By 1939 Bosch had gone to Cuba, where he directed an edition of the completed works of Eugenio María de Hostos, something that defined his patriotic and humanist ideals.

[10] At the same time, his literary career was ascending, gaining important acknowledgments like the Hernandez Catá Prize in Havana for short stories written by a Latin American author.

His works had a deep social content, among them "La Noche Buena de Encarnación Mendoza", "Luis Pié", "The Masters" and "The Indian Manuel Sicuri", all of them described by critics as masterpieces of their sort.

Bosch was one of the main organizers of the abortive Cayo Confites expedition of 1947, in which a military force backed by the Caribbean Legion unsuccessfully attempted to invade the Dominican Republic from Cuba.

In Cuba, where he returned by requirement of his friends in the Authentic Revolutionary Party, he played a notorious part in the political life of Havana, being recognized as a promoter of social legislation and author of the speech pronounced by President Carlos Prío Socarrás when the body of José Martí was transferred to Santiago de Cuba.

After being liberated, he left Cuba and headed to Costa Rica, where he dedicated his time to pedagogical tasks, and to his activities as leader of the PRD.

Molasses tycoon Jacob Merrill Kaplan earned his fortune primarily through operations in Cuba and the Dominican Republic.

[12] Via the Fund, the CIA gave Figueres money to publish a political journal, Combate, and to found a left-wing school for Latin American opposition leaders.

[13] In 1959 the Cuban Revolution took place, led by Fidel Castro, causing a major political, economic and social upheaval in the Caribbean island.

[13] He used the contacts with Bosch, Volman, and Figueres for a new purpose – as the United States moved to rally the hemisphere against Cuba's Fidel Castro, Rafael Trujillo, the strongman caudillo that ran the Dominican Republic for 30 years had become a liability.

[citation needed] For over a year, the CIA had been in contact with dissidents inside the Dominican Republic who argued that assassination was the only certain way to remove Trujillo.

[14] Richard N. Goodwin, Assistant Special Counsel to the President, who had direct contacts with the rebel alliance, argued for intervention against Trujillo.

An internal CIA memorandum states that a 1973 Office of Inspector General investigation into the assassination disclosed "quite extensive Agency involvement with the plotters."

On 27 February 1963, Bosch was sworn in as president in a ceremony that was attended by important democratic leaders and personalities of the region, like Luis Muñoz governor of the U.S. territory of Puerto Rico and José Figueres of Costa Rica.

Among other things, it declared specific labour regulations, and mentioned unions, pregnant women, homeless people, the family, rights for the child and the young, for the farmers, and for illegitimate children.

The United States dispatched 42,000 troops to the island in Operation Power Pack during the ensuing civil war in support of the anti-Bosch forces.

He published some of his most important works during this time: "Dominican Social Composition", "Brief History of the Oligarchy in Santo Domingo", "From Christopher Columbus to Fidel Castro", and numerous articles of different sorts.

By 1970, Bosch had the intention of reorganizing the PRD and turning its members into active, studious militants of the historical and social reality of the country.