Malaya were lacking just about all heavy weapons.
Lets Remember that the Japanese have said that if the British did not surrender at Singapore when they did the Japanese would have had to surrender or face starvation in just another few weeks.

That is an interesting point I think Singapore being at the mercy of not only battleships but freely roaming Japanese bombers put them at a severe disadvantage. This tended toward surrender.

`A few more Dutch destroyers (3?) and submarines (Dutch were building 8 in 1939-40, 3 escaped to England) ?

Japanese win the naval battles but loose more transports during the invasions of the DEI.
How long do the land battles last?

Hmm maybe. But without the US help? I doubt very long.

Can the Japanese afford to loose either the time needed or the planes and troops needed to overcome the French/Dutch defenses?

They can/will win but what happens to the time table/s?

Maybe with more carriers supporting the DEI invasions (not attacking Pearl) the Dutch planes are wiped out in the first two days, who knows?

I think all the colonial powers are in grave peril of swiftly falling under the ruthless control of the Southeast Asia Co-Prosperity sphere.

 

[Wild_Bill_Kelso]

Another interesting bit of kit which could be relevant to a Pacific campaign is the Repair Ship.

Repair ship - Wikipedia

en.wikipedia.org

The US had a ton of these (as in 20 large ones, and about 50 or 60 smaller ones) and they came in very handy, contributing to the (for the Japanese, often surprising) resilience of the American fleet in swiftly recovering from battle damage, without even having to go back to the shipyard in many cases.

It looks like the British started the war with one, but then quickly converted another 12, and got 5 more via Lend Lease.

The Japanese seem to have had two - the Asahi and the Akashi. They planned four more of the Akashi class, but they stopped building them due to warships having higher priority.

 

[Shortround6]

True, but Ki-27 (army fighters) seemed to do quite well against most of the Colonial aircraft in Malaya etc., and they had plenty of those. The A5Ms were also pretty capable though there weren't quite as many.

I think you may not be realizing the enormous amount of "stuff" that used up in the first 2 1/3 years of war in west.
Hawker and Gloster built 3770 Hurricane Is through June of 1941 (Gloster, Hawker had stopped Feb)
Hurricane IIs were started in Aug/Sept of 1940 by Hawker, they built 418 of them through April of 1941, although they had started production of the IIBs in Feb 1941, Gloster switched over in June 1941 and the IICs started showing up in March 1941
I don't have total as of Dec 31st 1941 but I think were can estimate at least several thousand more than the MK Is

Now the question becomes if there is NO war in Europe how many aircraft do the British produce?
Low tension?
High tension?
German invades Poland and stops?
Germany Invades France and the low Countries and is stopped in Northern France?
Germany takes France but it takes until Sept and the Bob is delayed?

and so on.

and lets face it, it doesn't actually take a whole lot to triple or quadruple the supply of aircraft, artillery, tanks and AA guns to the Far east over what was sent with the Battles in Greece and North Africa being much reduced or eliminated.

This is what I meant by shoe strings. The Japanese invaded using the number of planes that a European country could make in 1 or 2 months in 1940-41.

If the Germans don't actually attack France until 1941 and they stall, the British could send 1/10 of the Hurricane Is the far East while reequipping with Hurricane IIs and still send 4 times the number of Buffaloes sent. Send bombers to suit.
They can't do much worse than the Buffaloes. Maybe the Japanese still "win" but it is going to take a lot longer. And gives the British/allies more time to send more stuff.

 

[Wild_Bill_Kelso]

I think you may not be realizing the enormous amount of "stuff" that used up in the first 2 1/3 years of war in west.
Hawker and Gloster built 3770 Hurricane Is through June of 1941 (Gloster, Hawker had stopped Feb)
Hurricane IIs were started in Aug/Sept of 1940 by Hawker, they built 418 of them through April of 1941, although they had started production of the IIBs in Feb 1941, Gloster switched over in June 1941 and the IICs started showing up in March 1941
I don't have total as of Dec 31st 1941 but I think were can estimate at least several thousand more than the MK Is

I see your point, and I'm sure the Hurricane would be a more challenging opponent for the K-27s than the F2As were, in part because the Hurricanes were fully debugged etc., but the production of K-27s wasn't trivial. They made 3,300 by mid-1942. A large number of these ended up as trainers but I bet they had at least 1,000 available as fighters in the early year. Maybe a close match for the Hurricanes, but I don't see the UK being ready to disarm themselves if there is any tension in Europe, since they could see what the capacity of Germany was.

