Chad has completed a withdrawal of its entire contingent of soldiers from the Central African Republic (CAR) in the wake of accusations its troops waged an unprovoked attack in a market last month.
The pullout of more than 800 soldiers on Wednesday came despite French appeals for Chad to reverse its decision.
"The last soldier crossed the border on April 13," Souleyman Adam, head of the Chadian peacekeeping unit, said at a ceremony in the southern town of Sarh, about 100km from the frontier.
Chad's troops had made up a key contingent of the African peacekeeping force MISCA which is struggling to restore security in the CAR.
Chadian President Idriss Deby Itno had ordered the pullout after the United Nations said his country's troops had opened fire in a crowded market in the capital Bangui on March 29 in an attack that left about 30 people dead.
The UN Human Rights Commission said an investigation had found that the troops fired "without any provocation", claims branded defamatory by Chad.
They [the Chadian soldiers] left with all their kit without waiting to be relieved
The Chadian troops have faced repeated accusations of siding with Muslims in Central Africa's conflict, a charge they deny.
At Wednesday's ceremony, Prime Minister Pahimi Deubet Kalzeube chastised those he said were seeking to "tarnish the image of our valiant defence and security forces".
A total of 833 Chadian soldiers have returned home after a mission that left 15 of their comrades dead.
MISCA officers confirmed on Tuesday that Chad had competed its withdrawal and the AU mission and soldiers from a French intervention force had replaced them.
"They left with all their kit without waiting to be relieved," said a MISCA commander whose Congolese troops had replaced the Chadians in the towns of Kabo and Batangafo.
Thousands of people have been killed and many more have fled in waves of bloodshed that have gripped the CAR since a coup in March last year.
About 8,000 foreign troops - 2,000 from former colonial power France and most of the rest from the African MISCA force - are trying to disarm rival militias after a year of brutal Christian-Muslim violence.