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Documents Relating to New Zealand's Participation in the Second World War 1939–45: Volume III

Defence Problems

Defence Problems

13. Our Far Eastern interests are the security of:


Australia and New Zealand.


Malaya and the Netherlands East Indies. Both contain essential raw materials, the control of which at the source is now extremely important. Japanese occupation of either would directly threaten the security of Singapore.


Burma, also of importance on account of its oil resources and in connection with the sea and air communications with Singapore.


Trade routes in the Indian Ocean, the South China Sea and the Western Pacific (north of Australia), and also in the seas east and south of Australia, including the trans-Pacific routes.


The China trade. Considerable British capital is in the China trade, but this trade represents only 2 per cent of total British trade and its cessation would not affect our ability to continue the war.


Hong Kong, which is an all-important commercial harbour and naval harbour and the focus of British interests in China, although its value has already been considerably curtailed by Japanese action in China.


Shanghai, which is important mainly in connection with the China trade. The retention of the British garrison is largely a question of prestige.

14. The territorial integrity of Australia and New Zealand depends primarily on the control of the sea communications to them. A similar consideration governs the security of the British colonies in the Far East. The foundation of our strategy in the Far East is, therefore, still to base on Singapore a fleet strong enough to provide cover for our communications in the Indian Ocean and South-Western Pacific, and to frustrate any large expeditions which the Japanese may attempt against Australia, New Zealand, or Far Eastern possessions. Until, however, we have defeated Germany and Italy or have drastically reduced their naval strength, we should be forced, in the event of Japanese aggression, to attempt to defend our Far Eastern interests without an adequate fleet.

15. In the absence of a fleet, we could not in such circumstances prevent some damage to our interests in the Far East. Our object would, therefore, page 543 have to be to limit the extent of the damage and, in the last resort, to retain a footing from which we could eventually retrieve our position when stronger forces become available.

16. Japan could make the following forces available for new adventures:


Naval—10 battleships, 3 to 7 aircraft-carriers with the necessary cruiser and destroyer forces.


Military—6 to 10 divisions. Japan could make this force, and the shipping required for its transport and maintenance, available without having to carry out any serious withdrawal from her position in China.


Air—Up to 75 fighters and 206 bombers, carrier-borne. Once Japan had established herself ashore, she could dispose of the following shore-based aircraft: Between 8 and 10 squadrons of fighters, similar numbers of light bombers and of heavy bombers, and 4 to 6 squadrons of reconnaissance aircraft, giving a total of 28 to 36 squadrons or 336 to 432 aircraft. These forces are clearly large enough to give Japan a very wide choice of objectives.

17. The first course open to the Japanese would be direct attack on British possessions. In this event, her main effort would probably be directed ultimately towards the capture of Singapore, which would be necessary to secure her position permanently. In view of the traditional Japanese method of step by step advance, it is thought that her first action would be attack on our garrisons in China, including attack on, or at least blockade of, Hong Kong, all without declaration of war. The tempo and extent of her subsequent actions would be conditioned by the ease and success of these operations and their wider reactions; it is even possible that, if reactions were unfavourable, no further adventures would take place.

18. Assume, however, the worst case, in which Japan proceeded with the object of dominating the whole of the Far East. She would have ample naval strength, beyond that required for attack on Malaya, to attack British trade. Our China trade, except for the little that might be carried in neutral ships, would cease on the outbreak of war, and our trade through the Indian Ocean with Australia and New Zealand and across the Pacific would be exposed to the threat of Japanese action.

19. Apart from attacks on trade, no serious threat to Australia or New Zealand would be likely until Japan had consolidated her position at Singapore. Even then, it is unlikely that the Japanese would attempt to invade Australia or New Zealand, at least until they had consolidated their position in China and the Far East, which would take a very considerable time. This argument is expanded later.

20. The strain on Japan of war with the British Empire would be very great, even in the absence of the British Fleet, and probably Japan would hesitate to undertake this unless she felt certain that the United Kingdom was so heavily committed in Europe as to be unable to resist her aggression, or until she had liquidated the China campaign. It is, however, highly important to be prepared for an assault against Singapore and, by increasing our defences, to deter Japanese aggression.

21. The second course open to the Japanese would be penetration of Indo-China or Thailand, which would provide bases for an attack on Malaya and secure substantial rice supplies. Attack on Indo-China or Thailand would not be a formidable undertaking as Japanese action need only extend to seizing bases and aerodromes and controlling focal points in these countries. page 544 It might be effected without the United States breaking off economic relations. We could not effectively assist in the defence of Indo-China or Thailand and it is most unlikely that the Thai Government would oppose Japanese penetration by force, while the French forces in Indo-China could not prevent Japanese occupation of ports and railways. If Indo-China became hostile to us, it is conceivable that Japan might be granted bases in that country.

