The japanese road to singapore japanese perceptions of the singapore naval base, 1921 41 7

At a conference on 24 June, Colonel Iwakuro astonished members of the Army General Staff by suddenly presenting his view of the necessity of a surprise attack on Singapore.12 With regard

Chapter 4

The Road to Singapore

1940-41

Since Britain was included in the hypothetical enemies list of the

Teikoku Kokubō Hōshin of 1936, the Operations Sections of the General Staffs

began their studies for making their operational plans against Britain From

1939 onwards, they proposed their operational plans annually to Emperor Hirohito, which included operational plans for attacking British Malaya and Singapore However, making operational plans did not mean Japan decided to attack British Malaya and Singapore Even though the two General Staffs presented operational plans annually, Japan did not have the intention of waging war against Britain In fact, Japan did not examine even the possibility

of opening hostility against Britain until Germany dominated continental Western Europe in the summer of 1940

On 1 September 1939, the Second World War broke out with the

German invasion of Poland In May and June 1940, the Germany Blitzkrieg

conquered the Netherlands, Belgium and France France capitulated to Germany on 22 June 1940 Colonial masters of the Dutch East Indies and the French Indochina were in desperate straits Norway, Denmark, the Netherlands, Belgium and France were occupied by Germany This situation in Europe affected Japanese decision makers greatly The Imperial Japanese Army for the first time in its history turned its eyes to the south For the eyes of the Imperial

Japanese Army, Singapore appeared as the most important military target in the south One and half years later, the Second World War in the Asia-Pacific region broke out with simultaneous Japanese attacks on British Malaya, the Philippines and Hawaii In retrospect, it could be said, without the Second World War in Europe, Japan would not have attacked Singapore This chapter examines the history from the outbreak of the Second World War in Europe in September 1939 to the outbreak of the war in the Asia-Pacific region in December 1941 In particular, it analyses the following four aspects First, how did the Japanese react to the outbreak of the Second World War in Europe Second, how did the Japanese government decide to wage war against Anglo-American powers Third, how did the Imperial Japanese Army prepare

to attack British Malaya and Singapore Fourth, why Japan attacked British Malaya and Singapore?

Influence of the European War on Japan

Since the Teikoku Kokubō Hōshin (Imperial National Defence Policy)

was first sanctioned in 1907, Russia (the Soviet Union) had always been the principal hypothetical enemy of the Imperial Japanese Army The conclusion

of the German-Japanese Anti-Comintern Pact in 1936 and the outbreak of the Sino-Japanese War in the following year increased tension between Japan and the Soviet Union The Japanese turned their eyes on the Soviet Union as the backer of the Chinese Nationalists On 29 July 1938, there occurred skirmishes between the Imperial Japanese Army (the Chosen Army of Japan, 19th Division) and the Soviet Army in Changkufeng, an area in southern Manchuria

that bordered both on the Soviet Maritime Province and Korea Small-scale fighting ensued and there was a truce on 11 August in Moscow before it was enlarged This was an insignificant event in itself but showed Japanese army’s military unreadiness.1

In 1939, there were a number of border disputes between the Soviet-backed Outer Mongolia and Manchukuo From May onwards, they were escalated into Soviet bombing raids and Kwantung Army’s air attacks, which were not authorised by the Army General Staff, over the obscure border

At that time, general consensus of the Army General Staff was that, as long as the war in China lasted, Japan was in no position to engage in an all-out war against the Soviet Union But adventurous middle-echelon officers of the Kwantung Army, Captain Tsuji Masanobu and Lieutenant-Colonel Hattori Takushirō, did not share this view and were eager to strike a heavy blow at the Soviet Union On 2 July, Japanese infantry of the Kwantung Army crossed the border into Mongolia but was checked by the Soviet forces On 23 July, the Kwantung Army tried again but was checked again On 20 August, the Soviet forces, led by General Zhukov, launched a massive surprise offensive known

to the Soviet as the Kalkhin-Gol Battle and to the Japanese as the Nomonhan Incident By the end of August, the Russian had completed what they described as the most impeccable encirclement of an enemy army since Hannibal beat the Roman at Cannae in 216 BC The 23rd Division of the Kwantung Army was virtually wiped out At least 18,000 Japanese was killed

1 Akira Iriye, The Origin of the Second World War in Asia and the Pacific (London: Longman, 1987), pp.61-62

in this battle.2 Tsuji’s act of blind courage would work well in Malaya in later days, but brought disaster to the Kwantung Army in Nomonhan

While the Kwantung Army engaged in a life-and-death struggle against the mighty Soviet Army in vast plains in the Mongolia-Manchuria border zone, news from Europe gave Japanese leaders a shock German and the Soviet Union concluded the German-Soviet Nonaggression Pact on 23 August For Japanese leaders, especially for the army, the German’s conclusion of the German-Soviet Nonaggression Pact was hard to comprehend, and an act of disloyalty.3 Because, until then, the army had regarded German

as a partner to confront the Soviet Union Almost overnight, the army’s plan for seeking alliance with German to confront the Soviet Union vanished in smoke, at least temporarily Prime Minister Hiranuma Kiichirō threw up his job on 28 August with issuing the famous statement: “conditions in Europe are messed up beyond all recognition” Until then, he was torn between conflicting demands of the two armed forces: the army advocated alliance with German to confront the Soviet Union while the navy opposed it because the navy considered it would bring Japan into conflict with the United States

General Abe Nobuyuki was appointed as the new Prime Minister on

30 August His new government started every effort to end hostilities thought diplomatic channels On the same day, Vice-Chief of the Army General Staff, Lieutenant-General Nakajima Tetsuzō, flied to Manchuria to rein the

2 Sumio Hatano “Japanese-Soviet campaigns and relations, 1939-45.” in the Oxford Companion to the Second World War (Oxford: Oxford University Press, 1995), pp.634-637

3 Chihiro Hosoya, Ryōtaisenkan No Nihon Gaikō 1914-1945 (Japanese

Diplomacy in the Inter War Period 1914-1945) (Tokyo: Iwanami Shobō, 1988), pp.142-143

Kwantung Army On 1 September, the war in Europe broke out by German invasion of Poland The Abe Government adopted a non-intervention policy in Europe, which gave priority to settlement of the Sino-Japanese War, emphasising that Japan must aim to make third parties stop assisting the Chinese Nationalists This policy was endorsed by the Minister of Foreign Affairs, the Minister of War and the Minister of the Navy in late 1939 On the other hand, the outbreak of the European war convinced Moscow of the need

to come to an agreement with Japan Accordingly, the Japanese Ambassador to the Soviet Union, Tōgō Shigenori, and the Soviet Foreign Minister, Molotov Vyacheslav, arranged a cease-fire that became effective on 16 September.4 By the Nomonhan Incident and the conclusion of the German-Soviet Nonaggression Pact, the army lost confidence, so that the voice of the army within the Japanese government became weaker for a while.5 Even though the army did not abandon its north-bound policy, its conviction for it lost strength.6 Some in the Ministry of Foreign Affairs and a small number of

officers in the Army General Staff even explored possibility of rapprochement

with the Soviet Union, but a majority view of the Army General Staff did not support it.7 The Abe Government’s non-intervention policy to European war was followed by the Yonai Mitsumasa Government, which took power in January 1940.8

