Persian advance '' of Heraclius and his father in consular robes, struck during their revolt against Phocas During his
Balkan campaigns, Emperor
Maurice and his family were murdered by Phocas in November 602 after a
mutiny. The Persian King
Khosrow II of the
Sasanian Empire had been restored to his throne by Maurice, and they had remained allies until the latter's death. Thereafter, Khosrow seized the opportunity to attack the Byzantine Empire and reconquer
Mesopotamia. The Persians attempted to claim that Maurice's son
Theodosius had escaped to Persia, but in reality had perished in massacre of Maurice's family, and attempted to split with some success the Byzantines; some cities, such as
Theodosiopolis, were persuaded by the impostor to surrender. The war initially went the Persians' way, partly because of Phocas's brutal repression and the succession crisis that ensued as the general Heraclius sent his nephew
Nicetas to attack
Egypt, enabling his son Heraclius the younger to claim the throne in 610. By this time, the Persians had conquered Mesopotamia and the
Caucasus, and in 611 they overran Syria and entered
Anatolia. After gaining full personal control of the Byzantine armies, Heraclius led a counter-attack two years later to repel the Persian army. However, he was
defeated near Antioch by Persian general
Shahrbaraz and
Shahin, resulting in the loss of Syria to the Persians. In the following years, the Persians devastated parts of
Asia Minor and captured
Chalcedon across from Constantinople on the
Bosporus. Over the following decade, the Persians were able to conquer
Palestine and Egypt (by mid-621, the whole province was in their hands) and to devastate Anatolia, while the
Avars and
Slavs took advantage of the situation to overrun the
Balkans, however the extend of penetration and devastation is unknown. In 613, the Persian army took
Damascus with
the help of the Jews, seized
Jerusalem in 614, damaging the
Church of the Holy Sepulchre and capturing the
True Cross, and afterwards capturing
Egypt (618–622). The loss of Egypt significantly strained the budget of the Byzantine Empire. When the Sasanians reached
Chalcedon in 615, it was at this point, according to contemporary
Sebeos, that Heraclius had agreed to stand down and was about ready to allow the Byzantine Empire to become a Persian
client state, even permitting Khosrow II to choose the emperor. In a letter delivered by his ambassadors, Heraclius acknowledged the Persian empire as superior, described himself as Khosrow II's "obedient son, one who is eager to perform the services of your serenity in all things", and even called Khosrow II the "supreme emperor". Khosrow II nevertheless rejected the peace offer, and arrested Heraclius's ambassadors. In 618, Heraclius considered abandoning Constantinople in favor of Carthage as the capital was exposed to threats from the Avars and Slavs in the north and the Persians from the east, but the
Patriarch Sergius and the response by the citizens of Constantinople convinced him to stay. The loss of tax-rich provinces forced Heraclius to take drastic measures to raise the necessary funds to rebuild the army to reverse the Persian advances. Kaegi considers that Heraclius may have threatened to abandon the capital for Africa to persuade Sergius and the clergy to loan Church treasures (by melting down precious metals) to the state. Heraclius also drastically slashed non-military expenditure.
Byzantine counter-offensive and resurgence in 629 after
Heraclius had reconquered Syria, Palestine and Egypt from the
Sassanid Empire. and Heraclius receiving the submission of Khosrow II; plaque from a cross (
Champlevé enamel over gilt copper, 1160–1170,
Louvre, Paris). This is an
allegory as Khosrow never submitted in person.|alt=Medieval style portrait of
Cherub and Heraclius receiving the submission of Khosrow II; plaque from a cross (
Champlevé enamel over gilt copper). . On 4 April 622, Heraclius left Constantinople, entrusting the city to Sergius and general
Bonus as regents of his son. He assembled his forces in Asia Minor, probably in
Bithynia. He revived their broken morale with traditional Byzantine military drills, maneuvers, and formations. Additionally, Heraclius exposed the soldiers to the image of Christ, not made by human hand (
acheiropoietos), as a military standard, and roused them with speeches by emphasizing the religious nature of the conflict against the Persians, who looted the Christian cities of the east. After this, he launched a new counter-offensive. The Byzantine army proceeded to Armenia, inflicted a
defeat on an army led by a Persian-allied Arab chief, and then won a victory over the Persians under Shahrbaraz. Heraclius would stay on campaign for several years. On 25 March 624, he again left Constantinople with Martina and his two children; after he celebrated
Easter in
Nicomedia on 15 April, he campaigned in the Caucasus, winning a
series of victories against Khosrow and his generals Shahrbaraz, Shahin, and
Shahraplakan. In the same year the
Visigoths succeeded in recapturing
Cartagena, capital of the western Byzantine province of
Spania, resulting in the loss of one of the provinces that had been conquered by the armies of
Justinian I. In 626 the Avars and Slavs supported by a Persian army commanded by Shahrbaraz,
besieged Constantinople, but the siege ended in failure (the victory was attributed to the icons of the Virgin which were led in procession by Sergius about the walls of the city), while a second Persian army under Shahin suffered another defeat at the
battle of the Lycus against Heraclius's brother Theodore in mid-summer 626. Heraclius himself may also have been present in this encounter. With the Persian war effort disintegrating, Heraclius was able to bring the
Gokturks of the
Western Turkic Khaganate, under
Ziebel, who
invaded Persian Transcaucasia. Heraclius exploited divisions within the Persian Empire, keeping Shahrbaraz neutral by convincing him that Khosrow had grown jealous of him and had ordered his execution. Late in 627, he launched a winter offensive into Mesopotamia, where, despite the desertion of his Turkish allies, he defeated the Persians under
Rhahzadh at the
Battle of Nineveh. Continuing south along the Tigris, he sacked Khosrow's great palace at
Dastagird and was only prevented from attacking Ctesiphon by the destruction of the bridges on the Nahrawan Canal. Discredited by this series of disasters, Khosrow was overthrown and killed in a coup led by his son
Kavad II, who at once sued for peace, agreeing to withdraw from all occupied territories. In 629 Heraclius restored the
True Cross to
Jerusalem. Heraclius's defeat of the Persians ended a war that had been going on intermittently for almost 400 years and led to instability in the Persian Empire.
Kavad II died only months after assuming the throne, plunging Persia into several years of dynastic turmoil and civil war.
Ardashir III, Heraclius's ally Shahrbaraz, and Khosrow's daughters
Boran and
Azarmidokht all succeeded to the throne within months of each other. Only when
Yazdegerd III, a grandson of Khosrow II, succeeded to the throne in 632, was there stability. But by then the Sasanid Empire was severely disorganised, having been weakened by
years of war and civil strife over the succession to the throne. The war had been devastating, leaving the Byzantines in a much weaker state. Within a few years both empires were overwhelmed by the onslaught of the Arabs, ultimately leading to the
Arab conquest of Persia and the
fall of the Sasanian dynasty in 651. == Byzantine–Arab wars ==