WASHINGTON — It wasn’t the Bay of Pigs invasion or American embargo against Cuba that turned Fidel Castro against America. He was in the anti-American camp long beforehand.

He never wavered in his loathing of his powerful neighbor to the north.

His feelings were dramatized in a handwritten note he sent to a colleague in 1958, as a guerrilla commander, six months before taking power.

“I am going to launch another, much longer and bigger war against them (the Americans). I realize now that this is going to be my true destiny,” Mr. Castro, then 31, wrote.

He kept his word. His differences with America were more than just political; they were cultural as well. He ridiculed American elections, American consumerism, the American penchant for changing cars every few years and the perceived American indifference to society’s less fortunate

President Bush expressed hope today that the end of Fidel Castro’s presidency would launch a transition to democracy in Cuba after nearly 50 years of hardline, communist rule. Long a target of American criticism and sanctions, the ailing Mr. Castro, 81, announced he would not accept a new term.

“What does this mean for the people in Cuba?” Mr. Bush said at a news conference during his trip to Africa. “They’re the ones who suffered under Fidel Castro. They’re the ones who were put in prison because of their beliefs. They’re the ones who have been denied their right to live in a free society. So I view this as a period of transition and it should be the beginning of the democratic transition in Cuba.”

Fidel Castro has contended that American domination of Cuba during the last century was such that the island did not achieve genuine independence until his revolution in 1959. He once denounced American imperialism 88 times in a single speech. His government confiscated, without compensation, almost 6,000 properties belonging to Americans.

Cuba under Mr. Castro had a 30-year partnership with the Soviet Union. When it came to Moscow’s worldwide quest to pick up new allies for the socialist camp, no country was a more faithful supporter than Cuba. Mr. Castro also struck up friendships with other bitter enemies of America: North Korea, Iran, and Iraq under Saddam Hussein — all members of Mr. Bush’s “axis of evil.”

Mr. Castro dreamed of Cuban-style communist revolutions throughout the Third World and was displeased about the global trend toward the embrace of free markets and representative democracy.

But he welcomed the emergence in recent years of left and center-left governments in Latin America, most notably in Venezuela, whose petrodollars, mostly from America, finance Venezuela’s anti-American policies.

A major sore point for Cuba was the frequency with which anti-Castro militants launched attacks on Cuba, using Florida as a staging area.

During the early years of his rule, American missteps played into Mr. Castro’s hands. The botched Bay of Pigs invasion of 1961 made him the country’s unquestioned leader and sullied the American image around the world. Later, that image was further damaged by disclosures of repeated CIA attempts in the early 1960s to assassinate Mr. Castro.

Between 1959 and 1962, Mr. Castro had an enormous impact on American policy toward Latin America. Fearful of a wave of Castro-type revolutions in the hemisphere, President Kennedy promoted a dramatic expansion of American assistance to — and involvement in — Latin America.

It was only after the Cuban missile crisis in 1962 — in which Mr. Castro was essentially a bystander — that American concerns about Mr. Castro’s influence in the region began to ebb.

The centerpiece of American policy toward Cuba has been the economic embargo, first instituted in limited form in 1960 and strengthened in 1962.

Mr. Castro persistently called the embargo “criminal,” and claimed that its economic impact on the island ran well into the tens of billions of dollars. Politically influential anti-Castro militants have beaten efforts over the years to lift the embargo.

Internationally, the embargo has virtually no support. Each fall, the U.N. General Assembly takes up a Cuban-sponsored proposal to condemn the measure. Normally, America can count on few votes beyond its own.

Migration issues have repeatedly roiled the American-Cuban relationship. In 1980, 125,000 Cuban boat people fled to South Florida. Mr. Castro outraged many Americans by allowing criminals and the mentally ill to join the exodus.

The last president to make a serious effort to establish normal relations with Cuba was President Carter; he gave up the effort after less than a year. The two countries have not had discussions on political issues since 1982.

With the collapse of the Soviet Union in 1991, the focus of Washington’s complaints has shifted from Cold War concerns to the absence of freedom in Cuba and its treatment of dissidents.

When Cuban authorities arrested 75 regime opponents and sentenced them to lengthy prison terms in March of 2003, the Bush administration’s response was predictably harsh. Cuba accused the dissidents of engaging in subversive activities at America’s behest.

Washington insists that there can be no normal relations until Cuba releases political prisoners and takes credible steps toward establishing democratic rule.

Mr. Bush said in May 2002: “The goal of the United States policy toward Cuba is not a permanent embargo on Cuba’s economy. The goal is freedom for Cuba’s people.”

Today from Africa, Mr. Bush struck up the same theme, noting that he had met with the families of some of prisoners, and that their release should be the first step of any transition to democracy. “It just breaks your heart to realize that people have been thrown in prisons because they dare speak out,” he said.

Mr. Castro has expressed belief that his revolution will survive him. The administration sees the Cuban people as starved for freedom and is trying to hasten a transition to democracy. It has been assisting non-governmental groups in Cuba to achieve that goal. To reduce Mr. Castro’s access to dollars, it has sharply restricted travel by Americans to Cuba.

Only rarely during Mr. Castro’s rule did America and Cuba find common ground. One such occasion was the Elian Gonzalez affair between 1999 and 2000.

When the Clinton administration allowed the shipwreck survivor, age 7, to be returned to Cuba over the objection of Cuban-American relatives in South Florida, Mr. Castro expressed gratitude to the Clinton administration — but made clear his appreciation was only temporary.

“Tomorrow the struggle continues,” Mr. Castro said.