4 Sumio Hatano “Japanese-Soviet campaigns and relations, 1939-45.”

5 Hosoya, Ryōtaisenkan No Nihon Gaikō 1914-1945, p.143

6 Alvin D Coox, Nomonhan: Japan Against Russia, 1939, Volume 2 (Stanford: Stanford University Press, 1985), pp.1028-1032

7 Hosoya, Ryōtaisenkan No Nihon Gaikō 1914-1945, pp.195-215

8 Kiyoshi Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41” in T.G Fraser and Peter Lowe (eds.), Conflict and Amity in East Asia: Essays in Honour of Ian Nish (Basingstoke: Macmillan Press, 1992), p.41

The German Blitzkrieg to the Low Countries in May 1940 changed

the situation drastically It dazzled the Imperial Japanese Army Army officers, having been depressed since the debacle in Nomonhan and the conclusion of the German-Soviet Nonaggression, were rejuvenated by the new situation in Europe One day in late in May, Chief of Army Affairs Section of the Ministry

of War, Colonel Iwakuro Hideo told Chief of the Operations Section of the Army General Staff, Colonel Okada Jūichi: “For a while, it is important for the army to focus on settlement of the war in China, but the world situation drastically changed, so we have to start studies and preparations on the south just in case they become necessary Has the Army General Staff started preparations?”9 On the following day, there was a discussion in the Operations Section of the Army General Staff over whether Japan should advance to the south to capture natural resources areas or not Some claimed it would be necessary to do it in order to settle the war in China Some claimed it was not good to commence another war because it would lead Japan to dispersing its resources and forces There was no conclusion to this discussion, but they agreed to make operational plans which would include operational plans in the Dutch East Indies.10 The Imperial Japanese Army for the first time in its history turned its eyes to the south

France capitulated to Germany on 22 June Two days before, the French authorities in Indochina agreed to a Japanese request to stop the transit

9 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2 (Imperial General

Headquartes The Army Department, Vol 2) (Tokyo: Asagumo Shinbunsha, 1968), pp.47-48

10 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2., 47-48; Akira Iriye, The Origin of the Second World War in Asia and the Pacific (London: Longman, 1987), p.102

of war supplies to the Chinese Nationalists Before that, from late May to early June, a senior member of the Army Affairs Bureau of the Ministry of War, Lieutenant-Colonel Nishiura Susumu, by an order of Colonel Iwakuro drafted

a plan called “Guidance Plan for War in the South” The contents of it were:

(1) The war will start with a surprise attack

(2) We make policies on the assumption that the United States and Britain are separable We will keep an eye on the Philippines, but will not attack them unless it becomes unavoidable

(3) We will attack Singapore, and after that, will attack and occupy the Dutch East Indies For these purposes, we will consider using French Indochina and Thailand as advanced air bases

(4) We will attack Hong Kong when necessary

(5) If possible, we will separate Britain from the Netherlands In this case,

we will not attack Singapore We will make a surprise attack directly on the Dutch East Indies and occupy natural resources areas

(6) For these operations, we will use several divisions.11

This plan shows us three important things First, capturing natural resources areas in the Dutch East Indies was the main purpose of the supposed war in the south Second, to capture natural resources in the Dutch East Indies, Japan had to attack Singapore Singapore appeared as the most important military target in the south, because Singapore was the principal military base

11 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2., p.48 Nishiura himself was the editor of Senshi Sōsho This part was written on his memories

of Anglo-Dutch powers in the region Third, war against the United States should be avoided as much as possible unless it became unavoidable It was reasonable to limit the number of enemies as much as possible

After Germany dominated the Low Countries and France in June, there was an illusion in Japan, especially among army officers, that the fate of Britain was like a candle before the wind What occupied the interest of army officers was the future of European colonies in Asia As a defeat of France became definitive, south-bound policies obtained support quickly At a conference on 24 June, Colonel Iwakuro astonished members of the Army General Staff by suddenly presenting his view of the necessity of a surprise attack on Singapore.12 With regard to the Imperial Japanese Army, the south-bound policy was south-bound advancement to the Dutch East Indies and British possessions in Asia for capturing natural resources There was oil

in the Dutch East Indies, and rubber and scarce metals in British Malaya To acquire natural resources in the Dutch East Indies and British Malaya, the army had to conquer their principal military bases Accordingly, Singapore appeared as the army’s most important military target in the south This was how Britain became the principal adversary of the Imperial Japanese Army

In the meantime, the Imperial Japanese Army also considered it would

be best to readjust Japanese relations with the Soviet Union through a non-aggression pact But the Minister of Foreign Affairs, Arita Hachirō, feared that it would result in a further deterioration of Japan’s position vis-à-vis

12 Ichiji Sugita, Nihon no Sei-Senryaku to Kyōkun (Japanese Strategy and Lesson of It) (Tokyo: Hara Shobō, 1983), p.244; Chihiro Hosoya, “The

Tripartite Pact” in James William Morley (ed.), Deterrent Diplomacy: Japan, Germany and USSR 1935-1940 (New York: Columbia University Press, 1976), p.207

Britain and the United States As a result, Japanese military and civilian officials concluded that the best alternative would be a treaty of neutrality between Japan and the Soviet Union They considered political ties by a treaty

of neutrality were weaker and less hostile to Britain and the United States than those by a non-aggression pact Such an arrangement would ensure Soviet neutrality in the event Japan became involved in a conflict with the Anglo-American powers, while at the same time putting an end to Soviet assistance to China.13 However, this policy did not materialise until 13 April

1941

On 3 July, a handful of middle-echelon officers of the Ministry of War and the Army General Staff drafted a policy, “Outline of the Main Principles”, based on the Nishiura paper “Guidance Plan for War in the South” It revealed their impatience to take advantage of the war in Europe, and to resort to the use of force against French Indochina and, depending on the circumstances, against the Dutch East Indies also They considered that, if Britain were defeated, or if the United States entered the war in Europe with little strength

to spare in the Pacific, the great opportunity for south-bound military advancement would arise.14 This depended upon an assumption that Britain and the United States could be separated strategically The “Outline of the Main Principles” stated that, in case of south-bound military advancement, military targets should be limited to French Indochina, Hong Kong, British Malaya and the Dutch East Indies As for the United States, it stipulated, “A war with the United States should be avoided as much as possible, although

