"A splendid little war." (John Hay, US Ambassador to the United Kingdom, describing the war in a letter to Theodore Roosevelt)

In 1898, one of Spain's last possessions in the New World, Cuba, was waging a war for independence, and many Americans believed that the United States should side with Cuba against Spain.

Initially, Republican President William McKinley wanted to avoid any wars, and for its part, Spain also wanted to avoid any conflict with United States and its powerful navy. However, Spain also wanted to keep Cuba, which it regarded as a province of Spain rather than a colony. Cuba was very important to the Spanish economy as well, as it produced valuable commodities such as sugar and also had a booming port at Havana.

All the while, American economic interests were being harmed by the ongoing conflict between Cuban nationalists and Spain. Merchants' trading with Cuba was suffering now that the island was undergoing conflict, and the American press capitalized on the ongoing Cuban struggle for independence. In an effort to sell papers, the press frequently sensationalized stories, which came to be known as "yellow journalism." During the run-up to war, yellow journalism spread false stories about the Cuban conflict in order to sell newspapers in the competitive New York City market.

Despite President McKinley's wishes to avoid a war, he was forced to support a war with Spain after the American navy vessel USS Maine suffered an explosion in Havana harbor. McKinley had sent the ship there to help protect American citizens in Cuba from the violence that was taking place there, but the explosion devastated the ship, which sunk quickly in the harbor. 266 American sailors aboard the USS Maine died.

Although the cause of the explosion was never determined, yellow journalists in the American press blamed Spain, claiming the ship was sabotaged. President McKinley was unable to resist popular pressure after a US Navy report also claimed that the ship had been subject to an explosion outside of its hull which ignited powder magazines inside the ship. Later investigations proved inconclusive, but President McKinley was now forced to accept war with Spain.

Congress declared war, and the US Navy began a blockade of Cuba and Puerto Rico. The US Pacific fleet sailed to the Philippines, which were then a Spanish possession. Despite supply problems from operating so far from existing US Naval bases, the US fleet defeated the Spanish fleet in Manila.

The US Army, meanwhile, landed 15,000 troops on Cuba. New York politician Theodore Roosevelt, who had been advocating for war with Spain to support the Cuban revolutionaries, joined the US Army and participated in its Cuba campaign, becoming well known for his participation with the "Rough Riders". Despite the superiority of the Spanish rifles, they were overwhelmed by the number of US Army forces supported by artillery and Gatling guns.