Heraclius arrives by ship from Africa at Constantinople, overthrows Byzantine Emperor Phocas and becomes Emperor.

Africa Proconsularis was a Roman province on the northern African coast that was established in 146 BC following the defeat of Carthage in the Third Punic War. It roughly comprised the territory of present-day Tunisia, the northeast of Algeria, and the coast of western Libya along the Gulf of Sirte. The territory was originally inhabited by Berber people, known in Latin as Mauri indigenous to all of North Africa west of Egypt; in the 9th century BC, Phoenicians built settlements along the Mediterranean Sea to facilitate shipping, of which Carthage rose to dominance in the 8th century BC until its conquest by the Roman Republic.

It was one of the wealthiest provinces in the western part of the Roman Empire, second only to Italia. Apart from the city of Carthage, other large settlements in the province were Hadrumetum (modern Sousse, Tunisia), capital of Byzacena, and Hippo Regius (modern Annaba, Algeria).

Heraclius (Greek: Ἡράκλειος Herakleios; c. 575 – 11 February 641), sometimes called Heraclius I, was the Byzantine emperor from 610 to 641. His rise to power began in 608, when he and his father, Heraclius the Elder, the exarch of Africa, led a revolt against the unpopular usurper Phocas.

Heraclius's reign was marked by several military campaigns. The year Heraclius came to power, the empire was threatened on multiple frontiers. Heraclius immediately took charge of the Byzantine–Sasanian War of 602–628. The first battles of the campaign ended in defeat for the Byzantines; the Persian army fought their way to the Bosphorus but Constantinople was protected by impenetrable walls and a strong navy, and Heraclius was able to avoid total defeat. Soon after, he initiated reforms to rebuild and strengthen the military. Heraclius drove the Persians out of Asia Minor and pushed deep into their territory, defeating them decisively in 627 at the Battle of Nineveh. The Persian king Khosrow II was overthrown and executed by his son Kavad II, who soon sued for a peace treaty, agreeing to withdraw from all occupied territory. This way peaceful relations were restored to the two deeply strained empires.

However, Heraclius soon lost many of his newly regained lands to the Rashidun Caliphate. Emerging from the Arabian Peninsula, the Muslims quickly conquered the Sasanian Empire. In 636, the Muslims marched into Roman Syria, defeating Heraclius's brother Theodore. Within a short period of time, the Arabs conquered Mesopotamia, Armenia and Egypt. Heraclius responded with reforms which allowed his successors to combat the Arabs and avoid total destruction.

Heraclius entered diplomatic relations with the Croats and Serbs in the Balkans. He tried to repair the schism in the Christian church in regard to the Monophysites, by promoting a compromise doctrine called Monothelitism. The Church of the East (commonly called Nestorian) was also involved in the process. Eventually this project of unity was rejected by all sides of the dispute.