The Byzantine–Sasanian War of 602–628 AD and the Rise of the Muslims

The Byzantines and Sasanians were rival powers who fought each other for supremacy in the Middle East. Although the conflict between the two powers began during the 6th century AD, it is in fact a continuation of a much longer rivalry which was started by their predecessors during the 1st century BC. The Byzantine–Sasanian War of 602–628 AD is considered to be the most devastating of the wars fought between the two powers. Moreover, it is also the final conflict between them, as the Sasanian Empire was completely conquered by the Muslims shortly after the war concluded. The Byzantine Empire was also severely weakened and exhausted by the war, which contributed to the loss of much of their land to the Islamic Rashidun Caliphate. Nevertheless, the Byzantines, unlike its Persian rivals, were not entirely destroyed by the Muslims, and the two were engaged in a series of wars that lasted till the 11th century.

The Byzantine and Sasanian Empires in 600 AD, two years before the outbreak of the final Byzantine-Sasanian war. (Getoryk / CC BY-SA 3.0)

The Conflict Began Long Before the Byzantine-Sasanian War

The conflict between the Byzantines and Sasanians over control of the Middle East was only the latest version of a rivalry that began in the 1st century BC. In 54 BC, when Rome was still a republic, the triumvir Marcus Licinius Crassus launched a military campaign against the Parthians, the predecessors of the Sasanians.

The campaign ended in disaster with the Romans suffering a great defeat at the Battle of Carrhae. According to the ancient historian Plutarch, 43,000 soldiers participated in Crassus’ campaign, of whom an estimated 20,000 were killed, and 10,000 captured. The Battle of Carrhae is thought to be the Roman Republic’s worst defeat since the Battle of Cannae in 216 BC.

As one of the triumvirs, Crassus’ death at the Battle of Carrhae upset the balance of power in Rome. This led to a civil war between Gnaeus Pompeius Magnus and Gaius Julius Caesar, the two remaining triumvirs. Although Caesar emerged victorious, he was assassinated in 44 BC, sparking another round of civil wars in the Roman Republic. At the end of all this, Octavian, Caesar’s heir, emerged victorious and became the first ruler of the Roman Empire.

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Whilst all this was going on in the Roman world, the Iranian world was ruled by the Parthians. Originally, Parthia was a satrapy in the Achaemenid Empire, and continued to be one during the subsequent Hellenistic period. Tradition claims that the first Parthian ruler and founder of the Parthian Empire was Arsaces I, who had been a satrap under Diodotus, a ruler of the Graeco-Bactrian Kingdom. Around 250 BC, Arsaces revolted against his overlord, fled westwards, and established his own kingdom. The successors of Arsaces continued the expansion of the Parthian Empire. By the latter half of the 2nd century BC, the Parthians were in control of the entire Iranian Plateau as well as the Tigris-Euphrates valley.

Map of the troop movements during the first two years of the Roman–Parthian War of 58–63 AD over the Kingdom of Armenia. (Cplakidas / CC BY-SA 3.0)

The Conflict Between the Parthians and Rome Continued

The Parthians first encountered the Romans at the beginning of the 1st century BC, the first treaty being concluded between the two powers in 92 BC. The campaign of Crassus against the Parthians, however, brought the two sides into conflict with each other. In the centuries that followed, the Romans and Parthians fought a series of wars against each other, though neither was able to completely subdue the other. At times, the Romans supported one claimant or the other to the Parthian thrones. At other times, the Romans invaded the Parthian Empire. The emperors Trajan and Septimius Severus for instance, managed to capture Parthian territory during their campaigns.

The Parthian Empire came to an end in 224 AD. The wars with the Romans weakened the Parthian Empire significantly. On top of that, the empire was also suffering from internal turmoil. The last ruler of the Parthian Empire was Artabanus IV, who came to power around 213 AD following a dynastic struggle with his brother, Vologases VI. In 216 AD, the Roman emperor Caracalla invaded Parthia, but Artabanus was able to check his advances, and a peace treaty was concluded. Nevertheless, the days of the Parthian Empire were numbered. In 224 AD, Artabanus was defeated and killed in battle near Firuzabad in ancient Iran.

