Historical Investigation

Section A: Identification and Evaluation of Sources

This investigation will explore the question: to what extent was the assassination of Prime Minister Inukai a turning point in Taisho Democracy? It aims to analyse and evaluate the extent to which the May 15, 1932 Incident transformed Japan’s government system. The May 15 Incident is when the Prime Minister Inukai was assassinated by a group of young naval officers, driven by their anger against Inukai’s opposition to the military. The first source to be evaluated is a telegram The Ambassador in Japan (Grew) to the Secretary of State, selected as it offers a first-hand observation from the US ambassador of the political significance of the May 15 Incident. The second source to be evaluated is Herbert P. Bix’s book Hirohito and the Making of Modern Japan. This source is relevant because the author is an expert and he offers a detailed analysis of the assassination of Inukai and how the emperor’s role changed as a result.

Source 1: A telegram from The Ambassador in Japan (Grew) to the Secretary of State, 16 August 1940

A value of the origin is that Joseph Grew was stationed in Tokyo from February 1932 to 1941, allowing him first-hand observations of political developments in Japan. As an American diplomat, he operated outside Japanese domestic political pressure and censorship, lending his assessments greater candour. The purpose is equally valuable; as an internal government telegram, it was intended to provide Washington with accurate intelligence of the Japanese political climate, for more informed foreign policy decisions. Accordingly, the content further supports the investigation as Grew explicitly identifies the May 15 assassination as a “turning point” in the Japanese system of government, arguing that it led to abandoning party government (Grew). Another value of the source is that it was written 8 years after the incident so the author has the benefit of hindsight to reach more informed conclusions. However, the date is a limitation because it was written in August 1940, by which time US-Japan relations had deteriorated due to the Second Sino-Japanese war and Japan’s announcement of the Greater East Asia Co-Prosperity Sphere. This context may have led Grew to portray Japan’s political system more critically, especially as Japan ceased to be a democratic state.

Source 2: Bix, Herbert P. Hirohito and the Making of Modern Japan, 2000

The author is a value as Bix is a professional historian specialising in modern Japanese history, and the book was awarded the Pulitzer Prize, adding further credibility to the source (“Herbert P. Bix Archives”). As the source is an academic book with the purpose to educate students, it is highly objective. Also, Bix conducted thorough research while writing the book, looking at imperial archives and memoirs of high ranking officers (Bix VI). The source’s content is equally valuable as Bix frames the 1931 Manchurian Incident as a primary watershed in the trajectory of Japanese politics, while positioning the 1932 assassination as a subordinate event. Moreover, written in 2000, Bix has the benefit of hindsight to make more informed conclusions; however, this is simultaneously a limitation since new perspectives may have emerged after its publication, shedding new light on the 1932 incident that this source can not account for. Finally, a minor limitation is its content. The source extends far beyond the 1932 incident, covering the entire life of emperor Hirohito, while only dedicating one chapter related to the incident.

Section B: Investigation

Taisho Democracy was a period of government in Japan between 1912 to the early 1930s when liberal democratic governance was briefly adopted. Party politics began to emerge and the Japanese government settled on an informal convention whereby the leader of the largest party in the diet was appointed the prime minister. However, on May 15, 1932, Prime Minister Inukai Tsuyoshi, president of the Rikken Seiyuakai party, was assassinated by young naval officers who opposed his attempt to defend constitutional rule and halt military activity in Manchuria (Bix 252) This essay will discuss the extent to which the assassination of Inukai was a turning point in Japanese history and whether it marked the collapse of Taisho Democracy.

