Byzantine–Sasanian War of 602–628

The Byzantine–Sasanian War of 602–628 marked the culmination and the most destructive episode in a series of conflicts between the Byzantine/Roman Empire and the Sasanian Empire of Iran. The preceding war, which concluded in 591, saw Emperor Maurice aiding Sasanian king Khosrow II in reclaiming his throne. However, in 602, Maurice was assassinated by his political rival Phocas. In response, Khosrow declared war, ostensibly seeking vengeance for Maurice’s death. This conflict spanned decades, becoming the lengthiest in the series, and unfolded across the Middle East, encompassing Egypt, the Levant, Mesopotamia, the Caucasus, Anatolia, Armenia, the Aegean Sea, and the vicinity of Constantinople itself.

The initial phase of the war (602–622) saw the Persians achieving significant success, conquering substantial territories such as the Levant, Egypt, islands in the Aegean Sea, and parts of Anatolia. However, the rise of Emperor Heraclius in 610, despite initial setbacks, eventually led to a return to the pre-war status quo. Heraclius’ campaigns in Iranian lands (622–626) compelled the Persians onto the defensive, enabling his forces to regain momentum. In a final attempt to capture Constantinople in 626, the Persians, allied with the Avars and Slavs, were defeated. Subsequently, in 627, Heraclius, joined by the Turks, invaded the heartland of Persia. A civil war erupted in Persia, resulting in the death of the king, and the Persians sought peace.

Ultimately, both sides found themselves depleted in terms of human and material resources, achieving minimal gains. Consequently, they became susceptible to the swift emergence of the Islamic Rashidun Caliphate, which invaded both empires a few years after the war. The Muslim armies rapidly conquered the entire Sasanian Empire and Byzantine territories in the Levant, the Caucasus, Egypt, and North Africa. In the ensuing centuries, Byzantine and Arab forces engaged in a series of wars for control over the Near East.

Background

After decades of inconclusive warfare, Emperor Maurice brought an end to the Byzantine–Sasanian War of 572–591 by aiding the exiled Sasanian prince Khosrow, who would later become Khosrow II, in reclaiming his throne from the usurper Bahrām Chobin. In return for this support, the Sasanians ceded parts of northeastern Mesopotamia, significant portions of Persian Armenia, and Caucasian Iberia to the Byzantines, although the precise details remain unclear. More notably, the Byzantine economy benefited as they were no longer obligated to pay tribute to the Sasanians. Following this diplomatic success, Emperor Maurice initiated new campaigns in the Balkans to counter incursions by the Slavs and Avars.

The previous financial surplus in the treasury, a legacy of Emperor Tiberius II’s generosity and campaigns, had been depleted during the time of Justin II. To replenish the treasury, Maurice implemented stringent fiscal measures and reduced army pay, resulting in four mutinies. The final mutiny erupted in 602 when Maurice instructed his troops in the Balkans to sustain themselves by living off the land during the winter. In response, the army declared Phocas, a Thracian centurion, as the new emperor. Despite Maurice’s efforts to defend Constantinople by enlisting the support of the Blues and the Greens, followers of the two major chariot racing teams in the Hippodrome, they proved ineffective. Maurice fled, only to be intercepted and killed by Phocas’ soldiers.

Beginning of the conflict

Following the assassination of Maurice, Narses, the governor of the Byzantine province of Mesopotamia, rebelled against Phocas and successfully seized Edessa, a significant city in the region. In response, Emperor Phocas directed General Germanus to lay siege to Edessa, leading Narses to seek assistance from the Persian king Khosrow II. Khosrow, motivated by a desire to avenge Maurice, whom he considered a “friend and father-in-law,” used Maurice’s death as a pretext to launch an attack on the Byzantine Empire, aiming to reclaim control over Armenia and Mesopotamia.

During the conflict, General Germanus perished in battle against the Persians. An army dispatched by Phocas to confront Khosrow suffered defeat near Dara in Upper Mesopotamia, resulting in the capture of this strategically important fortress in 605. Despite escaping from Leontius, the eunuch appointed by Phocas to handle the situation, Narses’ attempt to return to Constantinople for peace negotiations was thwarted. Phocas ordered Narses’ capture and execution by burning alive. The death of Narses, coupled with the failure to halt the Persian advances, significantly tarnished the prestige of Phocas’ military regime.

