A Royal Navy for the Far East 1942 Onwards

[Siberia]

For the UK, the submarine flotilla wouldn't have been pulled from Singapore, giving much better reconnaissance of Japanese harbours.

Having the T class boats available is going to create some major changes as they were one of the main legs of what the UK was expecting to use to counter Japan. IIRC the Royal Navy some war games post-war to look at how things might have gone and it was not good for the Imperial Japanese Navy.

 

[EwenS]

Having the T class boats available is going to create some major changes as they were one of the main legs of what the UK was expecting to use to counter Japan. IIRC the Royal Navy some war games post-war to look at how things might have gone and it was not good for the Imperial Japanese Navy.

In Sept 1939 the 4th Submarine Flotilla based in Hong Kong and Singapore had 13 O/P/R class built in the late 1920s / early 1930s specifically for action against the IJN. There was also 2 Porpoise class minelying subs with another en route (it was turned back to Britain on the outbreak of war in Europe). They had the use of the depot ship Medway which refitted at Singapore 1939/40. All these vessels were withdrawn from the Far East between 3 Sept 1939 and the outbreak of war with Italy in June 1940.

The T class were the intended successors to the O/P/R classes. The first vessel Triton was ordered under the 1935 Programme and completed in Nov 1938. Only 3 completed before the outbreak of WW2 with another 4 by the end 1939, 7 in 1940 and 6 in 1941. These were from the 1935, 1936, 1937, 1938 and 1939 War Programmes. Broadly enough to replace the O/P/R classes on a one for one basis. But 5 were lost before war with Japan broke out.

The next subs in the Far East were 2 T class dispatched from the Med to Ceylon in late Dec 1941 and early Jan 1942.

 

[DWG]

Having the T class boats available is going to create some major changes as they were one of the main legs of what the UK was expecting to use to counter Japan. IIRC the Royal Navy some war games post-war to look at how things might have gone and it was not good for the Imperial Japanese Navy.

Even without the Ts on top, the South China Sea was the environment the Odins, Parthians, and Rainbows were designed for, and in this scenario 4th Submarine Flotilla would have remained on station.

 

[NOMISYRRUC]

Part of Post 62.

At some point I must work out how many FAA units there might have been in 1942 based on peacetime plans. I have a sneaky feeling there would have been more spaces in carriers than the FAA actually had units to equip them.

The Number of Aircraft

504 first-line aircraft in the equivalent of 42 squadrons by 31st March 1942 according to RAF Expansion Scheme F of 1936, which was approved by the Cabinet on 25.02.36.

Page 369 of "Grand Strategy, Volume 1, Rearmament Policy" says the FAA was to have a total of 1,954 aircraft on 31.03.42 as follows:

• 490 first-line aircraft;
• 490 aircraft Immediate Reserve (IR) - that is 100% of the first-line strength;
• 490 aircraft War Reserve (WR) - that is 100% of the first-line strength;
• 484 aircraft for training purposes.

They would be operated by 8,700 RN personnel, excluding reservists and trainees.

IIRC (and I'm confident that I do) the 504 first-line aircraft were to consist of 360 carrier aircraft in 30 squadrons and 144 catapult aircraft in the equivalent of 12 squadrons. Unfortunately, I don't remember where I read it, so I can't quote the source.

However, I do have copies of Cabinet Papers from late 1937, saying that the RN had increased its requirement to 650 first-line aircraft in 50 squadrons, which I think is a rounding of 648 aircraft in the equivalent of 54 squadrons. That's because the same documents say the previous scheme was for 500 aircraft in 40 squadrons, which is obviously a rounding of 504 aircraft in the equivalent of 42 squadrons.

Unfortunately, the Cabinet Papers don't say what the mix of carrier and catapult aircraft was. I don't know what the required number of backing aircraft was either. However, based on the previous scheme it would have been 650 IR, 650 WR and 650 for training for a grand total of 2,600 aircraft.

The Types of Aircraft

The Air Branch (which was the official title of the FAA between 1939 and 1952 IOTL) would have been stuck with the types that were in service or about to enter service in September 1939 IOTL. Therefore, the fighters would have been Fulmars, Rocs, Sea Gladiator and Skuas, the strike aircraft would have been the Albacore and Swordfish and the catapult aircraft would have been the Walrus.

