The Battle of Nineveh was the climactic battle of the Byzantine-Sassanid War of 602–628. The Byzantine victory broke the power of the Sassanid dynasty and for a period of time restored the empire to its ancient boundaries in the Middle East. This resurgence of power and prestige was not to last, however, as within a matter of decades an Islamic Caliphate emerged from the Arabian desert and once again brought the empire to the brink of destruction.

Prelude

When Emperor Maurice was murdered by the usurper Phocas, Khosrau II declared war, ostensibly to avenge his benefactor's death. While the Persians proved largely successful during the first stages of the war, conquering much of the Levant, Egypt, and even parts of Anatolia, the ascendancy of Heraclius eventually led to the Persians' demise. Heraclius' campaigns altered the balance, forcing the Persians on the defensive and allowing for the Byzantines to regain momentum. Allied with the Avars, the Persians attempted to take Constantinople, but were defeated there.

While the Siege of Constantinople was taking place, Heraclius allied with what Byzantine sources called the Khazars under Ziebel, who are identified with the Western Turkic Khaganate of the Göktürks led by Tong Yabghu. plying him with wondrous gifts and a promise of the reward of the porphyrogenita Eudoxia Epiphania. The Caucasus based Turks responded by sending 40,000 of their men to ravage the Persian empire in 626 to start the Third Perso-Turkic War. Joint Byzantine and Göktürks operations were focused on besieging Tiflis.

Invasion of Mesopotamia

In mid-September 627, leaving Ziebel to continue the siege of Tiflis, Heraclius invaded the Persian heartland, this time with between 25,000 and 50,000 troops and 40,000 Göktürks. The Göktürks, however, quickly deserted him because of the strange winter conditions. Heraclius was tailed by Rhahzadh's army of 12,000, but managed to evade Rhahzadh and invaded the heartland of Persia, in Iraq. Heraclius acquired resources from the countryside, which meant the following Rhahzadh had trouble acquiring provisions. This resulted in harm to Rhahzadh's animals.

Manoeuvres before and after the Battle of Nineveh

On 1 December, Heraclius crossed the Great Zab River and camped near Nineveh. This was a movement from south to north, contrary to the expectation of a southward advance. However, this can be seen as a way to avoid being trapped by the Persian army in case of a defeat. Rhahzadh approached Nineveh from a different position. News that 3,000 Persian reinforcements were approaching reached Heraclius, forcing him to act. He gave the appearance of retreating from Persia by crossing the Tigris.

Field

Heraclius had found a plain west of the Great Zab some distance from the ruins of Nineveh. This allowed the Byzantines to take advantage of their advantage in lances and hand-to-hand combat. Furthermore, the fog reduced the Persian advantage in missile troops and allowing the Byzantines to charge great losses from missile barrages. Walter Kaegi believes that this battle took place near the Karamlays Creek.

The battle

Rhahzadh deployed his forces into three masses and attacked. Heraclius feigned retreat to lead the Persians to the plains before reversing his troops to the surprise of the Persians. After eight hours of fighting, the Persians suddenly retreated to nearby foothills, but it was not a rout. 6,000 Persians fell.

Nikephoros' Brief History mentions that Rhahzadh challenged Heraclius to personal combat. Heraclius accepted and killed Rhahzadh in a single thrust; two other challengers fought and also lost. But either way, Rhahzadh died sometime in the battle.

The 3,000 Persian reinforcements arrived too late and likely joined with the remnants of Rhahzadh's force.

Aftermath

Cherub and Heraclius receiving the submission of Khosrau II; plaque from a cross (Champlevé enamel over gilt copper, 1160-1170, Paris, Louvre).

The victory at Nineveh was not total as the Byzantines couldn't even seize the Persian camp. However, this marginal victory was enough to shatter the resistance of the Persians.

With no Persian army left to oppose him, Heraclius' victorious army plundered Dastagird, which was a palace of Khosrau's, and gained tremendous riches while recovering 300 captured Byzantine flags. Khosrau had already fled to the mountains of Susiana to try to rally support for the defence of Ctesiphon. Heraclius could not attack Ctesiphon itself because the Nahrawan Canal was blocked due to the collapse of a bridge leading over it.

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 slowly 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 most importantly for them, the True Cross and other relics that were lost in Jerusalem in 614.

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