The japanese road to singapore japanese perceptions of the singapore naval base, 1921 41 6

143

Chapter 3

The Origin of the Plan to Attack Singapore
1936-40


In 1936, with the termination of the Washington Treaty and its Article
19, the Imperial Japanese Navy lost its reason to accept the Singapore Naval
Base. Furthermore, geopolitical advantages that Japan enjoyed until then were
beginning to disappear as a result of the termination of naval disarmament
treaties and technological advances. This year, Japan revised the Teikoku
Kokubō Hōshin (Imperial National Defence Policy), in which Britain was
included as one of its hypothetical enemies. It was the first time in Japanese
history that Japan formally regarded Britain as its hypothetical enemy. On 11
May, when Chief of the Army General Staff, Prince Kan’in, and Chief of the
Navy General Staff, Prince Fushimi, presented the newly revised Teikoku
Kokubō Hōshin, Emperor Hirohito asked: “Why add Britain?” Prince Kan’in
replied: “Recently Britain has been hastily strengthening fortifications in Hong
Kong and Singapore. Moreover, international relations are not stable. We have
to provide against an emergency”. Prince Fushimi added: “As far as the navy
is concerned, we consider it is better to avoid a war against Britain. If a war
against the Soviet Union should break out, the United States will join the
Soviet side. If a war against the United States should break out, the Soviet
Union will join the American side. In these cases, China will definitely join

144

our enemy. If Britain also joins our enemy, we stand no chance of winning. On

the other hand, if a war against Britain should break out, there will be a high
possibility that not only China but also the United States and the Soviet Union
will join our enemy. It is better to avoid these scenarios by diplomacy. The
reason why we added Britain is to provide against an emergency and no more
than that.”
1
But five years later, Japan plunged into war against Britain and
the United States by attacking British Malaya, the Philippines and Hawaii
simultaneously.
When considering Japanese policies against Britain in the period
between the two world wars, 1936 was an important turning point. On 15
January, the Japanese government announced withdrawal from the London
Naval Conference. On 26 February, there was the 26 February Incident, which
was an attempted military coup d’état. In the early hours of the morning,
soldiers led by radical junior-echelon army officers, attacked government
buildings in Tokyo. Several senior politicians were murdered. The Prime
Minister, Okada Keisuke, narrowly escaped being murdered. The Emperor,
believing the Prime Minister had been killed, ordered the Imperial Japanese
Army to suppress them. After the 26 February Incident, Hirota Kōki formed a
new cabinet on 9 March. The revision of the Teikoku Kokubō Hōshin was
approved on 3 June. On 7 August, the Hirota Government adopted
“Fundamentals of National Policy (Kokusaku no Kijun)” in which the

1
BBKS,
Senshi Sōsho, Daihon’ei Kaigunbu, Rengō Kantai, 1: Kaisen Made
(The Imperial Headquarters, Navy Combined Fleet, Vol. 1, Up to the Outbreak
of Hostility)
, (Tokyo: Asagumo Shinbunsha, 1975), p.325.

145

Japanese government stipulated expansion to both the south and the north. The
south-bound policy was officially approved as a national policy. On 25
November, it concluded the German-Japanese Anti-Comintern Pact.
2

This chapter examines the Japanese south-bound policies from 1936
to 1940 and the origin of the Japanese plan to attack British Malaya and
Singapore. In particular, it analyses the history of two different but related
aspects. The first is why the Imperial Japanese Navy proposed the south-bound
policy and how it became national policy. The second is the origin of
operational plans to attack British Malaya and Singapore made by the Army
General Staff and the Navy General Staff. How and when did the Navy
General Staff and the Army General Staff make their first operational plans to
attack British Malaya and Singapore? It has been widely believed in the
English-speaking world that Japan had been preparing to attack British Malaya
and Singapore for many years. On the other hand, some historians considered
that Japan made the plan to attack Singapore from scratch just before the war.
3

Both of these views should be reconsidered.




2
Kiyoshi Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41”, in
Fraser, T.G. and Lowe, Peter (eds.),
Conflict and Amity in East Asia: Essays in

Honour of Ian Nish
(Basingstoke: Macmillan Press, 1992), p.31
3
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 Volume
Three: The Military Dimention
(Basingstoke: Macmillan Press, 2003), p.176;
Brian P. Farrell,
The Defence and Fall of Singapore 1940-1942
(Stroud:
Tempus, 2005)
,
p.107.

146

The Origin of the South-bound Policies
The origin of Japanese south-bound military policies can be traced
back to 1933. Before that, Japanese south-bound movements did not assume a
military tone. As early as the early Meiji period, in the 1870s and 1880s, the
Japanese started living as immigrants in Nanyo. The Japanese word Nanyo
referred to islands in the south Pacific, and islands and islets in Southeast Asia
in the Meiji Period
4
, but from around the time of the First World War, it was
enlarged to refer to islands in the south Pacific and the region that we currently
know as Southeast Asia. Soto Nanyo or Omote Nanyo referred to Southeast
Asia while Uchi Nanyo or Ura Nanyo referred to islands in the south Pacific.

