Raúl Castro has been at the side of his brother Fidel since the very beginning. In the Moncada attack that took place in 1952, shortly after Batista's second takeover of the Cuban government, Raúl and his men were able to capture the Palace of Justice. The others were not as successful.
Five years later, he was one of just 16 men (of the original 82) who made it into the Sierra Maestra Mountains in 1956. Shortly thereafter Raúl and Che Guevara were made leaders in the Rebel Army.
Raúl united the various anti-Batista movements in the Northern Oriente, and was able to establish a public works corps, a health unit, an air base and a factory for producing bombs.
Unlike Fidel, Raúl has been a vocal communist since the beginning, and it is widely believed that he and Che were instrumental in pulling Fidel into the communist camp.
It was shortly after his trip to Moscow that the Soviet Union began to install nuclear missiles in Cuba, leading to what we now remember as the Cuban Missile Crisis.
Raúl has been designated to take over the position of Prime Minister of Cuba should anything happen to Fidel Castro.
A brief excerpt from Fidel Castro's speech at Havana's May Day celebrations on May 2 1961, less than two weeks after the Bay of Pigs invasion