During his university years, from 1945 to 1950, Castro was a political activist. In September 1947 he joined an armed expeditionary force composed of Cubans and exiles from the Dominican Republic intending to oust the government of the dictator Rafael Leónidas Trujillo (1891–1961). The invasion was never launched. The next year, in April 1948 as a representative of the Law Students Association of Cuba, Castro went to a Latin American University Students Congress in Bogotá, Colombia, which coincided with the United States’initiation of the Organization of American States and the advent of civil war in Colombia. The populist leader of the opposition was assassinated. For two days Castro participated in some of the early armed skirmishes, and then he returned home. Both incidents indicate that he, like many contemporaries in Cuba, identified with political struggles in the region. He was also involved in a political organization promoting the independence of Puerto Rico. By then he had acquired lifelong contacts with Latin American progressive political parties and leaders.He graduated in 1950 with a law degree, having specialized in international law and social sciences. His main interests were politics, sociology, history, theory, and agriculture. As a student leader, radio commentator, and investigative political journalist, he developed a significant following among young people. The Ortodoxo Party recognized his oratorical and organizational skills and nominated him for the planned June 1952 national congressional election. However, on March 10, 1952, the military, led by Batista, carried out a second coup d’état, ending hopes that electoral politics could reform the island and throwing Cuba’s constitutional system into a crisis.