Although most people's knowledge of Japanese imperialism is related to World War Two, Japan's mission to conquer Asia goes back decades before the attack on Pearl Harbor.
While the Pacific Theater often comes to mind when we recall battles against the Japanese during World War Two, a closer look reveals that the war in Asia began with the invasion of Manchuria. In the first half of the twentieth century, the Japanese military was divided into two rival factions: the Army and the Navy. Traditionally, the Army was dominant. Their power, however, would drastically decline with the rise of the Navy and the advent of the foreign policy doctrine known as Nanshin-ron.
To understand Japanese imperialism, let's look at the country's foreign policies at the time. Before the Second World War, there were two competing doctrines: Hokushin-ron and Nanshin-ron. The Army pushed the former, while the Navy promoted the latter. Hokushin-ron (which translates to "Northern Expansion Doctrine") focused on Manchuria and Siberia as Japan's main spheres of influence. Nanshin-ron (which translates to "Southern Expansion Doctrine") viewed the Pacific and Southeast Asia as the economic potential for the Empire of Japan.
After Japan's victory in the Sino-Japanese War in 1895 and the Russo-Japanese War in 1905, Japan was confident in its ability to enforce influence in northern Asia. Hokushin-ron enjoyed support from the Imperial Army and led to Japan's occupation of Korea in 1910. However, although they were able to capture valuable territories in the early twentieth century and make their mark as a military force on par with the West, Hokushin-ron was abandoned by the cusp of World War Two.
So what had happened? Why was a foreign policy doctrine that achieved widespread support during the interwar periods suddenly dropped in favor of Nanshin-ron?
A pivotal turning point for the Japanese in terms of northern expansion was the Battle of Khalkin Gol (or the Nomonhan Incident) in 1939. After four months of skirmishes along the Soviet and Mongolian borders, the Japanese Sixth Army was defeated. This loss eventually led to the signing of the Soviet-Japanese neutrality pact in 1941. The decrease in military action in the north, as well as assisting with British holdings in the Pacific in World War One, fueled Japan's growing interest in the Southeast. The focus on this area became known as Nanshin-ron.
Plagued by a history of factionalism, the Imperial Navy disagreed with the Army-backed Hokushin-ron. Seeing an opportunity to supersede the Army's power, the Navy began promoting Nanshin-ron as the more beneficial doctrine. After realizing the potential economic advantages, the military abandoned Hokushin-ron in favor of southern expansion.
Despite becoming the dominant foreign policy in World War Two, Nanshin-ron's roots can be traced back to the Meiji period. Seeking to find greater resources and develop a more capitalist economy, Japan saw controlling Southeast Asia and the Pacific as a way to achieve this. It was not until the interwar period, however, that Nanshin-ron's expansionist tone became prominent. By this time, Japan borrowed the same language as Western imperialist countries to justify their own colonial aspirations in the Pacific. Similar to the West, Tokyo insisted on "civilizing" other Asian ethnic groups. They pushed for a racial hierarchy narrative in which Japan (labeled at the top of the caste) would help uplift their "Asian brothers." Perhaps most sinister about Nanshin-ron was that Japan illustrated themselves as saviors liberating Southeast Asians from Western imperialists. They could play different countries against each other and install puppet governments who were loyal to the Japanese. This, however, was simply a way to cover up the fact that Japan exploited and destroyed millions of people's livelihoods without remorse.
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