Firstly, the assassination of Inukai Tsuyoshi was a turning point in Taisho Democracy because it ended the party cabinet system that defined democracy in Japanese politics. Beginning with the appointment of Hara Takashi from the Seiyukai party in 1918, it had become the established convention for the leader of the plurality party in the House of Representatives to be appointed prime minister (Bix 211). Between 1924 to 1932, all six prime ministers were drawn from the two major political parties, the Seiyukai and Kenseiaki, and as McClain observes, it became “routineised” (319). Inukai himself, as leader of the Seiyukai, was appointed accordingly. However, his assassination in the May 15 Incident overturned this political trajectory. No party politician became prime minister again until Japan’s defeat in 1945 (Gordon 333). Instead, the premiership was succeeded by Saito Makoto, a former admiral, whose appointment Bix claims to be dictated by the emperor and militarists in backroom politics (213). From 1932 onward, the army and navy ministers were involved in discussions over choosing the next prime minister (Grew). As a result, Grew identifies the May 15 incident as a “turning point” of Taisho Democracy (Grew). This is cogent with Gordon’s broader view that Taisho Democracy contained a contradiction between democratic participation and military authority (161). After Inukai’s assassination, that contradiction was resolved in favour of the military. Therefore, on top of its physical power, it has become capable of using the entire governmental apparatus to consolidate and justify its power (Takenaka 129). The democratic institution, on the other hand, became marginalised by virtue of the fact that no power is conferred upon them in accordance with the democratic mandate (McClain 330).

However, some historians argue that Taisho Democracy was already structurally limited before 1932, which challenges the view that Inukai’s assassination was a turning point in an otherwise secure democratic system. For example, Takenaka disagrees with McClain and suggests that inter-war Japan should be understood as “semi-democratic” rather than a fully democratic one (3). Firstly, under Article 10 of the Meiji Constitution, the right to appoint the prime minister ultimately lay in the hands of the emperor (“Constitution of Japan”). In practice, the Genro, or elder statesmen, often advise the Emperor on this decision. Therefore, fundamentally, electoral support had no direct legal bearing on the selection of the premiership (Murai 24). This weakens the argument that the party cabinet system rested on a secure democratic structure. Secondly, non-party prime ministers continued to exist after Hara’s cabinet, which historians often agree to identify as the beginning of Taisho Democracy (Young 119). The appointment of Kato Tomosaburo (1922) and Yamamoto Gonnohyoe (1923), both affiliates of the military, show that party government was still a political convention (Gordon 333). Some historians such as Shinichi claim that it is only a trend that had emerged partly to appease the public anger after the Rice Riots in 1918 (11). Furthermore, multiple assassinations of Japanese party politicians including Hara in 1921 and Hamaguchi in 1930 had already exposed the weakness of civilian control over the military. And it could be argued that the army has the capability to derail the government at any time as they are not constitutionally bound to the government, rather independent and only answerable to the emperor (“Constitution of Japan”). As a result, Beson states that the term “Taisho Democracy” should be used with “pathological distaste” (37), while Takenaka similarly warns against treating Inukai’s assassination as a single event that suddenly ruptured Japanese democracy (23). However, despite the non-democratic nature of the Meiji Constitution, at least between 1924 to 1932 Japan reached constitutional normality (Kensei no Jodo) and was democratic in the sense that it bypassed the oligarchy (Yamamoto). Kobayashi proposes a perspective that the military’s need to remove Inukai from the premiership itself shows that he remained a troublesome obstacle (Kobayashi 79). Historical evidence substantiates this as Inukai obstructed the military’s actions in Manchuria, refusing to recognise Manchukuo as an independent state and keeping negotiations with China alive (73). By assassinating Inukai, the military cleared a barrier; under Saito’s non-party cabinet, Manchukuo was immediately recognised.

