4-246 Memorandum for the President, February 12, 1944

Publisher: The Johns Hopkins University Press
Date: February 12, 1944

Subject: World War II

Memorandum for the President

February 12, 1944 [Washington, D.C.]


Subject: “Magic”

I have learned that you seldom see the Army summaries of “Magic” material. For a long time, the last two months in particular, I have had our G-2 organization concentrating on a workable presentation on “Magic” for my use as well as for the other officials concerned, particularly yourself. A highly specialized organization is now engaged in the very necessary process of separating the wheat from the chaff and correlating the items with past information in order that I may be able quickly and intelligently to evaluate the importance of the product.

Recently I have had these summaries bound in a Black Book both for convenience of reading and for greater security in handling. Sometimes two or three of these booklets are gotten out in a single day. I think they contain all of the worthwhile information culled from the tremendous mass of intercepts now available and that are accumulated each twenty-four hours. The recent discovery of the Japanese Army machine code has added a tremendous amount of such material and will continue to give us a great deal from day to day. The problem is how to avoid being buried under the mass of information, and I think the present arrangement satisfactorily meets that difficulty.1

I am attaching two of the current booklets which I hope you will glance through in order to familiarize yourself with the manner in which the information is presented. I should like to send these booklets each day direct to the White House and have them delivered to you by Admiral Brown.2

Document Copy Text Source: George C. Marshall Papers, Pentagon Office Collection, Selected Materials, George C. Marshall Research Library, Lexington, Virginia.

Document Format: Typed memorandum.

1. The Japanese diplomatic code had been broken prior to the Japanese attack on Pearl Harbor. The wartime Japanese army code had been broken in the spring and summer of 1943, and in early 1944 the code had been captured. Since early 1944 a Japanese Army Supplement had been issued in addition to the Magic Diplomatic Summaries. (Ronald Lewin, The American Magic: Codes, Ciphers and the Defeat of Japan [New York: Farrar Straus Giroux, 1982], pp. 191–96.) For a discussion of codebreaking successes against the Japanese army’s Water Transport Code and Japanese military attaché cipher system, and finding the Japanese cipher library near Sio, New Guinea, see Edward J. Drea, MacArthur’s ULTRA: Codebreaking and the War against Japan, 1942–1945 (Lawrence: University Press of Kansas, 1992), pp. 61–62, 73–78, 92–93.

2. Vice Admiral Wilson Brown was naval aide to President Roosevelt.

Recommended Citation: The Papers of George Catlett Marshall, ed.Larry I. Bland and Sharon Ritenour Stevens(Lexington, Va.: The George C. Marshall Foundation, 1981– ). Electronic version based on The Papers of George Catlett Marshall, vol. 4, “Aggressive and Determined Leadership,” June 1, 1943–December 31, 1944 (Baltimore and London: The Johns Hopkins University Press, 1996), pp. 293–294.

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