22. Japanese penetration of Thailand would enable them to establish shore bases for aircraft within range of Singapore, Penang, the Malacca Straits and the Rangoon oil refineries, organise a base for land advance beyond Malaya from the north, interfere with the air-mail route to India and Malaya, and possibly establish an advanced base for submarines and light craft at the northern entrance to the Malacca Straits.

23. The above action would therefore threaten Singapore and make the defence of Burma and Malaya far more difficult. Nevertheless, it would not seriously endanger our vital sea communications, and therefore under present conditions we should not be justified in going to war. For similar reasons we should not under present conditions go to war in the event of Japanese attack on Indo-China. Nevertheless, taking into account the probable reluctance of Japan to make an open breach with the British Empire and the United States, this does not preclude in both the above cases (penetration of Indo-China and Thailand respectively) unobtrusive measures of an economic character designed to retard the Japanese advance by playing on their uneasiness. It is important to try as far as we can to prevent Japan from gaining unhampered one position after another which would increasingly threaten the security of Malaya and our communications with Australia and New Zealand.

24. The third possible course would be attack on the Netherlands East Indies, which would be a more formidable undertaking for Japan than an advance into Indo-China or Thailand. Nevertheless it would probably not involve excessive military effort, especially if undertaken by stages, and occupation would not only provide Japan with an advanced base for a subsequent attack on Singapore but would secure oil and other urgently required raw materials. The possibility of the Japanese seizing Portuguese Timor as a first step to the above action is considered [group mutilated–remote?]. The security of the Netherlands East Indies would be considerably improved if the Dutch could be persuaded to agree to reorganising their defences in co-operation with us.

25. The above course is in a different category from the first and second courses considered above, since if Japan established herself in the Netherlands East Indies, our whole defence system would be most gravely compromised, our vital sea communications and base at Singapore would be endangered, and the air route to Singapore and the Commonwealth would be threatened. The security of the Netherlands East Indies is therefore an essential British interest, second only to the integrity of Australia, New Zealand and Singapore, and their defence is an important part of our Far Eastern defence plans. The establishment of a Japanese foothold in these islands would be so serious that, under normal conditions, the question of war with Japan to prevent it would arise. In the present circumstances, however, we could not prevent it by force, even with the full collaboration of the Dutch. The combination of British and Dutch opposition would, however, be a considerable problem for Japan. (Assumption 3 begins.) Every effort should therefore be made to induce the Dutch to resist any page 545 territorial demands, and we should offer them all possible support, including both military and economic action against Japan. This should be done without the formal declaration of war, since the presentation of a bold front to Japanese demands might cause Japan to draw back. (Assumption 3 ends.)

26. The fourth Japanese course would be the seizure of the Philippines. This would remove the threat to Japanese sea communications to the south which the United States fleet base at Manila provides. It would also afford Japan a suitable advanced base for naval forces and a useful air route from Formosa to Borneo. As, however, this course would involve Japan in war with the United States, and the Philippines would not be of great economic importance to Japan, its adoption is unlikely.

It would appear that, unless Japan is driven to extreme measures by her extremists or tempted by our apparent weakness, she will try to avoid war with the British Empire and the United States, and endeavour to achieve her aims by stages which she might hope would not involve her openly in war. Of these, the move against the Netherlands East Indies would afford greater economic and strategic advantages than the advance into Indo-China or Thailand, but, in Japanese eyes, these might be offset by the prospect of antagonising the United States, even if the consequences were confined to the economic sphere. Moreover, should United States hostility develop, Japan's lines of communication to the Netherlands East Indies would be threatened from the Philippines. Since the Dutch are our Allies, Japan must also assume that attack on the Netherlands East Indies might well involve her in war with us.

27. Therefore, while we must be prepared for sudden attack on the Netherlands East Indies or Singapore, the most probable Japanese first move would be into Indo-China or Thailand, possibly followed later by attack on the Dutch East Indies, if conditions at the time were judged favourable for such action, rather than attack on Singapore itself.

28. Our untenable position in North China in the event of war with Japan has already been recognised by the decision to withdraw our garrisons at Peking, Tientsin and Shanghai.