Now if France sent a bunch of D.520 or Hawk 75 to Indochina that might be a problem for the Japanese, but I think most of these will be kept home. Once the Ki-43s and A6Ms are arriving, most of the Allied fighter units are going to be in big trouble, at least until they improve their tactics. Spitfires might help but they will probably arrive late.

Now the question becomes if there is NO war in Europe how many aircraft do the British produce?
Low tension?
High tension?
German invades Poland and stops?
Germany Invades France and the low Countries and is stopped in Northern France?
Germany takes France but it takes until Sept and the Bob is delayed?

and so on.

I think we can just say 'moderate tension'

and lets face it, it doesn't actually take a whole lot to triple or quadruple the supply of aircraft, artillery, tanks and AA guns to the Far east over what was sent with the Battles in Greece and North Africa being much reduced or eliminated.

Sure, but if we are talking about British made tanks and artillery, there are some limitations. Cruiser tanks with 2 pounder guns (no HE) and Matilda infantry tanks with the same, are not necessarily going to pose a huge problem for the Japanese.

Type 97 Chi-Ha looks like a pretty challenging opponent for an A13. They did pretty well at Khalkhin Gol against similar BT-7, and they were used with success in Malaya and Singapore, and in the Philippines where they outgunned the US M3 light tanks. They built over 1,000 of them.

The type 13, type 91 or 96 howitzers looks pretty good to me compared to the 25 pounder. The type 92 cannon looks downright scary.

This is what I meant by shoe strings. The Japanese invaded using the number of planes that a European country could make in 1 or 2 months in 1940-41.

If the Germans don't actually attack France until 1941 and they stall, the British could send 1/10 of the Hurricane Is the far East while reequipping with Hurricane IIs and still send 4 times the number of Buffaloes sent. Send bombers to suit.
They can't do much worse than the Buffaloes. Maybe the Japanese still "win" but it is going to take a lot longer. And gives the British/allies more time to send more stuff.

I see the point, I think the Japanese were ready though.

 

[EwenS]

Here is a diagram i found elsewhere showing the major shipyards and the major RN ships built on them, from cruisers upwards. Not sure how accurate it is but it's very interesting nonetheless.

Note the greatly decreased number of major ships laid down after 1940, presumably in our ATL those slipways would mostly still continue to build major combatants such as BBs, cruisers and some CVs, at least until 1942, when i assume the war against Japan (which i expect to go quite badly at fiorst for UK) would compel different, more urgent, priorities.

That diagram is a very simplified account of the activity in these yards and omits much. I've looked at some of the Clyde yards and H&W at Belfast in some detail (down to what ships on what slips & when and the changing priorities) but still not managed to pin everything down.

Just to take John Brown, Clydebank as an example they had two yards (east & west) with 6 & 2 slips respectively of varying lengths (450-500ft to 900+ft), separated by a fitting out basin. In WW2 the west yard with two covered slips was able to build two destroyers simultaneously on each slip and spent the entire war doing so (some 27 ships for the RN plus 2 for export from Jan 1937). The longest slips were nos 3 & 4 and the ships on them looked as follows:-

Slip 3 - from May 1936 to the end of Nov 1944
DoY
Conqueror (cancelled)
Roberts
Vanguard

Slip 4 - from Dec 1936 to Dec 1942
RMS Queen Elizabeth
Indefatigable

But other major warships built in the east yard from 1936 included:-
Maidstone - depot ship
Bellerephon / Tiger - cruiser
Hecla - depot ship
Forth - depot ship
Nairana - laid down as a merchant ship & acquired in 1942 while on the slip for conversion to an escort carrier

And there were a number of merchants built over this time period for what had obviously been pre-war clients who sought and obtained permission from MOWT to have new ships built.