13 Iriye, The Origin of the Second World War in Asia and the Pacific, p.102

14 Asada, From Mahan to Pearl Harbor, p.237

preparations must proceed in anticipation of a probable military clash” It also mentioned strengthening relations with Germany and Italy.15 On the following day, there was a meeting between the two armed forces, in which the army submitted the “Outline of the Main Principles” Representatives from the navy

were pleasantly surprised by the army’s swing from its traditional Hokushin Nanshu Ron (Advance to the North, Hold in the South Policy” to Hokushu Nanshin Ron (Hold in the North, Advance to the South Policy) But the navy

had to point out the crucial defect of the “Outline of the Main Principles” It did not consider relations with the United States seriously enough South-bound military advancement without seriously considering the possibility of waging war against the United States was too dangerous for the navy to accept In the army’s assumption, Japanese military advancement to the south would not necessarily bring a clash with the United States, but the navy emphasised the “inseparability” of Britain and the United States.16 After the Russo-Japanese War, the Imperial Japanese Navy always regarded the United States as its principal hypothetical enemy What the navy cared about at that time was the American Pacific Fleet, which had been stationed at Pearl Harbour since April that year, and the American naval expansion programme The only naval force which had the capability to confront the Imperial Japanese Navy in the Asia-Pacific region was the American Pacific Fleet

15 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2 , pp.49-51; Nihon Kokusai Seiji Gakkai (Japanese Association of International Relations) (ed.), Taiheiyō Sensō e no Michi: Bekkan Shiryōhen (The Road to the Pacific War:

Supprementary Volume of Documents) (Tokyo: Asahi Shinbunsha, 1988), pp.315-318; Iriye, The Origin of the Second World War in Asia and the Pacific, p.102

16 Taiheiyō Sensō e no Michi: Bekkan Shiryōhen, pp.315-318; Asada, From Mahan to Pearl Harbor, p.237

Compared with American threats, the British China Fleet was negligible The Minister of the Navy, Yoshida Zengo, was surprised by the slipshod nature of the “Outline of the Main Principles”, and directed bureau and division chiefs of the navy to revise it.17 But, the Army General Staff rejected the necessity of major revision and unified interpretation between the two armed forces It preferred to leave room for interpretation so that policies

of it would not be too much restricted by the “Outline of the Main Principles”18 Without much deliberation, revision or agreed interpretation, after Prince Konoe Fumimaro formed a new cabinet on 22 July 1940, the Supreme Command Government Liaison Conference approved the “Outline of the Main Principles” with minor revisions made by the navy as a national policy bearing the ponderous title “Outline of the Main Principles for Coping with the Changing World Situation” on 27 July By adopting this policy, Japan for the first time gave shape to south-bound military expansion However, even though the “Outline of the Main Principles for Coping with the Changing World Situation” was adopted, there was no consensus over what south-bound military advancement meant precisely between the two armed forces

The “Outline of the Main Principles for Coping with the Changing World Situation” stated several policies using elusive phrases: the differences between the army and the navy were adjusted by using elusive phrases, not by adjusting policies The most important policy for the army stipulated in the

“Outline of the Main Principles for Coping with the Changing World

17 Asada, From Mahan to Pearl Harbor, pp.237-238

18 Atsushi Moriyama, Nichi-bei Kaisen no Seiji Katei (The Political Process Leading to the War against the United States) (Tokyo: Yoshikawa Kōbunkan, 1998), p.16

Situation” was the settlement of the war in China Other policies mentioned in

it could be interpreted as a means to this purpose The main points were: Japan would strengthen political relations with Germany and Italy, and would improve relations with the Soviet Union For French Indochina, it would demand passage of forces, using airfields and natural resources If French Indochina would not accept Japanese demands, Japan would use force But, when, where and how Japan would use force would be decided by various conditions, internal and external Unless the war in China were settled, Japan would not open hostilities with the third power, but if the situation were to become advantageous for Japan, it could consider the possibility of using force

In resorting to the use of force, utmost effort would be made to restrict the enemy solely to Britain, but hostilities against the United States might become unavoidable, so sufficient preparations had to be made For the Dutch East Indies, it would demand natural resources by diplomatic means.19

On adopting the “Outline of the Main Principles for Coping with the Changing World Situation”, the Imperial Japanese Navy adopted the particular importance of war preparation against the United States Naval leaders wanted

to avoid south-bound military advancement that would bring a clash with the United States.20 At that time, the navy was not yet confident about a war with the United States However, it could not admit this Commander Kawai Iwao

of the Operations Section explained, “If we say the navy is not confident, then the army will take away the navy’s share of matériel and try to cut down the

naval budget This was the navy’s weakness until the very end….Inwardly we felt we could not fight with the Anglo-American powers, but we could not unequivocally say so We have called ourselves an invincible navy and we have been telling the army that we could take on the United States….we could not say we lacked confidence now We were afraid that the army would say, ‘If the navy can’t fight, give us your matériel and budget.’”21

Behind the navy’s considerations of war preparations against the United States lay the navy’s strong desire to expand its armaments It was greatly alarmed by the huge building plans the United States recently announced The second Vinson plan of May 1938 authorised an increase of 20 per cent Japan responded with the huge “Fourth Replenishment Programme of 1939” which

involved the construction of eighty ships including two more Yamato Class

battleships and a doubling of naval aviation over a five-year period In June

1940, the American Congress, faced with the threat of German conquest of the European Continent and the fear of Japanese south-bound advancement, agreed to an 11 per cent increase of naval strength over two years This was followed on July 19 by the Stark Plan, the two oceans navy plan, which provided for a 70 per cent increase This astronomical American naval expansion was a great shock to the Imperial Japanese Navy.22 According to the Navy General Staff’s estimate, Japan’s capital ships ratio vis-à-vis the United States would be reduced to about 50 per cent in 1943 and 30 or below

by 1944 As for aircraft, American production capacity would be more than ten

times of Japan.23 Caught in the strains of an ever escalating arms race, the Imperial Japanese Navy desperately needed a rationale to establish its priority

in defence appropriations Viewed in this context, the Imperial Japanese Navy’s belligerent stance towards the United States was merely a verbal show

of strength, more budget-minded than war-minded.24 Prince Fushimi, Chief of the Navy General Staff, told the Emperor during lunch on 10 August that the navy wanted to avoid using force against the Dutch East Indies and Singapore, and it required at least eight months for war preparations.25 The navy wanted

to postpone a war as long as possible, but it could not express it

The Imperial Japanese Army and the Imperial Japanese Navy each interpreted the “Outline of the Main Principles for Coping with the Changing World Situation” according to its own policy The army’s interpretation was that, to obtain natural resources in the Dutch East Indies, it had to attack British Malaya and Singapore What the army considered was a war against Britain and the Netherlands It considered war against the United States should

be avoided as much as possible It was reasonable for the army to limit the number of enemies as much as possible On the other hand, the navy advocated that it was impossible to obtain natural resources in the Dutch East Indies without waging war against the United States It considered that the

23 Jun Kadota, “Nihon no Taibeikaisen (Japanese Decision of War Against the United States)”, in Nihon Kokusai Seiji Gakkai (Japanese Association of International Relations) (ed.), Taiheiyō Sensō e no Michi: 7 Nichi-bei Kaisen (The Road to the Pacific War: 7 Outbreak of Japanese-US War) (Tokyo: Asahi Shinbunsha, 1987), p.324; Asada, Culture Shock and Japanese-American Relations, p.158