Heraclius’ rebellion

In 608, General Heraclius the Elder, the Exarch of Africa, initiated a revolt prompted by Priscus, the Count of the Excubitors and son-in-law of Phocas. Heraclius declared himself and his son, sharing the same name, as consuls, implicitly claiming the imperial title. Coins were minted depicting the two in consular robes, reinforcing their imperial aspirations.

Simultaneously, rebellions erupted in Roman Syria and Palaestina Prima in the aftermath of Heraclius’ revolt. In 609 or 610, the Patriarch of Antioch, Anastasius II, passed away, with reports suggesting Jewish involvement in the conflicts, although their allegiance to Christian or opposing factions remains unclear. In response, Phocas appointed Bonus as the Comes Orientis (Count of the East) to quell the unrest, and Bonus took punitive actions against the Greens, a horse racing faction in Antioch, for their role in the violence in 609.

Heraclius the Elder dispatched his nephew Nicetas to attack Egypt. Bonus intervened in Egypt to confront Nicetas but suffered defeat outside Alexandria. In 610, Nicetas successfully captured the province, establishing a power base with the support of Patriarch John the Almsgiver.

The main rebel force embarked on a naval invasion of Constantinople, led by the younger Heraclius, who was destined to become the new emperor. Organized resistance against Heraclius quickly crumbled, and Phocas was delivered to him by the patrician Probos (Photius) and subsequently executed. A notable exchange of remarks occurred between Phocas and his successor, Heraclius, highlighting the shortcomings of Phocas’ rule.

The elder Heraclius faded from historical accounts soon after, presumably meeting his end, although the exact date remains unknown. Heraclius, at 35 years old, married Fabia Eudocia and received the imperial crown from the Patriarch, commencing his rule as emperor. While Phocas’ brother, Comentiolus, posed a significant threat in central Anatolia, he was assassinated by the Armenian commander Justin, removing a major obstacle to Heraclius’ reign. However, the delayed transfer of forces commanded by Comentiolus allowed the Persians to advance further in Anatolia.

In an effort to boost revenues and cut costs, Heraclius limited the number of state-sponsored Church personnel in Constantinople by refraining from paying new staff from the imperial treasury. Ceremonies were employed to legitimize his dynasty, and Heraclius earned a reputation for justice to solidify his grip on power.

Persian ascendancy

Exploiting the internal strife within the Byzantine Empire, the Persians seized the opportunity to conquer frontier towns in Armenia and Upper Mesopotamia during the civil war. Along the Euphrates in 609, they captured Mardin and Amida (Diyarbakır). The city of Edessa, believed by some Christians to be defended by Jesus on behalf of King Abgar V against all enemies, fell in 610.

In Armenia, the strategically vital city of Theodosiopolis (Erzurum) surrendered in 609 or 610 to Ashtat Yeztayar. This surrender was influenced by a man claiming to be Theodosius, the eldest son and co-emperor of Maurice, who purportedly sought refuge under Khosrow’s protection. In 608, the Persians, led by General Shahin, launched a raid into Anatolia that reached Chalcedon, situated across the Bosphorus from Constantinople. The gradual Persian conquest extended to all Roman cities east of the Euphrates and in Armenia by the time Heraclius assumed power.

Despite Heraclius’ accession as Emperor, the Persian threat persisted. Heraclius initially sought peace with the Persians, considering that Phocas, the original cause of hostilities, had been overthrown. However, the Persians, enjoying widespread victories, rejected these peace efforts. Historian Walter Kaegi suggests that the Persian goal may have been to surpass the boundaries of the Achaemenid Empire by destroying the Byzantine Empire, though conclusive evidence is lacking.

Heraclius, along with his general Priscus, participated in the siege of Caesarea Mazaca. Priscus, feigning illness, insulted Heraclius by avoiding a meeting. Shahin’s troops escaped the blockade, burning Caesarea, leading to Priscus’ removal from command. Heraclius appointed himself as commander alongside his brother Theodore. Taking advantage of Heraclius’ generals’ incompetence, Khosrow launched an attack on Byzantine Syria under Persian general Shahrbaraz.

