Introduction
Following Meiji’s restoration in 1868, Japan grew rapidly through annexation via wars with China (1894-1895, 1899-1901, 1937), the Russian Empire (1905), and the German Empire (1919). After decades of expansion Japan ran into its own economic limitations in the early twentieth century. Its economic issues were compounded due to competition with European colonial powers and the United States. Many Japanese leaders believed that military expansion would overcome its economic shortcomings. Thus, as Japan’s military autonomy grew (at the cost of civilian government control), further military expansion became assured. Despite this consensus, Japan’s military was were divided on the method for further expansion: the Army favored a northern campaign to continue its conquests through Manchuria towards Siberia, and the Imperial Japanese Navy (IJN) supported a southern campaign take over Southeast Asia.
Bolstered by its earlier successes in Manchuria and China, the Japanese Army prevailed and the empire elected to engage in hostilities with the Soviet Union and its client state, Mongolia. The Japanese Army fought the Soviets on two separate battles (the battle of Lake Khasan in 1938 and the battle of Khalkhiin Gol in 1939). It was the battle of Khalkhiin gol (also known as the Nomonhan Incident) that changed the course of conflict in the Pacific. Lasting between July and September of 1939, the battle involved the largest number of tanks and airplanes of the time and ended when Japan suffered a catastrophic loss at the hands of Soviet and Mongolian forces. As a result, the IJN’s alternate plan was put into place: Japan decided to attack the Allied colonies and possessions in the Pacific and Southeast Asia. The empire planned a swift strike on the British, American and French positions in the area in order to gain access to raw materials, especially oil.
Japan had built its maritime empire for the expressed purpose of ensuring supplies of raw materials from China, Korea, Taiwan, French Indochina, the Dutch East Indies and the rest of South East Asia. Spurred, in part, by western colonial competition in Asia and a 1940 U.S. oil embargo, Japan sought to create its own insular trading block.
Dubbed the “Greater East Asia Co-Prosperity Sphere”, Japan’s occupation would enable its quest for raw materials needed for its domestic industry and military. The Japanese merchant fleet was an indispensable means of delivering these supplies and maintaining the Emperor’s maritime empire.
On 8 December 1941 the United States declared war on the Empire of Japan in the wake of the surprise attack on Pearl Harbor. On the same day, Chief of Naval Operations Admiral Harold Stark issued a terse, eight-word order: “Execute against Japan unrestricted air and submarine war.” The U.S. Pacific fleet, joined by vessels from the United Kingdom, Australia and the Netherlands, would wage an unrelenting campaign against the Japanese fleet.
One component of this campaign was an offensive against Japan’s merchant marine. The unrestricted use of air and submarine warfare upon the Japanese merchant fleet was designed to choke off its imports, stunt the advance of the Japanese military, cripple domestic production, and undermine civilian morale. Additionally, the sinking of Japanese merchant vessels was integral to the Allied island-hopping campaign. The interdiction of supplies allowed the U.S. military to cut off some islands and erode the defensive capability of those targeted for invasion.
