The Spanish–American War (April 21 – August 13, 1898) was a period of armed conflict between Spain and the United States. Hostilities began in the aftermath of the internal explosion of the USS Maine in Havana Harbor in Cuba, leading to United States intervention in the Cuban War of Independence. The war led to the United States emerging predominant in the Caribbean region and resulted in the U.S. acquisition of Spain's Pacific possessions. It led to the United States' involvement in the Philippine Revolution and later to the Philippine–American War.
The main issue was Cuban independence. Revolts had been occurring for some years in Cuba against Spanish colonial rule. The United States backed these revolts upon entering the Spanish–American War. There had been war scares before, as in the Virginius Affair in 1873. But in the late 1890s, American public opinion swayed in support of the rebellion because of reports of concentration camps set up to control the populace. Yellow journalism exaggerated the atrocities to further increase public fervor and to sell more newspapers and magazines. Wikipedia