World War II Database

There were plenty of examples where intelligence played a critical role with key events, such as the American success prior to Midway in the intelligence realm that ultimately led to the sinking of four Japanese fleet carriers. Although the Japanese military intelligence apparatus, both army and navy, were not up to par when compared to their western counterparts, it still played a critical and successful role in the preparation and execution of war against Russia, China, and the United Kingdom.

Author Ken Kotani, an authority in this field with the National Institute for Defense in Japan, dove into very minute details with his book Japanese Intelligence in World War II. The book was translated from Japanese into English by his wife Chiharu Kotani, who had done a fairly good job. Kotani analyzed Japanese military intelligence from the pre-war years, carefully detailing its beginnings, its growth through the 1920s and 1930s, and its mission as the world prepared for another great war. Extensive understanding of British defense in Asia allowed the Japanese Army to plan a stunningly fast conquest of Malaya, and even more impressively, Singapore. However, as the war wore on, successes in the intelligence field that the Japanese had enjoyed during the war against China and the United Kingdom slowly vanished. Kotani contrasted Japanese military tradition, which placed much greater importance on placing top talent in operational roles, with the United States which tended to assign the smartest to intelligence, thus creating a chasm when comparing military intelligence results on the two sides of the Pacific War. Fundamentally, the Japanese understanding of intelligence was also flawed, resulting in many situations where raw information were submitted to top level decision makers without adequate analysis. While the Japanese were able to crack Chinese codes, and through this obtaining extremely valuable information on Russia and the United Kingdom, Japan's inability to recognize that the enemy had realized the breach also led to incidences where the enemy fed inaccurate information through the deciphered code to mislead the Japanese.

Kotani's fair evaluation of both strengths and weaknesses makes Japanese Intelligence in World War II among the best of the topic, particular in the west.