What Motivated Japanese Aggression in World War II?

JapaneseAdvance1940KeystoneHultonGetty.jpg
Japanese soldiers advance, 1940. Keystone, Hulton Archive / Getty Images

In the 1930s and 1940s, Japan seemed intent on colonizing all of Asia.  It seized vast swathes of land and numerous islands; Korea was already under its control, but it added Manchuria, coastal China, the Philippines, Vietnam, Cambodia, Laos, Burma, Singapore, Malaya (Malaysia), Thailand, New Guinea, Brunei, Taiwan... Japanese attacks even reached to Australia in the south, the US territory of Hawaii in the east, the Aleutian Islands of Alaska in the north, and as far west as British India in the Kohima campaign.

What motivated a formerly reclusive island nation to go on such a rampage? 

In fact, three major, interrelated factors contributed to Japan's aggression in the lead-up to World War II and during the conflict. The three factors were fear of outside aggression, growing Japanese nationalism, and the need for natural resources. 

Japan's fear of outside aggression stemmed in large part from its experience with the western imperial powers, beginning with the arrival of Commodore Matthew Perry and an American naval squadron in Tokyo Bay in 1853. Faced with overwhelming force and superior military technology, the Tokugawa shogun had no option but to capitulate and sign an unequal treaty with the United States. The Japanese government was also painfully aware that China, hitherto the Great Power in East Asia, had just been humiliated by Britain in the first Opium War. The shogun and his advisers were desperate to escape a similar fate.

To avoid being swallowed up by the imperial powers, Japan reformed its entire political system in the Meiji Restoration, modernized its armed forces and industry, and began to act like the European powers. As a group of scholars wrote in a government-commissioned pamphlet called Fundamentals of our National Polity (1937), "Our present mission is to build a new Japanese culture by adopting and sublimating Western cultures with our national polity as the basis and to contribute spontaneously to the advancement of world culture." 

These changes affected everything from fashion to international relations. Not only did Japanese people adopt western clothing and haircuts, but Japan demanded and received a slice of the Chinese pie when the former eastern superpower was divided into spheres of influence at the end of the nineteenth century. The Japanese Empire's triumphs in the First Sino-Japanese War (1894-95) and the Russo-Japanese War (1904-05) marked its debut as a true world power. Like the other world powers of that era, Japan took both wars as opportunities to seize land. Just a few decades after the seismic shock of Commodore Perry's appearance in Tokyo Bay, Japan was on its way to building a true empire of its own. It epitomized the phrase "the best defense is a good offense."

As Japan achieved increased economic output, military success against larger powers like China and Russia, and a new importance on the world stage, a sometimes virulent nationalism began to develop in the public discourse. A belief emerged among some intellectuals and many military leaders that the Japanese people were racially or ethnically superior to other peoples. Many nationalists emphasized that the Japanese were descended from Shinto gods and that the emperors were direct descendants of Amaterasu, the Sun Goddess.

As historian Kurakichi Shiratori, one of the imperial tutors, put it, "Nothing in the world compares to the divine nature of the imperial house and likewise the majesty of our national polity. Here is one great reason for Japan's superiority." With such a genealogy, of course, it was only natural that Japan should rule the rest of Asia.

This ultra-nationalism arose in Japan at the same time that similar movements were taking hold in the recently-unified European nations of Italy and Germany, where they would develop into Fascism and Naziism. Each of these three countries felt threatened by the established imperial powers of Europe, and each responded with assertions of its own people's inherent superiority. When World War II broke out, Japan, Germany, and Italy would ally themselves as the Axis Powers.

Each would also act ruthlessly against what it considered to be lesser peoples.

That is not to say that all Japanese were ultra-nationalist or racist, by any means. However, many politicians and especially army officers were ultra-nationalist. They often couched their intentions toward other Asian countries in Confucianist language, stating that Japan had a duty to rule the rest of Asia as an "elder brother" should rule over "younger brothers." They promised to end European colonialism in Asia, or to "liberate East Asia from white invasion and oppression," as John Dower phrased it in War Without Mercy. In the event, the Japanese occupation and the crushing expense of World War II did hasten the end of European colonialism in Asia; however, Japanese rule would prove anything but brotherly.

Speaking of war expenses, once Japan had staged the Marco Polo Bridge Incident and started its full-scale invasion of China, it began to run short of many vital war materials including oil, rubber, iron, and even sisal for rope-making. As the Second Sino-Japanese War dragged on, Japan was able to conquer coastal China, but both the Nationalist and Communist armies of China put up an unexpectedly effective defense of the vast interior. To make matters worse, Japan's aggression against China prompted western countries to embargo key supplies and the Japanese archipelago is not rich in mineral resources. 

In order to sustain its war effort in China, Japan needed to annex territories that produced oil, iron for steel-making, rubber, etc. The nearest producers of all of those goods were in Southeast Asia, which conveniently enough, was colonized at that time by the British, French, and Dutch. Once World War II in Europe erupted in 1940, and Japan allied itself with the Germans, it had justification for seizing the enemies' colonies. In order to ensure that the United States would not interfere with Japan's lightning-fast "Southern Expansion," in which is simultaneously struck the Philippines, Hong Kong, Singapore, and Malaya, Japan decided to wipe out the US Pacific Fleet at Pearl Harbor.

It attacked each of the targets on December 7, 1941 on the American side of the International Date Line, which was December 8 in East Asia.

The Imperial Japanese armed forces seized oil fields in Indonesia and Malaya (now Malaysia). Burma, Malaya, and Indonesia also supplied iron ore, while Thailand, Malaya, and Indonesia supplied rubber. In other conquered territories, the Japanese requisitioned rice and other food supplies - sometimes stripping local farmers of every last grain. 

However, this vast expansion left Japan overextended. Military leaders also underestimated how quickly and fiercely the United States would react to the Pearl Harbor attack. In the end, Japan's fear of outside aggressors, its malignant nationalism, and the demand for natural resources with which to pursue the resulting wars of conquest led to its downfall in August of 1945.

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Szczepanski, Kallie. "What Motivated Japanese Aggression in World War II?" ThoughtCo, Feb. 10, 2017, thoughtco.com/japanese-aggression-in-world-war-ii-195806. Szczepanski, Kallie. (2017, February 10). What Motivated Japanese Aggression in World War II? Retrieved from https://www.thoughtco.com/japanese-aggression-in-world-war-ii-195806 Szczepanski, Kallie. "What Motivated Japanese Aggression in World War II?" ThoughtCo. https://www.thoughtco.com/japanese-aggression-in-world-war-ii-195806 (accessed October 22, 2017).