Forgotten alliances: Japan’s role in World War I and its enduring impact on Southeast Asian geopolitics

Abstract

Purpose

This paper investigates Japan’s significant role as an Allied power during World War I, exploring its motivations, military contributions and postwar geopolitical ambitions.

Design/methodology/approach

Employing a meticulous analysis of primary sources such as historical documents and personal accounts, alongside secondary sources including scholarly articles and books, this study aims to provide a comprehensive understanding of Japan’s decision-making processes during the war. A comparative examination of Japan’s military contributions to the Allied Powers, particularly in securing sea lanes across the West Pacific and Indian Oceans, is conducted to assess their impact on the overall war outcome. Additionally, diplomatic records and negotiations are scrutinized to unravel Japan’s postwar geopolitical objectives, with a focus on its efforts to expand its influence in China.

Findings

The research reveals the multifaceted engagement of Japan in World War I, highlighting its motivations, military actions and postwar ambitions. Japan’s contributions to securing sea lanes and its postwar endeavors to enhance influence in China emerge as significant findings.

Research limitations/implications

The study’s reliance on historical documents and secondary sources may entail limitations in accessing comprehensive data, potentially impacting the depth of analysis. Furthermore, interpretations of events and motivations may vary based on different scholarly perspectives.

Practical implications

This study has practical implications for understanding the political and geopolitical context of Japan’s involvement in World War I and its aftermath. By recognizing Japan’s motivations and actions during this period, policymakers and international relations scholars can gain insights into the complexities of imperial ambitions, nationalism and power dynamics in global politics. Understanding these historical implications can inform contemporary discussions about regional stability, alliances and nationalism’s impact on international relations. Furthermore, this research encourages critical analysis of historical narratives and promotes a nuanced understanding of the consequences of imperialistic pursuits in shaping present-day dynamics.

Social implications

This study fosters a deeper understanding of the historical context and the impact of imperialism on society. By examining Japan's involvement in World War I and its subsequent imperialistic ambitions, the study sheds light on the complexities of nationalism, racial superiority and ideological justifications for expansion. This understanding can help societies reflect on the dangers of chauvinistic nationalism and its potential consequences. By critically analyzing historical events, societies can develop a more inclusive and empathetic perspective. This will promote dialogue, tolerance and the appreciation of diverse cultures in the pursuit of a more harmonious and equitable world.

Originality/value

By combining a thorough examination of primary materials with a comprehensive review of scholarly discourse, this paper offers a nuanced and well-rounded perspective on Japan’s involvement in World War I and its enduring geopolitical consequences. It contributes to the understanding of Japan’s role as an Allied power and its postwar ambitions.

Citation

Badawi, H. (2024), "Forgotten alliances: Japan’s role in World War I and its enduring impact on Southeast Asian geopolitics", Southeast Asia: A Multidisciplinary Journal, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/SEAMJ-07-2023-0056

Introduction

Japan's role in World War I, though often eclipsed by the actions of European powers, holds significant historical weight in shaping global dynamics. Historian Frederick R. Dickinson's seminal work, “War and National Reinvention: Japan in the Great War, 1914–1919” (1999), underscores the pivotal nature of Japan's decision to uphold its alliance with Great Britain and declare war on Germany in 1914. This strategic alignment with the Allies marked a turning point in Japan's ascent as a major player in global geopolitics, particularly in the Asia-Pacific region. Dickinson's analysis accentuates Japan's deliberate focus on seizing German colonial possessions in East Asia and the Pacific. Beyond serving imperial ambitions, this moves underscored Japan's burgeoning influence on the world stage. Additionally, historian Ian Nish, in “The Anglo-Japanese Alliance: The Diplomacy of Two Island Empires 1894–1907,” sheds light on Japan's substantial military contributions during the conflict, including naval patrols and ground troop deployments. These efforts played a pivotal role in securing Allied victories and reshaping the global balance of power (Daw, 1966). The postwar period witnessed the consolidation of Japan's expanded presence in Southeast Asia, a theme thoroughly explored by historian E. Bruce Reynolds in “Thailand and Japan's Southern Advance 1940–1945.” Reynolds delves into Japan's acquisition of former German territories and its consequential increase in economic and political influence in the region (Lowe, 1996). However, as historian Robert J. C. Butow extensively analyzes in “Japan's Decision to Surrender,” Japan's ascent also precipitated tensions with other colonial powers, concurrently fueling nationalist movements across Southeast Asia (Kane, 1995). This complex historical tapestry set the stage for subsequent conflicts and exerted a profound and enduring influence on the geopolitical dynamics of the region for decades to come.

