42 Report by Chiefs of Staff Sub-committee of Committee of Imperial Defence on Questions raised by Australian Delegation to Imperial Conference
Extracts LONDON, 9 June 1937
The Australian Delegation has submitted a number of defence questions for consideration at the Imperial Conference. These questions are contained in the following papers:-
Paper No. 1, C.O.S. 580.-British policy in the Far East.
Paper No. 3, C.O.S. 581.-Priority of provision for defence and rate of provision.
Paper No. 4, C.O.S. 582.-Defence against invasion and its reactions on priority.
Paper No. 5, C.O.S. 583.-Defence against raids and its reactions on priority.
Paper No. 5A, C.O.S. 584.-Defence of Port Darwin.
In addition, further questions which need to be considered in conjunction with the above papers are raised in:-
Paper No. 7.-The type of Squadron for the Royal Australian Navy.
Paper No. 8.-Strategical Naval Wireless Stations.
Paper No. 11.-The Royal Australian Air Force-organisation, priority of development and equipment.
2. In the following pages we review the problems raised by the Australian Delegation and formulate our answers to their questions.
BRITISH POLICY AND STRATEGIC OBJECT IN THE FAR EAST
BRITISH POLICY IN THE FAR EAST
3. The Commonwealth Government have submitted a series of questions on the political aim in peace of the United Kingdom foreign policy in the Pacific region. The Foreign Office has drafted answers to these questions; and questions and answers are set out in the following paragraphs:-
4. What are the guiding considerations in British policy for the realisation of the aim of permanent friendship with Japan? What is their relation to the maintenance of British interests in China in view of Japan's penetration in Asia and her claim to a special position in the Far East, which amounts to the dictation of the conditions under which she will co-operate in Chinese or Pacific questions?
His Majesty's Government in the United Kingdom naturally aim at the establishment of the friendliest possible relations with Japan and the adjustment of differences that exist between the two countries, but not at the expense of China or at the expense of their good relations with China, on the maintenance of which British interests depend.
They cannot be openly associated with a Japan that adheres to the policy which Japan has in recent years followed in regard to China. Happily there are signs that Japanese policy has taken a new direction, and His Majesty's Government may therefore now work in a more hopeful spirit for an improvement of the general situation in the Far East.
5. Is the present policy of accommodation to Japan a temporary one pending the strengthening of British defences, and does the United Kingdom Government propose to stiffen its attitude when its rearmament is complete?
His Majesty's Government's hope is for permanent friendship and a harder attitude in the future is not in contemplation.
6. Is the United Kingdom Government prepared to go to war in defence of its interests in China and Hong Kong?
His Majesty's Government in the United Kingdom are certainly resolved to defend to the utmost of their ability British interests in China and Hong Kong. It is, of course, impossible to say beforehand what circumstances or what degree of menace might lead His Majesty's Government to consider that a resort to arms was necessary for their defence.
7. In the opinion of the United Kingdom Government, is the maintenance of the integrity of the Netherlands East Indies vital to the security of Singapore and the scheme of defence of Empire interests that hinges on this base?
The importance of maintaining the integrity of the Netherlands East Indies has recently been emphasised by the Committee of Imperial Defence in the following terms:-
'That the integrity of the Dutch East Indies was a major British interest, but in existing conditions it was inadvisable to announce this'
8. To what degree is British policy in harmony with that of the United States on matters relating to Asia and the Pacific region generally?
General harmony appears to exist, but there is nothing in the shape of a definite agreement apart from the Nine-Power Treaty.
9. If a firm stand is taken, to what extent can the United States be relied on for co-operation in view of- The general American attitude of isolation from the League, even where they may have special interests, as in the Sino-Japanese dispute in 1932-33 ;
The desire to maintain neutrality as indicated by the recent legislation by Congress ;
The independent attitude revealed by their unwillingness to renew Article XIX of the Washington Treaty ?
Nothing specific can be relied upon from the United States of America.
(All the above questions ate contained in paragraph 11 of Paper No. 1.)