There would have been no combat experience between September 1939 and December 1941 to tell the Admiralty that its doctrine was faulty. So no Sea Hurricanes & Seafires.

Furthermore, as the British Aircraft industry wasn't overloaded due to not being at war for the previous 27 months and having to give priority to the needs of the RAF, no American carrier aircraft like the Martlet/Wildcat.

IOTL the first flight dates of the next generation of naval aircraft were;

27.02.42 Blackburn Firebrand.​

22.12.42 Fairey Firefly.​

29.06.41 Fairey Barracuda.​

06.02.43 Supermarine Type 322 "Dumbo".​

23.09.38 Supermarine Sea Otter.​

Firefly and Firebrand were intended to replace the fighters, the Barracuda and Albacore was intended to replace the Albacore and Swordfish, the Sea Otter was intended to replace the Walrus. ITTL the Sea Otter probably comes into service before 07.12.41 and I've no idea how 27 extra months of peace effects the development of the others. All I can say with some confidence is that the Barracuda probably goes into service with the Exe rather than the Merlin.

 

[EwenS]

June 1939 Minutes of meeting held by Fifth Sea Lord responsible for Naval Aviation.

Fairey Hayes - Swordfish to be followed by Albacore with production of 400 of the latter expected to complete by Aug 1941.

Fairey Stockport - Fulmars commencing about Nov 1939 and completing about March 1941, to be followed immediately by S.24/37 (Barracuda). Latter expected to complete by April 1942.

Supermarine Woolston - Walrus expected to complete by Jan/Feb 1940. To be followed by Sea Otter completing Jan 1942.

Production rates expected to be Fulmar, 20 per month, Swordfish, Albacore & Barracuda 35-40 per month, Walrus / Sea Otter, 8 per month. In war Air Ministry expected rates could be doubled.

At that point the new fighters were being designed to Specs N.8/39 (two seat fighter replacement for Fulmar) and N.9/39 (turret fighter replacement for Roc). All change in Dec 1939 using war experience to date. Result - selection of Firefly in early 1940 & single seat Firebrand. Latter was being driven by need to defend RN shore bases as the RAF were otherwise engaged after outbreak of war.

 

[NOMISYRRUC]

Link to the opening post.

For what it's worth I think His Majesty's Government would still be aiming for the following fleet by the middle of the 1940s.

82 Submarines (of which 7 could be over-age).​

20 Capital Ships.​

14 Aircraft Carriers.​

100 Cruisers (of which 15 could be over-age).​

22 Destroyer Flotillas (of which 6 could be over-age).​

226 Minor War Vessels.​

That was the "Two-Power Standard Fleet" of April 1937 that the Admiralty thought was required to fight a war against Germany and Japan at the same time and includes the naval forces of the Dominions and India as well as the Royal Navy proper.

 

[NOMISYRRUC]

This is how the requirement for 20 capital ships was calculated.

Capital Ship Strength.
6. Japan at present possesses 9 capital ships to our 15, and after 1940 her strength will become uncertain as she will probably not scrap any of her existing capital ships when she completes new vessels, which she can lay down after the 31st December, 1936.

7. When operating in the Far East our ships are far from their main repair facilities and sources of supply and have only the facilities of Singapore to rely on. The Japanese fleet, on the other hand, has its full home country resources available close at hand. These facts in themselves are equivalent to an advantage of two capital ships to Japan since at an average moment we could not rely on less than 2 ships being absent.

8. On the other hand, the stakes at issue in the event of a fleet action would be greater for Japan than for us. A British defeat would imperil our interests in the East: a Japanese defeat would imperil her home country. Thus, to achieve our object of acting on the defensive and serving as a deterrent against any threat to our interests in the East it is necessary that our capital ship strength should be such that Japan's chances of obtaining victory in a fleet action would be so slight that she would not seek one. This condition should be achieved if at our average moment we could meet the full Japanese capital ship fleet with a force less in strength than that fleet by one capital ship.