5

After the Russo-Japanese War, some of the leading Admirals, such as
Yamamoto Gombei and Satō Tetsutarō, envisaged south-bound advance as
future national policy. They considered south-bound advancement would be
more beneficial for national defence and development than the army’s
north-bound expansion into Manchuria and Mongolia. But their expectations
in the south were too vague to be formed into a concrete naval policy.
6
During

4
From 8 August 1868 to 30 July 1912.
5
Hajime Shimizu,
Southeast Asia in Modern Japanese Thought: Essays on
Japanese-Southeast Asian Relationship 1880-1940
(Nagasaki: Nagasaki
Prefectural University, 1997), p.4 ; Sumio Hatano, “Kokubō Kōsō to
Nanshin-ron (National Defence Policies and South-Bound Policies)”, in
Yano,Tōru,
Tōnan Ajia to Nihon (South East Asia and Japan)
(Tokyo: Kōbundō,
1991), p.149.
6
Kiyoshi Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41”,
p.35; Ken’ichi Goto,
Shōwa ki Nihon to Indonesia (Japan and Indonesia in
Shōwa Era)
(Tokyo: Keisō Shobō, 1986), p.20; Sumio Hatano, “Nihon Kaigun to

Nanshin Seisaku no Tenkai (The Japanese Navy and its Policies to the South”
in Shinya Sugiyama and Ian Brown (eds.)
Senkan-ki Tōnan Ajia no Keizai
Masatsu: Nihon no Nanshin to Ajia Ōbei (Economic Frictions in South East
Asia during the Inter War Period: Japanese South-bound Policies, Asia and
Western Powers
(Tokyo: Dōbunkan Shuppan, 1990), p.142.

147

the Taishō Period
7
, Japanese companies sought economic expansion in Nanyo.
Trading companies and banks established their branches in Singapore. As a
result, there was a sharp rise in Japanese exports to the Nanyo region. However,
the Imperial Japanese Navy had no military policy for the Nanyo region. From
the Japanese point of view, Japanese south-bound advancement did not
contradict the colonial policies of Western powers because the Japanese had no
intention to overthrow Western interests in Nanyo. It was not until the middle
of 1933－after Anglo-Japanese relations were deteriorating in consequence of
Japanese military actions in Manchuria in 1931, the Shanghai Incident in 1932,
the Japanese proclamation of Manchukuo on 1 March 1932 and the Japanese
withdrawal from the League of Nations in 1933－that the Imperial Japanese
Navy began to examine a policy of advancing into the south. In September
1933, when a Japan-India-Britain conference on the cotton trade had been
deliberating in Simla, which intensified anti-British feeling in the Japanese
public, the Minister of the Navy, Ōsumi Mineo, approved a “Guideline dealing
with China” which stipulated: “Faced with the military penetration by the
powers into the south of China, Japan must be more intensively watchful of
them, and try to prevent their aggressive moves. It is now inevitable for Japan

to adopt a more active strategy in this area within the very near future.”
8
A
historian, Ikeda Kiyoshi, pointed out that it was the first formal announcement

7
From 30 July 1912 to 25 December 1926.
8
Ikeda. “The Road to Singapore: Japan’s View of Britain, 1922-41”, p.36;
Gendaishi Shiryō (Documents on Modern History), Vol. 8
,
Nitchū Sensō 1
(Sino-Japanese War 1)
(Tokyo: Misuzu Shōbō, 1964), p.10, pp.351-53.

148

of south-ward advance made by the navy.
9
But at that time, south-ward
advance meant advance to southern China. There was no military plan for
advancing to the Nanyo region.
Economic reasons lay behind why the Imperial Japanese Navy
aroused interest in Nanyo in the mid-1930s. A historian, Asada Sadao, wrote:
“As long as Japan could obtain such resources as petroleum, rubber, and
scarce metals through trade with the United States and the western colonial
powers in Southeast Asia, the navy did not need to intervene. However, as
relations with the United States deteriorated, the navy became increasingly
concerned with the possible shortage of petroleum for its fleets and naval
aviation.”

10
Another historian, Goto Ken’ichi, pointed out that one of the two
reasons why the Imperial Japanese Navy did not have a south-bound military
expansion policy until the mid-1930s came from its oil supplying policy.
11

Since the time of the First World War, the Imperial Japanese Navy’s policy
consisted of two parts. The one was a self-support programme and the other
was an oil import programme. However, in 1916, it had already become clear
that it was impossible to self-support its oil consumption. In 1917, it
contracted an agreement with the Anglo Petroleum Company to import oil
from Tarakan, Borneo. This contract solved the navy’s oil supply problem. In
later years, the contract to import Borneo oil was succeeded by the Asiatic

9
Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41”, p.36.
10
Sadao Asada,
From Mahan to Pearl Harbor: The Imperial Japanese Navy
and the United States
. (Annapolis: Naval Institutional Press, 2006), p.207.
11
The other reason was pro-Anglo-American policies pursued by the “treaty
faction” of the Imperial Japanese Navy.

