In the 2026 posts I have been working to go into more depth on the events prior 1941 that drew the U.S. to become involved in the Asia-Pacific War. In the first post of the new series I wrote that I wanted to explore:

“…the currents and eddies of history that brought Japan its wars with China (1894-1895 and 1937-1945), with Russia (1904-1905), the annexation of Korea, Manchuria and French Indochina, and to wider war in the Pacific that stretched from Hawaii to Australia and nations in between, notably the Philippines, Malay, Borneo and the Dutch East Indies.”

And more, I wanted to delve into the milieu of conditions that led Japan to think that the wars were necessary, why it felt the U.S. needed to be drawn into the war, understand revisionist historians who assigned large elements of blame on the U.S. for forcing Japan’s hand making war inevitable, and so many other questions – especially what made Japan think they had any possibility for winning a war that would involve the United States.

To that end I have posted a bare bones history of Japan, her people, the ages and epochs she experienced, changes in people, in forms of governance, her relationship with other Asian countries, and especially the changes in Japanese society from the end of the Shogunate period of her history into the modern times of the Meiji Restoration. After covering multiple centuries in a single post, the focus began to narrow to cover decades, and sometimes events of just a single year.

What is common to so many of the posts was something I began to explain in the post “There’s Something About China.” That post tried to address the swirl of history surrounding China, European nations, and Japan in the days of the 19th and early 20th centuries. For business people, pirates, adventurers, explorers, seekers of the mysterious and exotic – all roads lead to China. The 1930s are no different.

But the 1930s are a confluence of many emerging influences within the Japanese world, changing the lenses by which she viewed the outside world. Although Japan had been an open country after Admiral Perry’s appearance in Tokyo Bay in the 1850s, had established a robust international trade, was an allied partner in World War I, and more – she was still a closed country in many other ways. Many of those trends were discussed in the web of previous posts and are just highlighted here:

• Social Darwinism had found its way into national strategy. Control of Korea and Manchuria were seen as strategic buffers and reserves of critical resources. This allowed Japanese leaders to claim: “We do not seek conquest; we seek existence.” It is a logic that removed ethical restraint.
• The traditional Samurai spirit had been morphed into bushidō as Japan’s equivalent to Western chivalry, and proof Japan possessed a moral civilization worthy of great-power status. This was installed in the military and imperial strategy of the 20th century – as well as popular culture.
• The Imperial Army (IJA) and Navy (IJN) received heavy investments in equipment and personnel in order to become a military of a leading world power. The goal for the IJA was control of China and Russia. The measure for the IJN was the U.S. Navy as seen in Japan’s war plan, Kantai Kessen (“Decisive Battle Doctrine”). For details see the post War Plan Orange.
• While the Meiji Constitution made provisions for a Constitutional Monarchy similar to Great Britain’s, the 1920s brought new challenges to that understanding. Liberal democracy was discredited by the post-WW1 financial crises and the Wall Street crash. Rising nationalism led to a decade of Governance by Assassination which led to a military operating with impunity, free of civilian controls and juridical consequences.

Whatever national restraints that were present in the 1920s had given way to the trends above. The 1930s were marked with a rejection of the Western nations that Japan felt had already rejected her in the Washington Conferences, the League of Nations charter, and host of other post-WW1 matters. At the same time there was an embrace of a selective account of Japanese history, culture and values. The Pan-Asian aspirations had been subsumed by Japanese nationalism so that Pan-Asian aspirations and Japanese conquest were the vision and destiny. All of this is wrapped into the promotion of racial superiority in spirit and morals, a homeland that had never been successfully invaded, all under the leadership of the divine Showa Emperor, Hirohito. Destiny called. The first call was China.

The Manchurian Campaign – Mukden

“On the roads that led Japan to and beyond Pearl Harbor, the Manchurian campaign was the first signpost. Milestones had been passed, but it was in Manchuria where the road, for the first time, divided.” (Tohmatsu and Willmott, 25). 

Until 1928 or so, China was a patchwork of local war lords and shifting alliances. It made Japan’s governance of Korea, Manchuria and the Liaodong Peninsula relatively simple. But in 1928 and 1929 the Nationalist Chinese Party (Kuomintang under the leadership of Chiang Kai-shek) began to assert control over central and northern China including large swaths of Manchuria. The Manchurian warlord Zhang Zuolin has been assassinated by elements of the Japanese Kwantung Army (Kwantung is the Japanese name for Liaodong) only to see his son Chang assume power and align with the Kuomintang. Japan had formally adopted a non-interference policy for China. In the eyes of the military it was time to ignore that policy.

