Piercing the Fog - Air Force Historical Studies Office

Tools of Air Intelligence
were into the American fighter control centers. At each fighter control center,
the Y officer sat beside the chief controller. This arrangement allowed for the
immediate operational application of time-sensitive Y information, since the
chief controller was in direct contact with airborne aircraft as well as with the
appropriate tactical air control headquarter^.'^'
Y intelligence's contributions to tactical air operations were particularly
important during the campaign in North Africa, the invasions of Sicily and Italy,
and the period surrounding the landing at Normandy. In North Africa, it
provided initial warning of incoming air raids before Allied radar was
operational or while the enemy was still beyond radar range.I7' Correlating radio
intercepts with sources such as radar and ULTRA, SIGINT also collected
information on enemy tactics and the disposition of his forces. By linking
enemy call signs with locations, Y intercepts often yielded clues on enemy
operating bases and provided the initial basis for attack planning. As with
strategic air operations, Y intercepts were essential to Allied efforts to
determine the location, organization, capabilities, and structure of the enemy's
air defense networks in these tactical campaigns. Y intercepts provided Allied
forces with timely intelligence on what enemy units were airborne and often
what their objectives were and what the specific rendezvous points were for
units coming from different bases.'72 Y intelligence was particularly effective
when properly fused with ULTRA. Decrypted German messages might indicate
the time and location of projected enemy missions, but Y intercepts provided
real-time, concrete information which confirmed German activities. It was, in
that sense, the most accurate and current intelligence available.
ULTRA and MAGIC in the Pacific and CBI
SIGINT in the war against Japan had an origin and prosecution unlike that
found in Europe. While European ULTRA began as a joint Polish-French-British
effort in the late 1930s, it became wholly British after the June 1940 fall of
France. The reading of German signals then became a bilateral Anglo-American
operation when the Americans joined as full partners in mid-1943. SIGINT that
concentrated on Japan began prewar as a largely American endeavor, and it
remained so throughout the war except for the CBI and Australian participation
in the Southwest Pacific. Both its development as a tool of air intelligence and
its use in strategic and tactical operations in the Pacific war were peculiarly
American. The term MAGIC has come to be applied indiscriminately to this
American scrutiny of Japanese radio traffic. In fact, MAGIC was a very specific
subdivision, correctly applied to the decryption of Japanese diplomatic
messages. Such information circulated through the hands of very few senior
civilian officials and military and naval commanders in Washington, D.C. Only
at times did it have a direct military application. In all theaters of the Pacific and
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