Or so the guerrillas thought. In fact, the gravelly voice that sounded so full of authority belonged not to a grizzled leader of Latin America’s most feared insurgent group, the Revolutionary Armed Forces of Colombia, or FARC, but rather to a government officer.

The fighters had been duped. With the help of satellite telephone intercepts and a spy who infiltrated the FARC’s upper echelons, the Colombian military had managed to plan and execute an operation that ended a long-running international hostage saga and upended Colombia’s four-decade civil war.

The voice was simply the most dramatic touch in a daring rescue that exploited the recent disarray within the FARC. The insurgency has now lost many of its top leaders and its most prized hostage: Ingrid Betancourt, the French-Colombian politician whose captivity since 2002 has attracted attention worldwide. Its founder, Manuel Marulanda, has died; security forces killed its second-in-command, Raúl Reyes, in March; and some 3,000 combatants have deserted in the last year.

The rescue, described by commanders of the Colombian Army and officials in Washington and Bogotá, was almost exclusively a Colombian operation that highlighted the growth of a military that has benefited from $5.4 billion in aid from the US since 2000. And while many here and in Washington stressed that the FARC remained a powerful force of several thousand fighters, earning around $200 million a year from drug trafficking, some analysts suggested that the raid combined with continued pressure might push the rebels to negotiate for peace.

The rescue alone could reverberate across the region. Hugo Chávez, the leftist leader of Venezuela who negotiated previous releases of hostages held by the FARC but failed to free Betancourt or three American contractors also rescued on Wednesday, has lost the regional spotlight to Colombia’s president, Álvaro Uribe, his top rival and a staunch ally of the Bush administration.

But for the FARC, the game has changed. The gritty leftist insurgency, which has survived for decades in the jungles of this Andean country and provided military cover to the world’s most productive coca growers, fell prey to an elaborate ruse that Colombia’s defense minister, Juan Manuel Santos, likened to a Hollywood script.

Betancourt, who was reunited on Thursday with her family, also said the raid seemed almost too fantastic to be true. It became real only when she saw Cesar, her captor, become a captive.

“Suddenly, I saw the commander who, during four years, had been at the head of our team, who so many times was so cruel and humiliated me,” she said. “And I saw him on the floor, naked with bound eyes.”

No other rebel movement is as well known in South America as the FARC, nor as widely reviled.

“The FARC and the paramilitaries in the mid-90s both had shots in the arm from the drug business,” said Bruce M Bagley, chairman of the International Studies Department at the University of Miami.

A turning point came in 2000 when Congress and President Bill Clinton agreed to send Colombia more than $1 billion to emergency aid to battle drug traffickers and their allies. President Andres Pastrana later broke off negotiations with the FARC, deciding instead to fight.

But the FARC would not be cowed. In 2002 it seized Betancourt, a Colombian senator who was campaigning, somewhat quixotically, for president on a platform of fighting corruption.

Meanwhile, the ordeal of Betancourt, the daughter of a diplomat and a beauty queen, pushed Colombia’s conflict to the front pages of Europe’s largest newspapers. Her two children living in Paris rallied support even as she slowly deteriorated.

In letters and interviews since her release, she has described a routine of cruelty that left her at many points without the will to live. Her captors chained her and others by the neck to trees. She rarely changed her clothes. Tropical diseases, long marches through the mountains and a lack of nutritious food eventually shriveled her to a thin post with stringy hair reaching her waist.

“It was not treatment that you can give to a living being,” Betancourt told France 2 television on Thursday.