In 1930 nationalist operatives shot Prime Minister Hamaguchi, who survived, but the vacuum of power allowed space for the military to plan and put in place their conspiracy to expand its presence in Manchuria. The conspiracy was rooted in the Kwantung Army as well as the Army Ministry and General Staff in Tokyo. They believed a pre-emptive strike would allow Japan to take advantage of Chinese weaknesses and division. The origin of the plan was among middle-ranking officers in the Kwantung Army who believed that their actions could not be repudiated by Tokyo given the popularity of the military at home. They firmly believed that if they took the unauthorized initiative they would be able to dictate national policy. They were firm in their convictions that neither senior Kwantung officers nor the Army Ministry and General Staff in Tokyo would be able to repudiate their insubordination even insubordination that brought war. The 1928 assassination of Zhang had been the test case.

By early September 1931 the conspiracy was evident. Chiang Kai-Shek had information of what was afoot but knew he was powerless to stop it militarily and a series of river floods within China complicated his never ending power struggles with warlords and the traditional government in Nanking. He instructed the Manchuria Chang to not resist. 

The conspiracy was also known to the Emperor and Prime Minister Wakatsuki. An officer from the General Staff, Major General Tatekawa, was sent to Manchuria specifically to ensure restraint, but he found himself distracted and attentive to other matters. 

On September 18, 1931, officers of the Kwantung Army staged a small explosion on the South Manchurian Railway near Mukden and blamed it on Chinese forces. Although the damage to the railway was minimal and no Japanese trains were seriously affected, the Kwantung Army treated the incident as justification for full-scale operations. Within two hours virtually every Japanese unit in Manchuria undertook pre-planned offensive action leading to a rapid, unauthorized military takeover of Manchuria. Tokyo’s civilian government ultimately accepted the fait accompli. The Mukden Incident led to the creation of the Japanese puppet state of Manchukuo (1932), Japan’s withdrawal from the League of Nations (1933), and marked another decisive step toward unchecked military expansion and the erosion of civilian control in Japan.

There are a host of events between Mukden and 1934 that are important but can largely be described as unsuccessful attempts by the Kuomintang and affiliated groups in other parts of Northern China and Inner Mongolia to thwart the expanding control of Japan over all of Manchuria. In April 1934 Japan issued the Amau Declaration that asserted Japan had a special responsibility and leadership role in East Asia, particularly in China, and warned that Japan would oppose any foreign actions that interfered with its efforts to maintain order and stability in the region. While it stopped short of announcing formal annexations, it made clear that Japan would not tolerate outside powers, especially Western nations, challenging its political, economic, or military influence in China.

The Amau Declaration formalized Japan’s claim to regional dominance in East Asia and marked another step away from international cooperation toward coercive imperial policy in the 1930s It effectively proclaimed a Japanese sphere of influence in East Asia and was seen as an Asian version of the Monroe Doctrine, but backed by military force rather than diplomacy. The declaration further isolated Japan diplomatically and reinforced perceptions that Japan was abandoning collective security in favor of unilateral expansion.

The campaign in Manchuria proved to be the first of three Japanese offensives north of and astride the Great Wall: within Manchuria itself, in Inner Mongolia, and then in northern China. These efforts, following one after the other, lasted until early 1937, by which time Japan had secured Manchuria and, by a combination of military and other means, had largely neutralized Chinese and Kuomintang influence in Inner Mongolia and northern China.

The Response of Nations

All that was left for China was the posture of no resistance, no recognition of Japanese gains, and no negotiations with Japan. The League of Nations issued the Lytton Commission report condemning Japan. It was ignored and the report’s failure to initiate international sanctions or action proved to be the death knell of the League of Nations. Since the United States was not a League member and was Japan’s largest western trading partner, Japan saw no need to take any action.

In the United States, Franklin D. Roosevelt became president in January 1933 and started to govern amidst a powerful isolationist sentiment among the people and in Congress. We had been drawn into the European morass of World War I and would not be fooled again.

Meanwhile… the Navy

In December 1934, Japan announced it would not renew its participation in the Washington Conference treaties, especially the limits on naval combatants and auxiliary ships. In fact, Japan was already “cheating” on the accords. The Navy began to mimic the Army’s attitude as it longed for the freedom of action that the Army had simply taken for its own. The difference is that the Navy is a capital intensive investment with long lead times. At issue was the need to be unrestrained from a naval inferiority to British and American fleets as a step into support of the vision of Japan’s Asian “Monroe Doctrine” to be implemented by force of arms.