149

Petroleum Company.
12
As long as the import of oil was secure by free trade, it

did not require a policy of forcefully capturing oil. In other words, importing
oil from Nanyo put the brakes on a naval south-bound military policy until the
mid-1930s. What was important for the Imperial Japanese Navy until the
mid-1930s was how to secure a stable supply of oil from Nanyo by
importation.
13
South-bound military advancement to Nanyo was incompatible
with this policy. However, as relations with the United States and Britain were
deteriorating, importing oil from Southeast Asia became uncertain.
To research the Nanyo region, the Imperial Japanese Navy established
on 15 July 1935 the Committee to Investigate Southern Policy, with the
Vice-Chief of the Navy General Staff, Shimada Shigejirō, as the chairman.
Members of this committee consisted of officers of the Ministry of the Navy
and the Navy General Staff. Commander Chūdō Kan’ei and Captain Nakahara
Yoshimasa proposed establishing this committee to Captain Oka Takazumi and
it was established on Oka’s initiative. Chūdō and Nakahara had developed a
passionate interest in Nanyo through books and voyages.
14
Chūdō realised
during a graduate voyage of the Naval Academy to Nanyo in 1916 that only a
small number of Western people exploited rich natural resources in
undeveloped Nanyo. Consequently, there would be great opportunities for the
Japanese to develop industries and foster trade in this region. The Imperial
Japanese Navy could back up their activities by financial aid, giving

12
BBKS,
Senshi Sōsho: Kaigun Gunsenbi, 1 (Naval Armament and War
Preparations, Vol. 19)
(Tokyo: Asagumo Shinbunsha, 1969), pp.694-95.

13
Goto,
Shōwa ki Nihon to Indonesia
, 22-31, pp.83-85.
14
Hatano, “Nihon Kaigun to Nanshin Seisaku no Tenkai”, p.149.

150

intelligence, and protecting sea routes. Nakahara, who had a nickname “The
King of Nanyo”, shared similar experiences.
15
The main purpose of the
committee was to research the oil question. For the first time, the Imperial
Japanese Navy began to systematically investigate petroleum resources in the
Nanyo region, especially in the Dutch East Indies, in order to prepare for a
Japanese-American conflict. The aims of the committee included conducting
various surveys and studies of everything related to Omote Nanyo－British
Malaya, Borneo, the Dutch East Indies and French Indochina－from the
viewpoints of national defence and the national policy relating to it.
Commander Nakazawa Tasuku, a member of this committee, was of the
opinion that any advance to the East Indies might very well result in a clash
with the Anglo-American powers. However, in this committee’s study, as
regards an advance on Omote Nanyo, the Imperial Japanese Navy did not
necessarily play a primary role, economic expansion or immigration were the
basic methods studied.
16
In other words, at this stage, Nanshin (South-bound
Advancement) to Nanyo did not mean military expansion.
After Hirota Kōki formed a cabinet on 9 March, to study and

formulate naval policies, the Ministry of the Navy established three new
committees on 19 March. Members of these committees consisted of officers
of the Ministry of the Navy and the Navy General Staff. Their aim was “to
prepare naval armaments that will give confidence in national defence in view

15
Ibid., pp.146-147.
16
Asada,
From Mahan to Pearl Harbor
, p.207; Kiyoshi Aizawa, “The Path
Towards an ‘Anti-British’ Strategy by the Japanese Navy between the Wars”,
in
The History of Anglo-Japanese Relations, 1600-2000 Volume Three: The
Military Dimention
, p.142.

151

of the fact that at the end of this year [1936] naval treaties will expire”.
17

Among these three committees, the most important for our purpose was the
First Committee. The task of the First Committee was to study and formulate a
firm and concrete policy of south-bound expansion. The Second Committee
was to study how to make the organisation of the Imperial Japanese Navy
more efficient and the Third Committee was to study naval budget and
financial affairs. The Chair of the First Committee was Vice-Admiral, Toyoda
Seomu, Chief of Naval Affairs Bureau. However, it has been said that the
officer who actually dominated the First Committee was Captain Nakahara

Yoshimasa who was the foremost exponent of a south-bound advancement
within the Imperial Japanese Navy. Policies set forth by the First Committee
were summarised in the paper “National Policy Guidelines (Kokusaku Yōkō)”
with army’s policies on the continent in April 1936. It stipulated: “The basic
policy of imperial national policy guidelines should be to reinforce various
policies domestically while securing a foothold for the Empire on the
continent and simultaneously expanding southwards”.
18
With regard to policy
towards the “various southern countries”, it insisted on:


17

Gendaishi Shiryō Dai 8 kan
,
Nitchū Sensō 1,
p.351; BBKS,
Senshi Sōsho:
Daihon’ei Kaigun-bu, 1.
, p.291; Asada,
From Mahan to Pearl Harbor
, p.207;
18

Gendaishi Shiryō Dai 8 kan
,
Nitchū Sensō 1,
p.354; Aizawa, “The Path
Towards an ‘Anti-British’ Strategy by the Japanese Navy between the Wars”,

p.142; ; Kiyoshi Aizawa,
Kaigun no Sentaku: Saikō Shinjuwan e no Michi (The
Navy’s Choice: The Road to Pearl Harbour Reconsidered
) (Tokyo: Chūō
Kōronsha, 2002), pp.123-24; BBKS,
Senshi Sōsho, Daihon’ei Rikugunbu, 1
(Imperial Headquarters, Army, Vol.1, Up to May 1940)
’(Tokyo: Asagumo
Shinbunsha, 1967), p.381; Ikeda, “The Road to Singapore: Japan’s View of
Britain, 1922-41”, pp.36-37.

