Final answer:
The immediate cause of the Spanish-American War was the publication of the De Lôme letter, which revealed Spanish diplomats mocking President McKinley.
Step-by-step explanation:
The immediate cause of the Spanish-American War was the publication of the De Lôme letter, which revealed Spanish diplomats mocking President McKinley. The letter, written by the Spanish Minister in Washington, criticized McKinley's handling of the Cuban crisis. This insult to the President caused public outrage in the United States and played a significant role in stirring up pro-war sentiment.
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