When the Great War broke out in Europe in August 1914, the Japanese Empire was called Dai Nippon Teikoku because of its rapid development and modernization over the previous forty years. For the first time in its history, it was qualified to participate in European conflicts as a newly established imperial power. Japan's goal was to become the ultimate power in East Asia. It was obvious that Japan's position would be strengthened by the destruction of foreign forces in East Asia.

Japan at the Dawn of World War I

The Great War began on June 28, 1914, following the assassination of the Austrian Archduke in Sarajevo, plunging the world into a catastrophic conflict. Amid the chaos of the struggle between the Central Powers and the Allied Powers, significant geopolitical shifts occurred. Germany's invasion of Belgium on August 4, 1914, reverberated globally, prompting a pivotal moment for the Japanese oligarchy.

In Japan, a profound divide emerged among its leadership. The Imperial Japanese Army, inspired by the Prussian army, favored aligning with Germany, reflecting Japan's admiration for German civilization. Conversely, the Imperial Japanese Navy and Foreign Ministry officials favored the Anglo-Japanese alliance, aligning with Britain.

On August 15, 1914, Japan issued an ultimatum to Germany, demanding the removal of German ships from Japanese and Chinese waters by September 15. Failure to comply would result in Japan assuming control of German colonies. Despite warnings, Germany ignored the ultimatum. Consequently, on September 2, 1914, Japanese forces landed on the Shantung Peninsula, eventually achieving victory on November 7, 1914, in collaboration with British units. This strategic move aimed to safeguard the Pacific and enhance Japanese control in the region (Burdick, 1976). Simultaneously, the Japanese navy asserted control over German Micronesian territories north of the equator, governing them as a Japanese mandate (Williams, 1933). This triumph not only eradicated the German military presence but also heightened Tokyo's political influence on both the national and international fronts (Schencking, 1998).

In the aftermath of these events, Japan extended its geopolitical reach to the Mediterranean, spurred on by promises from the Allies. A formidable Japanese naval squadron, including two dreadnoughts, one battle cruiser, ten pre-dreadnoughts, thirty-three cruisers, fifty destroyers, and twelve submarines, played a crucial role in the war effort (Saxon, 2000). Japanese losses in the conflict remained comparatively moderate, with 415 military dead and 907 wounded (Mougel, 2011). Fearing the potential redeployment of Japanese ground troops to the European theater, the German Foreign Office initiated peace talks with the Japanese mission in Stockholm (Iklé, 1965, p. 63).

The revolutionary winds of change swept through Russia with the Bolshevik Revolution in 1917. As the Eastern Front faced collapse post-October Revolution, the Allies deliberated on sending American and Japanese troops to Vladivostok. This ambitious plan aimed to control the Trans-Siberian Railway, cross the Urals, and reinstate the Eastern Front.

Although initially rejected by the Japanese cabinet, the idea of sending troops to Siberia found favor among Japanese army officers. They saw it as an opportunity to expand Japan's sphere of influence, securing strategic interests and resource access. In July 1918, the U.S. requested 7,000 Japanese troops for the Siberian Expedition, a coalition effort involving British, French, Japanese, and American troops (Bradley, 1963; Unterberger, 1969; Wright, 2017). The international force, comprising 70,000 Japanese soldiers, 9,000 U.S. troops, and units from Canada, Great Britain, France, Italy, and Poland, embarked on a complex mission in Siberia.

Japan's intervention in Siberia aimed to secure regions like Dongbei Pingyuan and Inner Mongolia, responding to perceived threats from the newly formed Soviet Union. In April 1919, the Kwantung government underwent a significant transformation, leading to the establishment of a separate military administration and the formation of the Kwantung Garrison. This force, comprising one division of the regular army and one regiment of artillery stationed in the chartered area of Kwantung, received support from six regiments of railway guards along the line, bringing the total number of personnel to 10,000 (Young, 1999, p. 30).