BRITISH STRATEGIC OBJECT IN THE FAR EAST
10. The Commonwealth Government asks for a clear definition of the strategical object of the Empire forces in a war with Japan or with Japan and another first-class Power. (Paragraph 13 of Paper No. 1.)
11. In the following paragraphs we outline the policy which should govern the conduct of a war with Japan- (a) When we are at peace in Europe, but must retain in Home waters a Fleet sufficient to neutralise the German Fleet.
(b) When we are already engaged in war with Germany before Japanese aggression occurs.
WHEN WE ARE AT PEACE IN EUROPE, BUT MUST RETAIN IN HOME WATERS A FLEET SUFFICIENT TO NEUTRALISE THE GERMAN FLEET
The basis of our strategy lies in the establishment of our Fleet at Singapore at the earliest possible moment after the outbreak of hostilities. Our own security and our ability to bring pressure to bear upon Japan are equally dependent on this action. It is, therefore, of paramount importance that the Singapore base should be available on the arrival of our Fleet. To ensure this, reinforcements must be moved to Singapore and the security of their routes safeguarded upon any state of tension developing.
In addition, all measures necessary for the security of our defended ports and our air and other routes to the Far East must be put into operation.
Before the arrival of our fleet at Singapore we should, where necessary, rely on evasion for the security of our commerce, and upon local defences for the security of out ports and territories, coupled with operations against the raiders by the forces immediately available. Once our main fleet is in the Far East we should rely on its presence to give adequate security to our communications.
Although our situation at Hong Kong is inherently weak, we should, as long as our policy is to hold the fortress, take any opportunity to reinforce the garrison during a period of strained relations, but not at the expense of reinforcements considered necessary for the security of Singapore.
Although we cannot foretell what the situation will be when the British Fleet arrives at Singapore, it is clear that, so long as Hong Kong is still holding out, the Fleet will be required to go forward either to reinforce or to evacuate the garrison. The decision as to which course of action is to be adopted must be made at the time in the light of all information then available.
The attitude of China will be an important factor in this situation, and we must from the outset take all possible steps to encourage the Chinese in active hostility to Japan. At the same time, we must so restrict our action in China as to avoid any liability of becoming involved in major land and air operations.
We must primarily rely upon the exercise of economic pressure to enable us to defeat Japan. With our Fleet based at Singapore or at any base further north, the restrictions which we could impose on Japanese trade give good prospects of breaking Japanese powers of resistance in the course of two years provided that at the same time we can sever her trans-Pacific trade. To this end, in addition to our naval operations, we should do all that is possible to enlist the sympathy and assistance of America.
A successful fleet action is our only apparent means of forcing an earlier decision. Not only would this give us complete control of sea communications, but the psychological effect on Japan might well be such as to force her to make terms. The decision to seek or decline a fleet action must rest with Japan. Our policy, therefore, should be to seek a fleet action under adequately favourable conditions and, as a corollary, to avoid exposing the fleet to any serious risk of attrition.
While this war will make very full demands on all our naval resources, and may continue for two or three years, the policy which we recommend does not visualise the employment of army or air forces on a national scale.
WHEN WE ARE ALREADY ENGAGED IN WAR WITH GERMANY BEFORE JAPANESE AGGRESSION OCCURS
Our policy for a war against Japan would remain unchanged except in the following respects:-
During the period immediately following the outbreak of war with Germany and before the outbreak of war with Japan, we should immediately avail ourselves of the opportunity of carrying out preparatory measures in the Far East without interference by Japan.
At Singapore we should, during this period, not only put into effect the existing reinforcement plans, but should also increase the reserves of supplies to the maximum extent possible.
We should concentrate our outlying battalions from North China at Hong Kong, but should send there no further reinforcements except those necessary to enable the existing fixed defences to be manned adequately. We should also increase the reserves of supplies at Hong Kong. Although we cannot, in this case, rely on our fleet being able either to reinforce or to evacuate our garrison at Hong Kong once war has broken out with Japan, our policy would still be to hold Hong Kong as an outpost for as long as possible.
