What has surprised analysts has been his conciliatory approach to some of his erstwhile adversaries, including Presidents Kennedy, Clinton and Carter, the latter of whom he termed "a man of honor, an ethical man."

As Castro steps down from the presidency, "Fidel Castro: My Life," provides a panoramic view of the 81-year-old leader's years in power. The book, first published in Spain in 2006, was edited by Castro in his sickbed for release in the U.S. last month.

Throughout the book, Castro touts what he considers prime accomplishments of his revolution: universal literacy, free higher education, one of the world's lowest infant-mortality rates and a healthcare network that treats all Cubans for free and provides relief in the Third World and to victims of natural disasters from Pakistan to Haiti.

What does Castro regret in five turbulent decades that included the Bay of Pigs invasion, the Cuban missile crisis, the Mariel boatlift and the fall of communism across much of the world? Nothing, he says -- not the dissidents jailed for demanding elections, the rivals executed nor the thousands of lives lost in the Cuban military's "internationalist" deployments.

"I have not one iota of regret about what we've done in our country and the way we've organized our society," Castro told coauthor Ignacio Ramonet during more than 100 hours of interviews over three years, ending in December 2005.

Castro insists throughout the discourse that the communist nature of Cuba's revolution is "irrevocable." But he also warns that Cubans can kill off his life's work if they continue to follow the siren cries of capitalism and self-enrichment.

"This revolution can destroy itself. We, we can destroy it, and we would be to blame," he says.

Bellicose and swashbuckling, with his trademark fatigues and scruffy beard, Castro frequently outmaneuvered his powerful neighbor and archenemy over the second half of the 20th century.

Though a succession of U.S. presidents and hard-line Cuban exiles in Miami regarded him as a dictator who trampled on the rights of his people, Castro stood as a symbol for many Latin American leaders who envied his defiance of the powerful norteamericanos.

His reach, and appeal, spanned the globe. He aided revolutionaries from Nicaragua to Angola, supported leftists such as Chile's Salvador Allende and Grenada's Maurice Bishop, fomented unrest against conservatives in Venezuela and Argentina, and kept allies in power in Mozambique.

Born in a village in eastern Cuba on Aug. 13, 1926, Fidel Alejandro Castro Ruz was the son of a prosperous Spanish immigrant and the servant he had taken as a mistress. He was sent to a Jesuit-run boys academy in the capital, and then studied law at the University of Havana.

Castro excelled at both basketball and baseball, but he also began plotting revolution as a student. Resentful of U.S. backing of corrupt leaders and ownership of exploitative factories and plantations, he joined the Orthodox Party, which embraced the legacy of Jose Marti.

He ran as an Orthodox Party candidate for parliament in 1952, but the vote was canceled when Gen. Fulgencio Batista overthrew the government and imposed a right-wing dictatorship.

Castro organized a revolutionary movement. An attack in 1953 on the Moncada military barracks in Santiago de Cuba failed miserably, and several dozen of his followers were killed. Castro and many others were captured. Freed two years later in an amnesty for political prisoners, he fled to Mexico.

Castro, Ernesto "Che" Guevara and 80 followers headed back to Cuba in late 1956 to launch the revolution that led to their seizure of power on New Year's Day 1959.

Initially acclaimed on the international stage, Castro charmed journalists and socialites in New York and Washington that April.

Countless biographers, interviewers and political scientists say his lifelong confrontation with his northern neighbor didn't have to happen. In their view, Batista supporters whose homes and businesses had been seized by Castro encouraged Washington to reject him, pushing him into the arms of the Soviet Union.

President Eisenhower slapped a trade embargo on Cuba in October 1960 and severed diplomatic relations three months later. The $1.8 billion worth of U.S.-owned property nationalized after the revolution remains uncompensated and a barrier to trade and diplomatic relations.