29. Our position at Hong Kong is different, as this is a British colony. On the one hand, Hong Kong is not vital and the garrison could not long withstand a Japanese attack. Moreover, even with a strong fleet in the Far East, Hong Kong could probably not be held with its present defences now that the Japanese are established on the mainland, and could certainly not be used as an advanced naval base. If, therefore, a general settlement could be negotiated in the Far East, the demilitarisation of Hong Kong with the best obtainable quid pro quo would be in our military interests. Without such a settlement, however, demilitarisation is impossible on account of the loss of prestige which such a course would involve. In the event of war, therefore, Hong Kong must be regarded as an outpost and held as long as possible, but we should be unable to reinforce or relieve it, and militarily our position in the Far East would be stronger without this unsatisfactory commitment.

30. Strategy in the Event of War in the Far East in the Absence of the Fleet.

The sea communications most likely to be threatened are:


Indian Ocean (including the west coast of Australia).


The South China Sea and the Western Pacific (north of Australia).


Seas east and south of Australia, including the trans-Pacific routes.

page 546

31. As regards (a), the main routes from the United Kingdom to the Middle East, India, the East Indies, Australia and New Zealand pass through the Indian Ocean, which would therefore be the most important area for Japanese action. Although the Malacca Straits might be denied to Japanese naval forces, these forces might use many other passages through the Netherlands East Indies for operations against our Indian Ocean trade and our lines of communication to the Middle East through the Red Sea. Although distances from Japan are great, there are several potential fuelling bases in the Indian Ocean. A force of enemy cruisers, particularly if supported by one or more heavy ships, would provide a most serious threat to our trade, since we could not spare adequate naval forces, either for operations in focal areas or, as would more probably be necessary, for the escort of convoys. Our communications with Malaya would be precarious but not necessarily completely severed. (Assumption 3 begins.) Our ability to use the Dutch islands and to establish depot ships there would act as a deterrent but would not prohibit Japanese access to the Indian Ocean. Such action would assist the maintenance of our communications with the Commonwealth and New Zealand. Dutch co-operation would be essential. (Assumption 3 ends.)

32. As regards (b), we could not maintain our sea communications to the north of the Malayan Archipelago (Assumption 3 begins) but could maintain local traffic within the Archipelago to a limited extent given Dutch co-operation. (Assumption 3 ends.)

33. As regards (c), the trans-Pacific trade routes are important in connection with supplies from America to Australia, New Zealand and the Far East, as well as providing alternative communications with the United Kingdom which would increase in importance if difficulties on the Cape route became acute. These routes are also essential to the economic life of the Commonwealth and New Zealand. Although distances from Japan are considerable, the Japanese (if not deterred by fear of United States action) could establish advanced fuelling bases in the South Sea Islands to facilitate operations in the South-West Pacific. The wide scope for evasive routing would provide a high degree of security for trans-Pacific trade, except in the neighbourhood of the western terminals. Routing, practicable to some extent, and the use of inshore routes would also provide some degree of protection for Australian and New Zealand trade. The danger of attack would be greatest in the approaches to ports, for which local air and naval protection would be required.

34. As regards the defence of Australia, New Zealand and the South Pacific islands, as previously stated, no serious threat to the territorial integrity of Australia or New Zealand would be likely to arise at least until Japan had consolidated her position in China and the Far East, which would take a considerable period. A Japanese major expedition to Australia or New Zealand would be an extremely hazardous operation so long as Singapore remained available to us as a base for the Fleet in being on the flank of their long lines of communication. Moreover, the protection of the lines of communication of an expedition of any considerable size over the distance involved would impose a very heavy drain on Japanese naval forces, as every important convoy has to be protected against the maximum scale of attack which we could bring to bear at our own selected moment and would probably therefore require escort by heavy ships. The scale of attack on Australia or New Zealand would be likely, therefore, to be limited to cruiser raids, possibly combined with a light scale of seaborne page 547 air attack against ports. The Japanese might decide to establish advanced fuelling bases in the South-West Pacific islands to facilitate such operations. There are innumerable potential bases in these islands which could not all be defended against Japanese attack, but their most likely objective would be the capture of a harbour with base facilities, particularly Suva. Suva is also useful as a potential advanced base for air forces.

35. As regards the defence of Malaya, the following are the factors affecting this problem in the absence of the Fleet:


The necessity for preventing the establishment of shore-bases for aircraft within close range of Singapore base.


Even if the Japanese had not previously established themselves in Thailand they would be more likely to attempt a landing up-country in Malaya and then operate southward, under cover of shore-bases for aircraft, than to risk direct assault on Singapore Island.


The rice-growing country, on which the native population partly depends, and most Government storage cereals are in the north.


The necessity for establishing the maximum possible food reserves for the garrison and for the civil population. Though our sea communications with Malaya might be precarious, it would be extremely difficult for the Japanese to blockade the Malayan Peninsula completely, and we should expect to get supplies intermittently to our forces, though not necessarily through Port Singapore.

