SLU and SCU were special liason units. They handled receipt and transmission of messages.
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On 15 March 1944 General Marshall, U.S. Army Chief of Staff, sent to General Eisenhower a letter which set forth the basis upon which German Ultra intelligence was to be made available to U.S. Army field commands in the European Theatre of Operations. The following paragraphs are taken from the letter:
"7.D. The receipt and distribution, at the field commands, of messages containing or relating to Ultra intelligence, is handled by Special Liaison Units furnished and controlled by the Director General, G.C. & C.S. The personnel of these units includes American officers attached to MID, War Department, London.
"7.F. One or more American officers assigned to MID, War Department, London, will be detailed to each American field command which receives Ultra intelligence. These officers will be subject to the administration and discipline of the commands to which they are detailed. They will work under the control of the G-2 or A-2 of the command as part of his staff. They will have had a period of training at G.C. & C.S., and, if possible, with operational commands in the Mediterranean Theatre, and this training will be directed toward equipping them to use Ultra intelligence effectively and securely. Their primary responsibility will be to evaluate Ultra intelligence, present it in useable form to the Commanding Officer and to such of his senior staff officers as are authorized Ultra recipients, assist in fusing Ultra intelligence with intelligence derived from other sources, and give advice in connection with making operational use of Ultra intelligence in such fashion that the security of the source is not endangered. If at any time the flow of Ultra intelligence is not sufficient to occupy fully the time of these officers, they may be used for other related intelligence assignments."
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The SLU/SCU detachments were composed largely of British officers and other ranks, although a number of American officers participated in the work and, in a few cases, commanded the detachments. The detachments were controlled by SLU 8, at SHAEF, and were attached to the U.S. field commands. Most of the detachments served the G-2 (or A-2) section but their anomalous administrative position led to a repeated and important recommendation for an organizational change.
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Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"