9. When allowance is made for our restricted repair facilities, which are referred to in paragraph 7, it follows that, to avoid at any time being inferior in ships available by more than one capital ship, we must have in the Far East a margin of one ship in excess of the Japanese total.

10. The strength of the German fleet is now calculable, since it is fixed at 35 per cent, of our own. The strategical situation in a future war with Germany must in general be similar to that which prevailed in the last war and while the German fleet would be likely to spend most of its time in harbour the initiative as to when it came out to dispute our control would rest with Germany. It follows that, as in the last war, we must be ready at our average moment to meet the German fleet at its selected moment. Home waters being our vital area in a way that the Far East never can be, it is essential that this margin shall be sufficient for all contingencies. The margin is composed partly of the superiority necessary to give reasonable certainty of success in battle and partly of that necessary to maintain our normal programme of docking. The proper minimum to meet these contingencies is a superiority of 3 ships.

11. The German capital ship fleet does not, unfortunately, correspond numerically to an exact 35 per cent, of our own, since its size is calculated on a total tonnage basis and the earlier German capital ships built and building are less than the maximum unit size. Thus, while our strength remains at 15 capital ships, 35 per cent, ought to give Germany only 5 ships. She will in fact have 6, assuming that the 3 " Deutschland " class are ultimately replaced by one large ship.

Thus, our capital ship strength in Home waters should not be less than 9 ships to six of Germany.

12. When this force is added to the force required in the Far East to meet the existing Japanese strength, we arrive at a total of 19 capital ships. This total would automatically allow Germany a further increase to 7 capital ships, which in its turn raises our number to 20.

13. With the proposed new standard it is clear that as the German strength is fixed at 35 per cent, of our own, both our strength and that of Germany will progress in proportion to the Japanese strength.

14. The capital ship strength required can be worked out mathematically, but, for practical purposes, our requirements to meet the conditions detailed above can be expressed as "1½ times the Japanese strength + 6 ships," or, in tabular form, as follows : —

​

Source:

• "APPENDIX TO ENCLOSURE - Calculation of the Size of Fleet required under the Proposed New Standard of Naval Strength".
• The enclosure being a Memorandum by the First Lord of the Admiralty called “A New Standard of Naval Strength”.
• Which was an enclosure to the Cabinet Paper, “Defence Expenditure in Future Years – Interim Report by the Minister for Co-Ordination of Defence”, dated 15th December 1937.
• National Archives Catalogue Reference: CAB/24/273 Image Reference: 0041

 

[NOMISYRRUC]

This is how the requirement for 14 aircraft carriers was requested.

Aircraft Carrier Strength.
15. The functions of naval aircraft are both strategical, such as reconnaissance for the fleet or for vessels operating in direct defence of trade, and tactical, such as attack on enemy vessels with torpedoes or bombs, observation of the gunfire of their own fleet, laying smoke screens, and attack on enemy aircraft.

Without aircraft a navy would be at a great disadvantage if opposed to a navy which possessed aircraft, but, apart from this, the existence of land aircraft, including possibly airships, capable of reconnoitring for enemy vessels to a considerable distance off the coast and attacking them when located renders the provision of naval aircraft a necessity in order to enable a Naval Power to carry out operations near an enemy's coast.

16. Although many countries, including ourselves, are fitting capital ships and cruisers to carry several aircraft, this method cannot provide either the numbers or types necessary, nor would it meet requirements in other respects, since the aircraft that have to be catapulted off ships may not be able to be recovered.

The aircraft carrier, designed primarily to enable aircraft to be operated from her as a floating aerodrome, is consequently an essential requirement in a modern fleet.

17. During the last 15 years our aircraft carrier tonnage has been limited by treaty, and the limits accepted allowed only for the maintenance of the aircraft carriers required for work with the Main Fleet with only a margin of possibly one ship for other duties. It has consequently not been possible for the Admiralty to provide aircraft carriers for employment on the trade routes to assist our cruisers and armed merchant cruisers in the protection of trade. Plans have been drawn up for the conversion of merchant ships into aircraft carriers after the outbreak of war, but this work would take about 12 months to complete.

