| ID: | 8345 |
|---|---|
| Entry Text: | Friedman, William Frederick & Mendelsohn, Charles J. The Zimmermann Telegram of January 1917: And Its Cryptographic Background. Washington: GPO, 1938, 1965, 1976, 33 pp. Official report; February 1917, at time Germany launched unrestricted submarine warfare, encripted telegram to Mexico offering support; Room 40 broke & informed US. |