 Llerena met Castro in the 1950s, and at his request wrote a document, "Nuestra Razón", explaining the democratic ideals of the uprising Castro was planning.In 1957, he was named chairman of the New York branch of the July 26 Movement, and played a pivotal role in circumventing Batista's attempts at censorship during the uprising.Citing ideological differences, he resigned from the movement before Castro's triumph on January 1, 1959.