18. With the end of quantitative limitations it is possible to give consideration to the construction of aircraft carriers for trade protection, and £2,060,000 was included in the new construction estimates put before the D.P.R. (D.R.) Committee (D.R.C. 37, Schedule 1, Appendix 1) for this purpose. The question of the possible reaction of the building of these vessels on our cruiser requirements is dealt with in paragraph 38 below.

19. Consequently, our aircraft carrier requirements must now be divided into those for work with the Main Fleet and those for trade protection.

20. Japan has 4 aircraft carriers built, 1 building and 2 projected. She also possesses 2 seaplane carriers built and 3 building or projected. In her own waters she has the great advantage of a chain of air bases in her islands which would enable her to keep a very large area under observation by shore-based air reconnaissance.

21. For offensive operations against Japan it would therefore be necessary for our fleet to possess a sufficient number of aircraft carriers. For the defensive role visualised in the new standard of naval strength, which need not necessarily involve operations near to Japan, it will only be necessary to provide our fleet with the carriers needed to maintain an adequate reconnaissance and a striking force of reasonable strength. It will also be necessary to make due allowance for docking and refit. It is considered that 4 carriers would meet these requirements.

22. In Home waters, Germany will be allowed 35 per cent, of our total carrier tonnage. Although we expect some assistance in the North Sea from shore-based aircraft, this is equally true of Germany, and it is not unlikely that the opposing land-based air forces will tend to some extent to cancel one another out so far as naval operations are concerned. It would not therefore be safe to accept an appreciably weaker carrier force with the Home Fleet than that possessed by Germany. To avoid this, provision is needed for not less than 4 aircraft carriers in Home waters.

23. The number of carriers suggested for the two main fleets must be regarded as tentative. By arguing on theoretical lines it is possible to arrive at much higher totals, and, if in the coming years all the claims now being made for aircraft are substantiated, it may become necessary to provide for greater strength in carriers. Alternatively, technical progress in aircraft may enable shore-based squadrons to perform some of the fleet duties for which we rely at present on carriers. Another factor the significance of which remains to be proved, is the adoption by the British navy of armoured carriers. The immediate effect of this is to give us only half as many aircraft for a given tonnage as are obtainable using carriers of the unarmoured type.

24. The use of carriers on the trade routes is a matter in which little experience is yet available, but a minimum of 5 is suggested herein for operations in conjunction with our cruiser forces. This number of 5 must remain open to review, and experience will very probably show that one aircraft carrier per cruiser squadron operating on trade protection work is required. It is hoped that by the building of these aircraft carriers for trade protection, an economy in the number of cruisers required can be effected.

25. In addition to the above, at least one large aircraft carrier must be retained for training duties in both peace and war. This vessel can be over-age.

​

26. The position is complicated, however, by the fact that we shall possess for many years a number of unarmoured carriers, which, though not at all satisfactory for fleet work, have a good aircraft capacity and cannot reasonably be discounted. They will include the Ark Royal, which is not yet complete and which will carry no less than 72 aircraft. It is accordingly proposed to accept 12 carriers, for whom aircraft and personnel shall be provided, and to retain 3 of our existing carriers in reserve at long notice. No personnel or equipment will be provided for the latter, but they will be available to bring forward in the event of war.

It comes from the same source as the calculation of capital ship requirements in Message 87.

 

[NOMISYRRUC]

This is how the requirement for 100 cruisers was calculated.

Cruiser Strength.
27. The need for a large number of cruisers is no new requirement, and it is not based on the imminence of a war threat, as may be seen from the numbers which we have possessed at various periods in the past, e.g.

​

28. For a war against Japan or against a single European Power, our cruiser requirements have, on many occasions in the past, been stated to be a minimum of 70, and then only on the assumption that arrangements have been made for the rapid conversion of a number of merchant ships (74) to armed merchant cruisers on the outbreak of war.

This requirement of 70 has been made up of:—

25 for work with the Main Fleet.​

45 for control of trade.​

The figure of 25 has been arrived at by the need for equality with the enemy cruiser strength in the war area (since the enemy at his given moment may always concentrate his cruisers with his fleet) and the strength of the battle fleets.