Once war with Japan has broken out, our policy must be governed by the consideration that, until the issue with Germany has been settled, we cannot count on being able to support anything more than a defensive policy in the Far East. Economic pressure would remain the essential feature of this policy, but owing to the heavier demands on our naval forces its action is bound to be slower.
EFFECT UPON OUR POLICY OF INTERVENTION OF THE U.S.S.R. OR ITALY
It seems unlikely that Soviet intervention on our side would introduce any serious change in our policy for war in the Far East.
The intervention of Italy against us would at once impose conflicting demands on our fleet.
In this situation our policy must be governed by the principle that no anxieties or risks connected with our interests in the Mediterranean can be allowed to interfere with the despatch of a fleet to the Far East.
DEFENCE AGAINST INVASION
12. The Commonwealth Government asks to be furnished with a strategical appreciation of the danger to Australia of invasion and the defence against same, in the light of the naval situation and the security of the Singapore Naval Base and line of communications thereto:-
(a) For the period up to 1942.
(b) After 1942.
The Commonwealth Government also wishes to know whether, in certain circumstances (the reasonable probability of which might be indicated), it would be possible for Japan to undertake major military operations with an object and on a scale amounting to invasion, against Australia. The probable form and scale of such an attack might be stated. They also wish to know the probable period of warning that might be available for completing preparations for defence after the first obvious indication of a threat of war. (Paragraph 10 (i) of Paper No. 4.)
DEFINITION OF INVASION
13. Invasion implies an attack by a force which is landed with the intention of prolonged or even permanent occupation of the territory invaded, and which is dependent for success on the maintenance of a line of communications.
We, therefore, assume that the invasion of Australia by Japan implies the establishment and maintenance of Japanese military forces in Australia on a scale sufficient to enable them to undertake operations with the object of eventually overcoming all Australian resistance and forcing Australia to sue for peace.
INVASION AND THE NAVAL SITUATION
14. In war, the fate and future of oversea territories has always been decided by the outcome of the war in the main theatre. In a Far Eastern war the fate of British Commonwealth territories in the East will be decided on the outcome of the struggle between the British Commonwealth and Japan for the control of sea communications.
This is a fundamental truth which has not changed, and it has in the past been reflected in the strategic disposition of Dominion navies in war plans.
15. A change has, however, taken place in the scale of preparations and the scale of armaments necessary for oversea expeditions. These are much greater to-day than formerly owing to the greater complications in war material, the more varied composition of armies and the fact that an expedition must be prepared on arrival at its objective to meet and overcome the shore-based air forces of the defence. A large expeditionary force requires to-day a large fleet of ships of all types, and these must be followed by a continual stream of war material. In a Far Eastern war even the Commonwealth of Australia, the Dominion nearest to Japan, is still so far distant that no Japanese Government could face the responsibility of committing a large expeditionary force for service in Australia unless the command of the sea line of communication was assured for a sufficient period to enable the object to be achieved.
In the opinion of the General and Air Staffs an invader must, in addition, be confident of being able, on arrival, to operate air forces adequate to ensure air superiority during the landing and subsequently to protect the expedition and its reinforcements and supplies on arrival at their destination, against action by the air forces of Australia. It is not considered possible to establish such air superiority with ship-borne aircraft against adequate land-based aircraft in so large a country as Australia.
16. A Japanese overseas expedition aimed at Australia may consequently be said to be a highly improbable undertaking so long as our position at Singapore is secure, and the fleets of the British Empire are maintained at such a strength as to enable a force capable of containing the Japanese fleet to be despatched to the Far East, should the occasion arise. We propose, therefore, to examine the question of the strength of the fleet that we can send to the Far East, and the time required for its arrival in that area, in the event of war with Japan.
17. In order to relate our examination to the practical political.
conditions of the world as they exist at present, we propose to consider war against Japan in the following cases:-
(a) When we are at peace with Germany, but must retain in home waters a fleet sufficient to neutralise the German fleet.
(b) If war with Japan breaks out when we, allied with France, are already at war with Germany.
We will then briefly outline the possible effects of intervention by the U.S.S.R. and Italy.
