The war originated in the Cuban struggle for independence from Spain, which began in February 1895. Spain's brutally repressive measures to halt the rebellion were graphically portrayed for the U.S. public by several sensational newspapers, and American sympathy for the rebels rose. The growing popular demand for U.S. intervention became an insistent chorus after the unexplained sinking in Havana harbour of the battleship USS Maine (Feb. 15, 1898; see Maine, destruction of the), which had been sent to protect U.S. citizens and property after anti-Spanish rioting in Havana. Spain announced an armistice on April 9 and speeded up its new program to grant Cuba limited powers of self-government, but the U.S. Congress soon afterward issued resolutions that declared Cuba's right to independence, demanded the withdrawal of Spain's armed forces from the island, and authorized the President's use of force to secure that withdrawal while renouncing any U.S. design for annexing Cuba.

The elusive Spanish Caribbean fleet under Adm. Pascual Cervera (Cervera y Topete, Pascual) was located in Santiago harbour in Cuba by U.S. reconnaissance. An army of regular troops and volunteers under Gen. William Shafter (and including Theodore Roosevelt and his 1st Volunteer Cavalry, the “Rough Riders”) landed on the coast east of Santiago and slowly advanced on the city in an effort to force Cervera's fleet out of the harbour. Cervera led his squadron out of Santiago on July 3 and tried to escape westward along the coast. In the ensuing battle all of his ships came under heavy fire from U.S. guns and were beached in a burning or sinking condition. Santiago surrendered to Shafter on July 17, thus effectively ending the war.

By the Treaty of Paris (Paris, Treaty of) (signed Dec. 10, 1898), Spain renounced all claim to Cuba, ceded Guam and Puerto Rico to the United States, and transferred sovereignty over the Philippines to the United States for $20,000,000. The Spanish-American War was an important turning point in the history of both antagonists. Spain's defeat decisively turned the nation's attention away from its overseas colonial adventures and inward upon its domestic needs, a process that led to both a cultural and a literary renaissance and two decades of much-needed economic development in Spain. The victorious United States, on the other hand, emerged from the war a world power with far-flung overseas possessions and a new stake in international politics that would soon lead it to play a determining role in the affairs of Europe.