It has also been assumed in these past calculations that the Japanese cruiser strength would be subject to agreed quantitative limitation.

The figure of 45 for control of trade has been based on the assumption that a serious threat to our trade is unlikely to arise in more than one ocean at the same time.

29. Under the new standard of naval strength the assumptions on which both the above figures were based require revision. Firstly, two enemy main fleets now have to be taken into account, and, secondly, a serious threat to our trade may arise simultaneously in the Atlantic and in the East, as Germany and Japan, situated at the opposite sides of the earth, may both concentrate on attacking it.

Cruisers with the Main Fleets.
30. The cruiser strength required with a battle fleet is dependent partly on the size of the fleet, and partly on the enemy's cruiser strength. Japan has at present 33 cruisers and she may increase this number in the future. To enable our battle fleet to act in the Far East as required by the new standard of naval strength we can accept a somewhat smaller cruiser strength than that which would be required for "an offensive strategy against Japan, and so long as Japan does not add to her present numbers, a strength of 25 cruisers should be sufficient.

Included in this strength is a small margin to allow the undertaking of small offensive operations with a view to causing dispersal of Japanese forces.

31. It is difficult to know exactly what Germany's intentions with regard to cruiser building are, as there is provision in our agreement with her for a certain transfer between various categories. It appears reasonable, however, to assume that Germany may have 20 cruisers in all in 1942. Thereafter she has the right to increase further if and when we exceed 60 under-age cruisers. Even if no transfer from other categories takes place, Germany could have 35 cruisers if and when we reach the proposed new total of 100 (see paragraph 39 below).

32. Until we know what Germany will build it is not practicable to make an exact estimate of the cruiser strength we shall require with the fleet in Home waters in a future war with that country, but the number of 30 is assumed for the present, and is certainly not excessive when the need for refits and dockings and the experience of the Great War are borne in mind.

33. The total strength required with the main fleets in war areas may consequently be estimated as:—

​

Cruisers for Control of Trade.
34. Cruisers and other vessels employed on the control of trade may be employed either as convoy escorts or on patrol of focal areas, &c, where the threat of attack is not such as to call for convoy. In addition, in each area certain cruisers will be required to operate against enemy trade and to round up enemy raiders.

35. Further, in certain areas the convoy escorts may have to be vessels with a specially powerful A/A armament to protect our shipping from air attack in the event of an enemy adopting unrestricted warfare from the air, against which there is at present no international agreement to correspond with the rules for the conduct of submarine warfare contained in Part IV of the London Naval Treaty.

Even if agreement is reached on this subject in the future, it will remain a potential menace, and the Admiralty are, therefore, taking steps to equip a proportion of our cruisers with the necessary special A/A armament.

36. The number of 45 cruisers for trade work, which has been put forward in the past took no account of the need for A/A escorts, and assumed that convoy would only be required in one ocean at a time, e.g., in the Indian Ocean. (The method of protection by convoy requires considerably more ships than that of patrol, but, of course, affords better protection.)

37. Under the new standard of naval strength it is necessary to make provision against an attack on trade by Germany and Japan at the same time.

This would necessitate putting convoy into force in both the Indian and Atlantic Oceans. On the face of it this would clearly call for far more than the 45 cruisers required for the Japanese threat above. Exactly how many more is, however, difficult to assess, because the estimate of 45 allowed for 10 cruisers in the Mediterranean and home waters, which latter become merged in the large force of cruisers allocated to the Home Fleet under the new standard proposals.

38. It is hoped, moreover, that the provision of aircraft carriers to co-operate with the cruisers on the trade routes will lessen considerably the chance of a hostile raider escaping detection. This, in turn, should mean that fewer cruisers will be needed to safeguard a given area. Pending more accurate knowledge of the efficiency of a combination of cruisers and carriers on the trade routes (which is to be tested by special exercises), the Admiralty are prepared to accept the same figure of 45 cruisers for trade protection as was originally contemplated for war with Japan alone.

39. The total cruiser strength necessitated by the new standard of naval strength is, therefore, as follows:—

​

40. Of this total of 100 it is considered that approximately 15 could be over-age, leaving 85 under-age cruisers to be maintained. Ultimately, this would involve an annual building programme of 4 ships, with a 5th ship every leap year.

