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Military history of Japan

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Table of contents
1 Russo-Japanese War and WWI
2 Invasions of Manchuria and China
3 Western Resistance
4 Sanctions
5 1941 - Planning the Greater East Asian War
6 The Atlantis

Russo-Japanese War and WWI

In the Russo-Japanese War in 1905 an Asian power defeated a European power for the first time. Japan was part of the Allies during World War I and was rewarded with control of German colonies in the Pacific.

Invasions of Manchuria and China

Japan invaded Manchuria in 1931. In 1937, the Japanese invaded China.

Western Resistance

Three factors led to Western resistance of Japanese ambitions:

  1. The popularity and sympathy that China had gained in the West
  2. Fear of loss of Western economic advantages in China.
  3. The brutality and heedlessness of the Japanese invasion, particularly the Nanjing Massacre.

The Western powers, particularly the U.S. and Great Britain, gradually resolved to resist Japanese expansionism, preferably through sanctions rather than direct military conflict.


In September of 1940, Germany, Italy, and Japan had allied under the Tripartite Pact. In July of 1940, the US banned the shipment of aviation gasoline, to Japan, and by 1941, shipments of scrap iron, steel, gasoline, and other materials had practically ceased. Meanwhile, American economic support to China began to increase.

In April of 1941, Japan and Russia signed a neutrality pact and Japan increased pressure on the French and Dutch colonies, in Southeast Asia, to cooperate in economic matters. On July 22, 1941, Japanese forces occupied the naval and air bases of southern Indochina. American officials would note that the Philippines were almost completely surrounded.

1941 - Planning the Greater East Asian War

The economic sanctionss imposed by the United States, Great Britain, and the Netherlands were weakening the Japanese economy. The leaders of Japan were faced with a choice: End the war in China, so as to end the sanctions, or obtain additional resources by some other means.

The Japanese government decided to seize resources under the control of Great Britain and the Netherlands, notably in Malaya and the Netherlands Indies, with the Southern Expeditionary Army. As the United States was their ally, it was decided to attack the US Pacific Fleet at Pearl Harbor, Hawaii, with carrier-based aircraft of the Combined Fleet. Following this attack, the intended to seize the Philippines, as well as cut the US lines of communication by seizing Guam and Wake. At the same time they intended to attack Malaya and Hong Kong. This was to be followed by attacks against the Bismarck Archipelago, Singapore, Sumatra, and Java. The Japanese then intended to go on the defensive and hold their newly acquired territory.

It is believed that the Imperial General Headquarters (Imperial GHQ) began planning the Greater East Asia War in April or May of 1941, by November their plans were essentially complete, modified only slightly over the next month. Japanese military planners argued that the British (and Russians, should they decide to declare war) would be unable to effectively respond to a Japanese attack, given the threat posed by the Third Reich.

There is no evidence that the Japanese planned to defeat the United States, intending to negotiate for peace after its initial victories. The Imperial GHQ noted that should acceptable negotiations be reached with the Americans, than the attacks were to be canceled, even should the order to attack have already been given. They further noted that should the US transfer it's Pacific Fleet to the Philippines, they would then intercept and attack this fleet enroute, with the Combined Fleet. The plans also stipulated that should the United States or Great Britain attack first, than the military was to hold and wait for orders from GHQ. Even should such a preemptive attack include Russia, the planners noted that attacking the Philippines and Malaya would probably remain the best course of action.

The Atlantis

It is sometimes argued that the Japanese decisison to attack the Allies was, in large part, influenced by the capture of British documents with regards to British forces, the defenses of Singapore, codes, and information on Australia and New Zealand, as well as an appraisal of Japanese intentions. These documents were captured by the German Hilfskreuzer (cruiser) Atlantis, on November 11, 1940.

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