History · Article
Heraclius and the Last Roman–Persian War, 602–628
The twenty-six-year war that destroyed Sasanian Persia and exhausted the Roman East. Heraclius's counter-offensive, the fall and recovery of Jerusalem, and the True Cross.
Rome and Persia had been fighting intermittently for nearly seven centuries when the last of their wars began in 602. It ran for twenty-six years, reached further into both empires than any previous round, and ended with one of them restored to its exact former borders and the other in political collapse. Within a decade of the peace, both had lost their southern provinces to the Arab conquests, and the strategic world that had shaped the Near East since Crassus was gone.
The war is the hinge of the seventh century, and its protagonist is the most difficult emperor in Byzantine history to characterise. Heraclius saved the empire by a campaign of extraordinary boldness and then watched, ill and grieving, as a new enemy took away more than the Persians ever had. The full context is set out in the Heraclian dynasty.
The Cause
In 602 the emperor Maurice was overthrown and murdered, with his sons, by a mutinous officer named Phocas. Maurice had a claim on Persian gratitude: in 591 he had restored the young Khosrow II to the Persian throne after a usurpation, at the price of Roman gains in Armenia and Mesopotamia. Khosrow declared that he was avenging his benefactor and invaded.
The pretext was transparent, and the opportunity was real. The Roman Balkan frontier had collapsed under Avar and Slav pressure; Phocas’s regime was unpopular and faced revolt; and the eastern army was disaffected. Persia took Dara in 604 and then moved steadily west.
Collapse, 610–622
Heraclius, son of the exarch of Africa, sailed from Carthage and overthrew Phocas in October 610. He inherited a war that was already being lost and made it worse before he made it better.
- 613 — Antioch falls; a Roman counter-offensive is beaten near the city.
- 614 — Jerusalem is taken after a siege of three weeks. The city is sacked, churches burned, and thousands killed; the relic of the True Cross, the most venerated object in Christendom, is carried to Ctesiphon. The shock in the Christian world is difficult to overstate, and the sources — Greek, Armenian and Syriac — are full of it.
- 619 — Alexandria falls; Egypt, the source of the capital’s grain, is under Persian administration within two years. The free bread ration at Constantinople is ended in 618 and never restored.
- 622–626 — Persian forces reach Chalcedon on the Asian shore, in sight of the city.
At the same time the Avar khagan was raiding Thrace almost at will, and in 623 nearly captured Heraclius himself in an ambush near Herakleia during what was supposed to be a negotiation.
Heraclius seriously considered moving the government to Carthage, and was dissuaded — according to the tradition — by the patriarch Sergius, who made him swear in Hagia Sophia not to abandon the city.
The Counter-Offensive, 622–628
What Heraclius did next was without precedent for a Roman emperor of the period. He raised money by borrowing the treasure of the church — the patriarch Sergius put the plate of Hagia Sophia and the other churches of the capital at his disposal, to be repaid — retrained the army in person over a winter, left the capital under a regency for his son and the patriarch, and campaigned in the field continuously for six years, far beyond the frontier.
The strategy was to strike at the Persian heartland and force the Persian field armies to follow him, rather than to reconquer the occupied provinces one by one. He operated out of Armenia and the Caucasus, wintering in friendly territory, using the mountains to protect his flanks, and picking off Persian armies separately.
Two elements made it work. The first was the alliance with the Western Turkic Khaganate, bought with gifts and the promise of a marriage, which brought a large steppe army against Persia from the north-east in 627. The second was Heraclius’s willingness to accept the risk of 626, when the Persians and the Avars coordinated an assault on Constantinople while he was in the Caucasus. He did not turn back. The siege of 626 was beaten off by the garrison, the walls and the fleet.
The war was decided in December 627 near the ruins of Nineveh, where Heraclius destroyed the last Persian field army in a battle in which he is said to have killed the enemy commander himself. He then marched down the Tigris, sacked the royal palace at Dastagird, and stood within striking distance of Ctesiphon.
The Collapse of Persia
He did not need to take it. Khosrow II, discredited, was deposed and executed by his own nobility in February 628, and his son Kavad II made peace immediately: complete Persian withdrawal from all occupied Roman territory, return of prisoners, and return of the True Cross.
Kavad died within months. Persia then went through a succession crisis of extraordinary severity, with something like ten rulers in four years, including two queens, before Yazdegerd III was installed as a boy in 632. The Sasanian state never recovered its coherence, and when the Arab armies arrived in the 630s they faced an empire in political dissolution.
The Restoration of the Cross
In March 630 Heraclius carried the recovered relic of the True Cross back into Jerusalem in person. The ceremony became one of the most celebrated images of the medieval Christian imagination and generated the feast of the Exaltation of the Cross in the western calendar and a large body of legend — including the story, told in the Golden Legend and painted by Piero della Francesca at Arezzo, that the emperor was stopped at the gate until he laid aside his crown and purple and entered barefoot.
