This distrust came in part from the Chadian Armed Forces (FAT) incapacity to deal with the rebellion that was inflaming the Muslim north from when the rebel insurgent group FROLINAT had been formed in 1966.

Chad's former colonial power, France, had urged Tombalbaye to involve the military leadership in power, and the President did reserve a place in his party, the Chadian Progressive Party (PPT), for the army commander; but much more important and decisive in undermining his support among the military was, in 1973, to be the arrest of the Army Chief of Staff, General Félix Malloum, for an alleged coup plot (the so-called Black Sheep Plot).

It was in this atmosphere of tension that Tombalbaye proceeded to yet another purge in the army, hitting this time the gendarmerie, the twelve hundred strong military police; its head, Colonel Djimet, and his aide, Major Kotiga, were both arrested on April 2, 1975, for the escape of some FROLINAT prisoners.

The coup started before sunrise on April 13 when in Boraho, a locality 35 miles (56 km) from the capital, army units led by Lieutenant Dimtolaum left their base and moved towards N'Djamena, where they converged on the president's white-walled palace on the edge of the city.

In a later communique the coupists were to justify their actions, accusing Tombalbaye of having governed by dividing the tribes, and of having humiliated the army and treated it with contempt.