Despite these concerted efforts, Japan found itself lacking the military prowess required to exert control over extensive territories spanning from southern Manchuria to Mongolia. Acknowledging this limitation, headquarters in Hinking devised a strategic shift, opting to form alliances with local ethnic minorities (Komatsu, 2018, p. 17). This diplomatic and strategic maneuver underscored the adaptability and complexity of Japan's engagement in the multifaceted theater of World War I.

Japanese imperialism on the Mainland

During the era of warlords in China, internal unrest, power fragmentation, and foreign intervention were prevalent. The northeastern region emerged as a volatile battleground with various factions vying for control, including Japanese and Russian armies, counterrevolutionaries, local militias, and warlord gangs. The Huanggutun Incident in the late 1920s exemplifies the interplay between Japanese interests, internal rivalries, and imperialist plans. Chang Tso-lin, a prominent figure in northeast China, was known for his pro-Japanese stance, supported by Japanese advisors, with fifty Japanese officers serving as advisors by 1928 (McCormack, 1977, p. 119). This alliance between Chang Tso-lin and Japan contributed to the delicate balance of power in the region. The Huanggutun Incident occurred in June 1928, and the assassination of Chang Tso-lin caused upheaval throughout the region. Surprisingly, it was not Chang Tso-lin's Chinese enemies who orchestrated his assassination, but a group of young Japanese officers. These officers accused Chang Tso-lin of incompetence and lack of cooperation, which led to his assassination. To disguise their involvement, the assassins used a Russian-made bomb and placed three Chinese bodies at the scene of the crime to give the appearance of Chinese involvement.

Deception played a key role in Japanese imperialism during this era. By leaving secret documents at the crime scene, the perpetrators attempted to cast suspicion on rival warlords and create chaos. Such tactics furthered Japan's imperialist agenda. The Huanggutun incident is an example of how far some Japanese officers were willing to go to achieve their goals. Even if it meant sacrificing regional stability and harmony, the assassination of Chang Tso-lin caught the Kwantung Army leadership off guard. Despite the Japanese advisers who were in Chang Tso-lin's forces, the Kwantung Army did not mobilize its troops in response to the incident. This unexpected reaction was because it was impossible to blame Chang Tso-lin's Chinese enemies. Consequently, the Kwantung Army could not use the Huanggutun incident as a justification for direct Japanese military intervention (Beasley, 1991, p. 187). It is noteworthy that, despite its severity, the Huanggutun incident did not escalate into a full-scale war. The delicate balance of power and the intricate web of alliances and rivalries in the region prevented the outbreak of a full-blown conflict. The incident served as a reminder of the ever-present threat of Japanese imperialism and the potential for further destabilization of China during the warlord era.

The Huanggutun Incident serves as a stark reminder of the complexities of Japanese imperialism during China's warlord era. It exposes the intricate interplay between Japanese interests, internal rivalries within the Japanese military, and the willingness of certain officers to pursue imperialist objectives at any cost. Through the assassination of Chang Tso-lin and clandestine maneuvers, junior Japanese officers aimed to further their agenda and sow discord among rival factions.

This incident also highlights the delicate power balance in the northeastern region at that time. The presence of Japanese advisors in Chang Tso-lin's forces underscores Japan's active role in shaping regional dynamics. However, the restrained response of the Kwantung Army, refraining from direct military intervention, reveals the complexities and limitations of Japanese decision-making. Despite manipulative actions and the potential for escalation, the incident did not escalate into full-scale war due to the intricate web of alliances, rivalries, and power struggles within the region. This underscores the fragile stability amid the chaos of warlords, offering insight into the complexities of the era.

Japan as an influential regional and international power

By the end of the First World War, Japan had developed into an important regional military power. Three political tendencies emerged among the heirs of the royal court: confirmation of the continuation of full cooperation and coordination between Japan and the West in Asia and all areas; Japan's control over neighboring Asian countries while avoiding conflict with the West; and Japan was to be a regional military shield preventing Western military presence in North and South Asia.

