Valeriano Weyler in the context of "Spanish Army"

The Spanish–American War (April 21 – August 13, 1898) 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 19th century represented a clear decline for the Spanish Empire, while the United States went from a newly founded country to a rising power. In 1895, Cuban nationalists began a revolt against Spanish rule, which was brutally suppressed by the colonial authorities. W. Joseph Campbell argues that yellow journalism in the U.S. exaggerated the atrocities in Cuba to sell more newspapers and magazines, which swayed American public opinion in support of the rebels. But historian Andrea Pitzer also points to the actual shift toward savagery of the Spanish military leadership, who adopted the brutal reconcentration policy after replacing the relatively conservative Governor-General of Cuba Arsenio Martínez Campos with the more unscrupulous and aggressive Valeriano Weyler, nicknamed "The Butcher." President Grover Cleveland resisted mounting demands for U.S. intervention, as did his successor William McKinley. Though not seeking a war, McKinley made preparations in readiness for one.

The reconcentration policy (Spanish: Reconcentración) was a plan implemented by Spanish military officer Valeriano Weyler during the Cuban War of Independence to relocate Cuba's rural population into concentration camps. It was originally developed by Weyler's predecessor, Arsenio Martínez Campos, as a method of separating Cuban rebels from the rural populace which often supplied or sheltered them. Under the policy, rural Cubans had eight days to relocate to concentration camps in fortified towns, and all who failed to do so were to be shot.

The quality of the camps was abysmal, with the housing being in poor condition and the camp rations insufficient and of poor quality; disease also quickly spread through the camps. By 1898, a third of the Cuban population had been moved into camps where at least 170,000 people died due to either disease or a variety of other causes, resulting in the deaths of at least 10% of all Cubans. The Spanish were eventually defeated in the conflict, and as a result all the camps were shut down.