Heraclius attempted to halt the invasion at Antioch, but despite the blessing of Saint Theodore of Sykeon, Byzantine forces suffered a severe defeat at the hands of Shahin. The details of the battle are unclear. Following the victory, the Persians looted Antioch, killed the Patriarch, and deported numerous citizens. Despite initial success, Roman forces lost while defending the area north of Antioch at the Cilician Gates. The Persians captured Tarsus and the Cilician plain, effectively splitting the Byzantine Empire in half by severing the land link between Constantinople and Syria, Palestine, Egypt, and the Exarchate of Carthage.

Persian dominance

Resistance to the Persians in Syria was relatively weak, as locals, while constructing fortifications, generally opted for negotiations. In 613, the cities of Damascus, Apamea, and Emesa quickly fell, allowing the Sasanian army to advance further south into Palaestina Prima. Nicetas, although putting up a fight, was defeated at Adhri’at. A small victory near Emesa ensued, resulting in heavy casualties on both sides, with a total death count of 20,000.

The lack of robust resistance enabled the Persians and their Jewish allies to capture Jerusalem after a three-week siege in 614. Ancient sources claim that 57,000 or 66,500 people were killed, and another 35,000 were deported to Persia, including the Patriarch Zacharias. Many churches, including the Church of the Resurrection (Holy Sepulchre), were burned, and significant relics such as the True Cross, the Holy Lance, and the Holy Sponge were taken to the Persian capital, Ctesiphon. The loss of these relics was considered by many Christian Byzantines as a sign of divine displeasure. Some attributed blame to the Jews, alleging their collaboration with the Persians in capturing certain cities and attempting to harm Christians in already conquered cities. These accusations are likely exaggerated and a result of general hysteria.

In 618, Shahrbaraz’s forces invaded Egypt, a province relatively untouched by war for three centuries. The Monophysites in Egypt, dissatisfied with Chalcedonian orthodoxy, did not eagerly support Byzantine imperial forces. Khosrow later backed them, but their resistance remained limited between 600 and 638, viewed negatively by many due to Persian occupation. Nicetas led Byzantine resistance in Alexandria, but after a year-long siege, the city fell, allegedly due to a traitor revealing an unused canal to the Persians. Nicetas fled to Cyprus along with Patriarch John the Almsgiver, a major supporter in Egypt. Nicetas’ fate is unclear as he disappears from records after this event, posing a setback for Heraclius.

The loss of Egypt dealt a severe blow to the Byzantine Empire, as Constantinople depended on grain shipments from Egypt to feed its population. Grain rationing, echoing Rome’s earlier grain dole, was abolished in Constantinople in 618. Following the conquest of Egypt, Khosrow allegedly sent Heraclius a letter taunting his resistance, questioning the efficacy of his God, and promising mercy if Heraclius submitted. However, the authenticity of this letter has been disputed by modern scholars.

In 615, when the Sasanians reached Chalcedon, it is reported, according to Sebeos, that Heraclius had contemplated standing down. At this point, he seemed prepared to allow the Byzantine Empire to become a Persian client state, even granting Khosrow II the authority to choose the emperor. The situation worsened for the Byzantines when Chalcedon fell in 617 to Shahin, bringing the Persians within view of Constantinople.

Despite reaching Chalcedon, Shahin received a peace delegation courteously. However, he asserted a lack of authority to engage in peace talks and directed Heraclius to Khosrow. Khosrow rejected the peace offer, which, in hindsight, proved to be a significant strategic error. Nevertheless, the Persian forces subsequently withdrew, likely to concentrate on their invasion of Egypt. Despite this withdrawal, the Persians maintained their advantage by capturing Ancyra, a crucial military base in central Anatolia, in either 620 or 622. In 622/623, Rhodes and several other islands in the eastern Aegean fell, posing a threat of a naval assault on Constantinople.

The despair in Constantinople was so profound that Heraclius considered relocating the government to Carthage in Africa.

Byzantine resurgence

Khosrow’s letter did not intimidate Heraclius but instead spurred him to undertake a desperate offensive against the Persians. In response, he initiated a reorganization of the remaining territories of his empire to better position his forces for the conflict. By 615, a new, lighter (6.82 grams) silver imperial coin featuring the usual image of Heraclius and his son Heraclius Constantine was introduced. Notably, it bore the inscription “Deus adiuta Romanis” or “May God help the Romans,” reflecting the empire’s sense of desperation during this period.

