Spanish–American War: After more than two months of sea-based bombardment, the United States invaded Puerto Rico.

The Spanish–American War was fought between Spain and the United States in 1898. It began with the sinking of the USS Maine in Havana Harbor in Cuba, and resulted in the U.S. acquiring sovereignty over Puerto Rico, Guam, and the Philippines, and establishing a protectorate over Cuba. It represented U.S. intervention in the Cuban War of Independence and Philippine Revolution, with the latter later leading to the Philippine–American War. The Spanish–American War brought an end to almost four centuries of Spanish presence in the Americas, Asia, and the Pacific; the United States meanwhile not only became a major world power, but also gained several island possessions spanning the globe, which provoked rancorous debate over the wisdom of expansionism.

The Puerto Rico campaign was the American military sea and land operation in Puerto Rico during the Spanish–American War, which resulted in the invasion, occupation, and annexation of the archipelago and island by the United States, and the cession of said territory by Spain. The offensive began on May 12, 1898, when the United States Navy attacked the capital, San Juan. Though the damage inflicted on the city was minimal, the Americans were able to establish a blockade in the city's harbor, San Juan Bay. On June 22, the cruiser Isabel II and the destroyer Terror delivered a Spanish counterattack, but were unable to break the blockade and Terror was damaged.