Raúl Castro, who recently turned 75, is Fidel Castro's younger brother, and since the two were expelled from school in the 1940s, has been at his side: in jail, in exile, in the mountains and then in power.

A social sciences student at the University of Havana, Raúl joined the Cuban Communist Party and travelled to Eastern Europe in the early 1950s, initially preferring a more strictly socialist revolution than his brother's violent assault on the regime of General Fulgencio Batista.

In 1953, he accompanied Fidel and his 160 followers in the doomed attack on the Moncada Barracks in Cuba's second city of Santiago that became the starting point of Castro's "26th of July Movement".

Imprisoned with his brother for just under two years, Raúl emerged as a fully fledged guerrilla. In exile in Mexico, he met the young Argentinian fighter, Ernesto "Che" Guevara and brought him into the Cuban revolutionary movement and helped find the weapons, supporters and supplies to fill the ship Granma that carried the Castros back to Cuba in December 1956.

For three years, at times with just 12 supporters, the Castros moved through the mountains of Cuba. Raúl led a force named "Frank Pa's Second Front", after a comrade who died, and eventually commanded several hundred men, gaining a reputation for ferocity and anti-Americanism that was strengthened by the kidnap of 50 Americans and Canadians in 1958, an attack that was disapproved by Fidel.

It was in the mountains that Raúl married Vilma Espín, a former MIT student and the daughter of a Barcadi rum executive, who fought under the name "Deborah".

In the following 40 years, Senora Espín has emerged as one of the leading women in the Cuban Government, juggling roles as an MP, a party official and the President of the Federation of Women.

After the revolution, Raúl, as dogmatic as he was popular, took firm control of the army, carrying out one of the most brutal acts of the early Castro Government: the execution of more than 70 officers in the Batista army in Santiago. The soldiers were shot by machine gun and buried in a large pit.

Raúl is known to have carried intermittent purges of the communist officials ever since, including the removal of party intellectuals with "capitalist ideas" as recently as 1996.

As head of the Armed Forces, Raúl was integral to the development of close military ties with the USSR and was one of the key players in the Cuban Missile Crisis in 1962, seeking the installation of Soviet nuclear warheads on Cuba.

He subsequently led the establishment of the infamous UMAP camps (Military Units to Help Production), where homosexuals and critics of the Castro Government were imprisoned and "reformed" through hard labour. In the 1980s, the Cuban army also administered the quarantining of HIV positive men in so-called "sidatorios". Sida is the Spanish acronym for Aids.

With his collection of titles — he is Vice President of the Council of Ministers, First Vice President of the Council of State of Cuba, Vice-Secretary of the Politburo and the Central Committe of the Communist Party of Cuba (PCC) as well Defence Minister — Raúl had long been regarded as Fidel's deputy and likely successor should the Cuban President die before him.

In view of his age and the increasingly open discussion of the post-Fidel Government in Havana, Raúl is now spoken of as the figurehead who will lead a trio of long-serving communist officials who will take over from Fidel: Felipe Pérez Roque, the fanatically loyal Foreign Minister, Ricardo Alarcón, the 69-year-old former diplomat and President of Cuba's National Assembly, and Carlos Lage, the Vice President who manages the Cuban economy.

In recent months, a press campaign has been under way to elevate the status of Raúl, who rarely gives speeches and has never given an interview to a Western journalist. The day before his 75th birthday, Granma, now the name of the Communist Party newspaper, ran an eight-page supplement lionising him as "the chief, the leader, the companion, the man".

The article, as reported this week by The New Yorker, ended with Fidel explaining why his brother should succeed him: "I choose him not because he is my brother, because the whole world knows how much we hate nepotism, but because on my honour, I consider him to have sufficient qualities to substitute for me tomorrow in case I die in this struggle."

Times Recommends

• Please help: maimed children of war want their lives back
• Cabal seizes diamond riches to buy power
• White House gatecrashers got to the president