The “Magic” Background of Pearl Harbor

Title:                      The “MagicBackground of Pearl Harbor

Author:                                U. S. Department of Defense (1978). The “MagicBackground of Pearl Harbor. Washington, DC: U. S. Government Printing Office

LCCN:    79601951

D742.U5 M33


Date Updated:  March 22, 2017

Reviewed by George C. Constantinides[1]

This great compilation was first completed in 1944; for its release, it was sanitized to a small extent and edited. Five of the volumes contain paraphrases of Japanese intercepts, collectively called “MAGIC.” Three volumes are appendixes and contain verbatim messages; Volume 5 contains an index. The introduction cautions that they do not necessarily compose a definitive history of the period but should be seen “as a compilation of historical source materials,” many disclosed to the public for the first time. Diplomatic messages and diplomatic historical material form the bulk of the contents, but Japanese messages dealing with espionage are also to be found. Admiral Tolley in his review in the USNI Proceedings judged this a storehouse of highly useful material for the historian or war buff, one that presents only factual evidence and avoids discussions and conclusions. It is, he said, useful for an understanding of what the U.S. leaders’ information was in 1941 for their decisions. But it is also, as he indicates elsewhere, more than that. It is a window into Japanese thinking and deliberations, Japanese information on Germany and the Axis war effort, and plans for the increase in Japanese intelligence in the United States. Along with ULTRA material released by the British Public Record Office beginning in 1977, these volumes provide a source of material to the researcher that is hard to equal.

This is a review by the Defense Intelligence School.[2]

(This work, numbered Vols. I-V, actually consists of eight volumes, as Vols. II-IV each consist of a volume of text and an Appendix volume).

These volumes cover the period from 14 February—7 December 1941. The major centerpiece comprises the instructions and preparations for each of the meetings between Secretary of State Hull and the Japanese Ambassador in Washington, Admiral Nomura, but much other material is included. The decrypted text of every available Japanese message during this period has been declassified and published here. Another integral part of this work is the lengthy historical material in textual form taken from Secretary Hull’s official memoranda and memoirs, as well as the Japanese position on given matters. The Hull-Nomura centerpiece comprises Part A in each volume. Parts B and C deal with Japanese espionage activities in the Western Hemisphere and Japanese diplomatic relations at the time world-wide respectively. Vols. II-IV are purely textual, based on the material described above, and appropriately footnoted to the decrypted Japanese messages. The Appendices to Vols. II-IV contain the full decrypted texts of all the Japanese messages involved in each of these volumes. Vols. I and V contain both text and decryptions. In addition, Vol. V contains a complete index for all volumes. This work is hardly “bedside” reading, but as an historical source, it is probably unequaled for material of this kind.

[1] Constantinides, George C. (1983). Intelligence and Espionage: An Analytical Bibliography. Boulder, CO: Westview Press, pp. 462-463

[2] Defense Intelligence School (1981). Bibliography of Intelligence Literature: A Critical And Annotated Bibliography of Open-Source Literature (7th ed, rev.). Washington, DC: Defense Intelligence School, p.


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