152

Domestically, a method which will permit unification [of making and
execution of policies] should be discussed and determined; and the
necessary organisations established, while the administration of Taiwan and
the Mandated Islands should be strengthened. Internationally, a gradual
expansion should be attempted, for the time being, through increasing
immigration and economic expansion, while careful preparations shall
constantly be made against pressure or interference from Britain, the United
States and the Netherlands, which is naturally to be expected. The
completion of preparations of forces, for an emergency, is necessary.
19

This paper stipulated increasing immigration and economic expansion
as means for Japanese south-bound policies but also anticipated the situation
that Britain and the Netherlands would become possible enemies. The United
States remained the main target of the naval expansion.
20
The Imperial

Japanese Navy’s policies for Britain and the United States were outlined in the
National Policy Guidelines as follows:

Policies Towards Britain
Great caution must be paid to possible action by Britain to use another
foreign power, in particular the United States, the Soviet Union or China, to
apply pressure on Japan, and we must take advantage, whenever possible, of
the delicate political situation in Europe and the political condition in the
British colonies in order to expand our national power into the cracks among

19
Ibid.
20
Asada,
From Mahan to Pearl Harbor
, p.207.

1
53

British interests in East Asia. Furthermore, economic and cultural ties with
British possessions shall be intensified, in order to check their anti-Japanese
policies.

Policies Towards the United States
In order to oppose the traditional Far Eastern policy of the United States,
armaments shall be held at a satisfactory level, the United States’ approval
of the Japanese Empire’s status in East Asia shall be sought, and the
establishment of a friendly relationship, based on economic interdependence,
shall be also sought.

21


In the National Policy Guidelines, a historian, Aizawa Kiyoshi, points
out: “the stance towards Britain was more confrontational and challenging
than the stance adopted towards the United States”
22
. However, it neither
anticipated military confrontation against Britain, nor advocated military
advancement to the south. It could not be regarded as a harbinger of attacking
Singapore.
The more urgent reason why the Imperial Japanese Navy laid out its
south-bound policy at the time was to counter the Imperial Japanese Army’s
Hokushin Nanshu Ron (Advance to the North, Hold in the South Policy) for
preventing a situation that the budget for the navy would be snatched by the

21

Gendaishi Shiryō Dai 8 kan
,
Nitchū Sensō 1,
pp.354-355; Aizawa, “The Path
Towards an ‘Anti-British’ Strategy by the Japanese Navy between the Wars”,
p.143.
22
Ibid.

154

army. On 1 August 1935, the army officer, Colonel Ishihara Kanji, who was

the mastermind of the Manchuria incident, became Chief of Operations
Section of the Army General Staff. He concluded that preparations for war
against the Soviet Union, which he thought would break out in the near future,
were unsatisfactory. He considered the Army General Staff would make
unified national policy with the Navy General Staff to confront the Soviet
Union by strengthening Manchukuo and seeking co-operation with China.
Accordingly, he started negotiations with his naval counterpart, Captain
Fukudome Shigeru, on 17 December 1935.
23
In these negotiations, Ishihara
told Fukudome: “In the next ten years, what Japan has to do is to strengthen
Manchukuo. Japan has no strength to implement other policies. It will not be
too late to frame the south-bound policy after that.”
24
However, Ishihara’s
plan which took strengthening Manchukuo and army’s preparations for war
against the Soviet Union as priority was not acceptable to the navy. The navy
also had to strengthen its armaments in view of the fact that at the end of 1936
naval disarmament treaties would expire. Furthermore, the navy looked
disapprovingly at what the army did in Manchuria and northern China. The
navy considered it had to prevent the army’s war against the Soviet Union and
present a counter plan. Commander Takada Toshitane, a member of the First
Committee at that time, recollected after the war that the prime aim of the First

23
BBKS,
Senshi Sōsho: Daihon’ei Kaigun-bu: Rengō Kantai. 1.,
p.290.
24
Shigeru Fukudome, “Hogo ni Kishita Teikoku Kokubō Hōshin (Throwing

National Defence Policy into the Wastebasket)” in
Chisei, Bekkan, Himerareta
Showa Shi (Intellectuals, Supplementary Volume, Secrets in Showa History)

(Dec, 1956), pp.176-177.