The copper follis also experienced a reduction in weight, dropping from 11 grams to a range between 8 and 9 grams. Heraclius faced a significant decrease in revenues due to the loss of provinces, exacerbated by a plague outbreak in 619. This plague not only further eroded the tax base but also heightened fears of divine retribution. To cope with these financial challenges, Heraclius implemented measures such as halving officials’ pay, enforcing increased taxation, imposing forced loans, and levying substantial fines on corrupt officials to fund his counter-offensive.

Despite controversies surrounding Heraclius’ incestuous marriage to his niece Martina, the clergy of the Byzantine Empire fervently supported his efforts against the Persians. They proclaimed the duty of all Christian men to fight and offered a war loan consisting of all the gold and silver-plated objects in Constantinople. Precious metals and bronze were stripped from monuments, including the Hagia Sophia. This military campaign has been regarded by some historians as the first “crusade” or an antecedent to the Crusades, although there is disagreement among scholars, as religion was just one element in the conflict.

To strengthen the Byzantine forces, thousands of volunteers were gathered and equipped with funds from the church. Heraclius himself assumed command from the front lines, revitalizing the troops with replenished ranks, improved equipment, and competent leadership, all while maintaining a full treasury.

Historian George Ostrogorsky proposed that volunteers were amassed through the reorganization of Anatolia into four themes, where individuals received grants of land on the condition of hereditary military service. However, modern scholars tend to reject this theory, placing the creation of the themes later, under Heraclius’ successor Constans II.

In 622, Heraclius, prepared for a counter-offensive, departed Constantinople the day after Easter on April 4, leaving his young son, Heraclius Constantine, as regent under the care of Patriarch Sergius and the patrician Bonus. Heraclius spent the summer training his men and refining his generalship skills. During the autumn, he marched to Cappadocia, threatening Persian communications from the Euphrates valley to Anatolia. This compelled the Persian forces in Anatolia, led by Shahrbaraz, to retreat from Bithynia and Galatia to eastern Anatolia to block Heraclius’ access to Iran.

The specific events following are not entirely clear, but Heraclius achieved a decisive victory over Shahrbaraz in the fall of 622. Heraclius’ key tactical move involved discovering Persian forces hidden in ambush and responding by feigning retreat during the battle. The Persians left their cover to pursue the retreating Byzantines, at which point Heraclius’ elite Optimatoi attacked, causing the Persians to flee. This victory saved Anatolia from the Persian threat. Heraclius, however, had to return to Constantinople to address the Avar threat to his Balkan domains, leaving his army to winter in Pontus.

While the Byzantines were engaged with the Persians, the Avars and Slavs invaded the Balkans, capturing several Byzantine cities and causing widespread destruction. The Avars and Slavs even threatened Thrace, including the vicinity of Constantinople. Although they failed to take Thessalonica, the most crucial Byzantine city in the Balkans, the Avar and Slavic incursions diverted Byzantine forces from the Persian front.

To counter the Avar threat, Heraclius negotiated with the Avar Khagan, offering tribute in exchange for their withdrawal north of the Danube. A meeting was arranged on June 5, 623, at Heraclea in Thrace, where the Avar army was stationed. The Khagan, however, planned to ambush and capture Heraclius, leading to a dangerous situation. Warned in time, Heraclius managed to escape, pursued by the Avars back to Constantinople. Despite Heraclius’ evasion, many members of his court and around 70,000 Thracian peasants were captured and killed by the Avars. In the aftermath, Heraclius, constrained by the circumstances, agreed to pay the Avars a subsidy of 200,000 solidi and provide hostages, including his illegitimate son John Athalarichos, his nephew Stephen, and the illegitimate son of the patrician Bonus, in exchange for peace. This allowed Heraclius to redirect his full attention to the Persian front.

In 624, Heraclius proposed peace to Khosrow, but the offer was rejected. Consequently, on March 25, 624, Heraclius left Constantinople to launch an assault on the Persian heartland. Ignoring securing his rear or communications with the sea, he marched through Armenia and modern Azerbaijan to directly attack the core Persian territories. Leading an army of no more than 40,000 (likely between 20,000–24,000), Heraclius recovered Caesarea in Cappadocia before advancing along the Araxes River, destroying Persian-held Dvin, Nakhchivan, and meeting Khosrow’s army at Ganzaka.