Priotities were set by the Admiralty and labour moved around between ships under construction, but destroyers employed the single biggest chunk of the workforce, peaking at over 40% in 1942. After DoY was launched, a matter delayed at the request of the Admiralty causing the yard to try to work around that to keep the ship on schedule as far as possible, priority was given to building the monitor Roberts (ordered March 1940 & launched Feb 1941), which meant that Vanguard which was not ordered until March 1941 wasn't able to be laid down until Oct. After a good start was made on Indefatigable in 1939/40 she was a low priority, including a period under suspension, until DoY was nearly ready to leave the yard.

Moore noted that Fairfield had a bigger order book early in WW2 than John Brown but with a smaller workforce, hence the delays.

Re H&W I immediately see that the Unicorn is missing, as well as the depot ship Adamant and the 3 LST Boxer, Bruiser & Thruster. Later in the war you have the situation that the light carrier Powerful could not be laid down until Glory had been launched from the same slip.

But take away the effects of war like ship repairs, emergency conversions, escort production, landing craft production, restricted working hours due to the threat of the blitz, actual damage from the blitz (Clydebank was one of the worst affected towns in March 1941 with a large part of the workforce "missing" for over a week) then some of the predicted completion dates of Sept 1939 may well have proved possible.

 

[Shortround6]

getting back to the British Cruisers.

This actually gets a bit boring. The British built basically different 4 cruisers right up until the late 30s.

The Heavy County Class Cruisers. 13 built in 3 groups

1928-1930 completion dates. About 10,400 tons (after refit) 31-31.5kts
8 X 8in guns, 8 X 4in AA guns, 16 X 2pdr AA, some smaller (?) . 8 X 21 tubes.

they started at just under 10,000 tons but that was with just 4 X 4in AA with lighter than the two octuple 2pdrs. and a few other mods (like the aircraft),
Solid reliable ships even if not outstanding. Light AA varied from ship to ship. Torpedo tubes tended to disappear as the war went on.

York Class 2 ships
1930-31 completion dates. About 8250 tons (after refit) 32.5kts
6 X 8in guns, 8 X 4in AA guns, 16 X 2pdr AA, some smaller (?) 6 X 21 tubes.

There may be some dispute about the AA guns, as built with 4. York may have gotten 2 more, Exeter got the twin mounts after the Graf Spee action.
They didn't get expected cost reduction from the reduced size. That ended the 8in Cruisers.

Leander Class 8 ships
1933-36 completion dates. About 7270 tons 32.5kts
8 X 6in guns, 8 X 4in AA guns, 8 X 2pdr AA, some smaller, 8 X 21 tubes.

HMS Perth. the twin 4in show up near the rear stack. 3 were sunk in action but they saw a lot of use. The Light AA tended to vary.
A few ships did not get the two quad pom-poms and had an assortment of singles before the 20mm guns showed up.

Arethusa class 4 ships
1935-37 completion dates. About 5270 tons 32.3kts
6 X 6in guns, 8 X 4in AA guns, 8 X 2pdr AA (by the spring of 1942)some smaller, 6 X 21 tubes.

April 1943 with some extra light AA. The British were fairly happy with this ships but since no other major power followed their lead to the smaller ships the British
went to the Southampton class although they copied the hull for the Dido's (told you this a bit boring).
The Galatea was sunk by a U-Boat on Dec 15th 1941.
An early 1942 match up with the old Japanese light cruisers would be interesting. Endless chain hoists delivered the shells and charges to the turrets and while the shells and charges were hand rammed the Shells were transferred a series of trays. British fire control and radar Vs Japanese fire control and night glasses.

Southampton and followers 10 ships
1937-39 completion dates. About 9100-10,550 tons 32-32.5ts
12 X 6in guns, 8 X 4in AA guns, 8 X 2pdr AA (by the spring of 1942)some smaller, 6 X 21 tubes.

Some lost X turret to fit more AA. Belfast and Edinburgh both got a lot heavier armor and 12 X 4in AA guns and octuple 2pdr AA mounts. There was no sense keeping to the treaty limits at this point. Originally 3 aircraft but they traded aircraft for more AA as the war went on. Again note the somewhat more powerful AA armament compared to the Japanese ships. The USS Wichita completed at about the same time had 8 5in/38s with the 5 gun broadside.


I will finish the Dido's and war construction later.