24 Asada, Culture Shock and Japanese-American Relations, p.158; Asada, From Mahan to Pearl Harbor, p.239

25 Kōichi Kido, Kido Kōichi Nikki, Ge-kan (Kido Kōichi Diary, Vol.2) (Tokyo: University of Tokyo Press, 1966), p.814

only naval force which had the capability to confront the Imperial Japanese Navy in the Asia-Pacific region was the American Pacific Fleet Furthermore, the United States was expanding its naval force Compared with the American threat, the British and Dutch fleets in the Asia-Pacific region were negligible Even though Britain had the Singapore Naval Base, there was no British capital ship in the Asia-Pacific region Also, Britain was too occupied with the war in Europe to send a fleet to the Asia-Pacific region It was reasonable for the navy to focus its attention on the United States For the navy, army plans, which did not regard the United States as a threat as seriously as the navy, were too risky to accept To prepare for a war against the United States, the navy had to strengthen its armaments and to do this, it required much more war matériel and a larger budget Therefore, policies of the two armed forces were fundamentally incompatible.26

The adoption of the “Outline of the Main Principles for Coping with the Changing World Situation” signalled the government’s commitment to preparations for south-bound military advancement, strengthening relations with Germany and Italy, reconciling relations with the Soviet Union and the navy’s full-scale war preparations against the United States But there was no consensus between the army and the navy over when, how, and where Japan would make south-bound advancement What is important for us is that the army, which had always regarded the Soviet Union as its hypothetical enemy until then, turned its eyes to the south as far as to consider reconciling relations

26 Atsushi Moriyama, “Nanshin-ron to Hokushin-ron (South-bound Policies and North-bound Policies)” in Aiko Kurasawa, et al Asia Taiheiyō Sensō 7, Shihei to Bouryoku (Asia Pacific War 7, Ruling and Violence) (Tokyo: Iwanami Shoten, 2006), p.196

with the Soviet Union.27 To attack the south, it had to secure the northern border For the army, it was a complete turnabout in its policy

Since mid June 1940, the Operations Section of the Army General Staff started preparations for attacking the south: British Malaya, the Dutch East Indies, Hong Kong and the Philippines At that time, it considered Operations

in Malaya as:

(1) The main forces for attacking Singapore will be four divisions

(2) The landing site in the Malay Peninsula will be Singora in northern Malaya

(3) The distance between the landing site and Singapore is approximately 1,000 km When it decides formations and equipment, it has to take this distance into accounts

(4) It will have to be determined to attack a fortress when it attacks Singapore

(5) The biggest problem will be air backup It will have to use aircraft carriers or air bases in southern French Indochina

(6) It will be necessary to win Thailand and French Indochina over to our side.28

Even though the Operations Section of the Army General Staff changed landing sites from Singora and Mersing to only Mersing on paper to satisfy the Emperor when it resubmitted the “Annual Army’s Operational Plan for 1939”,

27 Ibid., p.195

28 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, Vol 2 , pp.65-66

it did not change its consideration regarding suitable landing sites: it still regarded Singora as the best landing site in the Malay Peninsula With regard

to equipment for operations in the south, the Operations Section supposed,

“Taking condition of roads, hot weather and our capability of ship conveyance into account, it will have to mechanise our units as far as possible If possible, infantry will use motorised vehicles For scouting and advanced guards, it will have to equip as many bicycles and motorbikes as possible.”29 It realised the necessity of enhancing mobility of its forces as far as possible to fit local conditions in Southeast Asia

In order to make more practical plans for south-bound advancement, the Army General Staff realised in late June that operational plans in the

“Annual Army’s Operational Plan for 1940” for attacking the south, including attacking plans on British Malaya and Singapore, were far less complete compared with operational plans against the Soviet Union, so it decided to gather more information For this purpose, it established South Group in the European and North American Section in the Intelligence Division of the Army General Staff.30 The newly established group sent its members to each part of Southeast Asia and Hong Kong to gather information For British Malaya and Singapore, it planned to send Lieutenant-Colonel Tanigawa Kazuo

to gather information related to air operational plans, and Captain Kunitake Teruto for land operational plans Tanigawa observed British Malaya in July and early August but Kunitake’s trip was postponed to the next year because

29 Ibid., pp.66-67

30 There were three regional sections in the Intelligence Division of the Army General Staff: the Soviet Section, the Europe and North America Section, and the Chinese Section South Group was established in the Europe and North America Section because Southeast Asia was European colonies

he could not get a visa What mesmerised officers sent from South Group was the richness of natural resources in Southeast Asia Some of them became strong advocates for south-bound advancement after their trips.31 Their findings were reflected in a “Combined Operational Plans for the South

(Nanpō Sōgō Sakusen Keikaku)” drafted by Captain Sejima Ryūzō of the

Operations Section on 15 August 1940 It was the first combined operational plan against Southeast Asia.32 Before that, the Operations Section had operational plans for each theatre in Southeast Asia in its Annual Army’s Operational Plans, but it had no plan which combined all theatres in Southeast Asia Its points were:

(1) It will make a surprise attack on the Dutch East Indies by an Army (Bo Operations), then attack British Malaya by another Army (Tei Operations) If conditions demand, it will attack the Dutch East Indies and British Malaya simultaneously; otherwise it will attack British Malaya alone without attacking the Dutch East Indies

(2) Right after commencing operations in British Malaya, the South China Army will attack Hong Kong (Kō Operations) If conditions demand, it will attack Hong Kong before commencing operations in British Malaya

31 Ikuhiko Hata, “Futsu-in Shin-chū to Gun no Nanshin Seisaku (Occupation

of French Indo-China and Military South-bound Policies), in Nihon Kokusai Seiji Gakkai (Japanese Association of International Relations) (ed.) Taiheiyō Sensō e no Michi: Vol.6 (The Road to the Pacific War, Vol.6), (Tokyo: Asahi Shinbunsha, 1987), pp.175-177; Gunji-shi Gakkai (Association of Military History) (ed.), Daihon’ei Rikugun-bu Sensō Shidō-han (War Guidance Office of the Army General Staff), Kimitsu Sensō Nisshi, Jō (Confidential War Journal, Vol 1) (Tokyo: Kinseisha, 1998), p.25 It was the Journal of the War Guidance Office

32 Ibid

(3) After commencing operations in British Malaya, at a suitable opportunity, it will attack key areas in the Bismarck Archipelago

(4) If a war against the United States becomes unavoidable, it will attack the Philippines by an Army and Guam by a detachment.33

The designations of forces used for these operations were the 17th Army consisting of two divisions for operations in the Dutch East Indies, the 22nd Army consisting of five divisions for operations in British Malaya including Thailand, French Indochina and Kuching in British Borneo, the 15th Army consisting of three and half divisions in the Philippines and Guam, the South China Army consisting of two divisions in Hong Kong and one regiment in the Bismarck Archipelago.34

