Answer by taking a quote from the following article:

Jose Julian Marti Perez (January 28, 1853 - May 19, 1895) was a Cuban National Hero and an important figure in Latin American literature. During his life, he worked as a poet, essayist, journalist, translator, professor, and publisher. He was very politically active, and is considered an important revolutionary philosopher and political theorist. Through his writings and political activity, he became a symbol of Cuba's bid for independence against Spain in the 19th century, and is referred to as the "Apostle of Cuban Independence."

Jose Marti is usually honored as a great poet, patriot and martyr of Cuban Independence, but he was also a translator of some note. Although he translated literary material for the sheer joy of it, much of the translating he did was imposed on him by economic necessity during his many years of exile in the United States. Marti learned English at an early age, and had begun to translate at thirteen. He continued translating for the rest of his life, including his time as a student in Spain, although the period of his greatest productivity was during his stay in New York from 1880 until he returned to Cuba in 1895.  In New York he was what we would call today a "freelancer" as well as an "in house" translator. He translated several books for the publishing house of D. Appleton, and did a series of translations for newspapers. As a revolutionary activist in Cuba's long struggle for independence he translated into English a number of articles and pamphlets supporting that movement. In addition to fluent English, Marti also spoke French, Italian, Latin and Classical Greek fluently, the latter learned so he could read the Greek classical works in the original.  There was clearly a dichotomy in Marti's feeling about the kind of work he was translating. Like many professionals, he undertook for money translation tasks which had little intellectual or emotional appeal for him. Although Marti never presented a systematic theory of translation nor did he write extensively about his approach to translation, he did jot down occasional thoughts on the subject, showcasing his awareness of the translator's dilemma of the faithful versus the beautiful and stating that "translation should be natural, so that it appears that the book were written in the language to which it has been translated".

What kind of translation took place?
He translated several books for the publishing house of D. Appleton, and did a series of translations for newspapers.