Due to the overwhelming crisis facing the Empire that had pitched it into chaos, Heraclius the Younger now attempted to seize power from Phocas in an effort to better Byzantium's fortunes. As the Empire was led into anarchy, the Exarchate of Carthage remained relatively out of reach of Persian conquest. Far from the incompetent Imperial authority of the time, Heraclius, the Exarch of Carthage, with his brother Gregorius, began building up his forces to assault Constantinople.

After cutting off the grain supply to the capital from his territory, Heraclius led a substantial army and a fleet in 608 to restore order in the Empire. Heraclius gave the command of the army to Gregorius' son, Nicetas, whilst command of the fleet went to Heraclius' son, Heraclius the Younger. Nicetas took part of the fleet and his forces to Egypt, seizing Alexandria towards the end of 608. Meanwhile, Heraclius the Younger headed to Thessalonica, from where, after receiving more supplies and troops, he sailed for Constantinople. He reached his destination on 3 October 610, where he was unopposed as he landed off the shores of Constantinople, citizens greeting him as their deliverer.

The reign of Phocas officially ended in his execution and the crowning of Heraclius by the Patriarch of Constantinople two days later on 5 October. A statue of Phocas that rested in the Hippodrome was pulled down and set aflame, along with the colors of the Blues that supported Phocas.