The above factors emphasise the necessity for holding the whole of Malaya rather than concentrating on the defence of Singapore Island. This clearly involves larger land and air forces than when the problem was merely the defence of Singapore Island.

36. As regards the defence of Burma, the occupation of Thailand would enable the Japanese to attack from the air key points such as the Rangoon oil refineries and aerodromes on the Burmese section of the Singapore air route. Japanese invasion of Burma territory is a more distant threat, except in the extreme south, where she could capture aerodromes such as Victoria Point and Mergui. Establishment of air forces at bases such as Lashio, Rangoon and Tavoy, and the provision of additional troops and air defences would be desirable, but the defence of Malaya must have precedence over Burma, and the provision of such forces can only be the long-term project. On the shorter view, the problem is to limit the Japanese threat with the resources likely to be available. The air route between Singapore and Rangoon must be kept open. Burma aerodromes as far south as Tavoy, and in Malaya as far north as Alor Star, must therefore be held. If the aerodromes at Lashio, Rangoon and Tavoy are developed, stocked and defended, it may be possible to move air forces from Malaya or India to assist Burma in dealing with a sudden threat from the north. The aerodromes at Victoria Point and Mergui would be prepared for demolition to ensure that the Japanese could not use them. Both long- and short-term problems of the defence of Burma will be reviewed by the Governments of India and Burma in consultation with the Air Officer Commanding in the Far East.1

37. (Assumption 3 begins.) Defence of the Netherlands East Indies is important for the denial to the Japanese of the use of naval and air bases. page 548 Control over the channels through the Netherlands Islands could be exercised by air and light naval forces based on one of the following alternative lines:


Northern line of islands from Singapore to New Guinea, or


Southern line from SumatraJava to Port Darwin.

We could do little to dispute the passage of these channels with the forces at present available. The co-operation of the Dutch would improve the position, but the measure of control would still be very limited. Which line of defence to adopt could only be decided by the local Commanders. To deny bases, invasion must be prevented, which would entail attacks on the expedition during its approach, as the Dutch military forces are limited and mainly concentrated in Java. With our naval numerical inferiority, the best form of defence would be shore-bases for air forces in conjunction with submarines, light naval forces and mines. (Assumption 3 ends.) The establishment of a British air base in North Borneo to give our air forces greater mobility is our long-term aim, but this will take time, and resources which we do not at present possess. It is desirable for such action to be part of a general settlement with the Japanese. (Assumption 3 begins.) Meanwhile there would be no alternative to relying initially for the defence of this area on the operation of air forces from Dutch bases, of which there are several already established on both lines of defence. (Assumption 3 ends.) The Japanese might seize the Portuguese half of Timor as a first step, but owing to the absence of air or naval bases in this part and the risk that it might lead to war with us, such action appears unlikely.

38. (Assumption 3 begins.) The whole of the defence problem in the Far East would be greatly facilitated if we were certain of Dutch co-operation and could concert plans with them. Our aim should be a scheme of defence ensuring full mutual support, pooling of resources, and arrangements for the rapid movement of troops to threatened points. The Dutch would probably agree to prepare detailed plans for the defence of the Netherlands East Indies, though they might hesitate to assist us in the event of Japanese attack on British territory alone. With our present limited resources in the Far East we could not offer the Dutch any effective military support against Japanese military aggression. It is not therefore recommended that Staff conversations should be held with the Dutch immediately. It is most important, however, that plans should be concerted with the Dutch as soon as we have improved our own position in Malaya. Meanwhile our Commanders in the Far East should consider the problem of combined Anglo-Dutch defence plans, so that conversations may take place immediately the opportunity arises. (Assumption 3 ends.)

39. If the Japanese attacked Malaya without attacking the Netherlands East Indies, it is conceivable that Dutch co-operation would be withheld. We should then be faced with a gap in our defensive system and our sea communications in the Indian Ocean would be more seriously threatened. It should, however, still be possible, even without Dutch collaboration, to get some supplies into Malaya intermittently, but in such circumstances our difficulties in the Far East would be greatly increased.

40. Conclusions. In the absence of a capital ship fleet we could not fully secure our vital interests in the Far East. The problem is therefore the best disposition possible to secure the most important military interests without the cover which a capital ship fleet would provide. If, in addition to defending Malaya, we could deny to the Japanese the establishment of page 549 bases in the Netherlands East Indies, and if the movement of their naval forces through the line of these islands could be impeded, the security of our interests would be considerably improved. Our ultimate aim therefore should be to secure the full military co-operation of the Dutch. In the absence of full Dutch co-operation we should concentrate on Malaya.

1 Air Marshal Sir John Babington, KCB, CBE, DSO; AOC Far East 1938–41.