Chapter 12. From Normandy to the Seine

General Considerations

The SIGINT material presented in the following pages illustrates the way in which SIS, ETOUSA, contributed to the victory over Germany in Western Europe. The samples are illustrative; they are far from being comprehensive. To indicate the degree of reliability of terms of intelligence, those from SIGINT included in the daily intelligence summary (ISUM) by G-2, 12th Army Group, were tagged as CIRO-PEARL, PEARL, or THUMB. Most messages were not disseminated intact except as technical material; their significance for operations was extracted and reported. Signal Security Detachment "D" (SSD "D") received an average of almost 900 intercepted messages per month in medium-grade crytographic ...

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