More than a decade before Admiral Kato, chief negotiator at the 1922 Washington Naval Conference, had pointedly noted that the only eventuality that could be worse for Japan than an unrestricted naval race with the United States would be war against that country. The Washington Conference had not been perfect and had required unwanted compromises from Japan, but whatever its faults, it had limited naval construction, and provided Japan with a level of naval security in the western Pacific that had never been its own to command. “This advantage was to be thrown away, and the American and British navies were to be challenged to a naval race by a service that was convinced of Japan’s special place in history. Moreover, it was equally convinced that it had in place an organization and doctrine that, given assured moral superiority over the Americans, would ensure Japan against defeat in a naval war in the Pacific. It was somewhat ironic, under these circumstances, that once limitation arrangements lapsed, both Britain and the United States laid down battleships before Japan, and it was doubly ironic that after the end of limitation, the United States laid down as many capital ships as the rest of the world put together.” (Tohmatsu and Willmott, 40)

The Aftermath

From 1934 through 1944 Japan invested in Manchuria to the extent it promoted export of critical natural resources and food.  Perhaps the key investment was in the railroads. In 1931 Manchuria had 3, 600 miles of railbed. Japan added another 2,650 miles. This extended the reach of the rail system to areas of coal mining, iron ore prospecting as well as areas with valuable reserves of magnesite, molybdenum, tungsten, and vanadium. In general, production doubled between 1931 and 1936 – most of which was exported to Japan. Geological exploration saw estimates of iron ore reserves increase from 400 million tons to 2,700 million tons. All of these resources were critical to the military and the supporting industrial complex.

Ten years of Japanese rule witnessed the construction of 2,650 miles of railway to add to the 3,600 miles that had existed in 1931. Coal production in Manchuria rose from 8,950,000 tons in 1931 to 13,800,000 tons in 1936, and iron output rose from 673,000 tons to 1,325,000 tons in the same period. Japanese surveys and prospecting resulted in the revision of estimated reserves of iron ore from 400 million tons to 2,700 million tons and of coal from 4,800 million tons to 20,000 million tons as well as in the discovery of valuable reserves of magnesite, molybdenum, tungsten, and vanadium (critical to steel alloy production). 

U.S. Reaction

From 1931 to the outbreak of the Second Sino-Japanese War in 1937 the U.S. reaction was largely restrained and limited to what might be best described as moral opposition. The Stimson Doctrine refused to recognize Manchukuo, the Japanese puppet state in Manchuria as well as other territorial changes achieved by force. It placed U.S. opposition on record, but was otherwise meaningless to Japan.

In 1943 Congress passed The Tydings–McDuffie Act that granted a path to Philippine independence by 1946. Japan concluded that the U.S. was starting a long-term reduction in their military presence in what Japan considered its sphere of influence. It was also seen as a sign that America’s isolationist movement was also evidence of a lack of U.S. willingness and resolve to resist further Japanese expansion in the Asia-Pacific region.

In the period 1935-1937, Congress passed a series of Neutrality Acts aimed at avoiding entanglement in foreign wars. These laws restricted arms sales to belligerents and, it seemed to Japan, more indication of the strong isolationist sentiment in the U.S.  This reinforced Japanese assumptions that the U.S. would avoid direct involvement in an Asian conflict and limited Roosevelt’s freedom to act forcefully even if he had wanted to.

Within the diplomatic and intelligence circles, observers increasingly warned that Japan was moving toward full-scale war in China and that moderate civilian control in Tokyo was collapsing. The U.S. quietly increased naval planning and contingency studies, though without public confrontation with Japan.

Up to this point in time there were no embargoes, no assets were frozen, and no trade restrictions specifically targeting Japan. This restraint contrasts sharply with post-1937 policy, when sanctions gradually escalated.

All in all, U.S. actions signaled disapproval but not deterrence. This left a gap that Japanese leaders and officers increasingly understood.

Image credit: various photographs from Naval Aviation Museum, National World War II Museum, and US Navy Archives
Source credit: A Gathering Darkness: The Coming of War to the Far East and the Pacific, 1921–1942 by Haruo Tohmatsu and H.P. Willmott

After the First World War Japan experienced a political shift as liberal and democratic thinkers and politicians gained popularity. While there are many reasons for the shift, at the popular level it was clear that the winners of the war were the liberal democracies triumphant over the militaristic nations. At the same time there were currents within the Imperial Japanese Arm (IJA) that felt such a move might imperil the nation. While the political arm of the nation sought to form foreign relations, take their cooperative place in the world order of nations, the military continued to operate out of the long-held view that Japan needed a strategic buffer of allies or controlled lands that placed China and Russia at arm’s length. In addition, Japan was not able to feed its own population and as such was dependent on imports of food especially from Korea and Manchuria. Nor did Japan have room in the home islands for its burgeoning population; the late 19th and early 20th century saw extensive migration of Japanese citizens to these lands. Lands that were rich in resources needed for the continued industrialization of Japan, especially its heavy industries. The IJA saw it as their role to ensure the strategic and tactical future of Japan regardless of changes in the internal political landscape.

