Piercing the Fog - Air Force Historical Studies Office

Piercing the Fog
To facilitate identification of and successful attacks on Japanese airdromes,
Tenth Air Force daily intelligence extracts and weekly intelligence summaries
kept units advised of the pattern of enemy airfield construction and methods of
camouflage and dispersal. A February 1943 annex to the weekly summary
described in detail the enemy’s standard pattern for laying out major airdromes
and satellite fields and advised on which areas the attackers should focus.17 In
March 1943 the summary noted that the Japanese had begun to shift their
aircraft parking from revetments to wide dispersal and to conceal them using
villages and natural features as cover.’’
Intelligence on technical capabilities and tactics of the Japanese air forces
enabled friendly forces to devise effective methods to combat them. The best
source for such information was Chennault’s American Volunteer Group
(AVG). Although few AVG pilots remained in the theater after that organiza-
tion ceased operation, summaries and evaluations of their experiences circulated
widely. In August 1942, the Director of Intelligence Service, HQ AAF,
distributed an extensive report, “Information on Tactics of A.V.G.,” which
contained interviews with pilots, extracts of combat debriefs, and a report on
AVG experiences and activities previously compiled by Tenth Air Force.”
Technical data also provided tactical information useful for combating
Japanese flyers. Analysis of the location of pieces of destroyed aircraft
suggested structural weaknesses in Japanese bombers, most notably the absence
of self-sealing fuel tanks and inadequate wing-fuselage joinings. This
information led to suggestions that fighter pilots and gunners should aim for the
inner wing tanks since, even if they missed the fuel, they might hit the joints
and cause the plane to come apart in midair.m The results of flight tests on a
captured Japanese Mitsubishi A6M Zero fighter conducted in the United States
late in 1942 revealed that the aircraft’s excellent roll capability at low speeds
decreased significantly as speed increased.”
The aerial mining of the Rangoon River afforded an example of the use of
alternative sources of intelligence. This operation, using the Royal Navy’s
mines and enthusiastic British support, significantly retarded river traffic and
the movement of Japanese supplies. The Allies based the raid on little more than
the thoughtful use of readily available information. In January, while consider-
ing mining the river, planners first analyzed Burma’s available lines of
communication. Alternate port facilities were few, and there was but a single
railroad north from Rangoon that forwarded supplies sent by ship. The ocean
approaches to Rangoon were open, with ships difficult to intercept by bomber
patrols; thus the Gulf of Thailand was not amenable to an aerial blockade. The
planners quickly realized that the relatively shallow Rangoon River was a
natural funnel; closing it held great promise of cutting supply traffic to Japanese
forces in the north. Within days, B-24s flying up the river under a full moon at
low tide dropped forty mines, set to delay arming for from two to twelve days,
into the river channel, The results were hard to judge in terms of ships
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