Answer:
In January 1917, British cryptographers deciphered a telegram from German Foreign Minister Arthur Zimmermann to the German Minister to Mexico, Heinrich von Eckhardt, offering United States territory to Mexico in return for joining the German cause.
The Zimmermann Telegram, or Note, was significant to the history of World War I because it forced United States President Woodrow Wilson to reverse his initial position on American involvement in the European conflict and commit the United States to the war against Germany.
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