Piercing the Fog - Air Force Historical Studies Office

Taking the Offensive
Japan. The committee assumed, for the first part of its report, that Japan was to
be defeated by combined aerial bombardment and naval blockade, to include
mining of the seaways. In its report to Arnold, the COA reiterated the refrain
that ran through its deliberations the previous year, telling the commanding
general that a “lack of intelligence remains a major obstacle to careful target
selection.” Nevertheless, the committee also recommended a strategic bombing
campaign to encompass antishipping attacks and attacks on the aircraft industry,
as well as attacks on urban areas, followed by a review to determine what
changes might then be needed. For the second portion of the report, which dealt
with an invasion of Japan, the COA recommended “an attack on the aircraft
industry and on urban industrial areas and an intensification of the attack on
shipping by all available methods [including B-29s].”” During the same time,
AAF intelligence officers prepared several studies along similar lines, but with
more specifics.
Lacking full knowledge of Japan, the A-2 staff based their calculations
supporting urban area attack recommendations on the damage inflicted by the
RAF Bomber Command on German cities during 1943. The data that air
intelligence used came from appraisals of aerial photographs of German cities
and industrial areas, the tonnage of bombs dropped, and reports originating from
unspecified ground intelligence sources (much of it apparently ULTRA) on the
continent. Using this information, and comparing the relationships between
urban area destruction and apparent effects on industrial production for the
hardest hit cities, the A-2’s vulnerability specialists tried to determine the
probable impact of urban attacks. Their work was inconclusive. They believed,
however, that to affect production, bombardment had to destroy at least 30
percent of the housing that supported it. Extrapolating from the effects of the
September 1, 1923, earthquake and fire that destroyed much of Tokyo and
Yokohama, A-2 analysts prepared some rough guidelines for attacking Japanese
urban areas. The COA then modified these guidelines in their November 1944
revised report on Japan. The committee concluded that attacks would be
effective if “On each urban industrial area they were pressed to the point of over
fifty percent damage within about a month, and attacks on the most important
urban industrial areas were completedl within two or three months.””
The idea of firebombing Japanesft cities was more than just an analytical
proposal by some of the A-2 staff foryarded by the COA; it caught on within
the AAF at a much more practical leyel. Late in 1943 the Chemical Warfare
Service began a series of incendiary bomb tests at Dugway Proving Ground,
Utah. The tests involved, so the AAF’s senior chemical officer told the chief of
the air staff, a prototype village, “. . . the construction of which was as nearly
Japanese as could be reproduced in this country.”y2 By dropping large quantities
of various types of incendiary bombs on the village, the Chemical Warfare
Service concluded that the six-pound, oil-filled bomb probably would be most
effective on Japanese urban areas. Separately, in January 1944, Arnold visited
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