Rather than a rapid triumph over the Byzantines in North Africa, the Arab conquest in fact advanced at a snail’s pace over the course of many decades. In his biography of Justinian II, Peter Crawford reconstructs – as well as analyzes – the Arab conquest from multiple vantage points to highlight the operational and strategic push/pull of the conflict.
“More seriously, in Roman Lazica, a revolt broke out under the patricius Sergios, son of Barnoukios, which succeeded in handing the region over to the Arabs. Any seeming reticence from Leontios to meet the Umayyads in battle may have emboldened Abd al-Malik to target one of the empire’s overseas provinces: the Exarchate of Africa and its great bastion, Carthage.
“Such was the success of this Romano-Berber coalition in defeating Uqba and overturning much of his gains that the Liber Pontificalis, likely echoing papal/imperial propaganda, proclaimed that by 685 ‘the entire province of Africa was again totally subjugated to the Roman Empire’.
“The Exarchate of Africa was in dire straits, undermined by years of incessant Arab raids and drained through heavy tribute paid to both Damascus and Constantinople. Its brief successes were also reliant on Arab distraction and military aid from elsewhere. The Roman forces that had staged the raids on Cyrenaica and killed Zuhayr may well have been reinforcements from the central government, which could not be relied upon to always be around particularly once Justinian II had embarked on war with the Arabs, Bulgars and Slavs.
“Abd al-Malik sent up to 40,000 of his freed-up forces under Hasan b. al-Nu’man to re-establish the Arab position in Africa. With the biggest Arab army yet deployed to Africa, Hasan was to accomplish much more than that. His military achievements and administrative institutions were to create the first real Arab government in Africa, making him ‘in many ways, the real founder of Muslim North Africa’.
“As well as the battle for Carthage, Hasan also had to capture a series of forts along the north coast, such as Vaga and Hippo Regius. It could well be that there were other Roman held forts to the south of Carthage that Hasan either had to capture first or bypass en route to his showdown with John. This suggests that even with his expedition facing an existential threat in the face of a reinforced Hasan, John failed to bring together all of the forces available to him to defend Carthage.
*All excerpts have been taken from Justinian II: The Roman Emperor Who Lost His Nose and His Throne… and Regained Both!, Pen and Sword.