The victors of this battle were the Persians, who were one of the subjects of the Parthian Empire. The Persians were led by a man named Ardashir I, the founder of the Sasanian Empire. Ardashir was a local ruler from the province of Pars and rose to power as the Parthian Empire was crumbling.

Ardashir I revolted against the Parthians, defeated and killed Artabanus, and established the Sasanian Empire. In the decades that followed, the Sasanians expanded their empire. During the reign of Shapur I, Ardashir’s immediate successor, the Sasanian Empire stretched from Iberia (in the Caucasus) and Sogdiana in the north to Mazun (on the Arabian Peninsula) in the south, and from the upper Tigris-Euphrates valley in the west to the Indus River in the east.

A coin issued by Khosrow II, the leader of the Sasanian Empire during the Byzantine-Sasanian war. (Classical Numismatic Group, Inc. / CC BY-SA 3.0)

The Sasanians Continued to Battle the Romans

The Sasanians inherited and continued the Parthians’ enmity with the Romans. Shapur, for instance, commemorated his victories over the Romans rock reliefs, one of which can be seen at Bishapur. On this relief, Shapur is depicted with three Romans emperors: Gordian III (trampled under Shapur’s horse), Philip the Arab (kneeling and begging for mercy), and Valerian (led by Shapur as a captive). In 298 AD however, a peace treaty was signed between the Romans and Sasanians. This period of peace lasted until the conversion of Constantine to Christianity. Constantine’s interference in the affairs of Christians living in the Sasanian Empire led to the souring of relations between the two powers.

A few years before the peace treaty was signed between the Romans and Sasanians, the administration of the Roman Empire was reorganized. The emperor, Diocletian divided the empire between four co-rulers, thereby instituting a system known as the Tetrarchy. This effectively divided the empire into two parts. This division became permanent in 395 AD, following the death of Theodosius I, the last emperor to rule over both the eastern and western halves of the Roman Empire.

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In the centuries that followed, the Eastern Roman Empire, known also as the Byzantine Empire, and the Sasanian Empire were on generally friendly terms, and enjoyed a long period of relative peace. This ended at the beginning of the 6th century AD, when the Anastasian War erupted. Over the next century, the Byzantines and Sasanians were engaged in a series of wars. Although the Byzantines gained some victories, and the Sasanians others, there was no clear winner in the long run. Moreover, the intermittent wars served only to drain the resources of the two empires and ultimately weakened them.

Adur Gushnasp, a major Persian fire temple, destroyed during the Roman Byzantine campaign. Major Christian holy sites were destroyed after the Persian-Jewish capture of Jerusalem earlier in the war. (Jacopo188 / CC BY-SA 3.0)

The Final War Between the Byzantines and the Sasanians

The last and most devastating of the wars between the Byzantines and Sasanians was the one fought between 602 and 628 AD. During this war, the Sasanians were led by Khosrow II, whereas the Byzantines were led, first by Phocas, and later by Heraclius.

For a greater part of the war, i.e., from 602 to 622 AD, the Sasanians had the upper hand, seizing much territory from the Byzantines. From 622 AD onwards, Heraclius forced Khosrow II to go on the defensive, as he launched repeated attacks on Sasanian lands. The war came to an end when Heraclius invaded the Sasanian heartland. This triggered a civil war that overthrew Khosrow, and the rebels sued for peace.

The Byzantine-Sasanian War of 602–628 AD was caused by the murder of the Byzantine emperor Maurice. Maurice came to power in 582 AD and was involved in the last war with the Sasanians. Emperor Maurice succeeded in ending the war by helping Khosrow regain the Sasanian throne.

Khosrow ascended the Sasanian throne in 590 AD following the overthrow of his father, Hormizd IV. Shortly after that, however, he was forced to flee from his capital, Ctesiphon, by a rebellious general, Bahram Chobin. Khosrow fled to the Byzantines and obtained military support from Maurice to regain the Sasanian throne. Having regained his throne in 591 AD, Khosrow and Maurice concluded a peace treaty.      

In 602 AD, Maurice’s order to the army that they should set up winter quarters on the far side of the Danube River resulted in a mutiny, which was led by Phocas, a Thracian centurion. Phocas succeeded in capturing Constantinople, overthrowing and murdering Maurice, and usurping the throne.

