Final answer:
The Zimmermann Telegram was a message sent by Germany to Mexico offering a military alliance against the United States.
Step-by-step explanation:
The Zimmermann Telegram was a telegram sent by Germany to Mexico during World War I.
The telegram proposed a military alliance between Germany and Mexico, stating that if the United States entered the war, Mexico would side with Germany and be rewarded with territories lost to the US in the Mexican-American War.
This controversial telegram was intercepted and decoded by the British, who then shared it with the United States, contributing to the US decision to enter the war against Germany.
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