The Zimmermann Telegram: how one intercepted message pulled America into WWI
British codebreakers intercepted a secret German offer to Mexico, and revealing it helped tip a reluctant United States into the First World War — how intelligence changed the course of the conflict.
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Germany promised Mexico the return of Texas, New Mexico, and Arizona in exchange for a military alliance.
British intelligence intercepted the telegram by tapping neutral American diplomatic cables at a relay station.
Admiral Hall used a bribed telegraph employee in Mexico to provide plausible deniability for the interception.
Arthur Zimmermann publicly admitted the telegram was real, destroying the American peace lobby's influence.
The telegram shifted American focus from maritime disputes to direct territorial threats against the Southwest.
Germany's attempt to distract the United States backfired, leading to a formal war declaration in April nineteen seventeen.
- 01Intro1 min
- 02A Nation on the Brink of Neutrality2 min
- 03The Coded Proposal3 min
- 04Room 40 and the Intelligence Dilemma3 min
- 05The Public Explosion and Zimmermann's Blunder2 min
- 06The Path to War1 min
- 07Outro1 min
- Zimmermann Telegram (1917) | National Archives
- Zimmermann Telegram | Facts, Text, & Outcome | Britannica
- The Zimmermann Telegram | National Archives
- Why was the Zimmermann Telegram so important? - BBC News
- The Zimmermann Telegram - Teaching American History
- The Secret History of the Zimmermann Telegram | HISTORY
- The Zimmermann Telegram and American Entry into World War I
- The Zimmermann Telegram: The Telegram That Brought America Into WW1 | HistoryExtra
- The Zimmermann Telegram and the U.S. Entry Into World War I | Council on Foreign Relations
- Zimmermann Telegram | National WWI Museum and Memorial
- The Zimmermann Telegram | National Archives
- Historical Documents - Office of the Historian
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