Other posts in this series address have (or will) speak to the interservice rivalry between Army and Navy as well as the factional divides within each service. The reasons for these fracture lines include budgetary competition, difference in strategic vision, loyalty stretched to ultranationalism, and even what we might understand as end-of-the-world religious movements. Coupled to this is a divide between the old guard senior officers and the more radical junior officers; a division that was connected to trends in the national education that increasingly emphasized national destiny, racial superiority, and loyalty to the Emperor-and-the nation (the kokutai). The result was a military and nationalist movement that came to believe radical action was needed to keep the civil government “on the right track.”

It is important to keep in mind, unlike the U.S., the Japanese military had no civilian controls. They reported directly to the Emperor. This connection inspired and followed an emperor-centric ideology that also found a populism in non-urban areas that also held hostility towards capitalism and Western influences. If violence was necessary to keep the nation on the true, destined path, it was the sacred duty of the military to “correct” the civil government – at least in the eyes of the more radical elements, especially within the IJA. Assassination became a recurring political tool.

Setting the Stage at Home

The era of assassinations began at a key juncture of Japanese history. Prime Minister Hara Takashi was assassinated on November 4, 1921, amid growing backlash against political party government and perceived political corruption in early Taishō-era Japan (Hirohito’s father as Emperor). As Japan’s first commoner prime minister and leader of the Seiyūkai party, Hara symbolized the rise of parliamentary politics, which alienated conservative elites, ultranationalists, and sections of the military who believed political party rule weakened imperial authority and national unity.

Hara’s pragmatic policies such as restraint in military expansion, moderation in foreign affairs, and cautious handling of universal male suffrage angered extremists who viewed him as insufficiently patriotic or decisive. His reliance on party patronage and ties to bureaucratic and business interests also fueled public resentment, especially in the aftermath of the Rice Riots (1918), which exposed social inequality and government indifference to popular suffering.

The assassin, a right-wing railway switchman, acted independently but was motivated by a broader climate of anti-party sentiment, nationalism, and disillusionment with democratic politics. Hara’s murder reflected a widening crisis of legitimacy for parliamentary government and foreshadowed the increasing political violence and erosion of civilian control that would mark Japanese politics in the 1920s and 1930s. The event shocked the Taishō democracy system but it continued on.

On the International Stage

Zhang Zuolin was a Manchurian warlord and leader assassinated on June 4, 1928 by elements of the Kwantung Army (Japan’s standing army in southern Manchuria). Although Zhang had long cooperated with Japan and protected its interests in Manchuria, by the late 1920s he appeared unable to halt the advance of Chiang Kai-shek’s Nationalist China forces that sought to reestablish Chinese control in the area. Japanese officers feared that Zhang might accommodate the Nationalists or lose control of Manchuria altogether, threatening Japan’s strategic, economic, and military position in the region.

Acting without authorization from Tokyo, radical Kwantung Army officers assassinated Zhang by bombing his train. It was hoped that his death would justify direct Japanese military intervention or allow the installation of a more compliant Manchurian ruler. Instead, the plot backfired: Zhang’s son, Zhang Xueliang, consolidated power and soon aligned Manchuria with the Nationalist government. The assassination exposed deep divisions between Japan’s civilian government and its military, demonstrated the growing autonomy of field officers, and foreshadowed the later escalation of Japanese aggression in Manchuria, culminating in the Mukden Incident of 1931. It also showed the lack of will for the Japanese Courts to punish those responsible.

Prime Minister Tanaka Giichi and the civilian cabinet were outraged once it became clear that officers of the Kwantung Army had acted without authorization. Tanaka promised the Emperor a full investigation and punishment of those responsible, recognizing the act as a grave breach of civilian control and international law. However, Tanaka failed to follow through. Faced with resistance from the Army General Staff and fear of provoking a political crisis, no meaningful disciplinary action was taken. When Tanaka later attempted to revive the issue, he lost imperial confidence and was forced to resign in 1929, weakening civilian authority further.

Army leadership protected its own. While some senior officers privately acknowledged the recklessness of the act, the institutional priority was to avoid setting a precedent that officers could be punished for “patriotic” actions. The perpetrators were neither court-martialed nor seriously reprimanded. Many younger officers interpreted the outcome as proof that bold action would be tolerated or even rewarded if framed as serving national interests.

The lack of any punishment sent a dangerous signal: the military could act independently of the civilian government with impunity. This episode directly encouraged later acts of insubordination, most notably the Mukden Incident (1931). In hindsight, Japanese historians often identify this incident as the turning point in the erosion of constitutional government and the rise of military dominance in policy-making.

The League of Blood Incident

The League of Blood Incident was a series of political assassinations in early 1932 carried out by ultra-nationalist extremists who believed Japan was being betrayed by corrupt political, financial, and party elites. Rooted in the ideological climate of the late Taishō and early Shōwa (Hirohito) periods, the violence reflected deep frustration with parliamentary democracy, capitalism, and perceived moral decay – a theme recurring for the better part of a decade.

