The Arabs had seized Cyrenaica and the eastern half of Tripolitania, along with Tripoli, in 642–643, their westward expansion halted only by an order from Caliph Umar.

In 647, however, Umar's successor Uthman orders Abdallah ibn Sa'ad to invade the Exarchate with twenty thousand men.

The Muslims invade western Tripolitania and advance up to the northern boundary of the imperial province of Byzacena.

Gregory confronts the Arabs on their return at Sufetula, but is defeated and killed.

Agapius of Hierapolis and some Syriac sources claim that he survived the defeat and fled to Constantinople, where he was reconciled with Constans, but most modern scholars accept the Arab chroniclers' account of his death in battle.

The Arab accounts also claim that the Muslims captured Gregory's daughter, who had fought at her father's side.

She was carried along back to Egypt as part of the booty, but she fell from her camel on the march and was killed.

After Gregory's death, the Arabs sack Sufetula and raid across the Exarchate, while the imperial forces withdraw to their fortresses.

Unable to storm the well-defended fortifications, and satisfied with the huge amounts of plunder they had made, the Arabs agree to depart in exchange for the payment of a heavy tribute in gold.

Despite the fact that the Arab raid is not followed up for some time, and the restoration of ties with Constantinople, imperial rule over Africa is shaken to its roots by Gregory's rebellion and the Arab victory.

The Berber tribes in particular shake off their allegiance to the Empire, and most of southern Tunisia seems to have slipped outside the control of Carthage.