Piercing the Fog - Air Force Historical Studies Office

Tools of Air Intelligence
Second-phase interpretation, often accomplished by the same individuals,
or at least the same units, as those responsible for the first-phase work,
consisted of a more detailed analysis of photographs to find anything that might
have immediate operational value. This still rapid but more detailed assessment
allowed photointerpreters to look for and determine links between what might
at first glance be overlooked or be thought to be unconnected activities, if seen
in isolation. This phase lasted approximately 24 hours, until the next day’s batch
of material arrived.’24
While photointerpreters assigned to the operational units usually conducted
the first and second phases, personnel assigned to specific subjects or areas of
expertise did third-phase interpretations at a central facility. Thus the Central
Interpretation Unit (CIU) at Medmenham contained one section that concen-
trated on airfields, another that focused on aircraft, and a third that dealt with
aircraft factories. These central facilities performed the detailed and often long-
term analyses that influenced not so much daily operations, but longer term
strategic and policy decisions. Even before the American strategic bombers
began to concentrate on Axis oil production, Medmenham had seven photointer-
preters focusing on this Concentration of resources (both human and
materiel) at central locations provided the capability to review old photographs
in the light of new clues, to concentrate assets on high-priority projects, and to
have sections interact for new perspectives.
The organization of both photoreconnaissance and photointerpretation
assets underwent several changes as the war progressed. Early in the war,
limited resources necessitated centralizing the control of British reconnaissance
and interpretation functions. By the time the United States began air operations
in England, RAF photointerpretation had been largely concentrated at the CIU
at Medmenham, while reconnaissance units flew from RAF Benson. Eighth Air
Force assigned American photointerpreters to the CIU and established its flying
organizations (eventually evolving into the 7th Photo Reconnaissance Group,
and later into the 8th Reconnaissance Wing) at Mount Farm. At Medmenham,
the RAF had an extensive photointerpretation operation divided into several
sections. Film from regular reconnaissance flights over established enemy
facilities came to the CIU, where interpreters examined it in detail to discern
significant changes or other indications of suspicious enemy intent. For
example, one section at the CIU used reconnaissance photography to prepare
target folders, and another analyzed AA facilities. Each section prepared special
reports on its area of specialization. As another example, the AA analysts’ work
led to flak studies that allowed attacking aircraft to avoid some dangerous areas
on their runs to and from targets. In contrast, the AAF’s photointerpretation
capability was very limited early in the war. Photographic specialists who had
trained at the AAF’s Harrisburg Intelligence School worked at Medmenham for
some time before the Eighth Air Force established its own photographic
interpretation capability.
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