The central figure, Inoue Nisshō, a religiously-inspired nationalist preacher, promoted a radical vision that fused emperor-centered loyalty, agrarian idealism, and spiritual renewal. He and his followers believed that the continuing problems, outlined above, were caused by a small group of powerful politicians and business leaders who had subordinated the national spirit to selfish interests.

The assassinations of former Finance Minister Inoue and Mitsui Corporation director Dan Takuma were intended to awaken the nation through “one man, one killing”, provoking a moral and political rebirth so as to purify the nation under direct imperial rule. The perpetrators expected punishment but sought martyrdom to inspire others.

Although the conspiracy was limited in scale, public sympathy for the defendants and relatively lenient sentences revealed widespread disenchantment with party politics and contributed to the normalization of political violence. The incident further weakened civilian government and foreshadowed the more extensive military-driven radicalism that followed later in the 1930s.

The May 15th Incident

The May 15th Incident was an attempted coup and political assassination carried out on May 15, 1932, by radical Imperial Japanese Navy junior officers, aided by army cadets and civilian ultranationalists. It culminated in the assassination of Prime Minister Inukai and marked a decisive blow against the political parties that dominated government in Japan.

The incident grew out of intense dissatisfaction with parliamentary politics, which many young officers viewed as corrupt, weak, and dominated by self-interested party leaders and zaibatsu elites (large corporations, oligarchies, industrialists), failing the nation. Many officers also resented the 1922 naval arms limitation treaties, which they believed dishonored Japan and undermined national security.

The plotters were influenced by emperor-centered nationalism, agrarian populism, and the belief that direct imperial rule, free from parties and capitalism, was necessary for national renewal. They claimed loyalty to the Emperor while rejecting the constitutional system that mediated imperial authority through civilian institutions. The assassins expected that killing the prime minister would spark a popular uprising or force a political realignment. Instead, while the coup failed militarily, the public and judicial response was strikingly lenient, with widespread petitions pleading for mercy. This reaction legitimized political violence as patriotic action and effectively ended party-led cabinets, accelerating the rise of military influence in Japanese governance throughout the 1930s.

The May 15th Incident reflected the collapse of faith in democratic politics and demonstrated how unchecked radicalism within the armed forces fatally undermined civilian rule.

February 26 Incident

The 1936 incident was an attempted military coup launched by radical Imperial Japanese Army junior officers associated with the Kōdōha (Imperial Way) faction. They too were motivated by a belief that Japan was in an unresolved moral and political crisis. The officers sought to overthrow the existing government and initiate a “Shōwa Restoration” under direct imperial rule of Hirohito, the Shōwa Emperor. The roots of the incident were almost identical to the May 15 incident. Some four years later there was not sufficient change and so arose the belief that only violent action could purge selfish leaders and restore national unity.

The rebels held to a more intense emperor-centered mysticism and as such rejected constitutional governance in favor of what they believed was a purer, moral form of imperial authority. Finance Minister Takahashi and former Prime Minister Saitō were chosen for assassinaton was they were held to symbolize fiscal restraint, moderation, and compromise with civilian politics that endangered the nation. Also killed was the Inspector General of Military Education. Unlike earlier incidents, the coup failed because the Emperor explicitly condemned it, ordering loyal forces to suppress the rebels. The conspirators were executed but not for murder. The charge was insubordination.

The fallout from this was pivotal: political parties were sidelined; the Courts became reluctant to harshly punish defendants who claimed loyalty to the Emperor, even when their acts were illegal; the military was able to exercise even greater degree of autonomy from civil government and civil courts. Paradoxically, all this served to strengthen military dominance in national decisions.

The After Effects

Many historians conclude that after this period leaders made conscious choices under coercive pressure, shaped by the lesson that resisting radical nationalism could be fatal. Political violence worked not because it happened constantly, but because it had happened before and everyone remembered. This milieu had a lasting effect in several key policy areas.

Civilian leaders became hesitant to challenge IJA and IJN initiatives. As a result, budgets were rarely cut and the earlier violence ensured some degree of compliance without the application of current lobbying or force. Civilian cabinets increasingly deferred to military demands to preserve political survival. This fear-driven deference directly enabled escalation in Manchuria, North China, and later full-scale war with China in 1937 as unauthorized military actions in China were often retroactively approved rather than punished. There was a general reluctance (…tending towards inability) to restrain the military.

And “the military” was too often junior officers making field decisions. Aggressive expansion was framed as unavoidable once initiated by field officers. Looking back, historians describe this as a shift from policymaking to policy ratification. This was an ongoing dynamic in China and continued into the war even after the U.S. entered the conflict.

