Pearl Harbor: The Seeds and Fruits of Infamy - Ludwig von Mises ...

132 Pearl Harbor: The Seeds and Fruits of Infamy
Developing the “Purple” machine seemed almost miraculous,
so the information derived from it was code-named “MAGIC.”
Since this information was extremely valuable, the U.S. government
was anxious not to jeopardize its source. Should the Japanese
discover their code had been broken, they would undoubtedly
stop using it, revise it and/or adopt a diff erent code. Th e laborious
task of breaking a new code would then have to begin all over
again. So knowledge of “Purple” was confi ned to a very few offi -
cials and only about a dozen copies of each translated MAGIC
intercept were made. 2 Distribution of the MAGIC intercepts was
by a high-ranking special courier who usually waited to answer
questions while the intercepts were being read. To maintain security,
the intercepts were then retrieved and returned to a secure
fi le. Only four copies of each decoded/translated intercept were
kept; all others were destroyed. 3
Once the Japanese diplomatic code was broken, the Army
and Navy intercept stations rarely missed a message. With experience,
the Army and Navy specialists in Washington became
quite skillful at deciphering Japanese messages coded on the
“Purple” machine. As time went by, specialists were often able
to decode and translate messages so quickly that they were in
the hands of Secretary of State Hull before his meetings with
the Japanese ambassadors. “Of the 227 messages pertaining
to Japanese-American negotiations sent between Tokyo and
Washington from March to December 1941, all but four were
picked up.” 4 And the messages we intercepted dealt not only with
the U.S.-Japanese negotiations, but also with many other matters. 5
2 79th Cong., 1st sess. Joint (Congressional) Committee on the Investigation
of the Pearl Harbor Attack. Pearl Harbor Attack, 39 vols. (Washington, D.C.:
U.S. Government Printing Offi ce, 1946), part 36, p. 23. McCollum testimony
at Hewitt Inquiry.
3 Saff ord interview, April 5, 1966, notes in author’s possession.
4 Kahn, Th e Codebreakers, p. 13.
5 Joint Committee, Pearl Harbor Attack, part 33, p. 915.