The Battle of Nineveh was the climactic battle of the Byzantine-Sassanid War of 602–628. The Byzantine victory later resulted in civil war in Persia, and for a period of time, restored the Roman Empire to its ancient boundaries in the Middle East. This resurgence of power and prestige was not to last, as after a few years, an Arab Caliphate emerged from Arabia and once again brought the empire to the brink of destruction.
The victory at Nineveh was not total: the Byzantines were unable to capture the Persian camp. However, this victory was significant enough to shatter the resistance of the Persians.
With no Persian army left to oppose him, Heraclius’ victorious army plundered Dastagird, Khosrau’s palace, and gained tremendous riches. Khosrau had already fled to the mountains of Susiana to try to rally support for the defense of Ctesiphon. Heraclius could not attack Ctesiphon itself because the Nahrawan Canal was blocked by the collapse of a bridge.
The Persian army rebelled and overthrew Khosrau II, raising his son Kavadh II, also known as Siroes, in his stead. Khosrau perished in a dungeon after suffering for five days on bare sustenance—he was shot to death with arrows on the fifth day. Kavadh immediately sent peace offers to Heraclius. Heraclius did not impose harsh terms, knowing that his own empire was also near exhaustion. Under the peace treaty, the Byzantines regained all their lost territories, their captured soldiers, a war indemnity, and of great spiritual significance, the True Cross and other relics that were lost in Jerusalem in 614. The battle marked the end of the Roman-Persian Wars.