Over time, both civilian and military officers who favored diplomacy or fiscal restraint were marginalized, transferred to “backwater” assignments or removed from office. There was a fear of being labeled “weak” or “unpatriotic” unless one fell inline with the more nationalistic voices. The art of moderation or compromise was slowly eroded. The most immediate effects were a hardening of foreign policy and institutionalization of military autonomy from civilian control

In 1900, a government ordinance (not part of the Meiji Constitution) required that the Army and Navy Ministers be active-duty generals or admirals.  Up to this point, this gave the services an effective veto over cabinet formation, since they could refuse to nominate an officer. That was relaxed in 1913 to allow retired officers to fill those roles – but the service still exerted strong influence. After the February 26 Incident (1936), the military successfully pressured the government to restore the active-duty requirement. From this point forward the Army and Navy could, and did bring down cabinets by withholding nominees requiring the Emperor to appoint a new Prime Minister to form a new cabinet. This became a key mechanism by which the military dominated Japanese politics without disturbing the constitutional order.

The service Ministers were not the chiefs of the services. The leading general and admiral reported directly to the Emperor thus enabling other means of strong influence. In the 1940s a special council, sometimes called the “War Cabinet” or the “Supreme War Council” consisted of the two service ministers, two service chiefs, the Foreign Secretary, and War Minister (often also a military officer). From 1941 on, this became the de facto cabinet. It shows how over a 20 year period the military came to dominate all aspects of Japanese life.

Later historians will argue that, before Pearl Harbor, there was a moderate wing of the government that could be reasoned with to avoid U.S. participation in the already ongoing war in Asia-Pacific. It seems to me a difficult argument to make if one understands the hardening of control by the military and nationalist parties.

Image credit: various photographs from Naval Aviation Museum, National World War II Museum, and US Navy Archives. 

The previous posts have focused on the Japanese military in the period 1905-1930. After the conclusion of the Russo-Japanese War in 1905, the Imperial Japanese Army (IJA) was implanted in Korea (annexed in 1910) and in Manchuria with control of vital sea ports of Liaodong and the connected South Manchuria Railroad. This was the foundation of Japanese settlement in those areas and the start of exporting resources and food supplies to the home islands. This was part of Japan’s strategic buffer, but when Japan became dependent on the exports, the strategic buffer needed to expand, giving additional mission focus to the IJA to move south/southwest into China and northwest toward Inner Mongolia.

The Imperial Japanese Navy (IJN) enjoyed a period of extended accomplishments, namely, the defeat of the Russian Imperial Fleet at Port Arthur and most importantly at the Battle of Tsushima. The First World War expanded their mission as an ally of the British, securing Britain’s trade routes from the Pacific into the Indian Ocean, even supplying a destroyer flotilla to Mediterranean service. The goal of maintaining a first-world fleet ran headlong into the realities of post-war financial constraints. The goal became to reach an arms limitation treaty with Britain and the United States that limited their fleets to a size that Japan could proportionally build for themselves. The U.S. initiated Washington Naval Conference was the answer to Japan’s need – as described in the previous post.

Back Home in Japan

Now, if you consider these three treaties, it does not look like Japan came out all that well. It did not get the 10:7 naval tonnage ratio it wanted – but got close. Japan did get the commitment from the U.S. not to build west of Guam or the Philippines. Japan lost the China port/area of Shandong taken from the Germans during the war, but then it got formal recognition of dominance in Manchuria – which it already had. And…formal commitment to the China Open Door policy was a draw at best.

But Japan did get the one essential element it wanted: avoidance of a naval arms race in the Pacific against a country it had no hope of matching – the United States. But also inherited something it did not want: deep division within the Navy’s officer corps. For that we need to drop back in time and “into the weeds.”

The key Japanese figures in this mini-drama are:

• Hara Takashi, the Prime Minister of Japan who was in favor of arms limitation talks as a means of helping steer the nation into a peacetime economy.
• Vice Admiral Katō Tomosaburō, a career naval officer, hero of Tsushima, who had fleet commands before becoming Navy Minister in 1915. He was a realist understanding that an arms race with the United States was to be avoided, but defense of Japan and her holdings was also a goal
• Admiral Katō Kanji, the chief naval aide. He represented the “fleet faction” that strongly favored Japan’s naval power, contrasting with Katō Tomosaburō’s support for avoiding an arms race.

Hara promised to give Katō Tomosaburō the political “air cover” he needed to make the best decision for Japan as the circumstances allowed. Hara was assassinated before Katō reached Washington DC. During the Conference, Kanji the aide, maintained separate cable communications with others of a group that would come to be known as the  “fleet faction.” They were against the entire idea of the Washington Conference. His goal was to foster opposition and dissent within the ranks of naval officers, something heretofore unknown. 

Unbeknownst to Katō and Kanji, all the cables to/from Washington were being read by the United States as the diplomatic code had been broken for some time. Japan was at a distinct disadvantage in negotiations and forced to make decisions that Katō believed were the best to be obtained but sure to bring dissension on the home front.

