Final answer:
The Zimmermann Telegram was a secret communique from Germany to Mexico promising support in regaining lost territories if Mexico allied with Germany against the U.S., which, upon its interception and revelation, contributed to the U.S. entering World War I.
Step-by-step explanation:
Zimmermann Telegram and its Impact
The Zimmermann Telegram was an important communication sent by the German Foreign Minister, Arthur Zimmermann, to the German ambassador in Mexico. This 1917 correspondence encouraged Mexico to form an alliance with Germany in the event that the United States entered World War I on the side of the Allies. The proposal included an incentive for Mexico to engage in military action against the United States, promising assistance in helping Mexico reconquer lost territories such as Texas, New Mexico, and Arizona. Ultimately, Mexico declined the offer, but the revelation of the telegram to the public by British intelligence significantly increased tensions between Germany and the United States, influencing America's decision to enter the war.
The interception and publication of the Zimmermann Telegram were also significant as it revealed the unpreparedness of the US Army and the potential threat along the US-Mexican border. The entire episode played a critical role in swaying American opinion towards involvement in World War I.