Piercing the Fog - Air Force Historical Studies Office

Taking the Offensive
March 1945. When the operations planners judged that B-24 strikes consumed
too much fuel, Chennault ceased using the large aircraft and moved them to
India to haul supplies over the mountains. Fighters took over the railway attack
task, but they, too, soon had to reduce their efforts to conserve gasoline. The rail
targets remained known to Chennault and available, but he lacked the means to
destroy them as rapidly as he wished. This was the same situation that had
obtained so often in China since the AAF’s arrival in July 1942. Always ready
to fight the Japanese, the American airmen had too few aircraft, too little
gasoline, or too much of a need for parts and aircraft tires. The Fourteenth’s
bombardment and attack planning had been a function partly of knowing the
enemy’s whereabouts, but more importantly it was a question of how much of
a force could be mustered on any given day to hit the most worthwhile targets.56
Despite the supply problems, the Fourteenth had hit rail targets successfully,
and senior military leaders in Washington drew on ULTRA to oversee the
extent of those successes. General Marshall’s understanding of the railway
interdiction plan became the basis for some of the discussions at Potsdam in
July 1945. At the Allied Tripartite Meeting on July 24, Marshall told the Soviets
of the AAF’s destruction of railroads in Japanese-controlled China as he
encouraged the Soviet leadership to draw up plans to enter the war in Asia. He
noted that the bombing and sabotage had by that time substantially reduced
Japan’s ability to move troops from China proper to counter Soviet moves in
Manchuria. The Americans told also of the 500,000 Japanese troops that they
believed were on Kyushu, but they pointed out that naval and AAF mining of
Japanese waters had cut Japan’s ability to move her army from the home
islands. Arnold then added remarks that outlined rather specifically Japan’s
current air operations, her air logistics situation, and her ability to continue air
warfare; like Marshall, Arnold based his account on ULTRA intercepts plus
photographic reconnaissance of Japan’s airfield^.^'
Although Chennault had formal access to ULTRA information from at least
March 1944, a special security officer did not arrive at Fourteenth Air Force
headquarters in Kunming, China, until October of that year. Before then, such
ULTRA information as Chennault saw came to him via the special security
representative in New Delhi, India, or from Stilwell’s office in Chungking
which was served, in turn, by the radio facilities of the U.S. Naval Group China.
Because of the distance and time required to carry the material, Fourteenth Air
Force probably received little ULTRA data on a regular basis before March 1944.
The amount of other intelligence information derived from Japanese message
traffic available to the Fourteenth Air Force is unclear. Occasional data reached
Chennault, as in the December 1942 message from Washington. Miles, discreet
in discussing SIGINT, also hinted in his memoirs that his communication
people decrypted information valuable to the AAF in China and elsewhere in
the Pacific.
323