Upon return home Katō became Prime Minister but died in 1923 but was able to instill commitment to the treaties within the Navy Ministry. Kanji served as the Chief of the Navy General Staff. He was able to foster a cadre of naval officers opposed to the treaties. The split of the IJN into the Treaty Faction and the Fleet Faction after the Washington Naval Conference had deep, long-lasting ramifications that extended far beyond naval policy. It reshaped Japanese civil–military relations, weakened moderate leadership, radicalized strategic thinking, and contributed directly to the collapse of the interwar international order in East Asia.

Fallout of the Naval Factions

The Treaty Faction accepted the 10:6 ratio as a realistic acknowledgment of Japan’s industrial limits and the impossibility of winning a naval arms race with the U.S. and Britain. It believed security lay in diplomacy, alliances, and high-quality fleets with well trained sailors. They were dominant in the early 1920s naval leadership.

Fleet Faction rejected the ratio as a humiliation and proof of the systematic racial prejudice against Japan that would always foster an Anglo-American alliance for Japan’s national inequality. This faction argued for unfettered fleet expansion and a posture of preparedness for war with the U.S.  They gained support among younger officers, hardline nationalists and sections of the Army.

One of the key fallouts was the shift of Navy planning to be more ideological than technical. From the civilian perspective they used to be able to count on naval strategies as expert-driven, now they were sure and both sides were directly appealing to the Emperor, using the press and public opinion to promote their views. Not that the civilians had much control other than budgetary, but the once disciplined Navy was becoming less governable and more like dealing with the Army.

The Fleet Faction was more effective and practiced at framing the issues for public consumption. They framed treaties as a national humiliation, evidence of Western racial exclusion, and a betrayal by elites. The line of argument greatly resonated with the public after news of the 1924 Immigration Act became known. The net result was that naval issues were now linked to nationalist ideology. Disagreement became a question of loyalty and compromise was recast as treason.

This factional rivalry distorted naval development and planning. Where the Treaty Faction favored balanced fleets with an emphasis on quality, training, and technology, the Fleet Faction advocated for bigger battleships as a means of an outward show of symbolic parity and national pride. The Fleet Faction remained fixated on the Mahanian “decisive battle”.  In the short term (with long term implications) this led to an often incoherent strategy and compromised on design with an overconcentration on capital ships.

One of the great ironies of the naval war in the Pacific was that there never was the great “decisive battle” between the great battleships. Japan committed itself to the super battleship Yamato and her sister ship, the Musashi. Both were sunk. Meanwhile the most effective naval component of Japan’s fleet were the small ships, especially the destroyers and their long lance torpedoes.

By the 1930s the Treaty Faction leaders were marginalized; some were assassinated or silenced. More and more younger officers gravitated toward the Fleet Faction. Slowly institutional memory of restraint was lost. In a way there was a cross-service convergence of attitude that reinforced a militarist dominance that undermined moderates in both services. All this encouraged a worldview of inevitable conflict. The Navy’s traditional role as a moderating influence weakened.

Japan did not attend the 1930 London Naval Conference and in 1935 tendered its resignation from the 1922 treaties – although by then it had long abandoned treaty limitations in its building program.

Within the Japanese Navy, acceptance of war with the U.S. moved from being plausible to being inevitable. This would eventually morph the Mahanian idea of the decisive battle to one of preemptive strike. All of this diverted attention to the problem of logistics and economic sustainability in a short-term war or a long-term war.

The map above shows the maximum extent of the Japanese Empire in June 1942. Before the war, almost 70% of all merchant ships carrying supplies to Japan were not Japanese-flagged merchants; the majority were actually British flagged. Japan’s emphasis on combat ships and the focus on battleships as a symbolic pride of the nation, failed to pay attention to the basics. At the start of the war, Japan had only 8 fleet oilers. This would be the achilles heel that US unrestricted submarine warfare would exploit.

The Treaty Faction had been correct on the fundamentals: Japan could not outbuild the U.S. and a protracted war meant defeat. But being right was not politically survivable in the late 1920s and early 1930s. The Fleet Faction won the institutional battle even though it would lose the war to come. The “split” transformed the IJN from a professional, coalition-capable force into a polarized institution increasingly driven by ideology rather than strategy, with consequences that became tragically clear in 1942 and beyond.

Image credit: various photographs from Naval Aviation Museum, National World War II Museum, and US Navy Archives.

In the previous post, it was noted that at the end of the First World War the Imperial Japanese Navy (IJN) had expectations but were realistic. They expected that their coalition work with the British in the Indian Ocean, Mediterranean, and taking on maritime security in the Pacific had earned them recognition, respect and parity with the western navies. They had just successfully operated as a “global navy.” They also recognized that maintenance and expansion of their fleet was directly tied to shipyard capacity, raw materials and industrial throughput. These were industrial limits impossible to ignore and were not limitations on either British or the Americans.

