Final answer:
The explosion of the battleship USS Maine in Havana harbor triggered American cries for war against Spain.
Step-by-step explanation:
The specific event that triggered American cries for war against Spain was the explosion of the battleship USS Maine in Havana harbor. This incident occurred in February 1898 and was blamed on a Spanish mine. The American public and newspapers called for revenge and the U.S. Congress declared war on Spain on April 25, 1898.