The Spanish-American War, a military conflict between Spain and the United States, begins in April 1898 after the American demand for Spain's peacefully resolving the Cuban fight for independence is rejected, though strong expansionist sentiment in the United States may have motivated the government to target Spain's remaining overseas territories: Cuba, Puerto Rico, the Philippines, Guam and the Caroline Islands.Riots in Havana by pro-Spanish "Voluntarios" had given the United States a reason to send in the warship USS Maine to indicate high national interest.

Tension among the American people is raised because of the explosion of the USS Maine, and "yellow journalism" that accuses Spain of extensive atrocities, agitating American public opinion.

The war ends in August after decisive naval victories for the United States in the Philippines and Cuba.

In December, only 109 days after the outbreak of war, the Treaty of Paris, which ends the conflict, gives the United States ownership of the former Spanish colonies of Puerto Rico, the Philippines and Guam.