Captain Sejima made this operational plan based on the following six assumptions First, Soviet-Japanese relations were stable and it did not need to enlarge the Kwantung Army Second, Japan could continue waging the war in China by forces already deployed in China Third, the navy could annihilate Anglo-American-Dutch fleets in East Asia and would secure command of the sea Fourth, war matériel was sufficient enough for conducting the war for more than one year Fifth, French Indochina and Thailand were on Japan’s side Sixth, the United States would not open hostilities with Japan, and Britain

33 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2 , pp.67-68; BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 1 (War History Series: The Imperial General Headquarters Navy Section: The States of

Affairs until the Outbreak of the Greater East Asia War Vol.1) (Tokyo

Asagumo Shinbunsha, 1973), pp.453-454

34 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2, p.68; BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 1, pp.453-454

would be taken up with the war in Europe.35 Among these assumptions, Captain Sejima’s belief that the United States would not open hostilities with Japan was too optimistic for the navy to accept

On 16 August, there was a meeting between the Army General Staff and the Navy General Staff to coordinate their policies They discussed Sejima’s operational plan Naval officers claimed in this meeting that if the Germans should land and defeat Britain, Britain and the Netherlands would become separable In this case, Japan could capture natural resources areas in the Dutch East Indies without attacking Singapore Thus, it would be better to advance to the south only if this favourable opportunity arrived They advocated that Britain and the United States were inseparable, so it would be better to advance only on the Dutch East Indies to avoid war with the United States The navy still did not have confidence in waging that war.36 Colonel Okada Jūichi, Chief of the Operations Section of the Army General Staff, came to accept the naval staff’s view, thinking that it would attack the Dutch East Indies first and open hostilities against Britain only if the Anglo-Japanese war became unavoidable But Colonel Iwakuro did not agree with this view The army’s consideration at that time, represented by Colonel Iwakuro, was a mixture of two different, but related, considerations The first was that it would exclude Britain from Asia by attacking Singapore and Hong Kong using the opportunity presented by the German landings in Britain The second was that

it could capture natural resources in the Dutch East Indies to establish a self-sufficient sphere of interest in East Asia These two considerations were

35 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2, pp.68-69

36 Ibid., pp.69-70

interrelated and could not be fulfilled separately In this consideration, Britain and the Netherlands were inseparable, so naval opinion was unacceptable to the majority of army officers like Colonel Iwakuro.37 It was necessary for them to attack Singapore As a result, the differences between the two armed forces were not resolved at this meeting

On 22 September 1940, Japanese army troops began entering French Indochina forcefully by an arbitrary decision of the Operations Division and the South China Army without any order coming down the chain of command The navy, which disagreed with the use of force, was infuriated by this act.38The United States responded quickly They saw it as a prelude to Japanese further advancement in Southeast Asia.39 On 27 September, it embargoed the export of scrap iron to Japan On the same day, Japan signed the Tripartite Pact with Germany and Italy In exchange for withdrawing opposition to the Tripartite Pact－its enactment was promoted by the Imperial Japanese Army and the Ministry of Foreign Affairs while the navy had opposed to it－the navy gained precedence over the army in the materials mobilisation programme As a punishment for disorders the Operations Division of the Army General Staff War caused within the Japanese government by advancing the army units into northern French Indochina without an order, the Army General Staff reshuffled members of its Operation Division, established the War Guidance Office on 18 October 1940, and detached the authority to

37 Ibid

38 For the detailed study of this, see Ikuhiko Hata, “The Army’s Move into Northern Indochina” in Morley, James W.(ed,), The Fateful Choice: Japan’s Advance into Southeast Asia, 1939-1941, (New York: Columbia University Press, 1980), pp.155-208

39 Asada, From Mahan to Pearl Harbor, p.242

establish policy from the Operations Division From then onwards, the War Guidance Office had the authority to establish Army General Staff’s policy, working under the direct supervision of the Vice-Chief of the Army General Staff Colonel Arisue Yadoru was appointed Chief of the War Guidance Office.40 Major Imoto Kumao returned from China to the Operations Section

on 10 October from China After that, he took charge of conducting operations

in China until August 1941.41

From 26 to 28 November 1940, a map manoeuvre was jointly conducted by the Navy General Staff, the Combined Fleet and the Naval War College under the Commander-in-Chief of the Combined Fleet Admiral Yamamoto Isoroku’s direction The result of this map manoeuvre showed that Japan could not attack the Dutch East Indies without opening hostilities against the United States and Britain There would be a high possibility that, if Japan touched on the Dutch East Indies, the United States would intervene Yamamoto reported the result of the map manoeuvre to Prince Fushimi, Chief

of the Navy General Staff: “Unless American war preparation is greatly delayed and Britain’s war against Germany becomes too disadvantageous to Britain, using force against the Dutch East Indies will inevitably lead Japan to war against the United States Britain will follow the United States There will

be a high possibility that in the middle of operations in the Dutch East Indies,

we will have to fight against the Netherlands, the United States and Britain

40 BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 3 (War History Series: The Imperial General Headquarters Navy Section: The States of Affairs until the Outbreak of the Greater East Asia War Vol.3) (Tokyo: Asagumo Shinbunsha, 1973), p.71; Kimitsu Sensō Nisshi, Jō, p.ⅶ

41 Kumao Imoto, Daitō-A Sensō Sakusen Ni’shi (Operations Diary of the Greater East Asia War) (Tokyo: Fuyō Shobō Shuppan, 1998), p.63

Japan should not advance to the south without the resolution and preparations

to conduct war against these three powers If Japan should fight a war against these three powers, it will be better to attack the United States first and occupy the Philippines The purpose of operations in the Dutch East Indies is to obtain its natural resources Should we not obtain them peacefully, there will be the United States and Britain behind the Dutch authorities If the Dutch authorities cannot count on the support of Anglo-American powers, they will succumb to Japanese pressures and offer Japan the resources.”42 As a result of this map manoeuvre, the navy abandoned the consideration of opening hostility solely against the Dutch East Indies Should Japan open hostilities against the Dutch East Indies, Japan must take on the United States and Britain as well In case

of a war against the United States, the result showed, Japan should attack the Philippines, seizing Manila and turning it into a base of operations against the American Fleet Equally important places to capture and use were the Marshall and Bismarck Islands.43

From the autumn of 1940 to the spring of 1941, after the army had entered into northern French Indochina in September 1940, Japan could not advance its south-bound military policy further because there was no consensus between and within the two armed forces over when, how, where and why Japan would advance: was it for the settlement of the war in China, was it for capturing natural resources, was it for throwing out the Western powers from Asia, was it preparation for war against the United States, or was

42 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2 , pp.141-144; BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 3, pp.304-306