With the help of loyal Arabs, Heraclius captured and killed some of Khosrow’s guards, causing the disintegration of the Persian army. Subsequently, Heraclius destroyed Adur Gushnasp, the renowned Zoroastrian fire temple at Takht-i-Suleiman. Heraclius then wintered in Caucasian Albania, gathering forces for the next year. Khosrow, not content to let Heraclius rest, sent three armies commanded by Shahrbaraz, Shahin, and Shahraplakan to trap and destroy Heraclius’ forces.

Shahraplakan aimed to capture the mountain passes, Shahrbaraz blocked Heraclius’ retreat through Caucasian Iberia, and Shahin aimed to block the Bitlis Pass. Heraclius, planning to engage the Persian armies separately, managed to defeat Shahraplakan and Shahin in successive battles. He then crossed the Araxes and camped on the plains, where Shahrbaraz and Shahin pursued him. Heraclius launched a surprise night attack on Shahrbaraz’s main camp in February 625, destroying it and forcing Shahrbaraz to escape with minimal resources.

During the rest of the winter, Heraclius remained north of Lake Van. In 625, his forces attempted to push back towards the Euphrates. In a swift campaign, he captured Amida and Martyropolis, crucial fortresses on the upper Tigris. Heraclius then moved toward the Euphrates, pursued by Shahrbaraz. There were skirmishes along the way, including a notable encounter at the Sarus River near Adana. Despite a feigned retreat by Shahrbaraz leading to an initial setback for the Byzantines, Heraclius, with a strategic charge across a bridge, turned the tide of battle in his favor at the Battle of Sarus. The Byzantine army then wintered at Trebizond.

Climax of the war

In 626, a combined force of Sasanian, Avar, and Slavic troops laid siege to Constantinople. Khosrow, realizing the need for a decisive counterattack against the Byzantines, recruited two new armies. Shahin, with 50,000 men, stayed in Mesopotamia and Armenia to prevent Heraclius from invading Iran, while Shahrbaraz led a smaller army to Chalcedon, the Persian base across the Bosphorus from Constantinople. Khosrow also coordinated with the Avars to launch a coordinated attack on Constantinople from both European and Asiatic sides.

The Persian army stationed at Chalcedon, and the Avars positioned themselves on the European side, destroying the Aqueduct of Valens. However, the Byzantine navy’s control of the Bosphorus restricted the Persians from sending troops to the European side. The defense of Constantinople was commanded by Patriarch Sergius and Bonus. To support the city’s defense, Heraclius sent reinforcements, while another part of his army, led by his brother Theodore, confronted Shahin. The smallest part, under Heraclius’ direct control, intended to raid the Persian heartland.

The siege began on June 29, 626, with a coordinated assault. Despite continuous bombardment for a month, morale inside Constantinople remained high due to religious fervor inspired by Patriarch Sergius. On August 7, a fleet of Persian rafts ferrying troops was surrounded and destroyed by Byzantine ships. The Avar and Slavic assaults on the sea and land walls failed. With news of Theodore’s victory over Shahin, the Avars retreated, ending the serious threat to Constantinople. Additionally, after Heraclius revealed intercepted letters ordering Shahrbaraz’s death, the Persian general switched sides, moving his army to northern Syria. This neutralized Khosrow’s skilled general and deprived him of experienced troops before Heraclius’ planned invasion of Iran.

During the siege of Constantinople, Heraclius formed an alliance with the Western Turkic Khaganate, led by Tong Yabghu, whom Byzantine sources referred to as the “Khazars.” This alliance was established through diplomatic efforts, with Heraclius offering gifts and the promise of marriage to Eudoxia Epiphania, the porphyrogenita. This alliance was not a new development, as in 568, the Turks, under Istämi, had sought Byzantine support when their relations with Iran deteriorated. An embassy led by the Sogdian diplomat Maniah arrived in Constantinople, offering silk and proposing an alliance against Sasanian Iran. This diplomatic effort was successful, establishing a direct trade route for Chinese silk desired by the Sogdians.

In 625, taking advantage of Sasanian weakness, the Turks expanded their territory in the East, occupying Bactria and Afghanistan up to the Indus River and establishing the Yabghus of Tokharistan.

Responding to the Byzantine-Turkic alliance, the Turks, based in the Caucasus, sent 40,000 troops to raid the Iranian Empire in 626, initiating the Third Perso-Turkic War. The joint Byzantine and Göktürk forces focused on besieging Tbilisi, using traction trebuchets to breach the walls, one of the earliest known instances by the Byzantines. The city fell, likely in late 628. Ziebel, the leader of the Turks, died by the end of that year, saving Epiphania from the proposed marriage.

