General Mahamat Idriss Deby Itno, 37, who on Tuesday was named transitional leader as head of a military council in Chad following the death of his father Idriss Déby Itno, has been named president.
The youthful general Mahamat Idriss Deby, who stood watch over his father as head of the presidential guard, wore trademark dark glasses that hid a strong, little known personality.
In the aftermath of the death of president Idriss Deby Itno, who ruled the Sahel country for three decades, his 37-year-old son has quickly emerged as the new strongman.
The four-star general was not on any expert's list of potential successors. The widespread belief was that the veteran warlord and president had not been overly concerned about grooming one.
But on Tuesday, Mahamat immediately took charge of a transitional military council, appointing 14 of the most trusted generals to run Chad until "free and democratic" elections promised in 18 months' time.
And on Wednesday, the presidency released a charter saying the young general would "occupy the functions of the president of the republic" and also serve as head of the armed forces.
- Opposition parties denounce "an institutional coup" -
Chad's main opposition parties on Wednesday denounced "an institutional coup" after Mahamat Idriss Déby took power following the death of his father Idriss Déby Itno.
Some thirty "political parties of the democratic opposition call for the establishment of a transition led by civilians (...) through an inclusive dialogue" in a statement.
Mahamat Idriss Déby, at the head of a Transitional Military Council (CMT), is "President of the Republic", "Supreme Chief of the Armed Forces" and holds almost all powers.
The opposition "calls on the Chadian population not to obey the illegal, illegitimate and irregular decisions taken by the CMT, in particular the transitional charter, the curfew and the closure of borders".
Among the signatories are the party of Saleh Kebzabo, Idriss Déby's "historic" opponent, and the group of Succès Masra, one of the most fierce critics of the former president's regime.
These parties also "warned" France, a former colonial power, which has supported the former head of state since his accession to power in 1990 at the head of a rebellion, "not to interfere in the internal affairs of Chad".
Finally, they call on the international community "to accompany the Chadian people in the restoration of the rule of law and democracy".
- All-powerful guard -
Commander in chief of the all-powerful red-bereted presidential guard or DGSSIE security service for state institutions, he carries the nickname "Kaka" or grandmother in Chadian Arabic, after his paternal grandmother who raised him.
"The man in dark glasses", as he is known in military circles, is said to be a discreet, quiet officer who looks after his men.
A career soldier just like his father, he is from the Zaghawa ethnic group which boasts numerous top officers in an army seen as one of the finest in the troubled Sahel region.
"He has always been at his father's side. He also led the DGSSIE. The army has gone for continuity in the system," Kelma Manatouma, a Chadian political science researcher at Paris-Nanterre University, told AFP.
However over recent months the unity of the Zaghawas has fractured and the president has removed several suspect officers, sources close to the palace said.
With a mother from the Sharan Goran ethnic group, he also married a Goran, Dahabaye Oumar Souny, a journalist at the presidential press service.
She is the daughter of a senior official who was close to former dictator Hissene Habre, ousted by Idriss Deby in December 1990.
The Zaghawa community thus look with some suspicion on Mahamat Deby, some regional experts say.
- 'Night of long knives -
"He is far too young and not especially liked by other officers," said Roland Marchal of the International Research Centre at Sciences Po university in Paris.
"There is bound to be a night of the long knives," Marchal predicted.
Raised in the capital N'Djamena, Mahamat Deby was sent to a military school in Aix-en-Provence, southern France, but stayed only a few months.
Back home in Chad, he returned to training at a military school in the capital and joined the presidential guard.
He rose quickly through the command structure from an armoured group to head of security at the presidential palace before taking over the whole DGSSIE structure.
Mahamat was acclaimed for his combat performance, notably after government forces emerged victorious in 2009 against rebels led by Deby's nephew Timan Erdimi.
Erdimi's forces had launched a rebellion in the east and reached the gates of the presidential palace a year earlier, before being pushed back with the help of intervention by former colonial power France.
He finally moved out of the shadow of his brother Abdelkerim Idriss Deby, deputy director of the presidential office, when he was appointed deputy chief of the Chadian army deployed to Mali in 2013.
That mission saw Mahamat Deby work closely with French troops in operation Serval against jihadists in 2013-14.