Nevertheless, although the military had attempted to assert its influence before 1932, it was only after Inukai’s assassination that party politicians were decisively displaced from the centre of government. Unlike earlier political coups, by 1932 popular resentment and political disorder had reached a point where militarists felt empowered at exactly the moment the party politicians felt that they could no longer challenge the military (Takenaka 120). Particularly, the lenient punishment of Inukai’s assassins further weakened party politics. Despite killing a prime minister, several perpetrators received only one or two year sentences, and the court avoided imposing the death penalty because of pressure from the Navy (Grew). This intimidated politicians because it created a dangerous precedent. Moreover, McClain supports the argument, claiming that the wider context explains why the May 15 Incident had greater significance than earlier violence in the 1920s (422). By 1932, Japan had endured repeated economic and social crises, from the 1923 Great Kanto Earthquake to the 1927 Banking Crisis and the 1929 Wall Street Crash (Gordon 183-186) Thus Yamamoto agrees with Gordon and claims that these hardships intensified fears of communism, especially in social groups such as landowners and business owners (Yamamoto). Simultaneously, dissatisfaction with party politicians damaged public confidence in civilian-led government, while the military's prestige increased after the Manchurian Incident of 1931 and the seizure of Harbin in 1932 (Kobayashi 78). Considering these pieces of evidence, Inukai’s assassination was rather the culmination of a decade of growing anti-party sentiment (Takenaka 129). It became a straw that broke the camel’s back; democracy was weakening, but after the May 15 Incident it lost much of its remaining capacity to resist military pressure. The February 26 Incident, a failed coup in 1936 that killed multiple officials, including finance minister Takahashi Korekiyo, is also considered a turning point. Some historians such as Harries, argue that the coup “profoundly altered the balance” between the army and civilian government, since it removed remaining politicians defending democracy and ended “direct and overt opposition” to the army’s plans (qtd. in Fata). However, Crowley suggests that it is more precise to view February 26 as the consolidation of the shift that had already begun in 1932 (384). Unlike the May 15 Incident, which attacked the party government by assassinating a party prime minister, in 1936 it was mainly a struggle between factions within the military itself. The suppression of the coup neither marked a shift from civilian rule to military domination nor restored civilian democracy; instead, it allowed mainstream militarists to eliminate the radical Kodoha faction and strengthen their own rule (“4-7 The 2.26 Incident”). The restoration of the active-duty army and navy minister rule further increased military control over cabinets, showing that 1936 confirmed, rather than began, the collapse initiated by Inukai’s assassination (Hattori 88).

In conclusion, Inukai’s assassination on May 15, 1932 was a turning point in Taisho Democracy to a significant extent. Although Taisho Democracy was limited by the Meiji Constitution, the Genro, and the military’s independent authority, this did not mean the party government had already collapsed before 1932. By the 1920s, Japan had reached a degree of constitutional normality, and Inukai himself remained an obstacle to the military’s aims in Manchuria. His assassination therefore transformed existing weaknesses into a decisive political rupture. The party cabinet system ended, no party politician became prime minister again until 1945, and the military gained influence over cabinet formation and ultimately government itself. The February 26 Incident in 1936 was also considered, but it furthered military dominance and consolidated a shift begun by Inukai’s death. Hence, Inukai’s assassination did not single-handedly destroy Taisho Democracy, but it was the irreversible turning point at which civilian party rule lost its remaining authority.

Section C: Reflection

This investigation allowed me to engage with a variety of methods and challenges that historians face. To reach informed conclusions, I examined both primary and secondary sources, including diplomatic telegrams, academic books, journal articles, and constitutional documents.

Firstly, historians are challenged by arbitrary survival of primary sources. Unlike scientists, who can repeat experiments, historians are confined to surviving and accessible records. Historical knowledge is therefore incomplete, as some evidence may be destroyed, never recorded, or classified. This was especially significant in my investigation of Japan because many primary sources on Inukai’s assassins trials were state-censored at the time. Army and Navy sources were also deliberately destroyed after Japan’s surrender in 1945. Secondly, historians face the ambiguity of chronological concepts. In my investigation, the term “Taisho Democracy” was difficult to define because historians disagree over its boundaries. Although the Taisho period ended in 1926, it arguably continued into the 1930s and the Showa period. This lack of consensus creates chronological confusion. Thus I consulted a wide range of sources to compare how different historians defined the period to decide on what was most corroborated.

