Final answer:
The Spanish-American War in 1898 was catalyzed by the destruction of the USS Maine and intensified U.S. imperial ambitions, leading to significant American victories in the Pacific, including the Philippines, and the decline of Spanish colonial power.
Step-by-step explanation:
The Spanish-American War was a significant conflict between Spain and the United States in 1898, sparked by the explosion of the USS Maine in Havana Harbor. Prior to the incident, the USS Maine was sent to guard U.S. interests since American investors had substantial control over Cuba's sugar industry and other infrastructure.
The mysterious sinking of the ship, which killed 266 Americans, was sensationalized by the 'yellow press' to incite public opinion against Spain, promoting a war that became a momentous step in expanding the U.S.'s imperial power.
The war not only led to the liberation of Cuba but also the expansion of American influence into the Pacific, specifically the Philippines and Puerto Rico. Theodore Roosevelt, then Assistant Secretary of the Navy, was pivotal in the war's events, particularly at the Battle of San Juan Hill where his Rough Riders and Black troops fought.
Throughout this period, American imperialism was on the rise, influenced by ideologies like Alfred T. Mahan's vision of a strong navy. The conflict's aftermath saw the U.S. acquire territories extending its reach, which was in line with the strategic military and economic interests of the time.