3-478 Memorandum for Field Marshal Sir John Dill, January 6, 1943

Publisher: The Johns Hopkins University Press
Date: January 6, 1943

Subject: World War II

Memorandum for Field Marshal Sir John Dill

January 6, 1943 [Washington, D.C.]


Dear Dill:

Replying to your two communications of December 26th and January 5th regarding secrecy matters:1

First, with reference to the Bell Laboratories and the telephone scrambling device which Dr. Turing wishes to go into. I find that this involves other interests than the War Department and I have been unable to clear it in Dr. Turing’s favor.

As to the matter of cryptography, I understand from General Strong that he wanted further information regarding the Germans which is not wise for me to refer to in more detail, so that our G-2 could do its own evaluating. He tells me that he has been unable to secure this, but he agrees with me that turning this information over to us does actually involve increased hazard. Therefore my opinion is that your people should not release to us more detailed data of this kind than they do at present. As I said before, General Strong has accepted this view.

I will have to talk to General Strong again in relation to Colonel Tiltman to see if there are details regarding this cryptographic matter with which I am not sufficiently familiar to discuss at the moment. I apologize for the delay in handling this, but most of it has been due to my effort to meet your desires.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. On December 2, 1942, Dill had written to Marshall that Alan M. Turing, a mathematician and the leading British authority on voice-scrambling devices, had been denied permission to visit the Bell Telephone Laboratories in order to inspect the new telephone scrambling device being developed there (i.e., the “X-System,” code-named “Sigsaly” by the army). Dill appealed to Marshall to permit the visit. Turing’s request became enmeshed in the question of whether Britain and the United States were sharing signals intelligence adequately. In a December 26 memorandum, Dill said that “the difficulties which have arisen have been due to a mutual misunderstanding of the British and U.S. procedure in making these requests.” Dill directed that Colonel John H. Tiltman, a senior official of the British Government Code and Cipher School, which had authority in this area, “clear up any misunderstandings which still obtain.” On January 5 Dill wrote to Marshall that Tiltman and G-2 chief George Strong had discussed the matter and that Strong had insisted that the decision regarding Turing’s visit was up to the chief of staff. (Dill to Marshall, December 2 and 26, 1942, January 5, 1943, NA/RG 165 [OCS, 350.05 (12-26-42)].)

2. In his reply the next day, Dill said that “the proposals in your letter derogate from the principle of full reciprocity. . . We are prepared to show your people everything in England, but we reserve the right to refuse to allow ‘exploitation’ in the U.S. of vitally secret traffic where we are chiefly concerned, unless we are satisfied as to the necessity. . . It appears however from the refusal to permit Dr. Turing to have access to the scrambling device experiments at the Bell Laboratory that the U.S. wish to reserve the right not to show our people everything even in this country quite apart from the question of permitting parallel experiments in the U.K. This is a new principle contrary to the spirit of existing agreements. It would seriously disturb our people at home and would of course also involve the U.S. Navy who are very much dependent on free exchange with our people.” Marshall directed Deputy Chief of Staff McNarney to discuss the issue with Secretary Stimson, and on January 9 McNarney told the British that Turing’s visit was approved, but “the War Department must also reserve the right to refuse to permit the ‘exploitation’ of these secret devices by the British unless such use is approved in each instance.” (Dill to Marshall, January 7, 1943, and McNarney to Lieutenant General G. N. Macready, January 9, 1943, ibid.)

Recommended Citation: ThePapers 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. 3, “The Right Man for the Job,” December 7, 1941-May 31, 1943 (Baltimore and London: The Johns Hopkins University Press, 1991), pp. 506-507.

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