These trends manifested are:

Pressure on China: the twenty-one demands

The Japanese intervention in the First World War against the Germans took place on leased Chinese territory. The Kwantung Army took over the administration, prepared for a prolonged occupation, and, citing military necessity, took control of mines and railways, the 240-mile Tsingtao-Tsinan line being the most important (LaFargue, 1973, pp. 23–24). Sensing the increase in its military power, the Japanese government decided in 1915 to capitalize on the fact that European imperialism did not have enough military power to intervene in Chinese chaos. At this historical juncture, Japan had gained a large sphere of influence in northern China and Manchuria through its victories in the First Sino-Japanese War (Treat, 1939) and the Russo-Japanese War (HAMBY, 2004), which confirmed the Japanese presence in southern Manchuria and Korea. In addition, Japan had joined the ranks of European imperialist powers to gain political and economic dominance over defeated China (Spinks, 1936).

The Japanese government drafted the first list of Twenty-One Demands Taika Nijikkaj Yky (Minohara, Hon, & Dawley, 2014, p. 399), which was reviewed by the general and approved by parliament. The unalterable version, with an ultimatum containing twenty-one demands divided into five sections, was presented to the Chinese government in a private audience on January 18, 1915 (Dillon, 2010, p. 154), with a warning of profound consequences if China rejected it. The Japanese intervention in China during the First World War functions as a pivotal backdrop, offering insight into the intricate interplay of military, geopolitical, and economic factors that shaped the dynamics of East Asia in this era. The decision by the Japanese government to capitalize on China's perceived vulnerability and issue an ultimatum through the Twenty-One Demands represents a historically significant event with enduring consequences.

Upon delving into the complexities of this historical episode, it becomes evident that Japan's actions were not isolated but rather part of a comprehensive strategy aimed at consolidating its influence in the region. The demands, with their profound implications for China's sovereignty and territorial integrity, mark a critical juncture in East Asian history. A meticulous analysis of this episode affords valuable insights into the power dynamics prevailing at the time, elucidating the motivations propelling Japan's actions and delineating the far-reaching consequences for China's geopolitical landscape. The most critical articles in this ultimatum were:

Group I (four articles; Article 1 was controversial).

The Japanese Government and the Chinese Government, desirous of maintaining general peace in the Far East and strengthening the relations of amity and peaceful neighborliness existing between the two countries, agree to the following articles:

• Article 1: The Chinese Government undertakes to agree to all matters on which the Japanese Government agrees with the German Government. German interests, rights, and concessions about China are respected in this agreement.

• Article 1 stipulates that the Chinese Government commits to concurring in all matters on which the Japanese Government reaches an agreement with the German Government. Furthermore, it emphasizes that German interests, rights, and concessions in China are to be respected within the framework of this agreement.

This provision essentially signifies that China, through Article 1, is obligating itself to align its stance with that of Japan in matters involving agreements with Germany. Moreover, it explicitly acknowledges and respects the interests, rights, and concessions that Germany holds in China, as recognized within the context of this specific agreement.

The controversial nature of Article 1 likely stems from the perception that it places China in a position of subordination to Japan in diplomatic matters involving Germany. The alignment of Chinese interests with those of Japan in dealings with Germany might be seen as compromising China's autonomy and independence in its foreign relations, raising concerns and potential objections from those who view such alignment as disadvantageous to China's national interests.

Group II (seven articles).

The Japanese Government and the Chinese Government, since the Chinese Government has always recognized Japan's dominant position in South Manchuria and Eastern Inner Mongolia, agree to the following article:

• Article 1: The two contracting parties mutually agree that the terms of the lease of Port Arthur and Dairen and the terms respecting the South Dongbei Pingyuan Railway and the Antung-Mukden Railway shall be extended for a further period of 99 years, respectively.

Group III (two articles).

The Japanese Government and the Chinese Government, considering the close relations existing between Japanese capitalists and the Han-Yeh-Ping Company and desiring to promote the common interests of the two nations, agree to those two articles.

Group IV (only the preface).

