Piercing the Fog - Air Force Historical Studies Office

Tools of Air Intelligence
Italy, but it reached its zenith in the battle for Northwest Europe, two and a half
years after the United States entered the war. During the same period, the
Japanese messages the American cryptanalysts had been reading since 1941
contained both diplomatic and military information. Although the Navy began
its Japanese code-breaking efforts as early as 1927, and it had a fairly good
grounding in the analysis of Japanese naval message traffic, regular breaking
of the Japanese Navy and Army ciphers continued to be a long and laborious
process. The most valuable Japanese Army codes would not begin to be broken
until early in 1943.
The methodologies and characteristics of ULTRA, photointelligence,
MAGIC, and the form of tactical SIGINT known as Y intelligence collectively
became the major fundamental components of air intelligence. An understanding
of what they were, how they operated, and how they were incorporated into
the AAF’s planning and operations is essential for understanding the role of
intelligence in air operations.
ULTRA
Secretary of State Henry L. Stimson’s perhaps apocryphal admonition that
“gentlemen do not read other gentlemen’s mail” notwithstanding, nations
traditionally have done so, and World War I1 was no exception. As impressive
as the American effort was against the Japanese diplomatic and military high-
grade ciphers in the Pacific, the British had made even greater strides against
the European Axis. Assisted initially by the Poles and the French, they had
succeeded in breaking many of the German and Italian top-secret military
ciphers long before the United States became a belligerent. By the time
American forces began combat operations, the British had established extensive
facilities in England and throughout the Mediterranean to intercept German and
Italian radio signals. The nerve center of this far-flung effort was the innocu-
ously named Government Code and Cypher School located at Bletchley Park
(BP), a former country estate some fifty miles northwest of London.*3
Intercepting electronically transmitted signals is a simple process. For this
reason those who do not wish their signals to be read resort to ciphers-the use
of numbers, symbols, and letters to represent other symbols and letters. It was
BP’s role to decipher the enemy’s messages, then to translate them, and finally
*The Germans were, of course, doing the same thing, often very effectively.
During early operations in the Western Desert, for example, they routinely read
messages describing British intentions and capabilities sent by the American
military attach6 in Cairo. Similarly, the German Navy’s B-Diem radio intelligence
unit intercepted and skillfully used Allied naval messages to attack convoys until
the summer of 1943.
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