43 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2 , pp.141-144; BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 3, pp.304-306: Iriye, The Origin of the Second World War in Asia and the Pacific, p.126

it an excuse for gaining more matériel and a larger budget? During this time, each section of the Japanese government pursued its own policy without a unified national policy There were several meetings between the Army General Staff and the Navy General Staff, but contrary to coordinating their policies, both sides came to realise it was impossible to compromise The army pursued its policy on the assumption that war against the United States should

be avoided as much as possible while the navy tried to strengthen its armaments by stressing the American threat These two positions were fundamentally incompatible

Even though there was no consensus between the two armed forces over their south-bound policies, they agreed to take advantage of the border dispute between Thailand and French Indochina Both believed that, whether Japan would utilise force against both Britain and the United States or only one of them, establishing an influence in Thailand would help Japan.44 The army formulated a plan to mediate in the border dispute and use that as a lever for gaining French Indochina’s recognition of their demand for bases in southern French Indochina and for establishing a military alliance with Thailand For the Army General Staff, the purpose of mediation was to establish a co-ordinated defence of Japan, Thailand and French Indochina and

to establish bases for south-bound advancement In order to attack Singapore,

it was necessary to acquire advanced bases in Thailand and French Indochina considering the cruising range of aeroplanes Major-General Tanaka Shin’ichi, Chief of the Operations Division, wrote on 25 October: “In return for

44 Moriyama, “Nanshin-ron to Hokushin-ron”, p.196; Iriye, The Origin of the Second World War in Asia and the Pacific, p.127

mediation, it is necessary for us to demand that French Indochina approve an air-route to Saigon, airfields for it, ports of call, and stationing of forces for defending these places Between Japan and Thailand, it is necessary to enact a military treaty amicably for coordinated defence which includes the passage of Japanese forces, and establishing supply and air bases It would be ideal to finish these by the end of this year.”45

On 27 December, the Supreme Command Government Liaison Conference decided that Japan would proceed in accordance with this plan to intervene in the Thai-Indochina dispute, and on 30 January 1941, an “Outline

of Policy towards Thailand and French Indochina” was adopted According to these decisions, Japan would take “coercive action” or even use force, against French Indochina as necessary to achieve these goals The so-called “coercive action” actually began after the end of January The army, which increased its occupation forces in French Indochina under the pretext of sending replacement troops, and the navy, which concentrated its warships and aircraft

in the region of Hainan Island, engaged in “demonstration actions” As part of this “Operation S”, one cruiser and one destroyer were anchored in Saigon on

28 January and another destroyer off Bangkok on 1 February These Japanese actions gave rise to the idea in Britain of a “Far East Crisis”.46

The reason why the Imperial Japanese Navy agreed to take “coercive

action” was the “Automedon affair” of December 1940 On 11 November 1940, the British freighter Automedon, under way from Liverpool to Hong Kong and

45 BBKS, Senshi Sōsho: Daihon’ei Rikugun-bu, 2 , pp.118-119

46 Hosoya, “Britain and the United States in Japan’s view of the international system, 1937-41”, pp.66-67

Shanghai via Durban, Penang and Singapore, was captured by the German

auxiliary cruiser Atlantis in the southern Bengal Gulf Among freight the Atlantis seized, there were some top secret British documents: British War

Cabinet minutes of 8 August 1940 and 15 August, and the Chief of Staff report

on the defence of Singapore and the Far East dated 31 July 1940 Aware of the

importance of these documents, the commanding officer of Atlantis, Captain

Rogge, sent them to the German Naval attaché in Tokyo, Real-Admiral Paul

Wenneker, by a seized Norwegian tanker Ole Jacab Wenneker received the

documents on 5 December He sent the originals to Berlin by courier, radioed a summary of their contents, and telegraphically asked for permission to hand over copies of them to the Japanese Copies of them were delivered to the Vice-Chief of the Navy General Staff, Vice-Admiral Kondō Nobutake, on 12 December.47 The British documents portrayed an extremely pessimistic evaluation of Far Eastern defence, in which the British Chiefs of Staff concluded that, since Britain was unable to send the fleet to the Far East, it must avoid an open clash with Japan The Japanese naval leaders judged from these documents that it was safe to take “coercive action” Admiral Oikawa Koshirō, the Minister of the Navy, stated at the Supreme Command Government Liaison Conference on 27 December: “According to our intelligence documents, it is estimated that Britain will not go to war as long as Japan confines itself to advancing into French Indochina but a war will

47 Hans-Joachim Krug, Yōichi Hirama, Berthold J Sander-Nagashima, and Axel Niestlé, Reluctant Allies: German-Japanese Naval Relations in World War Ⅱ (Annapolis: Naval Institute Press, 2001), pp.34-35, 171-174, 240-241,

p 336; Yōichi Hirama, Dai-Niji Sekai-Taisen to Nichi-Doku-I Sangoku Dōmei (The Second World War and the Tripartite Pact) (Tokyo: Kinseisha, 2007), pp.33-35

become inevitable if Japan advances into the Dutch East Indies.”48

Japanese mediation efforts between Thailand and French Indochina conducted by Matsuoka Yōsuke, the Minister of Foreign Affairs, who did not support the policy of the two armed forces to take “coercive action”, proved successful, depriving the Japanese armed forces of an excuse for military intervention Thailand and French officials in Indochina accepted a compromise settlement and signed a new treaty on 11 March As a result, the navy and the army failed to seize the opportunity to occupy parts of Thailand

or southern French Indochina for establishing advanced bases to move further.49

Since it was established in October 1940, the War Guidance Office of the Army General Staff considered that it had to establish unified national policy for south-bound advancement and started studies on it From November

1940 to February 1941, it discussed its plan with related bureaux, divisions and sections of the Ministry of War and the Army General Staff, especially the Operations Division and its Operations Section On 6 February, it presented its proposed plan “Outline of Policy toward the South” to them The points were:

(1) The purpose of policy towards the south is to establish self-support Japanese economic sphere of interest and to reduce British influence there

(2) If opportunities such as the collapse of the British mainland or the

48 Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41”, p.43

49 Iriye, The Origin of the Second World War in Asia and the Pacific,

pp.131-132

British Empire should arise, or the United States and Britain should force total embargo on Japan, Japan will accomplish the purpose mentioned above by using force

(3) Japan will try to divide the United States and Britain and to restrict its adversaries to Britain and the Netherlands.50

On 8 February, the Ministry of War and the Army General Staff agreed with the War Guidance Office’s proposed plan On 10 February, Arisue Yadoru, Chief of the War Guidance Office, approached Captain Ōno Takeji, a staff officer of the Operations Division of the Navy General Staff, and told him the contents of the proposed plan as his personal opinion Ōno replied to Arisue that using force to the south would lead Japan to war against the United States

He did not consider the United States and Britain were separable On 17 February, Ōno visited Arisue reconfirming the navy’s opinions for south-bound advancement “The United States and Britain are absolutely inseparable Using forces to the south would lead Japan to war against the United States Consequently, we have to promote preparations for war against the United States.”51 The War Guidance Office started questioning the navy’s intention of advocating war against the United States It came to suppose that the reason why the navy advocated a war against the United States was for strengthening naval armaments, so that the navy did not have the actual intention of waging such a war An officer in the War Guidance Office wrote

in its journal: “Isn’t the navy a traitor to the country advocating war against the United States to strengthen its armaments?”52

