"The commander in chief of the Cuban revolution died... this evening," Cuban President Raul Castro said last night, referring to his brother and former President Fidel Castro. "Towards victory, always!" he added, using a revolutionary slogan.
A period of official mourning has been declared on the island until 4 December, when Fidel's ashes will be laid to rest in the southeastern city of Santiago.
An accomplished tactician on the battlefield, Fidel and his small army of guerrillas overthrew the military leader Fulgencio Batista in 1959 to widespread popular support.
Within two years of taking power, he declared the revolution to be Marxist-Leninist in nature and allied the island nation firmly to the Soviet Union.
Despite the constant threat of a US invasion as well as the long-standing economic embargo on the island, Castro managed to maintain a communist revolution in a nation just 90 miles off the coast of Florida.
Despised by his critics as much as he was revered by his followers, he maintained his rule through 10 US presidents and survived scores of attempts on his life by the CIA.
The Soviet Union's last leader, Mikhail Gorbachev, said: "Fidel stood up and strengthened his country during the harshest American blockade, when there was colossal pressure on him".