Closing the book on Pearl Harbor

Cryptologia, Apr 2000 by Budiansky, Stephen

In an even more fantastic excursion through the realm of negative evidence, Stinnett then points to the absence of any reference to this and other pre-Pearl Harbor decrypts in intelligence summaries issued by the Hawaii decryption station, or in material turned over the Congressional investigators, or in decrypt files released to the National Archives in 1979. Clearly this was all part of the cover up, he argues, done "deliberately to conceal American success in decoding Japanese naval communications." Similar paranoid reasoning appears throughout the book. Why wasn't Agnes Driscoll, who worked on the Operations Code, awarded a citation for her work? Simple: "Of course the Navy could not publicly credit her with the solution. Not to do so was a deliberate decision devised to mask America's success in learning Japanese military secrets." As alien as it may to be those who minds operate in these channels, it is at least worth considering the possibility that sometimes the reason no record of an event can be found is that the event in question never happened.

At times it seems Stinnett forgets what he is trying to prove. At one point he makes much of the supposed fact that the Hawaii unit was working on the Operations Code in 1940 and 1941, despite post-war testimony by its officer in charge, Joseph Rochefort,9 and by the Pacific Fleet's intelligence officer, Edwin Layton, that the job was taken away from Hawaii and given to Washington and Cavite. His evidence for this is that Hawaii was provided by Washington with "solutions" of the code in April 1941 and fall of 1941 and that in November 1940 "special IBM sorting equipment for use in decrypting the 5-Num [i.e., Operations code" was ordered for Hawaii. But this, too is nonsense; IBM machines were used for decrypting all enciphered codes, including German diplomatic codes, Russian diplomatic and KGB codes, Japanese army codes, and many other Japanese navy codes besides the Operations Code. There was no such thing as "special" IBM sorting equipment designed for just the Operations Code.10 (Hawaii had been assigned what proved to be the dead-end task of the attacking the Japanese navy "AD" code, apparently a little-used flag officer's and administrative system; according to Rochefort's and Layton's accounts, fully corroborated in the month-by-month progress reports, Hawaii had no success whatsoever in breaking this system. Nor were the other high-level Japanese Navy codes being studied by Washington, Hawaii, and Cavite broken.) Moreover, as Layton fully documents in his memoirs, And I Was There (and as Stinnett elsewhere acknowledges himself), the plan up until July 1941 had been to turn over the Operations Code to Hawaii; it was only a last minute change that led to the job being retained in Washington, with Cavite assisting in the additive recovery task. Elsewhere Stinnett confuses the intelligence that the Hawaii station was deriving from the process known as traffic analysis with actual decryption. The Navy radio intercept station at Hawaii was not only routinely intercepting all Operations Code traffic it could pick up, it was also taking radio bearings on the signals and studying call signs and other "externals" of the messages for clues about the location and movement of Japanese naval units. But the fact that references to radio signals transmitted in the Operations Code appear in Rochefort's intelligence reports says absolutely nothing about whether Hawaii was attempting to break and read the contents of the messages themselves; in fact all the evidence is in perfect agreement that Hawaii was not.