This comes from the same source as Messages 87 and 88.

 

[NOMISYRRUC]

This is how the requirement for 22 flotillas of destroyers was calculated.

Destroyer Strength.
41. Our total destroyer requirements can be divided into those which form part of the Main Fleet and would be employed tactically with the fleet in battle, and those employed on local defence, escort or patrol work. The former must all consist of under-age destroyers, but a proportion of the latter, particularly those employed on local defence and A/S escort, can be over-age vessels.

Requirements for the Eastern Fleet.
42. As explained in paragraphs 6-14, Capital Ship Strength, a battle fleet of 10 ships is visualised in the Far East. About 5 flotillas would ordinarily be required for tactical employment with a fleet of this size, but, as with cruisers, the actual destroyer force needed is partly dependent on that of the enemy.

Since Japan has 75 destroyers (i.e., 8½ flotillas by our reckoning) building and projected exclusive of over-age vessels, it is considered that we should need not less than 7 flotillas in the East for employment with our fleet. This is a reduction of 2 flotillas on the force that has been assumed in previous calculation to be required in a Far Eastern war, a reduction that is justified by the definition of the new standard of naval strength wherein it is stated that "the fleet in the Far East should be fully adequate to act on the defensive and to act as a strong deterrent, &c." Of these flotillas, 2 should be of the new "Tribal" type which is being developed for the purpose of strengthening the gun power of the flotillas, and it has been calculated is a sufficient set-off against the 23 destroyers of the ''Fubuki'' type in the Japanese fleet.

43. In addition, 2 flotillas must be allowed for A/S duties or escort work in the Indian Ocean and Malacca Straits for the protection of important convoys of fleet oilers and supply ships which might be the object of Japanese submarine attack.

44. Our minimum destroyer requirements for the Eastern area are, therefore, as follows:—

​

Home Waters.
45. The Home Fleet is expected to comprise 10 battleships for employment with which we need 5 modern flotillas. For the present it is assumed that these flotillas will all be of the ordinary type, but since Germany is, at present, building destroyers of 1,625 tons armed with 5-inch guns, the situation will require watching so as to ensure that the gun power of the fleet flotillas does not become greatly inferior to that of a possible German destroyer force that may operate with their battle fleet.

46. For patrol services in the North Sea and Dover Straits we require a force of 4flotillas of which at least 2flotillas should be of the "Tribal" or "J" type, so as to give superiority over the destroyers now being built by Germany. If Germany continues the construction of large destroyers it might be necessary that all 4 flotillas should be of the "Tribal" type, since the services on which they would be employed would be principally of the type of fighting that occurred in the Dover patrol and Harwich forces during the European War. For other local defence, escort and patrol work in the channel and the approaches to the British Isles, and for the protection of transports and important fleet communications, another 3flotillas of over-age destroyers would be required.

47. The calculation of the A/S forces required for the protection of our trade cannot be based solely on the size of the enemy submarine force that may attack it. It was demonstrated during the last war that, if unrestricted attack is embarked upon, the most effective protection is to use these forces as escorts in a general convoy system and thus make the submarine come to the A/S vessel.

If the severity of the attack is sufficient to require the organisation of a general convoy system, the minimum number of escort vessels required is dependent directly on the number of convoys to be escorted. It is estimated that over 100 A/S escort vessels are required for a complete convoy system in Home waters, the Atlantic and Mediterranean.

48. Although Germany has adhered to the rules for submarine warfare contained in Part IV of the London Naval Treaty, 1930, we cannot rely for our security on her observance of these rules, and, further, in conditions to-day air attack on our shipping in home waters is a possibility. The Admiralty are consequently increasing their strength in escorting vessels by converting 4 flotillas of old destroyers for special A/S and A/A duties, but though these vessels will be retained, they cannot be counted as ''destroyers'' when assessing our strength in this type of vessel.

49. Our minimum requirements in Home waters, therefore, are:―

​

50. Our total requirements for Far East and Home waters therefore become:―

​

That is, 22 flotillas in all, of which 16 flotillas should be under-age and 6 flotillas may be over-age.