Furthermore, historians are challenged by abundance of evidence available as well. At the start of my investigation, I was overwhelmed by the abundance of articles and books on Japanese history, and there were practical limitations to how much I could examine as a student. However, selection itself can create bias, since relying on certain sources may overemphasise some perspectives over others. To address this, I evaluated each source's origin, purpose, and content to check its reliability and validity.

Lastly, investigating turning points showed me why historians who disagree despite using similar evidence. Some historians such as Takenaka present Taisho Democracy as already fragile because of militarism, while others emphasise the May 15 Incident as the rupture of democracy in Japan. This showed me that evidence does not speak for itself; it depends on the historian's interpretation. As Ferguson argues, history does not lead all historians toward one single objective truth (Ferguson 89). Instead, it involves constructing the most justified interpretation from incomplete puzzles. Therefore my role in this investigation was not to find the “correct” answer, but to weigh competing perspectives and decide which was convincing.

Works Cited

• Benson, John. JAPAN 1868-1945 : From Isolation to Occupation. Pearson Education, 2016.
• Bix, Herbert P. Hirohito and the Making of Modern Japan. HarperCollins e-books, 2000.
• Crowley, James B. Japan’s Quest for Autonomy. Princeton University Press, 2016.
• Gordon, Andrew. A Modern History of Japan: From Tokugawa Times to the Present. New York, Oxford University Press, 2003.
• Grew, Joseph C. “The Ambassador in Japan (Grew) to the Secretary of State.” Foreign Relations of the United States, Diplomatic Papers, 1940, The Far East, Volume IV, Office of the Historian, 16 Aug. 1940, pp. 970–973, history.state.gov.
• Fata, Avan. “Contesting the “New Japan”: Rethinking Japanese Interwar Politics (1919-1941).” Columbia Journal of History, 11 Mar. 2019, columbiahistoryjournal.com/blog-2-1/blog-post-title-four-fclza.
• Ferguson, Niall. “Introduction: Towards a ‘Chaotic’ Theory of the Past.” Virtual History: Alternatives and Counterfactuals, edited by Niall Ferguson, Picador, 1997, pp. 1–90.
• Hattori, Ryuji. War and Diplomacy in Modern Japan. Springer, 15 July 2025.
• ‘Herbert P. Bix Archives’ Asia-Pacific Journal: Japan Focus, 23 Feb. 2015, apjjf.org/herbert_p_-bix. Accessed 14 May 2026.
• Kobayashi, Michihiko. Modern Japan’s Place in World History: Chapter 6 the Manchurian Incident and Party Cabinets. Springer.
• McClain, James L. Japan : A Modern History. New York Etc., Norton, 2002.
• Murai, Ryota. “Who Should Govern: The Political Reformation after the First World War in Japan.” Kobe University Law Review, 15 July 2006.
• Shin'ichi Kitaoka. From Party Politics to Militarism in Japan, 1924-1941. Boulder, Colorado, Lynne Rienner Publishers, Inc, 2021.
• Takenaka, Harukata. Failed Democratization in Prewar Japan. Stanford University Press, 20 Aug. 2014.
• “The Constitution of the Empire of Japan.” Ndl.go.jp, National Diet Library, 2019, www.ndl.go.jp/constitution/e/etc/c02.html.
• Yamamoto, Hiroyuki. “Democratic Backsliding and Party System in Interwar Japan.” Electronic Journal of Contemporary Japanese Studies, vol. 19, no. 3, 16 Dec. 2019.
• Young, Louise. The Breakdown in Democracy in 1930s Japan In: When Democracy Breaks. edited by Archon Fung et al., Oxford University Press, 14 May 2024.
• “4-7 the 2.26 Incident of 1936.” Ndl.go.jp, National Diet Library, 2010, www.ndl.go.jp/modern/e/cha4/description07.html.