Political map of North America & the Caribbean 11 August 1898 (Spanish-American War): By 1898, the long-running Cuban war for independence (Cuban War of Independence) was aggravating US-Spanish relations. In February, the USS Maine (USS Maine (ACR-1)) sunk in an unexplained explosion in Havana Harbor, leading to war (Spanish-American War). American forces swiftly defeated the Spanish at sea (Battle of Manila Bay) and in Cuba (Battle of Guantanamo Bay), Puerto Rico (Puerto Rican Campaign) and the Philippines (Battle of Manila (1898)), putting an end to Spain's 400 year old colonial empire.