In mid-September 627, Heraclius launched a surprising winter campaign into the Iranian heartland, while Ziebel continued the siege of Tiflis. The Byzantine army, numbering between 25,000 and 50,000 troops, was accompanied by 40,000 Göktürks who later deserted due to harsh winter conditions and Persian harassment. Heraclius faced a Persian army led by Rhahzadh, engaging in the Battle of Nineveh near the end of the year. Heraclius, using strategic maneuvers, feigned retreat and surprised the Persians, resulting in approximately 6,000 Persian casualties. Though the battle did not become a rout, Heraclius claimed victory, and Rhahzadh was killed, potentially in personal combat with Heraclius.

Significance

Short-term consequences:

Heraclius’ Triumph: After Heraclius successfully concluded the war, he entered Constantinople triumphantly. The recovery of the Holy Sponge, which was part of the True Cross, was celebrated in a grand ceremony. This event, on September 14, 629, marked a symbolic victory and was followed by a ceremonial parade towards the Hagia Sophia.

Symbolic Significance: The raising of the True Cross in the Hagia Sophia was seen as a sign of a new golden age for the Byzantine Empire. Many believed that this victory would usher in an era of prosperity and success.

Heraclius’ Reputation: The war solidified Heraclius’ position as one of history’s most successful generals. He was hailed as “the new Scipio” for his string of victories. The triumphal raising of the True Cross added to his achievements, and had he died at that moment, he might have been remembered as “the greatest Roman general since Julius Caesar.”

Sasanian Struggles: The Sasanians, on the other hand, faced internal struggles. The death of Kavadh II shortly after ascending the throne led to years of dynastic turmoil and civil war. Several rulers, including Ardashir III, Shahrbaraz, Purandokht, and Azarmidokht, succeeded each other rapidly.

Long-term consequences:

Empire Crippling: The war, coupled with a century of continuous Byzantine-Persian conflict, left both empires severely weakened. The Sasanians faced economic decline, heavy taxation, religious unrest, and internal power struggles. The Byzantine Empire, with its territories devastated and financial resources exhausted, struggled to recover.

Arab Onslaught: Within a few years, both empires faced the onslaught of the Arabs, united by Islam. The Sasanian Empire succumbed rapidly, leading to its complete destruction. The Byzantine Empire lost its recently regained territories in Syria, Armenia, Egypt, and North Africa to the Arab conquests.

Byzantine Survival: Despite significant losses, the Byzantine Empire managed to survive the Arab assaults. The strategic core consisting of Anatolia and scattered holdings in the Balkans and Italy endured. The Byzantines decisively repulsed Arab sieges of Constantinople in 674–678 and 717–718.

Permanent Losses: Some territories, like Spania (Iberian Peninsula) and Corsica, were permanently lost during subsequent conflicts. The Byzantines also faced losses in the Balearic Islands, Sardinia, and Sicily to Arab forces in the 10th century.

End of Antiquity: The war, especially in Asia Minor, is considered by some as the “first stage in the process which marked the end of Antiquity.” The conflicts and their aftermath contributed to significant geopolitical changes in the region.

Composition of the armies and strategy

Persian Aswaran: The elite cavalry corps of the Persians was known as the Aswaran. Armed with lances (kontos), their preferred weapon, the Aswaran were skilled cavalry capable of skewering two men simultaneously. Both the riders and their horses were covered in lamellar armor, offering protection against enemy archers.

Emperor Maurice’s Strategikon highlighted the Persian reliance on archers, emphasizing their speed rather than sheer power. Persian formations were designed to be equally strong in the center and on the flanks. To counter Roman lancers, the Persians utilized rough terrain, as Roman cavalry preferred to avoid direct hand-to-hand combat. The manual advised fighting on level terrain with rapid charges to minimize vulnerability to Persian arrows. Persian military strategy involved siege tactics, emphasizing planning and generalship.