To maintain this strength involves an ultimate steady replacement programme of 1 flotilla a year.

This comes from the same source as the previous messages.

 

[NOMISYRRUC]

This is how the requirement for 82 submarines was calculated and is from the same source as the previous posts.

Submarine Strength.
51. In all international discussions in the past 16 years we have stated our willingness to abolish submarines and failing abolition our policy has been to keep all submarine fleets down to the minimum, both in numbers and sizes of ships. In advocating this policy the Admiralty have had in mind that, while there are certain duties for which submarines are of great value to us and which they alone can perform, on the wider aspects the existence of the submarine is to our disadvantage, our interest being the supremacy of the surface ship.

All proposals for numbers and tonnages of submarines put forward by the Admiralty in recent years have accordingly been based on the above considerations rather than on our strategical needs for this weapon if it is retained.

52. It is now certain that the submarine will not be abolished nor can we obtain any limit to its numbers. The only thing we can obtain is an assurance (so far as the signed word can give such assurance) that submarines will not again be used in the inhuman manner in which they were used in the great war.

53. It is consequently necessary for the first time for many years to consider our submarine requirements on a strategical basis. The submarine strength required by a country is almost entirely independent of the submarine strength of other countries (i.e., it is absolute, not relative), because these vessels in general act independently and not even in company with one another, and also because the submarine is not the answer to the submarine.

54. Our submarine strength resulting from the policy outlined above was 50 vessels on the conclusion of the Treaty on the 31st December, 1936, and the Admiralty have always realised that this number did not meet our strategical requirement if the submarine was to be retained as a weapon of war-this was the case either on the old or the new standard of strength. The number of submarines required to meet our strategical requirements is examined below.

55. In carrying out this examination the numbers required have been kept down to the minimum because of the reactions of our strength on that of Germany. Though it is very unlikely that Germany would embark on unrestricted submarine warfare again, it is desirable to limit her number as far as possible, especially as she may in certain circumstances have up to 100 per cent of our strength in this category. The estimate which follows is consequently confined to essentials and results in a smaller total than would be desirable on purely strategic grounds.

56. In the Far East with our fleet on the defensive the submarine would be of great value in hampering the freedom of action of the Japanese fleet and obtaining information off the Japanese coasts which could not otherwise be obtained.

57. It is also of great importance that submarines should be stationed in the Far East in time of peace, because they are the only vessels which could operate against the Japanese forces with much prospect of success in the period before the battlefleet reached the East and thereby they could contribute greatly to the security of our bases in that part of the world. (To-day our submarine strength in the East is large in comparison to our surface strength, and it would be larger still had more submarines been available in recent years.)

58. The following submarines are considered the minimum to carry out the role required in the Far East:—

​

59. In Home waters in a war with Germany approximately 7 submarines will be required on continuous patrol in the North Sea, to maintain which a total of approximately 30 submarines is required. Included in this number is a small allowance for special operations as well as routine patrol work.

60. We also require a few submarines of a special type for work with the fleet, and a unit of minelaying submarines is also necessary.

61. In addition, it is essential in war as in peace to keep a number of submarines for training work because of the specialised nature of the training involved—this training is not only in the use of the submarine itself, but in the training of anti-submarine forces which can only be carried out against actual submarines.

62. Our total minimum requirements in Home waters are accordingly:—

​

Of the above, 7 training submarines can be over-age.

63. In addition to the above forces in the Far East and Home waters, it is considered necessary for a small force of submarines to be based in the Mediterranean to meet probable operations in that sea (as was the case in the Great War). These submarines would also form a strategic reserve to proceed to the Far East or Home waters if required. The number of submarines required for this duty is 6.

64. Our total minimum submarine requirements are consequently: —

*******************************************************************************************************************************​

Both London Naval Treaties said that a submarine became over-age 13 years after its date of completion. Therefore, an average building rate of 6 boats a year was required to maintain a fleet of 75 under-age submarines.

That was the end of the appendix to the enclosure. It didn't say how the requirement for 226 minor war vessels was calculated. That was because the enclosure didn't mention the 226 minor war vessels. They came from a different source.