The Japanese Government and the Chinese Government, to preserve China's territorial integrity, agree to the following article:

The Chinese government pledges not to cede or lease to any other power any harbor or bay on or on any island along China's coast.

[Group III and Group IV were not disputable].

Group V (seven articles; articles 1-2-3 were controversial articles).

• Article 1: The Chinese Central Government engages influential Japanese as political, financial, and military advisers.

• Article 2: The Chinese Government granted Japanese hospitals, temples, and schools in China the right to own land.

• Article 3: Given the numerous police disputes that have arisen between Japan and China to date and which have caused no small amount of irritation, the police in places (in China) where such arrangements are necessary will be placed under joint Japanese-Chinese administration, or Japanese will be assigned to police offices in such places, to help improve the Chinese police service (US-China Institute, 2022).

Realizing the negative reaction that Group V would provoke, Japan initially tried to keep its contents secret. The Chinese government tried to delay the matter as long as possible and sent the full contents of the Twenty-One Demands to the European powers in the hope that they would help contain Japan due to a perceived threat to their own political and economic spheres of interest. On May 7, 1915, the Chinese government agreed to only sixteen demands, while an anti-Japanese movement spread throughout the country. On May 8, China found itself in a tricky situation and reckoned that resistance to the 21 demands would be futile in the face of Japan's enormous military superiority without strong European support. In the end, the Chinese authorities accepted the Japanese demands. When the Chinese response to Japanese demands was sent, it stated: “The Chinese government, in its quest to maintain peace in the Far East, agrees, except for the five clauses in the fifth group (V), which will be discussed in subsequent negotiations... The Japanese ambassador must set up an appointment with the Ministry of Foreign Affairs to improve the text. He must then sign the agreement as soon as possible.”

Japanese participation in the versailles conference

The First World War ended in 1918 with the victory of the Allies. The following year, peace negotiations began in Paris, in which Japan played a key role. Japan made three demands at the peace conference. The first two were of a territorial nature. The third was the “proposal for racial equality,” which became the most hotly debated topic among the Japanese public during the 1919 peace conference.

The Japanese demands were centered on the mandate of the German colonies in the South Pacific north of the equator. They demanded to inherit German rights in the Chinese region of Shandong (Kawamura, 1997). The Japanese delegation, led by Kawakami (1919), advocated for the abolition of racial discrimination and demanded national equality. They strongly objected to discriminatory treatment against Japanese citizens in various countries, where no distinction was made between “white Caucasians” and “yellow Mongolians,” irrespective of nationality. This racial tension was exacerbated by ethnic politics influencing the political and military strategies of the Allied powers. Being the only non-white imperial power on the Allied side, Japan faced suspicion from the United States, with tensions peaking in 1913 due to the California Alien Land Law. President Woodrow Wilson even discussed mobilizing the Pacific fleet in preparation for a potential conflict with Japan (Shimazu, 1998, p. 76).

Japan at the league of nations

The League of Nations was an international organization based in Geneva, Switzerland, which was founded after the First World War. It provided a forum for international disputes. Although President Woodrow Wilson proposed it as part of his Fourteen Point Plan for a Just Peace in Europe, the United States never joined (Milestones, 2022). The League, lacking armed forces, depended on its allies from WWI. Great Britain, France, Italy, and Japan served as permanent members of the Executive Council, tasked with enforcing declarations of war, sanctions, or providing military support. Japanese diplomats collaborated with other officials to draft the League's laws. Its main bodies included the Assembly, Council, and Permanent Secretariat. Notable wings were the Permanent Court of International Justice and the International Labour Organization.

Japan attended the Washington naval conference

After WWI, leaders aimed to avert another conflict amidst rising Japanese militarism and a global arms race. Japan's “Eight-Eight” fleet program, achieving eight modern warships and battlecruisers, intensified concerns (Evans & Peattie, 1997, p. 197). By 1921, the US organized the Washington Conference to address naval reduction, particularly in Asia, and ease tensions in the Far East and Pacific. The conference, attended by major powers like Great Britain, Japan, France, and Italy, along with other stakeholders, lasted from November 12, 1921, to February 6, 1922, resulting in several significant treaties.