 

[ThomasP]

re when does the ATL diverge from the OTL

I think we have to assume that the ATL diverges from the OTL in 1935-36, as this was when the Admiralty decided (I think) to build the Illustrious class carriers instead of the improved Ark Royals. If we wait until after that, or not switch the build-up timline at all, then Japan does more or less what it did historically in the first year of of the PTO against the UK & Netherlands (plus maybe France, though not necessarily) and they would have an easier time of it without US opposition (assuming Japan left the US territories alone). As I said up-thread, after that it becomes a war of attrition until the UK gets the A-bomb in 1946.


re the distances involved and overseas manufacturing resources

I think we can assume that the UK/Commonwealth would have built up the overseas manufacturing capabilities to a greater extent than in the OTL, but how far was possible the practical sense is a very big question to my mind.

In the OTL, aside from mining and oil production/refining, Australia was the only high tech production base to the east of India. And as has been pointed out in other threads, building up a manufacturing base there was problematic - partly due to the distances involved, partly due to the minimal pre-war industrial base (nearly all strategic materials had to be imported), and partly due to the small population base (in the OTL the Australian armed forces had to be reduced mid-war to allow enough manpower to meet the perceived need for industry workers). If the US was not involved from the start of the war, and the Japanese decided to put more pressure on Australia, would Australia have been usable as an industrial base at all in the ATL?


re oil

Assuming the oil embargo occurs more or less as in the OTL, Japan must seize the DEI at the very least, or the equivalent production capabilities from other sources in the British/French/Dutch Far East. Without oil Japan cannot fight the war.

As pointed out by EwanS up-thread, without the war in Europe to swallow so much of the oil supply available to the UK, there should not be any problem as to the UK/commonwealth maintaining its oil supply chain at least to the eastern edge of the Indian ocean and Australia. If Singapore does not fall then they should be able to maintain the supply they need at the front lines as well.

Another question is do the Japanese still move to completely take the CB part of the CBI area (with or without French Indochina)? In the OTL they came close to succeeding - and that was with the US directly involved in the war. What would have happened in the CBI if the US was not (directly) involved from the start of the PTO. Again significantly more military resources available for the Japanese to deploy to the CBI theater.

etc.

 

[EwenS]

Getting back a bit to the potential UK shipbuilding program if no war in Europe (at least not with UK involved in it yet), do i understand correctly that if not for the war they would have probably continued to build 1-2 CV, 2 BBs, 7 cruisers and 2-3 DD flotillas in both 1940 and 1941? As i understand they wanted at least another pair of Implacables in 1940 but this was not done due to the war situation. Also, when was Vanguard supposed to be laid down if not for the war situation, perhaps 1940? Do you think they have the capacity to lay down all 6 Lions by 1942, or they would have to pare down the number anyway (maybe 4 plus Vanguard?).

Regarding carriers, apart from the 8 armoured ones, iirc at some point they wanted 6 smaller "trade protection" carriers, presumably something akin to Unicorn or the later Colossus CVL? Don't know if they will start building some of these in 1940 or 1941, would be interesting what more informed folks know on the subject.

As a sidenote, without the war in Europe, many of the lessons RN (with significant impact in ship design) and UK as a whole learned the (very) hard way would not have been learned yet when going against Japan in this ATL. So at first i think many of those lessons will be learned the hard way against the japanese. I would not be surprised in the least if a lot of equipment sent in FE initially would still be second rate even if there is no war in Europe, since the british and western powers in general were looking down on the japanese.

1938 Programme
2 Lion class BB - ordered 2/39, laid down 6-7/39. Est completion in Sept 1939 was 8/42. Suspended later in 1939.
Implacable - ordered 10/38, laid down 2/39. Est completion in Sept 1939 was 10/41
3 Dido class cruisers - ordered 8/38, laid down 11/38-4/39. Est completion 1941
4 Colony class cruisers - ordered March 1939, laid down 4-7/39. Est completion 10/41 - 6/42
No destroyers
3 Abdiel class fast minelayers - ordered 12/38, laid down 3-4/39
3 River gunboats
3 T class subs
Unicorn (aircraft maintenance ship) - ordered 4/39, laid down 6/39.
Depot ships Hecla & Adamant

1939 Programme
2 Lion class BB - 1 ordered 8/39, the other to be ordered 11/39. Both suspended on outbreak of WW2
Indefatigable - ordered 6/39, laid down 11/39. Est completion 6/42
2 Colony class- to be built in Royal Dockyards but cancelled at end of Sept 1939
2 Colony class - planned for order in March 1940 but see below in War Programme.
1 Abdiel class minelayer
M & N class destroyers - 16 ships
2 Black Swan class sloops
20 Hunt class destroyers
1 River gunboat - cancelled
54 Flower class corvettes
10 Flower class corvettes built in Canada in exchange for Britain building the first 2 Canadian Tribals.


