Most people in the crowd had no idea what Mr. Castro planned for Cuba. A master of image and myth, Mr. Castro believed himself to be the messiah of his fatherland, an indispensable force with authority from on high to control Cuba and its people.

He wielded power like a tyrant, controlling every aspect of the island’s existence. He was Cuba’s “Máximo Lider.” From atop a Cuban Army tank, he directed his country’s defense at the Bay of Pigs. Countless details fell to him, from selecting the color of uniforms that Cuban soldiers wore in Angola to overseeing a program to produce a superbreed of milk cows. He personally set the goals for sugar harvests. He personally sent countless men to prison.

But it was more than repression and fear that kept him and his totalitarian government in power for so long. He had both admirers and detractors in Cuba and around the world. Some saw him as a ruthless despot who trampled rights and freedoms; many others hailed him as the crowds did that first night, as a revolutionary hero for the ages.

Even when he fell ill and was hospitalized with diverticulitis in the summer of 2006, giving up most of his powers for the first time, Mr. Castro tried to dictate the details of his own medical care and orchestrate the continuation of his Communist revolution, engaging a plan as old as the revolution itself.

By handing power to his brother, Mr. Castro once more raised the ire of his enemies in Washington. United States officials condemned the transition, saying it prolonged a dictatorship and again denied the long-suffering Cuban people a chance to control their own lives.

But in December 2014, President Obama used his executive powers to dial down the decades of antagonism between Washington and Havana by moving to exchange prisoners and normalize diplomatic relations between the two countries, a deal worked out with the help of Pope Francis and after 18 months of secret talks between representatives of both governments.