Chad President Idriss Dévi died of his injury after clashing with rebels in the northern part of the country over the weekend, the military said.
It was announced the day after the results of the interim election predicted that he would win his sixth term.
The government and parliament have dissolved. A curfew was also imposed and the border was closed.
Debbie, 68, has been in power for over 30 years and was one of Africa’s longest-serving leaders.
A trained army officer, he came to power through an armed uprising in 1990. He was a longtime ally of France and other Western nations in the fight against jihadist groups in the Sahel region of Africa.
Debbie told state television on Tuesday that he “revived the last breath of defending a sovereign state on the battlefield.”
Over the weekend, he went to the front line, hundreds of kilometers north of the capital N’Djamena, to visit an army fighting rebels in a group called Fact (the front line of Chad’s change and Concord).
The state funeral is scheduled to take place on Friday.
The military council, led by Debbie’s son, a 37-year-old four-star general, will rule for the next 18 months.
The military said in a statement that Mahamato Idris Devi Itono, who will lead the council, will have a “free and democratic” election at the end of the transition period.
He later issued a statement nominating 14 other generals to form the new governing body.
A BBC Monitoring journalist tweeted a copy of the notification.
Experts told the BBC and other broadcasters that the move was unconstitutional and should be taken over by the chairman of Congress if the incumbent president dies before organizing the election.
Prior to the April 11 elections, Debbie campaigned on a platform to bring peace and security to the region. Provisional results showed that he had 80% of the votes.
However, there was growing misery about his government’s control of Chad’s oil resources.
Death leaving a vacuum
Idriss Dévi was known for its rarity-the true warrior president. The former rebel-trained pilot was the opposition of the armchair general.
For thirty years he came to power in Chad. Chad is a vast country that straddles the Sahara Desert and is surrounded by the longest conflicts on the continent.
And Debbie was involved in everything from Darfur to Libya, Mali, Nigeria and the Central African Republic. His army was one of the most combat-enhanced units on the planet.
At home, he was becoming an increasingly dictatorial figure. With his recent election victory, he claimed nearly 80% of the votes.
It is unclear if the poor, feud, and fragile state he left behind can manage a smooth transition.
And there are broader concerns. For many years, President Devi was an integral western ally in the war against Islamic extremists, including Mali and Niger.
His death leaves a void that many may now fight to fill.
In a statement, the French president described Mr Debbie as a “brave friend” and said he confirmed Chad’s attachment to stability. Over the years, France has deployed troops and fighters to push Debbie’s enemies back.
The Chad army is considered to be the most effective of the Western-backed “G5” countries fighting Islamic extremists in the Sahel region.
Also, regions, including Libya, Sudan, and the Central African Republic, are often proven to be more stable, with armed groups roaming freely and trading conflict-promoting weapons and lucrative resources. , Says BBC Catherine Byarhanga.
A rebel faction group founded in 2016 by a disillusioned former Army officer has accused President Devi of cracking down on elections.
They built a base in Libya in the Tibesti Mountains, which straddles northern Chad and parts of southern Libya.
On election day, the group launched an attack on the border post and gradually advanced to N’Djamena.
The latest clash began on Saturday. The military says that 300 armed groups were killed and 150 were captured. It says five government soldiers were killed and 36 were injured. The numbers could not be confirmed immediately.
Some foreign embassies in the capital urged their staff to leave.
A former BBC journalist in N’Djamena said the situation there seemed relatively calm.
“The news is pervasive, but the city is calm and many people didn’t know him, so people were shocked to hear it. [President Déby] I was injured or I was at the forefront. “
“On the streets of downtown, there are armored cars at the junctions of the main roads. Of course, there is a sense of’what will happen’, but nothing more.”
N’Djamena had previously been attacked by rebels, and parents took their children home from school when a panic occurred in the city on Monday and tanks were deployed along the main road.
5 things about Chad:
1) Named after Lake Chad. This is Africa’s second largest lake, but it has shrunk 90% since the 1960s. The basin covers parts of Nigeria, Niger, Chad and Cameroon and is a source of water for 20 to 30 million people.
2) The Sahara Desert covers about one-third of the country. Most of the north is desert and is home to only 1% of Chad’s population. In the south, there are wooded savanna and forest areas.
3) In 2001, a 7 million-year-old human-like creature called “Tokai”, that is, the body of an ape, was excavated. The discoverers claimed that Tokai was the oldest known ape in science.
4) Chad became an oil-producing country in 2003, completing a $ 4 billion (£ 2.87 billion) pipeline connecting the oil field to the Atlantic terminal. The industry has been plagued by allegations of corruption.
5) Agriculture is the main livelihood for most people. Cotton is cultivated in the South and exported to Europe and the United States.