On 15 March, there was a long meeting until late at night between the War Guidance Office of the Army General Staff and the Operations Division

of the Navy General Staff to coordinate their south-bound policies They honestly discussed their standpoints, during which army officers firstly knew the true intention of the navy: even though it advocated war against the United States, the navy did not want to wage war unless it became inevitable, and it had no interest in using force in the event of an expedient moment.53 On 20 March, Commander Onoda Sutejirō visited the War Guidance Office to explain the navy’s intentions According to the journal of the War Guidance Office, Onoda said:

(1) The navy has no intention to use force even if good opportunities arise The defeat of Britain is not an opportunity If Britain is beaten, pressure

on Japan [from the United States] will strengthen

(2) For the navy, the concept that south-bound military advancement means using force against the United States is an absolute

(3) Japan will use force in the south only if the United States threatens Japan (total embargo on Japan)

(4) Whether the United States is currently threatening Japan or not? The navy’s answer is No Therefore, the navy has no intention to use force (5) But preparations against the United States are necessary, so that the navy

52 Kimitsu Sensō Nisshi, Jō, p.75

53 Ibid., pp.84-85

will demand more war matériel and a larger budget.54

He admitted in front of army officers that the navy had no intention of waging war but wanted more war matériel and a larger budget for war preparations On 17 April, the Operations Division of the Navy General Staff and the War Guidance Office of the Army General Staff agreed to proceed with, “Outline of Policy toward the South” as their plan, which they made based on Onoda’s explanation with adding army’s policies

What was important was that the policy defined two conditions of south-bound military advancement, which the two armed forces until then had disagreed on The first condition was that there should be no recourse to force unless the United States, Britain or the Netherlands imposed a trade embargo

on Japan The second condition was that the United States, alone or in alliance with Britain, the Netherlands and China, threatened its existence by encirclement and there was no way to break through it.55 They agreed, unless either of them were fulfilled, they would not implement their plans for forceful advancement to the south Preparations for south-bound advancement were consistent with the army’s and navy’s interests, by which they could claim more war matériel and a larger budget However, should they implement them,

it meant war They were not ready for war

In the process of making the “Outline of Policy toward the South”, the War Guidance Office made a large compromise with the navy The reason why the War Guidance Office could do this was the diminishing of the likelihood of

54 Ibid., pp.85-86

55 Ibid., pp.218-219

German landings in Britain In the summer of 1940, the army considered it would attack Singapore in concert with German landings in Britain By the spring of 1941, however, the army came to realise that it was not easy for the Germans to land and conquer Britain From the summer of 1940 to the spring

of 1941, Japanese south-bound military policies were greatly influenced by events in Europe

The Road to the War

In Germany on 27 December 1940, after obtaining British documents

in the “Automedon affairs”, the German Navy High Command (Oberkommando der Kriegsmarine) submitted a report to Adolf Hitler, in

which it advocated that a Japanese attack on Singapore would cause a disturbance in India, East Asia and Australia but would not bring the United States into the war.56 In January 1941, meetings were held at the German Embassy in Tokyo over a week in which Eugen Ott, the German Ambassador

to Japan, and his Army, Navy and Air Force Attachés discussed the feasibility

of the Japanese attack on Singapore They concluded that Japan could conquer Singapore by attacking through the Malay Peninsula if it made a surprise attack They supposed it would take at least three months for the Japanese to finish it Naval Attaché, Real-Admiral Paul Wenneker, reported this to the German Navy High Command Subsequently, Ott tried to persuade the Japanese General Staffs to attack Singapore during February and March.57 In

56 Hirama, Dai-Niji Sekai-Taisen to Nichi-Doku-I Sangoku Dōmei, p.36

57 Gendaishi Shiryō (Documents on Modern History), 1, Zoruge Jiken, Vol 1

Germany, Joachim von Ribbentrop, the German Foreign Minister, persuaded

Ōshima Hiroshi, the Japanese Ambassador to Germany, to attack Singapore

Ōshima personally agreed with Ribbentrop and promised to transmit the message to Matsuoka Yōsuke, the Minister of Foreign Affairs.58

However, the Germans failed to persuade the Japanese General Staffs

On 4 March, Ott informed Vice-Admiral Kondō Nobutake, Vice-Chief of the Navy General Staff, that Germany had completed all preparations for the invasion of Britain; the time of execution only awaited Hitler’s decision In concert with the invasion, Japan should not miss the golden opportunity of attacking Singapore without delay Kondo’s response made clear that the Imperial Japanese Navy had no intention of employing force against Singapore or the Dutch East Indies There was a great possibility that the United States would go to war if Japan used force, and the Dutch East Indies would immediately suspend the shipment of raw materials to Japan of which Japan had great need for its survival of the nation and the acceleration of the build-up of its war potential.59 Wenneker also visited Kondo to urge the Imperial Japanese Navy to attack Singapore, but Kondo’s answer was the

(Tokyo, 1962), pp.271-272; Haruo Tohmatsu, “The Imperial Army Turns South: the IJA’s Preparation for War against Britain, 1940-1941” in Ian Gow, Yoichi Hirama and John Chapman (eds.), The History of Anglo-Japanese Relations, 1600-2000 Vol 3: The Military Dimention (Basingstoke: Palgrave Macmillan, 2003), p.177; Hirama, Yōichi, Dai-Niji Sekai-Taisen to Nichi-Doku-I Sangoku Dōmei, pp.36-37

58 BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 3, p.366

59 BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 2 (War History Series: The Imperial General Headquarters Navy Section: The States of Affairs until the Outbreak of the Greater East Asia War Vol.2) (Tokyo: Asagumo Shinbunsha, 1979), pp.213-217; Arthur, J Marder, Old Friends, New Enemies: The Royal Navy and the Imperial Japanese Navy Strategic Illusions, 1936-1941 (Oxford: Clarendon Press, 1981), p.154

same.60 As for the army, Sugiyama Hajime, Chief of the Army General Staff, explained to Ott on 4 March that the Imperial Japanese Army had already begun its preparations for attacking Singapore but Japan would decide for itself whether Japan would implement it.61 The two Chiefs of the Japanese General Staffs avoided giving a promise to the Germans to attack Singapore

After settling mediation between Thailand and French Indochina, Matsuoka left for Europe on 12 March 1941 Before that, General Sugiyama warned Matsuoka that Japan would decide by itself whether it would attack Singapore, so did not promise anything to the Germans,62 because Matsuoka repeatedly advocated the necessity of the attack at that time He arrived in Berlin on 5 March On 27 March 1941, Ribbentrop told Matusoka, “A quick attack on Singapore would be a very decisive factor in the speedy overthrow

of England” The capture of Singapore would “perhaps be a better opportunity for Japan to take actions in the Pacific” Above all, the Tripartite Pact had the goal of frightening the United States “and of keeping it out of the war.” Hitler,

in the afternoon meeting on the same day, repeated the same refrain “Never in the human imagination, could there be a better opportunity for Japan to take military actions in the Pacific.” “Such a moment will never return It is unique

in history.” Matsuoka’s response was that, unfortunately, he did not control Japan and he did not have the power to negotiate on matters involving the supreme command.63 On 13 April in Moscow, Matsuoka succeeded in signing

