Piercing the Fog - Air Force Historical Studies Office

CHAPTER 2
The Tools of Air Intelligence:
ULTRA, MAGIC, Photographic Assessment
and the Y-service
THE REVELATION IN 1974 that the western Allies had been reading the
most secret German messages throughout the Second World War has led to a
new interest in the relationship of intelligence to the planning and conduct of
operations in that conflict. Unfortunately, the tendency in some quarters has
been to overemphasize the role of what has come to be called ULTRAinformation
from high-grade signals intercepts-while neglecting other
elements of intelligence. American air leaders and their staffs drew upon a full
range of intelligence sources and methods of collection and analysis to gain the
most complete picture of the enemy, including his tactics and technology, his
strengths and weaknesses, and his capabilities and objectivm. These methods
included photointelligence, economic studies based on prewar statistics and
extrapolated wartime production levels, elaborate networks of informants, wellplaced
observers, resistance groups, and analyses of aircraft components and
designs by aviation technicians thousands of miles from a combat theater.
Although signals intelligence (SIGINT) in Europe and the Far East eventually
became a primary source of air intelligence, it attained this position only
gradually, and it succeeded then because SIGINT could reach into the most
sensitive of the enemies’ activities. For much of the war, more of the intelligence
that went into the planning and execution of strategic and tactical air
operations came from other sources.
ULTRA and diplomatic cryptography (MAGIC) were not the only elements
within the field of SIGINT. SIGINT included interception, deciphering,
translation, and analysis of enemy low-grade ciphers; interception of unencoded
enemy radio transmissions; analysis of radio and wireless traffic patterns (traffic
analysis); and efforts to locate and catalog enemy electronic emissions.
Direction finding (DF), the process of determining the location of enemy
transmitters through a process of triangulation based on the angle at which
transmission signals were received by two or more receivers, was primarily of
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