WHEN WE ARE AT PEACE WITH GERMANY, BUT MUST RETAIN IN HOME WATERS A FLEET SUFFICIENT TO NEUTRALISE THE GERMAN FLEET
Strength of fleet for Far East
18. The strength of the fleet that we could send to the Far East must be governed by consideration of our home requirements. In the new standard of naval strength we would aim at:-
(i) Placing a fleet in the Far East fully adequate to act on the defensive, and to serve as a strong deterrent against any threat to our interests in that part of the globe.
(ii) Maintaining in all circumstances in home waters a force able to meet the requirements of a war with Germany at the same time.
NOTE:-Included in (i) and (ii). would be the forces necessary in all parts of the world behind the cover of the main fleets, to protect our territories and merchant ships against sporadic attacks. 19. When considering what naval strength we must retain in home waters as a counter to Germany, we might count on France as an ally in the event of war actually breaking out. In their Annual Review for 1935 the Chiefs of Staff stated: 'Although His Majesty's Government in the United Kingdom would never, we presume, confide the entire protection of this country (i.e., the United Kingdom) and its vital sea communications to a foreign navy in the absence of our main fleet, yet if France were our ally, her naval forces could undertake part of this responsibility. A British capital ship, cruiser and destroyer strength in home waters equal to that of Germany is probably the least we could accept.' On this basis we review below the situation as regards our heavy ship strength vis-a-vis Germany and Japan.
20. The following table shows a provisional allocation of heavy ships between the Home and Far Eastern Fleets during the next three years to meet the increasing German Navy and the nine modernised heavy ships of Japan. The withdrawal for modernising of three of our heavy ships introduces an element of weakness in the situation, particularly from the spring of 1938 to the summer of 1939, but even during this period we can regard our Far Eastern Fleet as at least equivalent in fighting value to the Japanese Fleet.
HEAVY SHIP STRENGTH AVAILABLE TO MEET THE GERMAN FLEET AND NINE MODERNISED JAPANESE HEAVY SHIPS
Period German Fleet Our Fleet at Home Our Far Eastern Fleet Out of action (modernising) Summer 1937 to Spring 1938 3 Deutschlands Hood Repulse 2 Nelsons Warspite (fully modernised) Malaya, Royal Oak (partly modernised) Barham 4 Revenges (unmodernised) Total: 10 ships Renown Valiant Queen Elizabeth
Spring 1938 to Summer 1939 3 Deutschlands 2 Scharnhorsts Hood Repulse Malaya Barham 2 Nelsons Warspite Royal Oak 4 Revenges Total: 8 ships Renown Valiant Queen Elizabeth
Summer 1939 to Spring 1940 3 Deutschlands 2 Scharnhorsts 2 35,000 ton battleships* Hood Repulse Renown 2 Nelsons 3 Warspites Malaya Royal Oak Barham 4 Revenges Total: 10 ships
* 1 at the end of 1939; 1 in the spring of 1940
Although it will be seen from the above table that our battleship strength will be at a low ebb in 1939 compared to Germany and Japan, at no time up to 1940 will we be unable to send a fleet to the Far East; and with the completion in 1940 of five new battleships (already laid down) for this country the period of weakness will be past, provided we retain all our existing ships and the crews to man them.
21. As regards classes of ships other than heavy ships, the numbers available will vary according to the year in which war breaks out. Taking conditions in 1939, we might retain at home two Aircraft Carriers (excluding 1 for training and 1 refitting), six 8-inch and twelve 6-inch cruisers, and four destroyer flotillas.
This would leave available for the Far East and trade protection four aircraft carriers, seven 8-inch and forty-eight 6-inch cruisers and five destroyer flotillas. When the demands for cruisers to work with the fleet have been met, there will be a shortage of cruisers for the protection of our own trade and action against that of Japan. In these circumstances, we shall have to rely largely on the seventy-four armed merchant cruisers to be taken up on the outbreak of hostilities. It appears most improbable that we shall be able to spare any aircraft carriers for operations on the trade routes.
