Cuba had long been a colony of Spain, with almost its entire economy based on sugar production. As the second half of the 19th century wore on, many people in Cuba, which had been a Spanish colony, became dissatisfied with the ruling Spanish regime. The Spanish government was riddled with corruption, inefficient, and unwilling to grant the Cuban population any concessions.
Despite obvious Cuban dissatisfaction, the Spanish authorities refused to grant any amount of self-government to the Cubans. As a result, Cuban Nationalists, who wanted to end Spanish rule, fought the Ten Years' War against the Spaniards from 1868-1878. The rebellion finally petered out, though the dissatisfaction motivating the fighting did not disappear. After the war, the Spanish promised reforms, but the Nationalists considered this too little, too late.
When a Nationalist-initiated conflict broke out again in Cuba in 1895, the Spanish, remembering the lengthy Ten Years' War, sent 200,000 troops to Cuba. The Cuban insurrectos responded by wrecking Spanish property in hopes that the Spanish would leave, or at least hoping for US intervention (since the US had significant economic investment in Cuba). The insurrectos directed their destructive rampage at both sugar mills and sugar fields.
In 1896, the Spanish sent the infamous General Weyler, known as "The Butcher," to Cuba to put down the insurrection. Weyler lived up to his name. To prevent the insurrectos from leading the population against Spanish rule, Weyler built concentration camps in which he imprisoned a large portion of the population. Under the harsh and unsanitary conditions in the concentration camps, Cuban prisoners died rapidly, especially from disease.
Segments of the US public, outraged by reports of atrocities in Cuba, immediately cried out for action. President Grover Cleveland (1893-1897), however, was dead set against going to war. He issued an ultimatum: even if Congress passed a declaration of war, he vowed as commander-in-chief of the army to never send the military to Cuba.
The Cuban Nationalists moved against Spain partly because they thought the US likely to come to their aid. The US was investing increasing amounts of money into Cuban sugar production ($50 million by 1895) and conducted a trade with Cuba worth $100 million annually. From the 1860s on, the US had even tried to purchase Cuba from Spain several times.
Other causes underlying the 1895 Cuban revolt include a general opposition to a long history of Spanish control, and the more immediate effects of the American Wilson-Gorman Tariff of 1894. The tariff, which raised prices on sugar imported from Cuba in order to protect US sugar growers, ended up hurting the Cuban economy significantly. Hard times in Cuba led to public unrest and conflict with the Spanish regime. However, it should be noted that although Spanish atrocities against the Cubans are often emphasized, both sides in the Cuban conflict beginning in 1895 killed civilians and destroyed private property.
The US was alarmed by developments in Cuba and had sympathies with the insurrectos from the beginning. First and foremost, the US was always concerned about having a strong European power just offshore the Florida coast. The Spanish, who were considered (wrongly) to have a powerful Navy at the time, posed a potential threat to US trade in the Caribbean. With the Panama Canal on the collective US drawing boards, US policymakers were particularly concerned with the future of maritime shipping in the Caribbean. And of course, the US had financial reasons for wanting to stop the conflict. As mills and plantations went up in flames, American leaders and businessmen increasingly feared that American investments in Cuba might be harmed, not to mention American citizens currently in Cuba.Less specific to the region, the US had long held a position of anti-colonial tradition, originating fromt he fact that the US had once been a set of colonies that had themselves #revolted against their British overlords##. Americans quickly drew parallels between themselves and the Cubans, seeing the Cubans as facing a similar situation to the one the 13 colonies had faced. For all these reasons, the US was happy to have an excuse to oppose the Spanish.
None of the above events or commentary seem to suggest that the after the Spanish-American War in 1898 the US would annex several territories (taking colonies). However, in many ways, the early 1890s were the perfect incubator for imperialist expansion at the end of the decade. The Depression of 1893-1897 and the continuing switch from a predominately agricultural export economy to one in which manufactured goods were the primary export combined to fuel the search for foreign markets. The actions of the US during and just after the Spanish-American War can thus be seen as a redefinition of values, or as an illumination of the separate values simultaneously animating American policy and public debate.