The killing of Maurice was seized upon by Khosrow as an excuse to wage war on the Byzantines. The war was declared ostensibly to avenge the murder of Maurice. In reality however, the Sasanians saw this as a chance to get rid of the Byzantines in Armenia, which had been given to them at the end of the previous war.

The Sasanians dominated the Byzantines for much of the war. Between 602 and 622 AD the Sasanians seized Armenia, Mesopotamia, Syria, Asia Minor, and Egypt. Additionally, the Sasanians captured Jerusalem, where they carried off many Christian relics to their capital as war booty. Whilst the Sasanians were ravaging these Byzantine territories, an appeal was sent from Constantinople to Heraclius, the Exarch of Africa, to save the Byzantine Empire. Heraclius and his brother sent their sons and an army to deal with the situation.

In 610 AD, Heraclius’ son, also named Heraclius, arrived in Constantinople, overthrew Phocas, and was declared emperor. Heraclius tried to sue for peace, but this was rejected by Khosrow. Moreover, it was during Heraclius’ early reign that the Byzantines lost even more territories to the Sasanians, including Syria, Palestine, Egypt, and Cappadocia. In 615 AD another Byzantine delegation was sent to Khosrow to sue for peace, with the same results as the previous one. It seems that Khosrow was bent on the total destruction of the Byzantine Empire.

The tide began to turn in 622 AD. Heraclius reorganized the empire, mustered an army, and launched a counter-offensive on Easter Monday. This campaign was full of religious overtones, as the emperor is reported to have been clad as a penitent and bore the image of the Virgin as he set out from Constantinople.

In the meantime, prayers were made for the emperor’s victory over the Sasanians, the recovery of the relics, especially the True Cross, and the reconquest of Jerusalem. In a way, Heraclius was a crusader.

Cherub and Heraclius receiving the submission of Khosrow II on a plaque from a cross. This is only an allegory, since Khosrow II never submitted in person to Heraclius of the Byzantine forces. (Louvre Museum / Public domain)

The Byzantine Victory Over the Sasanians

By the end of the year, Heraclius had defeated the Sasanians in battle, and forced them out of Cappadocia. Although Heraclius tried to sue for peace, it was rejected once again by Khosrow. Therefore, the war continued for several more years, with the Byzantines gaining the upper hand. In 623 AD, for instance, the Sasanians were defeated near Canzaca. The town, its fire temple, as well as the temple at Lake Urmia, traditionally associated with Zoroaster, were destroyed. The destruction of these sacred sites would have dealt a huge blow to the morale of the Sasanians. In 624 and 625 AD Heraclius campaigned successfully across northern Syria and Mesopotamia.

In 626 AD, Khosrow decided to counter-attack by besieging Constantinople itself. The siege, conducted by the Sasanians and their Avar allies, however, ended in failure. In the following year, the Byzantines attacked the Sasanian heartland itself.

By 628 AD, Heraclius had reached Dastagird, the Sasanian royal residence 113 kilometers (70 miles) to the north of Ctesiphon. As the Byzantines approached Dastagird, Khosrow fled. Soon after the royal residence was captured, the Sasanian elites revolted, captured Khosrow, and executed him. The new Sasanian ruler, Kavad II, negotiated a peace treaty with Heraclius, thus ending the war.

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Lastly, the Byzantine–Sasanian War of 602–628 AD had repercussions that neither side could have imagined. Not long after the conclusion of the war, the Muslims were united by the Prophet Muhammad under the banner of Islam. Both the Byzantine and Sasanian Empires were exhausted and weakened by the protracted war, which facilitated the expansion of the Muslims under the Rashidun Caliphate.

In 633 AD, the Arabs launched their campaign against the Sasanian Empire. The conquest of the Sasanian Empire was completed in 654 AD. Around the same time, the Muslims also attacked the Byzantines. By the time the Sasanian Empire fell, the Byzantines had lost the Levant, Syria, and Egypt. The Byzantines, however, did not suffer the fate of their Sasanian rivals, as their empire continued to exist for several more centuries.

Top image: Anachronistic painting by Piero della Francesca of the Battle of Nineveh (627) between Heraclius' Byzantine army and the Sasanians under Khosrow II, which was pretty much the end of the Byzantine–Sasanian War. Source: Piero della Francesca / Public domain

By Wu Mingren