December 7th marks the 75th Anniversary of the attack on Pearl Harbor.
One of our volunteers, Geoff, is keenly interested in the history surrounding this and has written this post.
Why Pearl Harbor? At the dawn of the 20th century, Japan had emerged as the dominant industrial and military power in the western Pacific, and had already been victorious against the Chinese (First Sino-Japanese War, 1894-95) and the Russians at Tsushima in 1905.
Japan had very few natural resources and the raw materials, that are necessary for an industrial power, had to be imported. Displacing China as the dominant force in Korea in the 1890s assured her of a supply of coal and iron. But oil and gas were imported from the U.S.
Japan aspired to be a colonial power similar to some of the European countries, and began to see S.E. Asia as the resource-rich area that would satisfy the needs of an ambitious, but resource-poor country. Oil and gas and other raw materials were plentiful but were controlled by European powers. That the acquisition, or colonization, of these Asian countries would eventually lead to war was a risk that Japan was willing to take.
Japan wanted to institute “The Greater East Asia Co-Prosperity Sphere”. This would be a co-operative of most of the eastern Asian countries under the supervision and control of Japan. Military action had to be part of the Master Plan.
The army assumed the leadership of the country during The Great Depression. The armed forces grew and in 1931, the army overran Manchuria. The Japanese military had invested in railroads and other infrastructures as a safe-guard against Russian activity in the region. They also hoped to provoke the Chinese into action, which would legitimize Japan’s future actions.
Border clashes and disputes continued until 1937. The League of Nations had taken no action over Manchuria, and Japan began waging war on China (The Second Sino-Japanese War 1937-1945). As the war dragged on, it became apparent that Japan’s oil reserves were insufficient to fight a protracted war and preparations were made to take over French Indo-China, after having made a deal with the Vichy French government in 1940.
The U.S. was getting alarmed by the aggressiveness of the Japanese, and after the invasion of the Dutch East Indies in early 1941 (more oil reserves), she froze Japan’s assets, and shortly afterwards placed an embargo on oil shipments to Japan.
Further expansion by the Japanese in S.E. Asia would certainly bring the U.S. fleet into action. The U.S. Pacific fleet, which had expanded greatly since WWI, was comprised of a large number of battleships and aircraft carriers and was stationed in Hawaii.
Japan, while preparing to send an armada to other S.E. Asian countries in order to further her acquisitive and ideological interests, had to be prepared for intervention by the U.S. fleet. Their oil interests now satisfied, they planned a pre-emptive strike.
What About American Intelligence?
How could American intelligence have failed so spectacularly? The diplomatic situation had grown more tense; it was known that Germany, Japan’s ally, was pushing for Japan to distract American attention away from Europe. As early as January, 1941, the U.S. Ambassador in Japan reported to the Secretary of State that the embassy had learned from Japanese sources that a mass attack on Pearl Harbor was planned in case hostilities broke out. The Americans had broken the Japanese diplomatic code (called Purple), so war planners from the president on down knew that spies had been reporting on the fleet deployment in Hawaii. In fact, in the weeks and days prior to the attack, encrypted diplomatic traffic became heavier. On November 19th, for example, American codebreakers intercepted a message from Tokyo to diplomatic posts in Washington, as well as several west coast cities. The message instructed the offices to destroy all codes, coding machines, papers, etc. if they heard the words “East Wind Rain” (Higashi No Kazeame) in the daily weather forecast. On December 4th the U.S. intercepted the “winds message”. Even on the morning of December 7th, Army Chief of Staff General George C. Marshall sent an urgent warning to commanders in the Pacific that intercepted Japanese diplomatic messages strongly suggested an attack was imminent. Military signalmen, though, could not raise Pearl Harbor on military channels, so the message was sent by slower commercial cable. By the time it arrived, Japanese planes were already in the air over Pearl Harbor.