Cuba was the last major Spanish colony to gain independence, following a lengthy struggle begun in 1868. Jose Marti, Cuba's national hero, helped initiate the final push for independence in 1895. In 1898, the United States entered the conflict after the USS Maine sank in Havana Harbor on February 15 due to an explosion of undetermined origin. In December of that year, Spain relinquished control of Cuba to the United States with the Treaty of Paris. On May 20, 1902, the United States granted Cuba its independence but retained the right to intervene to preserve Cuban independence and stability in accordance with the Platt Amendment. In 1934, the Platt Amendment was repealed. The United States and Cuba concluded a Treaty of Relations in 1934 which, among other things, continued the 1903 agreements that leased the Guantanamo Bay naval base to the United States.

Independent Cuba was often ruled by authoritarian political and military figures who either obtained or remained in power by force. Fulgencio Batista, an army sergeant, organized a non-commissioned officer revolt in September 1933 and wielded significant power behind the scenes until he was elected president in 1940. Batista was voted out of office in 1944 and did not run in 1948. Both those elections were won by civilian political figures with the support of party organizations. Running for president again in 1952, Batista seized power in a bloodless coup 3 months before the election was to take place, suspended the balloting, and began ruling by decree. Many political figures and movements that wanted a return to the government according to the Constitution of 1940 disputed Batista's undemocratic rule.

On July 26, 1953, Fidel Castro, who had been involved in increasingly violent political activity before Batista's coup, led a failed attack on the Moncada army barracks in Santiago de Cuba in which more than 100 died. After defending himself in a trial open to national and international media, he was convicted and jailed, and subsequently was freed in an act of clemency, before going into exile in Mexico. There he organized the "26th of July Movement" with the goal of overthrowing Batista, and the group sailed to Cuba on board the yacht Granma, landing in the eastern part of the island in December 1956.

Batista's dictatorial rule fueled increasing popular discontent and the rise of many active urban and rural resistance groups, a fertile political environment for Castro's 26th of July Movement. Faced with a corrupt and ineffective military--itself dispirited by a U.S. Government embargo on weapons sales to Cuba--and public indignation and revulsion at his brutality toward opponents, Batista fled on January 1, 1959. Although he had promised a return to constitutional rule and democratic elections along with social reforms, Castro used his control of the military to consolidate his power by repressing all dissent from his decisions, marginalizing other resistance figures, and imprisoning or executing thousands of opponents. An estimated 3,200 people were executed by the Castro regime between 1959-62 alone. As the revolution became more radical, hundreds of thousands of Cubans fled the island.

Castro declared Cuba a socialist state on April 16, 1961. For the next 30 years, Castro pursued close relations with the Soviet Union and worked in concert with the geopolitical goals of Soviet communism, funding and fomenting violent subversive and insurrectional activities, as well as military adventurism, until the demise of the U.S.S.R. in 1991.

Relations between the United States and Cuba deteriorated rapidly as the Cuban regime expropriated U.S. properties and moved toward adoption of a one-party communist system. In response, the United States imposed an embargo on Cuba in October 1960, and, in response to Castro's provocations, broke diplomatic relations on January 3, 1961. Tensions between the two governments peaked during the October 1962 missile crisis.