60 Hirama, Dai-Niji Sekai-Taisen to Nichi-Doku-I Sangoku Dōmei, p.38

61 BBKS Senshi Sōsho: Daihon’ei Kaigun-bu: Dai Tōa Sensō Kaisen Keii, 3, pp.372-374

62 Ibid, p.39

63 David J Lu, Agony of Choice: Matsuoka Yōsuke and the Rise and Fall of the Japanese Empire, 1880-1946 (Lanham: Lexington Books, 2002), p.201

a neutrality pact between Japan and the Soviet Union, which secured the northern Manchuria frontier Lieutenant-General Yamashita Tomoyuki also visited Berlin in the capacity of the head of the military observer mission around the same time The German Army General Staff also tried to persuade Yamashita to attack Singapore

After the Supreme Command Government Liaison Conference on 27 July 1940 which approved “The Outline of the Main Principle for Coping with the Changing World Situation”, Matsuoka claimed that, whether Britain would

be defeated or not, Japan should advance to the south.64 Matsuoka was one of the leading actors alongside the army and the navy within the Japanese government for formulating south-bound policies at that time.65 Since December, Matsuoka had repeatedly advocated attacking Singapore What he claimed was that it was necessary for Japan to attack Singapore if Japan wanted to move to the south, because, even though Japan would advance without using force, it would bring an inevitable clash with Anglo-American powers.66 Matsuoka maintained that a swift attack on Singapore could be carried out without provoking American intervention, but gradual advancement to the south would invite it.67 However, both the army and the navy supposed that limited advance to French Indochina and Thailand could

be done without Anglo-American intervention and there was no other way to

64 Shigeki Mori, “Matsuoka Gaikō ni Okeru Tai-Bei oyobi Tai-Ei Saku (Policies towards the United States and Britain in Matsuoka Diplomacy)”, in Nihon-shi Ken-kyu (Journal of Japanese History), Vol 421 (September 1997), p.41

65 Moriyama, Nichi-bei Kaisen no Seiji Katei

66 Moriyama, “Nanshin-ron to Hokushin-ron, p.197

67 Sanbō Honbu (The Army General Staff) (ed.) Sugiyama Memo (Tokyo Hara Shobō, 1967), p.165; Shigeki Mori, “Matsuoka Gaikō ni Okeru Tai-Bei oyobi Tai-Ei Saku”, p.57

attack the south But Matsuoka repeatedly advocated that advancement to these places would bring clashes with the Anglo-American powers He claimed that, should the army and the navy advance to French Indochina and Thailand, it had to make a resolution to attack Singapore As for the necessity

of attack, Matsuoka went further than the army because he advocated attacking without considering how At that time, the army did not have complete preparations for this Moreover, without advanced bases in southern French Indochina and Thailand, it was technically impossible for the army to launch an attack

On 25 April, the Prime Minister Konoe invited the Minister of War and the Minister of the Navy to present their opinions on Matsuoka’s assertion that Japan should attack Singapore immediately Both replied they could not agree with Matsuoka.68 On the following day, the Sections Chiefs’ meeting of the Army General Staff decided that they should make a policy to check Matsuoka’s assertion.69 Preparations for attacking Singapore were compatible with the army’s policy, but implementing it right away was not On 22 May, at the Supreme Command Government Liaison Conference, Matsuoka advocated the necessity of the attack A staff officer of the War Guidance Office of the Army General Staff wrote in its journal that “What Matsuoka claimed is preposterous The navy has nothing to do with it What should we do?”70Officers in the Army General Staff were perplexed by the situation They wanted to promote preparations for military advancement to the south,

68 Kimitsu Sensō Nisshi, Jō, p.97

69 Ibid., pp.97-98

70 Ibid., p.105

including preparations for attacking Singapore, but it was too early to carry them out What they chose was to use the “Outline of Policy toward the South”, which was an agreement between the War Guidance Office of the Army General Staff and the Operations Division of the Navy General Staff over conditions for south-bound movement, to check Matsuoka’s assertion.71Imperial General Headquarters approved the “Outline of Policy toward the South” on 6 June 1941 But they failed to obtain approval of it as a national policy at the Supreme Command Government Liaison Conference or at the Imperial Conference because of Matsuoka’s opposition

The Intelligence report made by the Intelligence Division of the Navy General Staff in February 1941 judged that, even though there were news reports on an Anglo-American agreement regarding shared use of the Singapore Naval Base, there was no confirmation of this As for the number of aeroplanes stationed in British Malaya, including Singapore, it reported that there were 36 bombers, 24 torpedo bombers, 24 reconnaissance planes and 4 flying boats in August 1940 It reported that the British had added 32 fighters and 24 reconnaissance planes by the end of 1940, so that at the end of 1940, there were 144 planes Of these, 32 fighters and 32 bombers were in Singapore

It also anticipated that the number of aeroplanes in the Far East would reach

336 by the end of 1941: for northern Malaya, 4 bomber and 2 fighter squadrons (64 bombers and 32 fighters), for Singapore, 2 torpedo bomber and

2 fighter squadrons (32 torpedo bombers and 32 fighters), and for reconnaissance east of Malaya, 2 reconnaissance and 1 flying boat squadrons

71 Ibid., p.106

(42 reconnaissance planes and 6 flying boats) The total number for Malaya was 208 planes The Intelligence report also reported that there was a small possibility that, if the war in Europe became favourable for Britain, Britain would send capital ships to Singapore, but it would be difficult for Britain, if not impossible, under the current situation.72 The numbers of aeroplanes stationed in the Far East completely matched the British plan suggested by the British Chiefs of Staff in July 1940 to a single digit.73 These figures were

written in documents obtained by the “Automedon affair”

Since the summer of 1940, Singapore became the most important military target in Southeast Asia for the army, but the navy did not regard it as

so important In March 1941, Commander Fujii Shigeru, a member of the Naval Affairs Bureau of the Ministry of the Navy, considered that attacking Singapore would have little effect It was irrelevant to the war in China Also, the Singapore Naval Base was too small to accommodate the American Pacific Fleet Therefore, the United States would be unaffected by Japanese attack on Singapore.74 In late April, the head of the Intelligence Division of the Navy General Staff, Real-Admiral Maeda Minoru, was secretly dispatched to Indochina and Thailand to estimate the consequence of an advance into southern French Indochina He visited Bangkok, Chiang Mai, Saigon and Hanoi The primary purpose of his trip was to judge whether or not British

74 NIDS, Naval Documents, ①Ni’shi Kaisō 632, “Fujii Shigeru Ni’shi (Fujii Shigeru Diary)”, description on 8 March 1941