1939 War Programme ordered 4/9/30 to 1/40
6 Dido class
2 Colony class cruisers - ordered 4/9/39 (brought forward by about 6 months from previous plans)
16 O & P class destroyers
36 Hunt class destroyers (20 in Sept 1939 and another 16 in Dec)
7 T class subs
5 S class subs
12 U class subs
48 Flower class corvettes

When we come to the 1940 Programme it becomes more complicated as war approached. So the final Programme was not what was envisaged when discussions about it began in July 1939. But initially it looked something like this (extracted from Moore "Building for Victory"):-

2 Lion class - talks with industry suggested orders could be placed with Swan Hunter and Harland & Wolff around 7-8/40 with completion 42 months later i.e. early 1944. caveat that assumed delivery of armour, guns and mounts on the required schedule.
New 15" gun BB could be built at VA Tyne in an optimistic 36 months subject to the above caveats. But that depended on the H&W gun factory on the Clyde having the gun pits reinstated before any work on refurbishing the old turrets from Courageous & Glorious could begin.

A maximum programme could include
1 or 2 carriers
7-9 Dido/Colony class cruisers
2 depot ships
2 fast minelayers
2 fleet destroyer flotillas (16 ships) of K class or possibly a new class
4 Hunts
4 Black Swans
The position re subs was unknown at that time.
And there was also a new Royal Yacht in the mix!!!

On 15 Aug 1939 Sir Stanley Goodall noted in his diary that the Controller of the Navy wanted:
4 BB
2 carriers
4 Heavy 8" cruisers
6 Small cruisers
PER YEAR!!!

I've already talked in this and earlier posts about what happened on the outbreak of WW2 so won't repeat it here. But in the latter part of 1939 there is a huge amount of chopping and changing, plans made, plans changed. Even ships already building or planned were being affected with completion dates pushed back.

So in Jan 1940 the 1940 Programme now looked like this as a plan only:-
2 Lion class
New 15" gun BB
2 carriers (a new assessment was that the fleet now needed a total of 14/15)
5 Belfast type cruisers
5 Dido class cruisers

Of that little lot the only survivors as actual orders were the 15" BB in the shape of Vanguard and 1 carrier, tentatively named Irresistible, intended as a modified Implacable. Space for the carrier in the Programme could not be found and its design was further modified in the light of war experience and eventually ordered in March 1942. Then in late 1942 it was decided to build her as the third unit of the Audacious class (Audacious & Eagle had been ordered in May & Aug 1942 respectively). She was finally laid down as Ark Royal iv in May 1943. (In 1945 Eagle was cancelled and in 1946 Audacious became Eagle).

So the final 1940 Programme and its Supplementary partner included:-
4 flotillas (32 ships) of Intermediate destroyers
18 Black Swan class sloops
30 Hunts
9 T class subs
20 S class subs
22 U class subs
3 minelaying subs of a new class cancelled 7/41
30 Flower class corvettes (6 cancelled 1/41)
27 River class frigates (design began around 10-11/40)

Pre WW2 there was a need seen for a trade route carrier and the 1936 tentative building plan incuded 1 per year 1936 -1940. There were also plans drawn up for conversions of fast cargo liners to fill the role (these proved too valuable in other roles in WW2). But beyond some plans set out in Friedman's "British Carrier Aviation" book they came to nothing. RN plans for mid-1939 looking forward to war in either Europe or the Far East in 1942 show Hermes, Courageous & Glorious seemingly in the role (the latter pair with only 24 aircraft).