PASSAGE OF FLEET TO FAR EAST
22. As regards the time of arrival of the fleet in the Far East, for the actual passage from home waters and the Mediterranean, the combined Home and Mediterranean Fleets would require 28 days to reach Singapore via the Suez Canal and Malacca Straits. If the Sunda Straits are used, an extra 2 days must be added. If the fleet has to use the Cape of Good Hope route, the passage time would be 45 days. Apart from passage time, however, an allowance of 10 days must be made for preliminary preparations, and is days for possible fuelling delays and weather conditions en route.
Plans for the necessary fuelling arrangements on passage have been made by the Admiralty. Hence, the maximum time that must be allowed for the arrival of the fleet at Singapore is 70 days.
IF WAR WITH JAPAN BREAKS OUT WHEN WE, ALLIED WITH FRANCE, ARE ALREADY AT WAR WITH GERMANY
Our naval situation
23. Our naval situation will be largely governed by the time at which war with Japan breaks out, and the action which the German naval forces have taken up to that time. In the best case, war with Japan might not occur until our naval resources had been fully developed, while German naval forces had acted entirely on the defensive, being held back in the Baltic and North Sea. In the worst case, war with Japan might occur before our naval resources had been fully developed, while German naval forces had assumed a vigorous offensive against our trade in the Atlantic, and possibly elsewhere. The time at which we can send a fleet to the Far East, and its strength, will depend upon the conditions which have actually arisen. Again, as shown in paragraphs 20 and 21 above, the year in which war breaks out will also determine the allocation of naval forces between the European and Far Eastern theatres. We are thus faced with many varying factors, and can only endeavour to make some general deductions.
24. To take a probable situation in the European theatre, our naval forces may be operating at strength in the Atlantic, considerably dispersed. French battle cruisers may be assisting in these operations, while a proportion of our heavy ships may be assisting with French African convoys. If, in these circumstances, we have to deal with Japan, a very considerable period may elapse before the progress of our operations against Germany and the redistribution of our forces permit of a fleet arriving in the Far East.
25. Thus, the strength of the fleet for the Far East, and the time within which it would reach Singapore, must be variable factors, dependent both upon naval and political considerations.
Nevertheless, the basis of our strategy will lie in establishing at Singapore, at the earliest possible moment after the outbreak of hostilities with Japan, a fleet whose strength, as a minimum, will enable it to act on the defensive and to serve as a strong deterrent against any threats to our interests in the Far East.
THE PROBLEM OF INVASION FROM THE JAPANESE POINT OF VIEW
26. It may be of value now to examine the problem of invasion as it might appear to Japan. Although in the absence of the British main fleet from the Far East Japan can obtain control of sea communications, she must take into account the possible presence and operations of our China, East Indies, African, Australian and New Zealand naval forces, amounting to seven 8-inch and nine 6- inch cruisers, one aircraft carrier, fourteen destroyers and fifteen submarines (June 1937). So long as these forces, or a proportion thereof, are in being, Japan will have to take adequate naval measures for the security of the passage to Australia of her expeditionary force, and for its maintenance and reinforcement.
This operation to be successful, would necessitate the defeat not only of the Australian army, having in mind the great power of defence in modern warfare, but also the air forces of Australia, which by 1939-40 will amount to a total of twelve squadrons R.A.A.F.
27. To estimate the probable size of the initial expeditionary force sent to Australia from Japan, its point or points of landing, the scale of its reinforcements, and the subsequent military operations in Australia, would demand an extensive appreciation, which might best be prepared by the Australian General Staff and Air Staff. It is noted that the Australian General Staff consider that the Japanese political object might be achieved most readily by the capture of Sydney and/or Melbourne, possibly preceded or accompanied by hostile air attack on those cities. The capture of cities, however, presents a problem of considerable military difficulty, and would not, in our opinion, be of itself necessarily decisive.
28. Without making a detailed appreciation it appears reasonable to assume that Japan would not undertake the initial act of invasion with a land force of less than two divisions as an absolute minimum.