155

Committee was to propose counter plans to the army from the naval side.
25
In
the National Policy Guidelines, the Imperial Japanese Navy proposed a
Hokushu Nanshin Ron (Hold in the North, Advance to the South Policy) by
stating “the basic policy of imperial national policy guidelines should be to
reinforce various policies domestically while securing a foothold for the
Empire on the continent and simultaneously expanding southwards”.
26

The Hirota Government, which was unable to decide on priority
between the army’s plan to the north and the navy’s plan to the south, settled
on a compromise between the two armed forces on 7 August 1936 at the Five
Ministers’ Conference which consisted of the Prime Minister, the Minister of
Foreign Affairs, the Minister of Finance, the Minister of the Navy and the
Minister of War. It was the famous “Fundamentals of National Policy
(Kokusaku no Kijun)” which stipulated expansion towards both the south and
the north.
27
This showed the fact that the government could not co-ordinate
the contradictory policies of the Imperial Japanese Navy and the Imperial
Japanese Army. What the government did was to formulate bureaucratic

compromising policies as the “Fundamentals of National Policy” which
incorporated incompatible policies enacted by two armed forces separately.
For the navy, enactment of “Fundamentals of National Policy” was a success
in “Defence against the army” preventing a situation where the budget for the

25
BBKS,
Senshi Sōsho: Daihon’ei Kaigun-bu: Rengō Kantai, 1.,
pp.290-300
.

26
Aizawa, “The Path Towards an ‘Anti-British’ Strategy by the Japanese
Navy between the Wars”, p.142.
27

Gendaishi Shiryō Dai 8 kan
,
Nitchū Sensō 1,
pp.361-62.

156

navy would be snatched by the army by stipulating the south-bound policy.
28

The army also succeeded in stipulating its assertion to the north. By adapting
the “Fundamentals of National Policy”, the two armed forces justified the
expansion of their budgets and armaments. Hirota explained to Tōgō Shigenori
after the war in Sugamo Prison, “I considered that the real aim of the

“Fundamentals of National Policy” was to justify expansion of the budget of
the two armed forces and no more than that. The navy justified fleet expansion
after the naval treaties expired. The army also took advantage of the
opportunity [to expand its budget].”
29
Consequently, “Fundamentals of
National Policy” expressed a policy of gradual advance to the south, especially
to the Soto-Nanyo (Southeast Asia) region, through peaceful means. In this
way, the south-bound expansion policy was formulated officially as a national
policy in 1936. What is important is that the Japanese government failed to
formulate either strategic priority, or coordinated military policy between the
two armed forces. “Fundamentals of National Policy” stated that:

Japan expects its national and economic advance into the south, especially
into Soto-Nanyo areas through gradual and peaceful means, with avoiding
hostilities with other countries in order to consolidate its national and
economic power as well as strengthening of Manchukuo.
30


28
BBKS,
Senshi Sōsho: Daihon’ei Kaigun-bu: Rengō Kantai, 1.,
p.290.
Vice-Admiral Oka Takazumi used the term “Defence against the army” in an
interview by Nomura Minoru on 9 April 1963.
29
Shigenori Tōgō,
Jidai no Ichi Men (An Aspect of Showa Era)
(Tokyo:

Kaizōsha, 1952), p.98.
30

Gendaishi Shiryō Dai 8 kan
,
Nitchū Sensō 1,
pp.361-62.

157


As for naval armament, it said: “The aim of naval armament is to
establish enough power to secure command of the western Pacific against the
United States Navy.”
31
What aroused our interest is that, even though
“Fundamentals of National Policy” proclaimed south-bound economic
expansion, the target of the build up of naval armaments was still the United
States Navy.


Revising Teikoku Kokubō Hōshin
As we saw in Introduction and Chapter 1, the Teikoku Kokubō Hōshin
was first sanctioned in 1907 as a post Russo-Japanese War defence policy.
This was revised in 1918 and 1923. Until the 1936 revision, the hypothetical
enemies mentioned in the Teikoku Kokubō Hōshin were the United States,
Russia (the Soviet Union), and China. The Imperial Japanese Army regarded
the Soviet Union and China as its hypothetical enemies while the Imperial
Japanese Navy regarded the United States as its hypothetical enemy. The
listing of Britain as one of the hypothetical enemies alongside the Soviet

Union, the United States and China in the 1936 revision of the Teikoku Kokubō
Hōshin was undertaken on the initiative of the Navy General Staff. Captain
Fukudome Shigeru, Chief of the Operations Section of the Navy General Staff,
recollected after the war that “it had become impossible to leave Britain and

31
Ibid.

158

the Netherlands out of our calculations as hypothetical enemies, aside from the
United States, the Soviet Union and China, which had heretofore been our
hypothetical enemies”.
32
Commander Nakazawa Tasuku, a member of the
Operations Section of the Navy General Staff and the navy’s representative to
the group that actually drafted the revisions of the Teikoku Kokubō Hōshin,
pointed out five reasons why they added Britain to the hypothetical list:

(1) Britain contributed greatly to Peace in the Far East by the
Anglo-Japanese Alliance for a long time, from 1902 to 1921. However,
with the conclusion of the Washington Treaty, the Anglo-Japanese
Alliance was abrogated and the Four Power Treaty was enacted;
(2) after the abrogation of the Anglo-Japanese Alliance, Britain established
greater intimacy with the United States;
(3) after the Manchuria Incident, British attitude toward Japan had
deteriorated and Anglo-American relations became inseparable;
(4) if Japan executed its policy in the continent, there was a high possibility
that Britain and the United States would be obstacles to Japan; and
(5) if Japan adopted a southern advance policy and carried out an economic

expansion into the Dutch East Indies, it was to be expected that the
Netherlands would depend on Britain and harden their anti-Japanese
attitude.
33


32
Fukudome, “Hogo ni Kishita Teikoku Kokubō Hōshin”, p.176; Aizawa, “The
Path Towards an ‘Anti-British’ Strategy by the Japanese Navy between the
Wars”, p.143.
33
Nakazawa Tasuku Kankō Kai (ed),
Kaigun Chūjō Nakazawa Tasuku:

159


What is interesting for us is that he did not mention the Singapore
Naval Base in these five reasons. This backs up the view this thesis presented
in Chapter 1 that the Imperial Japanese Navy did not consider the Singapore
Naval Base as an imminent threat in the 1920s.
After the Russo-Japanese War, especially after the Washington
Conference in 1921/22, the United States was the Imperial Japanese Navy’s
only hypothetical enemy. In fact, as we saw in Chapter 1, various naval
armament plans were only aimed at the United States until the mid-1930s.
However, as a result of a consequence of situations in the mid-1930s, there
appeared a possibility for the Imperial Japanese Navy that, if Japan carried out
expansion to the south, even though it would be economic expansion, Britain
would become a confronting power to Japan. The German Naval Attaché in
Tokyo, Paul Wenneker, described the change in the Imperial Japanese Navy in

June 1936 as follows:

I was able to confirm, to my surprise that, by contrast with the period of
more than six months before, when the whole Japanese Navy had still, as
much as ever, seemed to be fixed intently and unflinchingly on the United
States as its only future opponent, of late a fundamental change in this
attitude has come about even among front-line units. In the front line, they
actually advocate an even tougher line than the Ministry of the Navy itself,

Sakusen Buchō, Jinji Kyokuchō (Vice-Admiral Nakazawa Tasuku, Chief of the
Operations Division and Personnel Bureau)
(Tokyo: Hara Shobō, 1979), p.14.

160

from which the influence in this direction undoubtedly stems and where I
have for sometime past been observing the phenomenon. The United States
is no longer regarded exclusively as the future enemy, but now it is primarily
Britain. It is practically certain that operational investigations are being
conducted against a fleet attacking from the south-west－Singapore.
34


There is no evidence that the Imperial Japanese Navy anticipated a
British attack from Singapore at that time, but Wenneker recognised the abrupt
change of atmosphere among the younger generation of naval officers.


Advocates of South-bound Policies
In 1936, Commander Ishikawa Shingo, then a staff officer of the

Second Fleet, made a fact-finding tour to Europe. On his way to Europe, he
visited the Philippines, Java, Sumatra and Singapore. In the summer of 1941,
he took a leading role to establish a consensus among middle-echelon naval
officers that war against the United States and Britain was unavoidable. Before
this tour, he had strong anti-American feelings, but he had no interest in
Southeast Asia. In 1931, he published a book Nihon no Kiki (Crisis of Japan)
under the pen name of Ōtani Hayato, in which he expressed his opinion that
Japan would fight a war against the United States over interests in Manchuria,
but he did not mention advancement to Southeast Asia or a clash with Britain

34
Aizawa, “The Path Towards an ‘Anti-British’ Strategy by the Japanese
Navy between the Wars”, p.144.

161

in this book.
35
However, after returning from this tour, he became a strong
advocate of south-bound expansion.
Ishikawa looked back on this tour in his book published in 1960, in
which he stated that he had an impression that an ABCD (American, British,
Chinese and Dutch) encirclement was in the making to the south of Japan. In
Java, he recognised that the Dutch authorities in the Dutch East Indies kept
strict watch on him. In Singapore, he was impressed by the number of oil
tanks. He estimated from the size and number of oil tanks that Britain stored at
least a half of million tons of oil in Singapore. Considering that Britain could
also be backed up with oil fields in Sumatra, he realised, if a war should break
out, it was suitable for Britain to use Singapore as the base for long-term
operations. He wrote in the book: “I observed that the British intention to build

a huge base here [in Singapore] was very serious. The influence of the base
spread over the South China Sea, Indochina and the Dutch East Indies. It also
could work in concert with American bases in Hawaii and the western Pacific.
Consequently these bases could overwhelm Japan without difficulty. The
Washington Treaty prohibited Japan from establishing bases in the Bonin
Islands and Omami Oshima but allowed Britain to build such a huge base in
Singapore. The treaty advocated World peace but actually it just forcefully
oppressed Japan.” On the day of leaving Singapore, he was investigated by the
British authorities. At the place of investigation, a Dutch officer sat with
British officers and they asked what Ishikawa did, not only in Singapore, but