The four powers pact treaty

On December 13, 1921, the four-power treaty Yonkakoku Jyaku was signed by the United States, Great Britain, France, and Japan. It was partly a follow-up to the Lansing-Ishii Treaty, which had been signed between the USA and Japan. All parties agreed to maintain the status quo in the Pacific by respecting the Pacific territories. They did not want further territorial expansion and sought mutual consultations in a dispute over territorial possessions. At this point, we should point out that the controversies referred to in the second paragraph of Article One do not involve questions that, according to the principles of international law, are exclusively within the domestic jurisdiction of the respective powers.

• Article 1: The High Contracting Parties agree to respect their rights in relation to their insular possessions and insular dominions in the Pacific Ocean.

If there should develop between any of the High Contracting Parties a controversy arising out of any Pacific question and involving their said rights that is not satisfactorily settled by diplomacy and is likely to affect the harmonious accord now happily subsisting between them, they shall invite the other High Contracting Parties to a joint conference to which the whole subject will be referred for consideration and adjustment” (Office of the Historian, 2022).

This treaty replaced the Anglo-Japanese Treaty of 1902, which concerned the United States (Spinks, 1937).

The five powers pact treaty

The agreement aimed to fix the respective numbers and tonnages of capital ships possessed by each contracting nation's navies. The United States, Japan, Britain, and France signed it, in addition to Italy, and among its most prominent articles are:

• Article 1: The signatory countries agree to determine their naval arsenals following the current treaty.

• Article 4: Determining warship weight in tons.

• Article 7: Determining aircraft carriers' weight.

According to this treaty, the contracting countries own ships according to the following ratio: Britain, America, Japan, France, and Italy = 1.67 (GRIPS, 2022).

The Five Powers Pact Treaty stands as a testament to the diplomatic efforts undertaken by major naval powers in the post-World War I era to foster stability and prevent a naval arms race. The specificity of articles addressing naval arsenals, warship weight, and aircraft carriers highlights the treaty's comprehensive approach to regulating naval forces. Moreover, the carefully devised ratio of naval ownership among the contracting countries illustrates a commitment to fairness and equity in naval power, acknowledging the diverse geopolitical landscapes and historical contexts of the signatory nations. As we delve into the intricacies of this treaty, it becomes evident that it not only encapsulates a moment in history but also reflects a collective commitment to international cooperation and the pursuit of a peaceful and stable world order.

The nine powers pact treaty

The Treaty on the Nine-Power Pact, Kykakoku Jyaku, was the last multilateral agreement of the Washington Naval Conference. The Nine-Power Treaty marked the internationalization of the US open-door policy in China towards the Japanese (Kim, 2019). The treaty promised that each signatory—the United States, the United Kingdom, Japan, France, Italy, Belgium, the Netherlands, Portugal, and China—would respect China's territorial integrity. The agreement provided for an easing of military presence in Asia, which was seen as an international embargo against Japanese militarism. The most relevant articles include:

• Article 1: Respect China's sovereignty and independence.

Full support for China to develop and maintain itself through an effective and stable government.

• Article 3: Increasing the Effectiveness of the Open-door Policy.

In Article 6, China is required to meet its neutrality obligations when declaring neutrality at war (Treaty Series No. 723, 1922).

These agreements were promulgated to ensure China's national security. However, they were criticized because the Allies were unwilling to enforce them by force against Tokyo (Brownlee, 2011, p. 131). This was mainly due to Japan's militaristic ambitions to control and occupy northern China and its natural resources. Although China was neutral during the First World War, Japan claimed German spheres of influence in the country. It imposed economic privileges on Japanese subjects living in some parts of China (Spence, 1990, p. 281). As Japan honored most of its demands during the First World War, one of the hidden objectives of the Nine-Power Pact was to limit Japanese rapid expansion into Central Asia.

Domestically, the Washington Conference was an important turning point at the government level. The anti-British and anti-American lobbies came to the fore, even within the Japanese navy, clashing with the pro-British and pro-Anglo-American groups that had been the dominant view in the past (Komatsu, 2018, p. 46). In return, Japan lifted the ban on building military fortifications on the Pacific islands. It also ensured that only a few large naval bases were built in Hong Kong or the Philippines (Giffard, 1994, p. 63).