This would necessitate about 400,000 tons of shipping or from 40 to 70 ships. From Japan to Sydney is a distance of 4,400 miles.
From the Pelew Islands, where the force might be assembled, to Sydney is a distance of about 3,000 miles.
In view of our remarks in paragraph 26 above, Japan, despite her initial superiority in the Far East, would be faced with a considerable naval commitment in escorting, maintaining and reinforcing such an expedition.
In view of our remarks in paragraph 15 above, it is clear also that Japan would be faced with a considerable air problem; and if she relied on ship-borne aircraft she could not hope for air superiority.
29. Assuming the successful landing of the expedition in the vicinity of Sydney or Melbourne, Japan would have to establish herself in sufficient depth to build up her forces for her subsequent operations. The length of the communications between Japan and Australia, and the necessity for their protection, militates against the rapid reinforcement of her initial expedition. It is difficult to see how Japan could build up in Australia an adequate force to embark on operations on the necessary scale in any period under six months. In effect, Japan would require to be certain of ample time if she hoped, by means of invasion, to force Australia to sue for peace.
30. Japan, however, can never be certain of being allowed time.
She cannot prevent the passage of a British fleet to the Far East, nor rely on circumstances being or remaining such as to prevent its despatch. With a British fleet established at Singapore, and operating therefrom against the Japanese lines of communication with Australia, the whole position of the Japanese invading forces in Australia would become precarious, unless Japan could decisively defeat the British fleet. It is in the highest degree unlikely that Japan would engage upon operations for whose success she would have ultimately to rely on a decisive victory in a fleet action fought under conditions not of her own choosing and possibly disadvantageous to her.
31. In effect, if Japan wishes to ensure time for the invasion of Australia, she must endeavour to prevent the British fleet from operating in the Far East; one means to this end would be for Japan to capture Singapore. The defence of Singapore has been fully examined, and the main conclusion drawn was that deliberate operations held out the best hope of success for Japan. These, however, required time, and though the possibility of such operations could not be definitely excluded, it appeared unlikely that the Japanese would undertake them even if a 60 to 70 days' delay in the arrival of the British main fleet could be anticipated.
This conclusion was based on the fact that Japan can never exclude the possibility of having to fight a fleet action in the Singapore area in support of her deliberate operations against Singapore;
and, as in the case of the invasion of Australia, Japan would be in the highest degree unlikely to commit her forces to an operation for whose ultimate success she might have to rely on a decisive victory in a fleet action fought under conditions, in this instance, certainly disadvantageous to her.
Even if Japan captured Singapore, she could not absolutely rely on preventing operations in the Far East by the British Fleet, despite the great difficulties with which it would be faced in such circumstances.
32. To sum up, apart from the magnitude of the task involved in any effort to overcome the military and air opposition to her landing and subsequent operations in Australia, Japan, from the strategical point of view, would be unjustified in committing large military and air forces to such an operation unless the British Fleet had first been defeated and largely destroyed.
INTERVENTION OF THE U.S.S.R.
33. The intervention of the U.S.S.R. against Japan would involve Japanese land and air forces in major operations in Manchukuo and the countries round the Sea of Japan. In these circumstances the possibility of Japanese action against Singapore, or to invade Australia, would become even more remote than under the conditions already examined.
INTERVENTION OF ITALY
34. The intervention of Italy against us would at once impose conflicting demands on our fleet. In this situation our policy must be governed by the principle that no anxieties or risks connected with our interests in the Mediterranean can be allowed to interfere with the despatch of a fleet to the Far East.
35. With the naval forces of the British Empire at their present strength, and maintained in the future at the standard laid down in paragraph 18, His Majesty's Government in Australia need not regard the danger of invasion as a real one.
SCALE OF RAIDS AND REVIEW OF PROGRESS IN FIXED DEFENCES
42. The Commonwealth Government asks advice on the validity of assuming the arrival of the British main fleet at Singapore with a minimum delay after the outbreak of war in the Far East.
(Paragraph 10 (iii), Paper No. 5.) Answer
43. This question has been fully covered in Part II of this paper.