Fidel and Raúl Castro were scruffy young guerrillas in 1959, when they descended from Cuba's eastern mountains, seized power, and never relinquished it.
As they aged into their 80s and 90s, the Castros and their fellow fighters cast a shadow so deep that Cubans born in the first decades after the revolution became known as Cuba's "lost generation," men and women who spent their lives executing the orders of graying revolutionaries.
Next week, Raúl Castro will step down as president after a decade in office, handing the position to a successor widely expected to be Vice President Miguel Díaz-Canel. The April 19 handoff is the centerpiece of a broader transition to a group of leaders from the lost generation, who face an unprecedented test of their ability to guide a nation that has followed the same "commandantes" for 60 years.
Despite a series of reforms under Mr. Castro, Cuba remains locked in grinding economic stagnation that has driven hundreds of thousands of Cubans to emigrate in search of better lives. Change will require potentially painful reforms, like the elimination of a dual-currency system that has created damaging economic distortions.
"A great number of this country's young people will be watching to see if they're capable of changing things, of offering something new, of going beyond what's seemed like a great grayness until now," said Yassel Padron Kunakbaeva, a blogger who writes frequently from what he describes as a Marxist, revolutionary perspective.
The world should expect no immediate radical change from a single-party system dedicated to stability above all else. Raúl Castro will remain first secretary of the Communist Party, described by the Cuban constitution as the country's "highest guiding force." Castro has said nothing publicly about how he will use that position. But Cuban leaders have been making clear that a generational handover is underway.
On Feb. 24, Castro awarded one of Cuba's highest honors, the title Hero of Labor, to fellow guerrillas José Ramón Machado Ventura, a vice president and second secretary of the Communist Party, as well as vice president Ramiro Valdés, and former rebel leader and vice president Guillermo García Frías. For many Cubans, the elaborate ceremony in the soaring, newly reopened neoclassical Capitol building had a valedictory tone, a sign that the powerful Mr. Valdés and Mr. Machado Ventura will have far less important roles in Mr. Díaz-Canel's administration. While the inner workings of the Cuban government are opaque, both men were widely perceived as conservatives slowing reform.
"We're practically already in that future that's been talked about so much, that a moment of transition had to arrive," Machado Ventura told state television in March. "Now it's generational. It has to materialize, has to be that way."
Along with Díaz-Canel, a group of middle-aged leaders are being closely watched as candidates for more powerful positions. They include Foreign Minister Bruno Rodrguez, Havana party leader Mercedes López Acea, economic reform czar Marino Murillo, and Lázaro Expósito, party head in Cuba's second most-populated province, Santiago.
Behind the scenes, Raul Castro's son, Alejandro, is a powerful figure in the Interior Ministry, who secretly negotiated the reopening of diplomatic relations with the US under President Barack Obama. Castro's former son-in-law, Gen. Luis Alberto Rodríguez López-Callejas runs the economic arm of Cuba's military, which controls a vast swathe of state-run businesses ranging from tourism to shipping.
Born in the years after the Cuban revolution, leaders from the lost generation lack the credentials of their revolutionary predecessors, who were adored by some, despised by others, but always recognized as figures of historical importance endowed with popular credibility among Cubans on the island by their actions on the battlefield. Díaz-Canel and his cohort of middle-aged leaders rose through the Communist Party bureaucracy thanks to their success in local governance.
"This government that we're choosing today will be a government that will owe its existence to the people," Díaz-Canel told state-run media after voting for members of the National Assembly in March. "The people will participate in the decisions that this government takes."
Whatever his style, the Cuba that Díaz-Canel will lead is radically different from the country that he knew as both a child and a younger adult.
For those growing up in pro-revolutionary families in the heyday of Soviet aid to Cuba, the socialist state was a paternalistic presence that provided modest but comfortable lives to virtually everyone on the island. Russian products filled the stores and Russian cartoons played on Cuban television.
"There was the sensation that we were living very happily, everyone mixed together, with no pressure to earn money in the marketplace," said Abelardo Mena, a fine art curator.
Mr. Mena remembers receiving three nearly free toys a year from the government, and never worrying about his parents putting enough food on the table. There were ample supplies of coffee, Russian television sets and wristwatches, and canned meat from Bulgaria.
Instead of defending their homeland, Díaz-Canel's generation fought overseas in wars waged by Cuban forces alongside Soviet allies in Angola and Nicaragua.
For those who disagreed with the communist system, times were harsh. The government organized public gatherings to "repudiate" those who spoke against the system or wanted to emigrate. Gays and even mild dissenters were sent to work camps and "hippies" were forced to cut their hair and hide their rock-and-roll records in album covers of more acceptable musicians.
Life changed dramatically after the fall of the Soviet Union, which nearly eliminated Cuba's exports and imports, and cut gross domestic product by more than 30 percent in a crisis known as the Special Period. There were blackouts, shortages, and questions about domestic and foreign policy.
"We realized we weren't saving much. We weren't ready for the Special Period. Cuba spent 15 years fighting wars in Africa. We gave a lot away for nothing," said Carlos Alberto Careaga, a parking attendant at Havana's Commodore Hotel.
Díaz-Canel's generation was marked by three waves of mass migration from Cuba. Some 125,000 fled in 1980 when Fidel Castro allowed free migration from the port of Mariel outside Havana. The Special Period saw tens of thousands more Cubans fleeing on homemade rafts. And Raúl Castro's elimination of mandatory exit permits for most Cubans saw hundreds of thousands other Cubans leave over the last decade.
As a result of the migratory waves, hundreds of thousands of Cubans in their 50s and 60s have regular contact with friends and relatives in other countries, a sharp distinction from Cuba's original revolutionaries.
That increased contact with the outside world is boosted by a broad set of changes implemented by Raul Castro that include the spread of cell phones and internet and a private sector that's come to employ nearly 600,000 Cubans.
Cuban officials did not respond to requests by The Associated Press for interviews with Díaz-Canel and other leaders expected to assume higher profiles when a new Cuban government is seated this month. In occasional public statements, Díaz-Canel has given indications of support for some of those changes and hostility toward others. But his most defining characteristic in recent years has been his low public profile. Many Cubans believe he's been trying to avoid the fate of men like former Vice President Carlos Lage and former Foreign Minister Felipe Pérez Roque, young stars who rose to prominence under Fidel Castro and were pushed out of power in the first years of Raul Castro's presidency.
"Díaz-Canel has spent years in a very uncomfortable position. No one of his generation has managed to get to the level he's at, and that creates a certain amount of tension," said Harold Cardenas, a pro-revolutionary blogger whose work has been supported by Díaz-Canel.
After years in the shadows, Díaz-Canel and his generation now must show they are able to lead a nation facing deep economic problems, a hostile US administration, dwindling ranks of regional allies, and increasing disenchantment among younger generations of Cubans. But just a week before a new president takes office, many Cubans are unconvinced leaders from the lost generation will be able to fix the problems they have inherited from the founders of communist Cuba.
"This generation hasn't been able to make any proposals of its own, and those who've shown initiative have paid a heavy price," said Armando Chaguaceda, a Cuban political scientist at the University of Guanajuato, Mexico. "It's a very gray generation, or so they'd have us believe."
This story was reported by The Associated Press.