A cryptologic veteran's analysis of "day of deceit"--a book review

Cryptologia, Apr 2000 by Jacobsen, Philip H

Apparently, Stinnett did come up with records to substantiate Hypo's summaries about the carrier Agaki being active on the air several times up to 26 November 1941. However, there is no documentation that any high frequency direction finder (HFDF) fixes were available to Hypo on such transmissions. The single line bearings reportedly obtained by Corregidor's HFDF went by the island of Honshu as well as the Kurile Islands and the former location with acceptable HFDF variations was within Hypo's previous general determination of carrier locations. According to the book, a possible cross bearing from Dutch Harbor was found in that station's November monthly report that did not reach Station H until after 7 December and for some reason was not reproduced in the book. No documentary evidence was shown that such bearing was actually transmitted to Station H or subsequently forwarded to Rochefort at Hypo except a general statement as to routine forwarding by a Dutch Harbor operator.

Although the book claims more carrier and carrier commander transmissions were made after 26 November (the Kido Butai sailing date), this information is apparently due to a possible misinterpretation of the TESTM reports from Corregidor to Station H and a misunderstanding of traffic analysis procedures identifying call signs appearing in broadcast and point to point messages sent by shore communication stations. The single TESTM report provided in the book first lists the transmissions heard and their bearings and such bearings are on unidentified call signs. Then, any fleet level call signs identifications made from the traffic analysis of message headings in shore station transmissions by Station Cast are given. In the enthusiasm to support its conspiracy theory, the book apparently assumes that the latter call sign identifications by traffic analysis of shore station transmissions actually represent high frequency radio transmissions by such fleet units and commanders. Layton, Pelletier and Whitlock among others deny such transmissions were ever received. One wonders why Stinnett did not reproduce the other two TESTM reports upon which he relies to make his specific allegations to clarify his identification and deductive processes, especially since the one page reproduced does not support his allegations.

Gross misinterpretations of two decrypts and translations in the SRN series at the National Archives make up the other parts of the book's centerpiece of its conspiracy theory. In an effort to give some credence to its allegation of a massive conspiracy, the book contradicts the plain meaning on the face of translations of these two decrypted messages, established Japanese naval communications practice, and standard decryption procedures. These messages were reported on long ago by Frederick D. Parker in Cryptologia Volume 15, Number 4, p. 295. However, Parker fully reported that JN-25B was being decrypted at best on a 10 percent basis in Washington and those November and December 1941 raw messages discussed were enroute to Washington DC so that they were not available to be worked on until long after the Pearl Harbor attack. The glaring omission in the book of this vital "unavailability" information is instructive.