The title “Red Book” was our covering name for the “Imperial Japanese Navy Secret Operations Code – 1918”. Naval Intelligence obtained a photostat copy, including recent changes, in 1926 or 1927.

This code was translated in the Navy Department by Dr. B.C. Haworth, assisted by his wife, and the translation was typed by Miss Castleman and Mrs. DuVerger. The original translation was completed early in 1926, but Dr. Haworth was permitted to verify the translation of the vocabulary, and did not complete his final translation until 1927. The original translation was typed on 8×13 inch paper and was bound with Arco fasteners into about ten volumes, very inconvenient to use. Only two copies were made. In 1929 the translation was retyped on special 12×18 inch forms and bound in two volumes in red buckram McBee Binders. Four copies were typed, this work being performed by Miss Feather, Mrs. Wedding, Miss Calnan (Mrs. McCarthy), Mrs. Wilson (Flrs. Craven), and Mrs. Talley. The job was completed in the spring of 1930. One copy was immediately sent to the Officer-in-Charge of the Asiatic R.I. unit on the U.S.S. HURON, one copy was retained by the Research Section for its own use, and the remaining two copies were placed in war-reserve in the R.P.S. vault. One of these latter copies was issued to the R.I. Unit at Pearl Harbor in 1936. The photostatus of the original code were “re-phostostated’ in 1930 and given the same distribution as the translations.

Why was the RED BOOK important?

(1) It was the determining factor in establishing the Research Desk of the Code and Signals Section (January 1924).

(2) It was a constant incentive to build up an R.I. organization to exploit our possession of this code.

(3) It assisted our early efforts to a great degree hen our cryptanalytical force was very small and rather inexperienced.  We had only to solve the ciphers used with this code in order to decrypt messages.  If we had been faced at the beginning with the task of solving the cipher plus an unknown code, it might have been too much for us and, at least, it would have slowed our early efforts.

(4) It showed us that possessing of the code and its translation was not enough and that we must have qualified Japanese translators as an integral part of the R.I. Organization.

(5) It gave us invaluable information concerning the Japanese Navy and Japanese war plans that we could not possible have obtained in any other way.  (See “1930 Grand Maneuvers,” which follows.)

(6) It forecast the Japanese intention of the conquest and annexation of Manchuria, China, and the East Indies, through the composition of the Geographical Section; the general ignoring of Europe, Africa, and the Americas, and the complete listing of even the smallest towns in China.  

(7) It was useful even after supersession giving a probable vocabulary of later codes and a list of place names in Chinese characters, Kana, and English equivalents.

(8) It taught the great danger of issuing Fleet Systems to minor shore activities where proper military guard was not maintained.

The “Red Book” contained a total of 100,000 expressions and had three independent code-equivalents for each expression, namely: 5-digit number, Roman letters, and 3-character Kana group. The Kana code was arranged in sections, the Geographical List plus Ship Lists amounting to exactly one-half of the code. The Geographical Table was arranged in geographical order by areas, Ship Lists were arranged alphabetically by countries, other sections were arranged in alphabetical or numerical order, or in the order found in the conventional character dictionary. There were a few variants in the code, evidently for the convenience of the user, as they were always found in a location were the character or expression might be found. The instructions for the code stated that it was never to be used without super-encipherment. However, the instructions called for a simple substitution or additive cipher whereas all the ciphers within our knowledge were of the transposition type. In 1926, when we made our first solution of the cipher used with this code, only one cipher was being used and it was a relatively simple nature; a “key” remained in effect for several weeks. Each succeeding cipher was more complex than its predecessor and changed “key” more frequently, but, as our decrypting unit “grew up with the ciphers,” at no time did these ciphers exceed our capacity. By the autumn of 1930 four different ciphers were used simultaneously with this code.

Mrs. Driscoll

Lieutenant J.J. Rochefort was in charge of the Research Section when actual cryptanalysis of the “Red Book” messages was first undertaken. “Mrs. Driscoll was responsible for the initial solution and for the solution of most of the new ciphers and transposition forms” used with this code. The various “keys” used with a specific cipher or “Form” were often solved by officers under instruction in cryptanalysis. We had no other personnel, at that time, capable of doing that kind of work. Altogether, 14 different cipher systems or cipher “forms” were used with the “Red Book,” all of which were solved by the Research Desk, as well as all of the individual keys used with these systems and “forms”. We did not, however, attempt to decipher more than a small fraction of the messages, partly because we did not have a large enough force to handle the routine decryption after the Cipher keys had been solved and Partly through lack of Japanese translators.

The information gained from this code included:

(1) Form, phraseology, and subject matter of secret Japanese naval messages.

(2) Various accidents and casualties on Japanese men-of-war.

(3) General knowledge that Japanese naval maneuvers were much more realistic than ours, particularly in night torpedo attacks.

(4) Exact knowledge of Japanese fuel supplies (oil, coal, and gasoline).

(5) Early knowledge of Japanese advances in naval aviation.

Naval Intelligence comes into the picture in the following respects:

(1) O.N.I. obtained the photostats of this code.

(2) It arranged and paid for its translation.

(3) It turned the code over to Naval Communications, rather than attempting to handle it itself, with the agreement and expectation that it would be furnished the information obtained by use of this code. This agreement was followed until about 1930, when the C.N.O. [Chief of Naval Operations] thought that he could not trust his Director of Naval Intelligence [DNI] and ordered Captain Hooper to show intercepted messages to him (CNO) and to no other person. (This order was revoked in 1933.)

(4) The D.N.I. agreed with the D.N.C. that the R.I. Organization should come under Naval Communications, at least in peacetime.

(5) O.N.I. was given secret information from this code that could not be obtained from any other source.


The Orange Grand Maneuvers of 1930 were of particular importance for the

following reasons:

(1) They were a dress rehearsal of the Japanese Navy war plans – a prelude to the Japanese occupation of Manchuria the following year – and Japan was ready to fight.

(2) A complete mobilization of the Japanese Navy and its reserve personnel plus the recommissioning of every vessel in the Japanese Navy list was conducted with such secrecy that the Naval Attaché in Tokyo was entirely unaware that anything outside of the ordinary was taking place. Therefore, the U.S. Navy would have to depend on Radio Intelligence to avoid being taken by surprise.

(3) Our Intercept and Decrypting personnel came through with flying colors.  The information gained by radio intelligence and presented to the C.N.O and Director of War Plans was used as a basis for our own war plans. To this extent the Maneuvers may be considered the first military victory for the United States in the undeclared war waged by Japan.

(4) Our inability to track the Japanese Fleet demonstrated the necessity of establishing a strategic D/F network as part of the R.I. Organization (in distinction from the navigational D/F setup in the United States), the urgency of obtaining some sort of high-frequency direction finders regardless of how crude) and the desirability of prosecuting the development of both H.F. and I.F. D/F apparatus.

(5) The exposure of the Guam Intercept Station to early capture meant that its real importance was a stop-gap (until the intercept stations in Hawaii and Manila were further developed), as a potential site for a strategic direction-finder station, and as a minor intercept station to cover frequencies and circuits which could not be heard elsewhere.

(6) The long delay in getting intercepted messages back to the Navy Department in peace time and the impossibility of doing so in war showed the urgency of enlarging the “Asiatic Decrypting Unit,” which at that time consisted, of one officer. Second in priority was the creation of our proposed Hawaiian Decrypting Unit.

(7) Our success gave us confidence for the future and an incentive to even better effort.

By L. F. Safford, Captain, USN