35
Hayato Ōtani,
Nihon no Kiki (Crisis of Japan)
(Tokyo: Moriyama Shoten,
1931).

162

also in the Dutch East Indies. From these experiences in Singapore, he
speculated that Britain and the Netherlands had made some kind of a secret
agreement.
36
In Europe, he realised the rise of Germany and the decline of
Britain as world powers.
On his return from his tour, Ishikawa presented his report to naval
leaders, including the Minister of the Navy, Nagano Osami. He expressed his
personal views in this report: “As the influence of the Japanese Empire
advances, Anglo-Japanese conflicts shall become inevitable”
37

. As for the
Nanyo region, he advocated demanding Open Door Policies for the Straits
Settlements, British and Dutch East Indies, the Philippines, Australia and the
New Zealand, which meant Britain and the Netherlands should open their
trade doors to the Japanese. The three main points of the report were as
follows. First, an ABCD (American, British, Chinese and Dutch) encirclement
was in the making to the south of Japan. Second, Japan could count on
Germany which would rise up in arms around 1940. Ishikawa predicted that it
would be a golden opportunity for Japan to break through this ABCD
encirclement. Third, before 1940, it would be premature to rise up in arms.
However, the reaction of the naval leaders to the Ishikawa’s report was chilly.

36
Shingo Ishikawa,
Shinjuwan made no Keii: Kaisen no Shinsō
(Circumstances Leading to Pearl Harbour: The Truth about the
Commencement of the War)
(Tokyo: Jiji Tsūshinsha, 1960), pp.110-113.
37
“0257, Teikoku no Tōmen suru Kokusai Kikyoku Dakai-saku Shian
(Personal Views on Challenging International Situation the Empire Faces)” in
Institute of Oriental Studies, Daito Bunka University (ed.),
Shōwa Shakai
Keizai Shiryo Shūsei: Dai 2, Kaigun Shō Shiryō (2) (Documents of Society and
Economy in Shōwa Period, Vol. 2, Documents of the Ministry of the Navy (2))
(Tokyo: Institute of Oriental Studies, Daito Bunka University, 1980),

p.286.

163

He wrote that no one showed any interest in it.
38
His fears and anxieties were
premature for several years and in 1936 only existed in Ishikawa’s imagination.
In spite of his ambition to work in Tokyo, he was sent back to work at sea as
captain of the tanker, Shiretoko. At that time, Ishikawa’s view was too radical
for naval leaders to accept.
39

On 3 September, a great opportunity came for south-bound advocates
within the Imperial Japanese Navy. A Japanese national was murdered by a
Chinese thug in Peihai on the coast of Kwangtung. The Navy’s Third Fleet
stationed in China dispatched a group of vessels to demonstrate its aggressive
attitude. Facing the incident, Captain Nakahara Yoshimasa, then a staff officer
of the Navy General Staff, advocated the occupation of Hainan Island, lying
off French Indochina and rich in iron ore. He wrote in his diary, “To change
the situation radically, there remains nothing but to face down Britain. Thus
the occupation of Hainan! We should occupy Hainan while Britain is
unprepared”.
40
However, the occupation of Hainan Island did not materialise
because of opposition from senior naval leaders.
41
But this episode showed
how radical middle-echelon officers who advocated south-bound policy
regarded Britain at that time. Their perceptions of Britain were different from
those held by senior officers.
As we saw above, as a younger generation naval officer who did not

38
“0257, Teikoku no Tōmen suru Kokusai Kikyoku Dakai-saku Shian”, in
Shōwa Shakai Keizai Shiryo Shūsei: Dai 2,
pp.286-291; Ishikawa,
Shinjuwan
made no Keii: Kaisen no Shinsō
, pp.122-23.
39
Goto,
Shōwa ki Nihon to Indonesia
, p.47.
40
Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41”, p.37.
41
Ikeda, “The Road to Singapore: Japan’s View of Britain, 1922-41”, p.37;
Asada,
From Mahan to Pearl Harbor,
p.209.

164

participate in discussions over naval disarmament in the 1920s, Ishikawa’s
view on relations between the Singapore Naval Base and the Washington
Treaty was different from those of senior generation who had participated in
the discussions. From the mid-1930s to the outbreak of war in 1941,
south-bound policies were advocated by younger generation represented by
Ishikawa Shingo, Nakahara Yoshimasa and Chūdō Kan’ei. They entered the
Imperial Japanese Navy in the 1910s and spent junior officers’ years at sea in
the 1920s. They might be influenced by anti-Anglo-American public opinion
in the 1920s outside of decision making processes of the navy. In the 1930s,

these officers started working in the Ministry of the Navy or the Navy General
Staff as junior or middle echelon officers. Traditionally, the Imperial Japanese
Navy had been under the strong influence of Britain and the Royal Navy. By
the mid-1930s, however, younger naval officer’s views of Britain became
more similar to those of ordinary Japanese.
With the adoption of several policies in 1935 and 1936, the Imperial
Japanese Navy’s south-bound advance policies entered a new stage. With the
introduction of “Fundamentals of National Policy”, the south-bound policy
became official national policy. Within the Imperial Japanese Navy, there
appeared advocates of south-bound expansion such as Ishikawa Shingo and
Nakahara Yoshimasa. Later, in the summer of 1941, Ishikawa Shingo took a
leading role in establishing a consensus among middle-echelon officers that
war against the United States and Britain was unavoidable.
42
However, it is