A 1938 a policy document set out the RN carrier requirement and it was revised in Jan 1940. The numbers of carriers required in each case was 14 but there was a change in emphasis. Figures are for 1938 and 1940:-

Home waters - 4 / 2 (minimum, or 3)
Med & Far East - 4 / 4
Trade routes - 5 / 7
Gunnery co-operation training - 1 / 1 (Argus)
Total - 14 / 14 (or 15)

And in Jan 1940 the carrier fleet consisted of:-

Argus (training carrier)
Furious
Eagle
Hermes
Glorious
Ark Royal
Building - 6 armoured carriers (3 expected in 1940, 2 in 1941 & 1 in 1942)

So at that stage the fleet was considered to be 2 short. Of course it would only have been 1 short but for the loss of Courageous. This may be how the 1940 Programme was originally being looked at. IIRC the next time this exercise was carried out it was 1942 and the number of carriers had reached huge numbers, leading to the large numbers of the Colossus / Majestic classes being ordered in 1942 as well as 3 Audacious class (2 light fleet carriers being deemed the equivalent of 1 fleet carrier). But that was with 3 years of war experience off Norway & in the Med.

Unicorn's intended role has been much misunderstood. She was designed as an aircraft maintenance ship ( a depot ship for aircraft if you like) with the ability to be used as a training carrier. She had much more in the way of workshop spaces than any normal carrier would require. But it was the shortage of carriers that caused her initial use in 1943 to be as an operational carrier, for which role she was not ideal (Seafire pilots on her at Salerno have described the experience of landing on her as like dropping off a cliff due to the poor airflow around the aft end of her flight deck). By the end of the year she had been refitted to fulfil her original role and sailed to the Indian Ocean to support Illustrious and her air group in the IO. AFAIK there were never any planned follow ons for her. When more aircraft maintenance ships were seen as being needed to support IO/Pacific operations in 1943, 2 of the Colossus class hulls were converted to emerge 1945/46 as Pioneer & Perseus.

By 1941 the trade protection threat had evolved from chasing raiders to protecting convoys in the Atlantic against submarines and aircraft. The soluion to that was then seen as the escort carrier. The first, Audacity, was converted 1-6/1941 and was lost before the year was out. 6 were ordered from the USA in 1941 under Lend Lease. And from there the fleet expanded.

 

[ThomasP]

re the sea keeping ability of RN ships

For the most part the post-WWI through WWII RN ships were more capable of handling heavy seas and bad weather than the other combatants. Having to operate in the North Atlantic and North Sea required relative high design standards for ruggedness and sea keeping/handling. Post-war the USN adopted some of the Admiralty standards, while the UK continued to refined the pre-war standards through to current times.

This is an oversimplification, but basically the RN designed their fleet combat ships (regardless of size) to handle a minimum sea state, while the USN based their maximum sea state capability on the size of the ship. The RN minimum required sea state was ~equal to the maximum sea state required of the largest USN ships. The IJN ship seakeeping standards were somewhere in between the RN and USN.

I have never been able to find the standards for the KM so cannot comment on their standards.

 

[EwenS]

Southampton and followers 10 ships
1937-39 completion dates. About 9100-10,550 tons 32-32.5ts
12 X 6in guns, 8 X 4in AA guns, 8 X 2pdr AA (by the spring of 1942)some smaller, 6 X 21 tubes.
View attachment 733395
Some lost X turret to fit more AA. Belfast and Edinburgh both got a lot heavier armor and 12 X 4in AA guns and quintuple 2pdr AA mounts. There was no sense keeping to the treaty limits at this point. Originally 3 aircraft but they traded aircraft for more AA as the war went on. Again note the somewhat more powerful AA armament compared to the Japanese ships. The USS Wichita completed at about the same time had 8 5in/38s with the 5 gun broadside.

Octuple 2pdr mounts

The Edinburgh group did seek to comply with the Treaty limits as built. Laid down in 1936 they used up the last of the tonnage available to Britain under the 1936 London Treaty after allowing for planned scrappings etc. They were designed to a standard displacement of 10,000 tons but came out about 10,500 tons on completion. Not a margin that anyone worried about.

But in Nov 1939 Belfast was mined in the River Forth by a magnetic mine and required a total reconstruction that lasted 2 years. She emerged from that process with bulges amongst many other changes, that increased her standard displacement to around 11,600 tons.

