Pearl Harbor: The Seeds and Fruits of Infamy - Ludwig von Mises ...

Army Pearl Harbor Board 481
Marshall Defends Government’s Policy of
Secrecy; Doesn’t Recall Important Documents
On Monday, October 2, 1944, Marshall returned once more
to the APHB to answer questions posed in the board’s September
30 letter. He explained that it was considered essential at all cost
to prevent the enemy from learning that Japanese intercepts were
our source of secret information. War and Navy department policy
concerning “secret, ultrasecret information” directed that “No
action is to be taken on information herein reported, regardless
of temporary advantage, if such action might have the eff ect of
revealing the existence of the source to the enemy.” According to
Marshall,
there have been cases where convoys have been permitted to
go into the most serious situations rather than diverting them
from the assemblage of the so-called wolf packs because of the
fear that that would convey to the Germans that we had some
means of knowing just how this was managed.
Apparently, Marshall continued, the Japanese thought we
were obtaining knowledge of these convoy movements from
spies and observation posts. So long as they did, we felt free to
go ahead.
[B]ut if there is any danger of our giving away our sources,
then we would have to hold off somewhat on seizing each
opportunity, for fear we would lose tremendous long-term
advantages. 146
Marshall believed he had been “kept fully informed by the
State Department on the development of the relations between
the Japanese Empire and the American Government.” Even so,
he couldn’t remember some important events. He didn’t recall
146 Ibid., p. 2403.