42
Asada,
From Mahan to Pearl Harbor,
pp.250-269.

165

wrong to overestimate the introduction of this policy and the influence of
radical middle-echelon officers. At that time, the Imperial Japanese Navy had
no military plan against the Nanyo region and views expressed by radical
middle-echelon officers were rejected by their superiors. What the Imperial
Japanese Navy considered was that, if Japan advanced to the south
economically, there would be a possibility that Britain would become a
confronting power for Japan. It is wrong to consider, however, that at this

stage the Imperial Japanese Navy regarded an Anglo-Japanese military
confrontation as inevitable. In 1935/36, it did start examining the possibility of
waging war against Britain, but it was considered no more than a remote
possibility.


Evolution of Operation Plans to Attack Singapore 1936-1940
As we saw above, from around 1935 to 1936, Japan started
considering south-bound policies against the Nanyo region, but until 1939
there was no substantial operational plan for British Malaya and Singapore. In
this section, we trace the origin and evolution of operational plans for
attacking British Malaya and Singapore in Annual Operational Plans. The
Army General Staff and the Navy General Staff made and presented their
Annual Operational Plans against each hypothetical enemy stipulated in the
Teikoku Kokubō Hōshin annually to the Emperor and received approval for
them. Annual Operational Plans for the next financial year were made by

166

members of the Operations Sections of the General Staffs usually in summer
43
.
In peace time, they were used for establishing military or naval policies on
armaments, formations, manoeuvres, education, communications and
intelligence. If war should break out, the Army General Staff and the Navy
General Staff composed Imperial General Headquarters and made its
operational (war) plan based on the Annual Operational Plans.
In 1936, Britain was first included in the hypothetical enemy list in
the Teikoku Kokubō Hōshin. In August that year, the Navy General Staff
included its first operational plan against Britain in its “Annual Navy’s

Operational Plan for 1937”. However, this plan simply stipulated without
detail, “the navy will annihilate British fleet in East Asia, bring East Asia seas
under its control, and destroy British bases in cooperation with the army”
44
.
There was no description of how to attack, where to attack, and how many
forces would be required for the attack. It was “Operational Plan” without any
operational plan. But it is natural to suppose that “British bases” meant
Singapore and Hong Kong. According to Nakazawa Tasuku, a staff officer of
the Operations Section, the Navy General Staff lacked information on British
Malaya and British Borneo, so it could not make a detailed plan.
45
Meanwhile,
the Army General Staff, which also had scarce information about Southeast
Asia with which to make an operational plan, dispatched its staff officer,
Major Arisue Yadoru, who had just returned from Britain where he had been

43
Japanese financial year is from April to March.
44
BBKS,
Senshi Sōsho: Daihon’ei Kaigun-bu, 1.
, p.350.
45
Ibid.

167

stationed as the Military Attaché, to Hong Kong and Singapore to gather
information.

46

The Sino-Japanese War started at Marco Polo Bridge on 7 July 1937.
On 13 August, the war spread to Shanghai, the centre of the British sphere of
interest in China. On 20 November, Imperial General Headquarters was
established. In December, Japan occupied Nanjing but the Chinese
Nationalists did not surrender. Faced with stronger resistance than anticipated,
the Japanese turned their eyes on Britain and the Soviet Union as the backers
of the Chinese Nationalists. Robert Craigie, then the British Ambassador to
Japan, found anti-British feelings “still very strong even in naval circles” in
the spring of 1938 and at the end of the year he reported that the “Japanese
Navy－and particularly in its younger officers－are manifesting such strong
anti-British sentiments.”
47
In September 1938, Captain Yokoi Tadao, a staff
officer of the Operations Section of the Navy General Staff, wrote a paper
entitled, “Why Anti-British Feeling Rising?” In this paper, he argued that the
direct reason for deteriorating Anglo-Japanese relations was that, even though
Britain declared neutrality, Britain backed up the Chinese Nationalists in the
Sino-Japanese War. In this paper, he pointed out several indirect reasons such
as the abrogation of the Anglo-Japanese Alliance and the 5:5:3 capital ship’s
ratio at the Washington Conference. But he did not mention the Singapore

46
BBKS,
Senshi Sōsho: Daihon’ei : Daihon’ei Rikugunbu, 1
, p.416.
47
TNA, FO 371/21521; ADM1/9909, Craigie to Foreign Office”, dated on 7
May 1938, “Craigie to Halifax, dated on 14 December 1938, cited in Marder A.,

Old Friends, New Enemies
, (Oxford: Clarendon Press, 1981), 25; Ikeda, “The
Road to Singapore: Japan’s View of Britain, 1922-41”, p.39.