It was the high point of the reign and lasted about four years. The relic was later removed to Constantinople for safety as the Arab conquests began; fragments of it circulated as gifts and diplomatic presents for centuries, as relics and pilgrimage in Byzantium describes.
Why Victory Was Worthless
Within four years of the triumph, Arab forces were raiding Palestine; within eight, Yarmouk had destroyed the Roman field army in Syria; within twelve, Jerusalem had surrendered again, this time permanently.
The reasons are structural.
Both empires were bankrupt. Twenty-six years of total war had consumed the fiscal reserves of two states and killed a generation of soldiers. Heraclius could not put a comparable army into the field in 636.
The reoccupied provinces were unreconciled. Ten to twenty years of Persian administration had disrupted the Roman apparatus of government, and the imperial return brought religious coercion with it — Heraclius’s attempt to enforce doctrinal unity through Monothelitism alienated the Miaphysite majority in Syria and Egypt, and his forced baptism of Jews in 632 was both brutal and counter-productive.
The frontier arrangements were gone. The Ghassanid Arab federates who had guarded the desert approaches had been neglected, and the subsidies that kept them loyal had been cut.
Reputation
Byzantine writers remembered Heraclius as the emperor who saved the empire; Syriac and Armenian sources are more ambivalent; and modern historians have called him everything from the first Byzantine emperor to the last great Roman one. The case for the first label rests on real changes: he adopted the Greek title basileus in place of the Latin imperator and Augustus, he conducted his war as an explicitly Christian campaign under icons and relics, and the state that emerged from his reign was the one that developed the theme system.
He died in 641 of a long illness, leaving a disputed succession and an empire losing a province a year. His own assessment, if the chroniclers are to be believed, was made at the Syrian frontier as he withdrew for the last time — a farewell to a province he knew he would not see again.
The Campaign Route
Heraclius’s strategy is easier to follow with the geography in front of you, and it was genuinely original for a Roman commander.
Rather than fighting for Syria, which the Persians held in strength, he shipped his army to the north-east corner of Anatolia and operated out of Armenia and the Caucasus, where the mountains covered his flanks and the local Christian populations supplied food and recruits.
| Year | Where |
|---|---|
| 622 | Lands in Bithynia; trains the army; first victory in Cappadocia |
| 623–624 | Marches through Armenia into Azerbaijan; sacks the great fire temple at Ganzak |
| 625 | Campaigns in Cilicia and Armenia against three Persian armies |
| 626 | Winters in Lazica; the capital is besieged in his absence |
| 627 | Joined by the Western Turks; invades Mesopotamia; wins at Nineveh in December |
| 628 | Sacks Dastagird; Khosrow deposed; peace |
Two things stand out. He wintered in the field, year after year, which Roman armies did not normally do. And he never tried to relieve the occupied provinces, accepting the loss of Syria, Palestine and Egypt for six years in order to strike at the enemy’s centre — a decision that would have ended his reign if it had failed.
The Religious Framing
This was the first Roman war fought explicitly as a holy war, and the framing was deliberate.
The campaign was funded by the treasure of the church, advanced by the patriarch Sergius as a loan against future repayment — an arrangement that required a theological justification and got one. The army carried the acheiropoietos, an image of Christ “not made by human hands,” as a standard. Heraclius addressed his troops in terms of martyrdom and promised the dead a heavenly reward. George of Pisidia’s verse accounts present the war as a cosmic struggle.
Historians have argued about what this means. Some see the first crusade in embryo, four and a half centuries early; others note that Roman armies had always invoked divine favour and that the difference is one of intensity rather than kind. The strongest version of the case is that the war produced a vocabulary of sanctified violence against a religious enemy that had not existed in Roman practice before and did not disappear afterwards.
What the Victory Cost
The peace of 628 restored every lost province, and the empire was bankrupt.
The church loan was never fully repaid. The gold coinage was supplemented by a heavy silver piece, the hexagram, struck as an emergency wartime measure from 615 and inscribed with a prayer for peace in the Roman state. The army was unpaid and its numbers reduced; Heraclius cut military pay by half in the 620s and again afterwards. The frontier federates in the Syrian desert had their subsidies stopped.
In 636, when the Arab armies arrived, the empire could not field a force comparable to the one that had won at Nineveh nine years earlier, could not pay the one it did field, and had no allies on the desert edge. The victory over Persia is a textbook case of a war won at a price that made the next one unwinnable.
- The Heraclian Dynasty — the century this war opened
- The Avar Siege of Constantinople, 626 — the crisis Heraclius chose not to return for
- The Battle of Yarmouk — what the victory could not prevent
- Relics and Pilgrimage in Byzantium — why the True Cross mattered so much
- The Byzantine Army — the force Heraclius retrained
- The Theme System — the settlement that followed the war
- History of the Byzantine Empire — the wider narrative