Deby officially won 61 per cent of the May 6 vote international NGOs said was neither credible nor free, and which his main rival called a “masquerade”.
He was proclaimed transitional president in April 2021 by a junta of 15 generals after his father, iron-fisted president Idriss Deby Itno, was shot dead by rebels after 30 years in power.
The swearing-in marks the end of three years of military rule in a country crucial for the fight against jihadism across Africa’s restive Sahel region.
In 2021, Deby was quickly endorsed by an international community led by France, whose forces in recent years have been ousted by military regimes in its other former colonies Mali, Burkina Faso and Niger.
The investiture ceremony also officialises what the opposition has denounced as a Deby dynasty.
Prime Minister Succes Masra, one of Deby’s fiercest opponents before becoming prime minister, handed in his resignation Wednesday in the wake of his party’s election defeat after just four months in office.
Masra, an economist who won 18.5 per cent of the vote, has contested the results.
He claimed victory after the first round of voting but faced accusations of being a junta stooge by the opposition, which has been violently repressed in Chad, with its top members barred from the election.
After Chad’s Constitutional Council rejected Masra’s bid to annul the result, he said there was “no other national legal recourse” and called on supporters to “remain mobilised” but “peaceful”.
Deby’s own cousin Yaya Dillo Djerou, who had emerged as the leading opposition candidate to the general, was shot and killed at point-blank range during an army assault on February 28, his party said.
The turnout of heads of state at the investiture should provide an idea of international support for the 40-year-old president.
French President Emmanuel Macron, who travelled to N’Djamena in 2021 to pay homage to the late Marshal Deby before his son and successor, is sending his minister for foreign trade and Francophonie, Franck Riester.
Chad, one of the poorest nations on Earth, is France’s last military foothold in the Sahel region, with 1,000 soldiers, and Macron was one of few leaders to congratulate Deby on his election.
Several Sahel nations, reeling from jihadist insurgencies, have strengthened ties with Russia after severing them with Paris.
Russian President Vladimir Putin was among the first to congratulate Deby, and the level of the delegation Moscow sends to N’Djamena for the ceremony will be closely watched by analysts.