Byzantine Military Composition: The Byzantine army featured diverse units, each serving specific roles:

• Cataphract Cavalry: The heavily armored cataphract cavalry, symbolic of Byzantium, wore chain mail, rode heavily armored horses, and primarily used lances. They were equipped with small shields, bows, broadswords, and axes.
• Heavy Byzantine Infantry (Scutati/Skoutatoi): Wearing lamellar or mail armor, the infantry carried large oval shields and various weapons, including spears to repel cavalry and axes to target horses.
• Light Byzantine Infantry (Psiloi): Armed with bows and wearing leather armor, the light infantry primarily served as archers. They played a crucial role in stabilizing battle lines against enemy cavalry and supporting friendly cavalry attacks.

Byzantine military strategy combined aspects of the Roman legion and the Greek phalanx, providing a versatile and effective force.

Avar Military Tactics: The Avars employed mounted archers with composite bows that could also function as heavy cavalry with lances. Skilled in siegecraft, they utilized trebuchets, siege towers, and defensive structures like walls of circumvallation and mantelets during the siege of Constantinople. The Avars, nomadic in nature, gathered allied warriors, including Gepids and Slavs, but faced challenges in sustaining long sieges due to their dependence on raiding for supplies.

Byzantine Diplomacy and Logistics: The Byzantines, according to Walter Kaegi, had a preference for maintaining the status quo through diplomacy. While unsuccessful against Khosrow and the Avar Khagan, Byzantine ties with the Slavs and negotiations with the Göktürks proved fruitful. These diplomatic efforts resulted in Slavic opposition to the Avars and a key alliance with the Göktürks.

Logistics posed challenges for both sides. In Heraclius’ initial campaigns, he likely relied on requisitioning from the surroundings for supplies. During offensive raids into Persia, winter conditions forced Heraclius to desist, considering the need for stored fodder for both his and Persian horses. The alliance with the Göktürks, known for their hardy horses, played a crucial role in overcoming logistical challenges during Heraclius’ winter campaign in 627. After the victory at Nineveh and the capture of Persian palaces, logistical issues in supplying troops in foreign territories were mitigated.

Historiography

Sources on the Byzantine-Sasanian War (602–628):

The available sources on the Byzantine-Sasanian War (602–628) are predominantly of Byzantine origin, offering insights into the conflict. Some of the key sources include:

Chronicon Paschale: An unidentified Greek author from around 630 wrote this chronicle, providing contemporary Greek texts on the war.

George of Pisidia: A contemporary poet whose works offer insights into the events of the war.

Theophylact Simocatta: While his historical account covers the period from 582 to 602, it still provides valuable political perspectives from the Byzantine side.

Theodore the Synkellos: His surviving speech, made during the Siege of Constantinople in 626, contains useful information on specific events.

Papyri from Egypt: Some surviving papyri from Egypt provide additional perspectives from that period.

On the Persian side, the loss of Persian archives means there are no contemporary Persian sources. However, later Islamic sources like al-Tabari’s “History of the Prophets and Kings” use now-lost Persian sources to cover the Sasanian dynasty’s history.

Non-Greek contemporary sources include:

Chronicle of John of Nikiu: Originally written in Coptic and surviving in Ethiopian translation, it provides a non-Greek perspective on the events.

History attributed to Sebeos: An Armenian compilation with uneven coverage, combining various sources and correlating Biblical prophecy with contemporary events.

Chronicle of 724 by Thomas the Presbyter: A Syriac source composed in 640.

Chronicle of Guidi or Khuzistan Chronicle: Provides the perspective of a Nestorian Christian living in Persian territory.

Later Greek accounts include:

Chronicle of Theophanes the Confessor: Useful in creating a framework for the war.

Brief History of Patriarch Nikephoros I: Offers additional insights.

Later Syriac sources, such as the Chronicle of 1234 and the Chronicle by Michael the Syrian, supplement the Byzantine accounts. The 10th-century Armenian History of the House of Artsrunik by Thomas Artsruni and the History of Aluank by Movses Kaghankatvatsi are considered important non-Muslim sources.

The Quran provides some details, particularly in the Ar-Rum sūrah, offering perspectives on the war from Mecca.

Byzantine hagiographies, especially those of Saints Theodore of Sykeon and Anastasios the Persian, provide helpful insights, though there are doubts about potential interpolations. Numismatics, sigillography, art, archaeology, and epigraphic sources contribute to dating and understanding the historical context. The “Strategikon of Maurice” is highlighted as a valuable Byzantine field manual providing insights into military thinking and practices of the time.