Japanese Naval Planning

The nation of Japan continued to struggle financially with the burden of Russo-Japanese war debt, expenditures on military replenishment, expenses on the build up and securing their footholds in Manchuria, Korea, and Liaodong. At the same time, like all nations post-WW1, there was a desire to return to a consumer economy after the deprivations of the war years.

The Navy’s planning division began to look ahead a decade to see what would be needed in the 1930s in order to support nascent plans for a Japanese-led Asia prosperity zone. The conclusion was that the Navy required two fleet groups, each consisting of 4 battleships and 4 heavy cruisers. Thus was born the 8-8 plan. The basis of the plan was the theory of sea power of Alfred Thayer Mahan which was the foundation of both Japanese and American naval strategy. One of the central theses of Mahanian thought was the “decisive battle” after which “control of the sea” would automatically default to the winner. The Japanese had to control the Western Pacific.

The problem was that in 1918-1919 Japan was experiencing a post-WW 1 economic depression making their 8-8 fleet plan financially impossible. Nishihara Hajime, Vice Minister of Finance noted to the Navy Minister Kato that not only would the capital budget for new construction consume 20-30% of the national budget, the outyear expenses for maintenance, operations, etc, for a fully operations 8-8 fleet would extend the budgetary consumption at similar percentage rates. It was not viable or sustainable. And the problem with that was the overall naval strategy was based on several premises:

• The U.S. would not construct any fortifications/bases west of the Philippines or Guam.
• So that in the event of a US-Japan conflict, the U.S. fleet would have to cross the Pacific for any hostile action against Japan.
• Based on Mahan’s theory, the U.S. would lose 10% of its force effectiveness for every 1,000 miles of steaming – so after 3,000 miles of Pacific transit, the U.S. fleet would effectively be 70% of its original force structure.

Japan was in a position that it needed to understand what it could afford to build and maintain a 10:7 ratio of naval combatants. In other words, the two nations that had access to raw materials, finances, and shipyard capacity to outbuild Japan – they needed to be constrained to a limitation that fit within Japan’s strategic plan.

Forestalling an Arms Race

Meanwhile, there were growing tensions in East Asia over an unstable China, Japanese occupation of Shandong (former German territory), Manchuria, and more. Leaders in the international community sought to prevent the possibility of another war. Rising Japanese militarism and an international arms race heightened these concerns. Within the United States there were congressional calls for the U.S. to engage Britain and Japan in naval arms limitation negotiations.

In what must have seemed like a godsend to the Japanese in this era of growing tension, in 1921, U.S. Secretary of State Hughes invited nine nations to Washington, D.C. to discuss naval reductions and the situation in the Far East. This gathering is known as the Washington Naval Conference which produced three treaties: the Five-Power Treaty, the Four-Power Treaty, and the Nine-Power Treaty. Not terribly imaginative, but nonetheless descriptive.

• The Five-Power Treaty, signed by the United States, the United Kingdom, Japan, France and Italy was the cornerstone of the naval disarmament program. It called for each of the countries involved to maintain a set ratio of warship tonnage which allowed the United States and the United Kingdom 500,000 tons, Japan 300,000 tons, and France and Italy each 175,000 tons. If you do the math the ratio between US/Britain and Japan was 5:3 (10:6 equivalent and not the 10:7 Japan desired)
• In the Four-Power Treaty, the United States, France, the United Kingdom, and Japan agreed to consult with each other in the event of a future crisis in East Asia before taking action. This nullified the Anglo-Japanese Treaty of 1902, freeing Britain from coming to the aid of Japan in the event of war.
• The Nine-Power Treaty, marked the internationalization of the U.S. Open Door Policy in China. The treaty promised that each of the signatories (the United States, the United Kingdom, Japan, France, Italy, Belgium, the Netherlands, Portugal, and China) would respect the territorial integrity of China. The treaty recognized Japanese dominance in Manchuria but otherwise affirmed the importance of equal opportunity for all nations doing business in China.

Japan and China also signed a bilateral agreement, the Shandong Treaty, which returned control of that province and its railroad to China. Japan had taken control of the area from the Germans during the First World War and maintained control of it over the years that followed. Combined with the Nine-Power Treaty the effect was meant to reassure China that its territory would not be further compromised by Japanese expansion. All of these treaties were set to expire in 1936.

The treaties of the Washington Naval Conference stabilized naval competition but ignored land-based conflicts. Rising Chinese nationalism with its own imperial privileges and Japanese ambitions. Manchuria remained unresolved as Soviet reemergence added strategic anxiety for Japan. Meanwhile, Western powers lacked capacity or will to enforce the system they had just created. East Asia was not at peace, it was balanced as long as there was restraint from all parties, but ready to topple once the first party was willing to move unrestrained.

Image credit: various photographs from Naval Aviation Museum, National World War II Museum, and US Navy Archives.