Where have Chad rebels prepared for their own war? In Libya.

NAIROBI, Kenya – The rebels have done an amazing job. Barely a week after their armed convoy swept through the desert to northern Chad, they started a battle that claimed the biggest scalp of all on Monday: Idriss Déby, Chad’s iron-fisted president of three decades, killed on the battlefield when a grenade exploded in near his vehicle, according to a senior assistant.

On Wednesday, a day after his death was announced, a sense of concern and disbelief echoed through the capital, Ndjamena, where the military formally installed Mr Déby’s 37-year-old son, Mahamat Idriss Déby, as interim president. Rumors of an upcoming rebel attack on the city spread through the streets.

But the secret to the rebels’ striking success so far lay behind them, across Chad’s northern border in Libya, where they spent years fighting as soldiers of fortune, amassing weapons, money and battlefield experience, according to researchers from the United States. Nations, regional experts. and Chadian officials. In fact, the rebels used Libya’s chaotic war to prepare for their own campaign in Chad.

Until recently, they were employed by Khalifa Hifter, a powerful Libyan commander once defended by President Donald J. Trump. They fought with weapons supplied by the United Arab Emirates, one of Mr. Hifter.

And they were stationed last year at a sprawling Libyan military air base alongside mercenaries from the Wagner Group, the Kremlin-backed private company believed to have spearheaded Russia’s covert efforts to spread its military influence across Africa.

Experts say the unexpected coup by the Chadian rebels is a clear example of how Libya’s decade-old power vacuum, starting with the expulsion of dictator Colonel Muammar el-Qaddafi in 2011, has hatched a string of mercenaries and other armed groups. , some of which are now spreading chaos in the region.

“The civil war in Libya has created an environment where armed groups, not just from Chad but from all over, can thrive and find sponsors and allies,” said Nathaniel Powell, a research associate at the Center for War and Diplomacy at Lancaster University in Great Britain. Britain, and the author of “France’s Wars in Chad.”

Uncertainty has gripped Chad since Mr. Déby’s death, casting doubt on the stability of a nation considered by the United States and France to be a cornerstone of their efforts to overcome the Islamist militancy that has spread across West and Central Africa. spreads, to counteract it.

In a statement on Wednesday, the rebels, who bear the name Front for Change and Concord in Chad (FACT, from the French acronym), threatened to march to Ndjamena this weekend, following Mr Déby’s funeral scheduled for Friday.

Whether the rebels can live up to this threat is unclear. They suffered heavy casualties early this week – Chad’s army claimed to have killed 300 rebels – and foreign military officials are unsure how far the rebels are from the capital.

Still, the Chadian army strengthened defenses around the presidential palace on Wednesday, where officials denied persistent rumors that Mr Déby’s successor, his son Mahamat, had also been killed or injured.

“If he’s shot or dead, it means he’s a good actor because he’s very much alive,” said Acheikh Ibn-Oumar, a senior presidential adviser who said he was speaking from the palace.

There are still questions about the circumstances surrounding the elder Mr. Déby’s death and whether he was actually murdered by a rival. But Mr. Ibn-Oumar, echoing statements made by military leaders, insisted that the president be killed when a rebel grenade detonated near his vehicle near Nokou, 270 miles north of Ndjamena.

Mr. Déby was murdered the day he won his sixth election, marred by irregularities. Western countries had largely overlooked his dismal record of corruption and violations of rights, as he was a bulwark against the emerging wave of Islamist militancy in the Sahel, a barren strip of the Sahara that spans six African countries.

France has had a military presence in Ndjamena since 1986, and the Sahel-based anti-terrorism operation known as Operation Barkhane has been headquartered in Chad’s capital since its launch in 2014. France says at least 1,000 of its soldiers are currently stationed in Chad. .

But the rebels seeking to overthrow Mr. Déby represented a string of local grievances against the ironclad, 31-year rule of an old-fashioned African strongman accused by critics of squandering Chad’s considerable oil revenues, making it one of was the poorest countries in the world. .

Since the 1990s, a slew of rebel groups, many of which are defined by ethnic identity, have tried to overthrow him. Some were based in the Darfur region of Western Sudan, where they received funding and weapons from Sudanese dictator Omar Hassan al-Bashir.

After Mr al-Bashir and Mr Deby signed a peace deal in 2010 and agreed to stop supporting rebels who fought against each other’s governments, the Chadian rebels were forced to leave Sudan. A year later they found a new base in Libya.

In the chaos that followed Colonel Qaddafi’s impeachment and death in 2011, rival Libyan factions hired African mercenaries to fight alongside their own forces. The Chadians, who have a reputation as stubborn desert hunters, were in high demand.

Some Chadians even switched sides, if the price was right.

The FACT began with a Libyan faction in the central city of Misurata, a United Nations official who has spoken with the group’s leaders but was not authorized to speak to the media said. But by 2019, they had switched their support to a rival faction, led by Mr. Hifter, who had launched a campaign to capture the capital, Tripoli.

The Chadians are by no means the best-known foreign mercenaries in Libya. Much more attention has been paid to the Russian and Syrian fighters who played a key role in Mr Hifter’s pressure on Tripoli.

But the money, weapons and experience gathered by African mercenaries, mostly from Chad and Sudan, are now used in other countries.

A UN report published in February noted that FACT fighters were stationed at a large military air base in Al Jufra, in central Libya – an airfield that is also a hub for Russian Wagner group mercenaries, and that received cargo flights with weapons from the United Arab Emirates, the report notes.

The UN also noted that a plane owned by Erik Prince, the former Blackwater owner who staged an ill-fated $ 80 million mercenary operation for Mr. Hifter, had been photographed at Jufra Air Force Base.

Following the collapse of Mr Hifter’s attack on Tripoli last year, the warring factions in Libya signed a truce in October that largely lasted.

When the fighting in Libya was over, the Chadian fighters returned home for the revolt they launched against Mr. Déby on April 11. They may have brought some of the advanced weapons from Libya, said Cameron Hudson, a former State Department official. the Atlantic Council, an investigative body in Washington.

He said the Chadians appeared to be traveling in the same kind of armored vehicles that the Emirates donated to Mr. Hifter.

The UN official said that even at the height of the Libyan war, the rebels had always intended to return to Chad.

“That’s their real interest,” he said. “They were talking about collecting as many weapons as possible and going back to Chad.”

Mahamat Adamou contributed from Ndjamena, Chad, and Elian Peltier from London.