To many people, Pearl Harbor is not only a synonym for infamy, but also for the
failure of American intelligence and the monumental triumph of Japanese
espionage. This is by no means an accurate picture. On the eve of Pearl Harbor, the
Japanese Intelligence set-up was enormous, to be sure, but, like Porgy, it had
plenty of nothing. They knew minute details of the American and British order of
battle, of the disposition and movements of the fleets, the
tactical
data a prudent
commander must have on the eve of attack. At that point their wisdom ended. They
gave Pearl Harbor their Sunday punch and expended on it all the intelligence they
possessed.
So deficient, indeed, was the vaunted Japanese secret service that on the morning
after Pearl Harbor, it could not
tell its High Command the full measure of the
Japanese success. On the night of December 7, an American admiral was asked at
Oahu,
“Do you think they could come back with troops, land here and take the
islands?”
“Yes, damn it,”
he answered,
“but if they let us hold on for the next couple of weeks,
we can make it.”
The Japanese did not come back, because they did not have the
strategic
information to take advantage of their historic opportunity.
The United States, on the other hand, was extremely poor in tactical intelligence
about the Japanese. But on the
strategic
level it had a single secret service arm that
was ingenious, technically competent, and reached into the very heart of the
Japanese government. It was the world’s best cryptographic secret service; thanks
to it the United States could read some, though by no means all, of Japan’s most
confidential communications and acquire a general picture of her intentions and
dispositions. Yet even this superb intelligence weapon could not overcome a
mountain
of deficiencies elsewhere.
Cryptographic analysis had demonstrated its usefulness as far back as the
Washington Naval Conference of 1922. The Japanese came to the conference with
great expectations, but returned home sorely disappointed. Japan had to agree
to
a ten-year naval holiday, and to limit her naval strength to three hundred and
fifteen thousand tons as against an aggregate of one million two hundred and fifty
thousand tons of American, British and French warships. Japanese acquiescence
in this arrangement was largely the result of the uncanny skill with which the
American delegation had maneuvered the negotiations. Throughout the
conference, the Americans appeared to be anticipating every move of the Japanese,
defeating them at every step. How was that possible?
