Featured image: Captian Laurance Safford, USN
There were no problems of collaboration for strictly military COMINT matters where each service was working alone in its proper sphere of activity. The Navy COMINT team did a thorough job on the Japanese Navy with no help from the Army. [Redacted] No assistance was requested from the Army other than permission to establish a Navy COMINT Unit on Corregidor. The Navy gave the Army all its Japanese Army intercepts, assisted in training an Intercept Unit at Manila, never denied the Army any legitimate information it requested, and gave the Army all the help it was willing to accept. The Army, in turn, provided the Navy copies of all its technical cryptanalytical manuals and training courses.

A summary of the Navy’s pre-Pearl Harbor COMINT effort and COMINT concepts may be obtained from a secret letter (Serial 081420) sent by the CNO to the Commander-in-Chief of the Asiatic and Pacific Fleets and to the Commandants of the 14th and 16th Naval Districts, in October 1940, extracts from which hare quoted below:

“Subject: Crytanlytical Activities, status of.

“1. In view of the present serious international situation, it is desired to acquaint the addresses with the present status and prospects of solution of Orange naval cryptographic systems. …

“2. During the past ten years, Orange intelligence has been provided by solution of Orange cryptographic systems, and to a lesser extent by direction finding and traffic analysis.  Every major movement of the Orange Fleet has been predicted, and a continuous flow of information concerning Orange diplomatic activities has been made available. …

“3. There are five major Orange naval cryptographic systems in current use, all of the enciphered code type, namely:

Administrative Code system.

The cipher used with this code changes every ten days.  Code and cipher recovery is in the hands of Commandant, Fourteenth Naval District, and has progressed to the point where intelligible text can be obtained from nearly all intercepted messages.  …

Merchant Ship Code system.

The system itself is 99% readable, but an auxiliary system of ship and place names has not yet been recovered.  The cipher changes quarterly, and has been predicted through June, 1941.  …

Material Code system.

This code has its cipher changing at irregular intervals of from ten to thirty days.  Current information is not now being obtained from this system, but it is estimated that within six months we will be able to read most of tis traffic shortly after receipt.   …

Operations Code system

An additive key cipher is employed with this code, and although the methods of recovery is well defined, the process is a laborious one, requiring from an hour to several days for each message.  … Recovery is being pursued by the Department, and details will be promulgated later.

Intelligence Code system.

This system, being of least importance, has been neglected in favor of the others.  … Solution is being handled by the Department.

“4. With regard to the immediate dissemination of intelligence, it is incumbent upon the Communications Intelligence Units to provide the proper authorities with information and inferences obtained from Communication Intelligence.  Since it is manifestly impracticable for the Command-i-Chief, U.S. Fleet, to gather such information first hand, and impossible for him even to use recovered cryptographic systems without an Orange language officer of his staff, it is desired that Commandant, Fourteenth Naval District, and Commandant, sixteenth Naval District, disseminate such intelligence from time to time to both Commanders-in-Chief and to the Department.   This will re quire that all messages in readable Orange navy systems be translated promptly upon receipt, to insure intelligence of as fresh a nature as possible, and all cryptanalytical and cryptographic activity must be subjected to this end.  As a general rule, readable Orange navy encrypted communication should be handled in inverse order of interceptions.

“5. It must be borne in mind that the present Orange cryptographic systems may be replaced by new ones immediately upon the outbreak of war.  Therefore, cryptanalytic intelligence, per se, may not be available from that time until after successful attack has been conducted.  Meanwhile, enemy information can be obtained from radio intercept and direction finder activities as has been the case during the past year.

(Signed)   R. E  INGERSOLL
Acting.”

Footnotes:

1.         The phrase “communications intelligence”, abbreviated for the sake of convenience to “COMINT”, means intelligence produced by the study of foreign communications, including the breaking, reading and evaluating encyphered communications; “cryptology” is a synthetic which is applied to the combined cypher activity ‑ i.e., constructing cyphers as well as breaking cyphers, to which, in turn, the synthetic “cryptography” and “cryptanalysis” are applied, respectively. 

2.         Mr. Stimson’s now famous remark was that “Gentlemen do not read each other’s mail.” 

3.         The American Black Chamber by H.O. Yardley; Bobbs Merrill, Indianapolis, Indiana, 1931. 

4.         When Admiral Moreal was “propositioned” on the Corregidor Project a few days after taking office as Chief of The Bureau of Yards and Docks he exclaimed, “Hell ‑ I don’t need Congressional authorization to dig a hole in the ground! But I will need it before I put up any buildings. If the Chief of Naval Operations (CNO) can get me funds for the Tunnel I will start it immediately and I will also get the funds for quarters and take care of Congressional approval.” 

5.         It is fashionable nowadays to sneer at battleships, but when the war was on and Japanese battleships and heavy cruisers were active our Naval aviators were very glad to include fast battleships in the Carrier Task Forces. A carrier, at night, is an easy victim to any heavy surface craft.

6.         “COM 16 OPNAV CINCAF ‑ TOP SECRET ‑ 151250 ‑ TWO INTERCEPTS IN [DELETED] PLAIN CODE SIXTH AND THIRTEENTH FOLLOWED WITHIN A FEW HOURS BY ENCIPHERED VERSIONS CONFIRMED IN­DICATOR [DELETED] ALREADY RECOVERED BY MATHEMATICAL ELIMINATION PM CODE REMAINS UN­CHANGED X WILL SEND [DELETED] RECOVERIES THIS SYSTEM IF YOU DESIRE BEGIN WORK ON CUR­RENT PERIOD.” 

7.         “The Committee has been intrigued throughout the Pearl Harbor proceedings by one enigmatical and paramount question: Why, with some of the finest intelligence available in our history with the almost certain knowledge that war was at hand, with plans that contemplated the precise type of attack that was executed by Japan on the morning of 7 December ‑ why was it possible for a Pearl Harbor Attack?” (Senate Document No. 244 ‑ 79th Congress) – page 253 (Recommendations).

Source: SRH-149