Most of the cruisers heading for the Far East in 1944/45 were making main or secondary sacrifices to gain additional light AA outfits which varied from ship to ship while maintaining their stability. The folowing lost X turret in the process:-

County class - Devonshire, Sussex & Norfolk (no plans for the RN Kents due to their age). HMAS Australia had a refit in the UK in 1945/46 and lost her X turret.
Leander class - Achilles & Leander (Hobart was found to have sufficient stabilty to gain extra AA and keep X turret)
Towns class - Glasgow, Sheffield, Birmingham & Liverpool. Newcastle was next in as the war ended and lost the turret but it was a few years before the extra AA was added.
Belfast - kept all her main turrets but lost the after pair of 4" mounts instead
Dido - Phoebe (from completion), Argonaut, Euryalus & Cleopatra all lost Q turret. Dido's late 1945 refit to the same standard was cancelled. The modified units all completed with 4 turrets.
Colony - Kenya, Bermuda, Jamaica & Mauritius all lost X turret leaving only Nigeria & Gambia as 4 turret ships at the end of the war. The 3 modified units were completed to a 3 turret configuration.

 

[EwenS]

I think we can assume that the UK would have built up the overseas manufacturing capabilities to a greater extent than in the OTL, but how far was possible the practical sense is a very big question to my mind.

This is something that most in the US do not understand, believing that the "British Empire" is some single entity run from London. That was far from the truth.

It was not up to Britain to build up the "overseas manufacturing capabilities". The Dominions were self governing entities courtesy of the Balfour Declaration of 1926 at the Imperial Conference and the subsequent 1931 Statute of Westminster which each Dominion applied in slightly different ways and times in their own legislation. So Britain could suggest / encourage the Dominions to increase defence spending, increase manufacturing capabilities etc but it could not dictate to them to do it or simply spend its own money on their territory. And this was one of the problems with Australia in particular. Inter-war it didn't want to spend money on its own defence, preferring to rely on Britain to do it for them. At least that was the case until around 1938.

When it came to the Washington Treaty in 1922, while the British Empire was treated as a single entity (no one in the world at the time would have accepted anything less), and a British representative signed on behalf of the King there were also signitories from most of the Dominions as well. Same thing happened with the 1936 London Treaty.

 

[Juha3]

...Sure, but if we are talking about British made tanks and artillery, there are some limitations. Cruiser tanks with 2 pounder guns (no HE) and Matilda infantry tanks with the same, are not necessarily going to pose a huge problem for the Japanese.

View attachment 733390
Type 97 Chi-Ha looks like a pretty challenging opponent for an A13. They did pretty well at Khalkhin Gol against similar BT-7, and they were used with success in Malaya and Singapore, and in the Philippines where they outgunned the US M3 light tanks. They built over 1,000 of them.

The type 13, type 91 or 96 howitzers looks pretty good to me compared to the 25 pounder. The type 92 cannon looks downright scary.



I see the point, I think the Japanese were ready though.

Sorry but the tank in the photo is in fact Type 97 Shinhōtō Chi-Ha, armed with a 47 mm cannon, max armour 33 mm (turret front), otherwise 20 - 26 mm. Its contemporary was A15 Crusander III, armed with 57 mm cannon and max armour 51 mm (turret front), otherwise 20 - 40 mm.

 

[ThomasP]

re building up the industrial capabilities of the Commonwealth/Dominion countries

Hey EwanS,

I am assuming that the build-up of industry would have to originate from the UK since they controlled 90%(?) of the Empire's discretionary wealth in one way or another. As far as I know Australia had no independent native ability to quickly build its industry base to any degree that might be needed. Even with the impetus of WWII, Australia was very limited in what it could do/managed to do. (No insult to the the Australians, they were limited by population base and pre-existing investment in the industrial sectors.)

As an aside, are you saying that if the UK had tried to invest (in a big way) in the build-up of industry in Australia during the mid- to late-1930s, under a perceived threat of war with Japan, that Australia would have refused (or could have refused in a practical sense)?

 

[Shortround6]

Octuple 2pdr mounts

You are correct, brainfart. I will correct.
Thank you.