Fidel and Raul Castro- and other officers such as Abel Santamaria, second chief during the assault on the Moncada headquarters in 1953, the beginning of the armed struggle against the dictatorship- arose from a movement whose center lay in the University. The meeting with the great contingents of the population- the already enlisted Che Guevara, also an extraction from the University- developed since 1956 when the scene of the armed struggle was situated with the peasants of the Sierra Maestra. Two years later, virtually all of Cuba was turned over to Fidel Castro and his Rebel Army, even including the wealthy sugar bourgeoisie who assumed “neutrality” in fact favorable to the revolution, leaving the then governing party of the dictator Fulgencio Batista, without any social support. Political opportunism? Maybe, but only as a result of basic factors- competition with the American sugar producers, saturation of the international market, and so on- studied in this paper which is based on original sources.