The Geneva naval conference

The 1927 Geneva Maritime Conference in Switzerland aimed to extend restrictions on naval weaponry following the Washington Naval Treaty. While the Washington Treaty regulated warships and aircraft carriers, it left cruisers, destroyers, and submarines unchecked. A major point of contention was the 5:5:3 ratio, particularly concerning cruisers, which the Japanese delegation argued was vital for strategic advantage. Despite Japan's insistence, the conference failed to reach a consensus due to disagreement between British and American delegations. Ultimately, Tokyo's concerns did not sway the conference's outcome.

London naval conference

The conference took place in London between January 21 and April 22, 1930. It was to discuss the disarmament of naval forces and review the treaties of the Washington Conference of 1921. Representatives of the United States, France, Italy, and Japan took part in the conference, which was organized by Great Britain. At the end of the three-month meetings, a general agreement was reached on regulations for submarine warfare and a five-year moratorium on the construction of large ships (Maurer & Bell, 2022).

The West wanted to restrict the construction of non-capital combat ships, but negotiations stalled. Great Britain called to discuss the construction of auxiliary ships. The Japanese delegation succeeded in improving the ratio of Japanese ships to other ships. At the Washington Conference, Japan's ratio of capital ships compared to America and Britain was 5-5-3, so the ratio became 10-10-6, and the ratio of destroyers was 10-10-7. In the London Naval Treaty, signed on April 21, 1930, a parity in the size of submarines was documented, which was reflected in Article 16.

• Article XVI: “If, before the keel of any vessel coming within the categories or sub-categories mentioned in Article 12(a) is laid, any important modification is made in the particulars regarding her that have been communicated under Article 12(b), information concerning this modification shall be given, and the laying of the keel shall be deferred until at least four months after this information has reached all the other High Contracting Parties.”

The post-World War I phase enabled Japan to play an increasingly significant role at the global level, and its participation in international conferences and its signing of treaties aimed at world peace and international cooperation between the powers in the Pacific and East Asia made it one of the makers of the reformatted global policy known as “The Washington System” (Asada, 2006).

Concluding remarks

Japan's involvement in World War I was a pivotal period that set the stage for its subsequent imperial endeavors, notably in World War II. The nation's modernization during the Meiji era propelled it into the ranks of influential Asian powers, challenging Western dominance in the region. As Japan aligned with the Allied Powers in WWI, it aimed to not only contribute to the defeat of the Central Powers but also assert itself internationally and renegotiate unequal treaties imposed by Western powers.

The Treaty of Versailles in 1919 acknowledged Japan's war efforts and granted it territorial gains in East Asia, shifting the region's geopolitical dynamics. However, it was the post-war period that witnessed the rise of national pride and chauvinistic nationalism, fueling Japan's expansionist ambitions. Pan-Asianism gained prominence, advocating for Japan's leadership in unifying Asian countries and establishing an independent Asia. Rooted in the belief of Japan's superiority, Pan-Asianism provided justification for its expansionist policies, framing them as a mission to liberate Asian nations from Western colonialism.

Japan's imperialist ambitions, despite initial success, eventually led to the Second World War due to escalating tensions driven by historical, ideological, and geopolitical factors. The invasion of Manchuria in 1931 and subsequent military campaigns in China ignited conflicts culminating in the devastating war.

Debates persist over the causes of Japan's imperialism after WWI. While some attribute it to a desire for international recognition, others emphasize nationalism and a misguided mission to liberate Asia. Understanding this period's complexity is crucial for grasping the factors behind Japan's rise as an imperial power. Reflecting on Japan's actions post-WWI underscores the need to examine the interplay of nationalism, geopolitics, and historical narratives. The repercussions of Japan's imperialist expansion are deeply felt in Southeast Asia, where WWII battles left enduring scars, shaping historical narratives and geopolitical dynamics.

Comprehending Japan's role in WWI and its aftermath demands a holistic analysis of alliances, military contributions, and postwar influence. This period's lessons emphasize the importance of diplomacy and cooperation in shaping a future free from past conflicts, offering insights for navigating present challenges and fostering global harmony.