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

Modus Vivendi—Yes? No! 131
to thwart would-be code-breakers. In time, six of these machines
were constructed.
For some time, the U.S. code name for Japan had been
“Orange.” Th e machine used for decoding a previous Japanese
cipher had been known as the “Red” machine. So in the tradition
of color code names, this new machine was called “Purple.”
Th e fi rst “Purple” machine was retained in Washington.
When additional machines became available, they were distributed
to stations where they were expected to be most valuable.
Th e Navy retained one, the Army two. Th e others were sent to
commanders in the fi eld where confl ict with Japan seemed possible.
Two machines were sent to England, one of which was later
forwarded to Singapore. Another machine went to Corregidor in
the Philippines. Because personnel was limited there and because
atmospheric conditions prevented picking up more than about
10 percent of the Tokyo-Washington messages, the Philippines
handled primarily local traffi c. 1 No “Purple” machine was ever
sent to Hawaii. Th e Pearl Harbor commanders had to rely for
intelligence about the Japanese on radio directional fi ndings they
could pick up and on reports relayed to them from Washington.
Intercepting and decoding a Japanese message was only the
fi rst step on the road to turning it into useful intelligence. Once
deciphered, an intercept had to be translated into English. But
this translation was not “intelligence”; it was only raw material.
To become useful “intelligence,” it had to be properly analyzed
and interpreted. Th en it had to reach those who could use it to
advantage. And all this had to be accomplished without the enemy’s
knowledge.
1 Percy L. Greaves, Jr., “Th e Pearl Harbor Investigations,” in Harry Elmer Barnes,
ed., Perpetual War for Perpetual Peace (Caldwell, Idaho: Caxton Printers, 1953),
p. 410; David Kahn, Th e Codebreakers: Th e Story of Secret Writing (London:
Weidenfeld and Nicholson, 1967), p. 23. See also Laurence F. Saff ord, twohour
tape, notes in author’s possession.