[8] Anthony Kaldellis argues that there is no primary source that says that Heraclius [the Elder] was an Armenian and that the assertion is based on an erroneous reading of Theophylact Simocatta.

[12] Heraclius's younger cousin Nicetas launched an overland invasion of Egypt; by 609, he had defeated Phocas's general Bonosus and secured the province.

When he reached the capital, the Excubitors, an elite Imperial Guard unit led by Phocas's son-in-law Priscus, deserted to Heraclius, and he entered the city without serious resistance.

[19] Phocas, an unpopular ruler who is invariably described in historical sources as a "tyrant" (in its original meaning of the word, i.e. illegitimate king by the rules of succession), was eventually deposed by Heraclius, who sailed to Constantinople from Carthage with an icon affixed to the prow of his ship.

A major counter-attack led by Heraclius two years later was decisively defeated outside Antioch by Shahrbaraz and Shahin, and the Roman position collapsed; the Persians devastated parts of Asia Minor and captured Chalcedon across from Constantinople on the Bosporus.

[22] Over the following decade the Persians were able to conquer Palestine and Egypt (by mid-621, the whole province was in their hands)[23] and to devastate Anatolia,[c] while the Avars and Slavs took advantage of the situation to overrun the Balkans, bringing the Empire to the brink of destruction.

[25] When the Sasanians reached Chalcedon in 615, it was at this point, according to 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.

[27] With the Persians at the very gate of Constantinople, Heraclius thought of abandoning the city and moving the capital to Carthage, but the powerful church figure Patriarch Sergius convinced him to stay.

[28][better source needed] The peace allowed him to rebuild the Empire's army by slashing non-military expenditure, devaluing the currency, and melting down, with the backing of Patriarch Sergius, Church treasures to raise the necessary funds to continue the war.

He assembled his forces in Asia Minor, probably in Bithynia, and, after he revived their broken morale, he launched a new counter-offensive, which took on the character of a holy war; an acheiropoietos image of Christ was carried as a military standard.

[34][35] On 25 March 624,[36] he again left Constantinople with his wife, Martina, and his two children; after he celebrated Easter in Nicomedia on 15 April, he campaigned in the Caucasus, winning a series of victories in Armenia against Khosrow and his generals Shahrbaraz, Shahin, and Shahraplakan.

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.

[41] 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.

Kavad II died only months after assuming the throne, plunging Persia into several years of dynastic turmoil and civil war.

[51] The religious zeal of the Arab army, which was a recent development following the rise of Islam, ultimately contributed to the latter's success in its campaigns against the Romans.

Ultimately, the reformed army halted the Arabs in Asia Minor and held on to Carthage for another 60 years, saving a core from which the empire's strength could be rebuilt.

[58][failed verification] The recovery of the eastern areas of the Roman Empire from the Persians once again raised the problem of religious unity centering on the understanding of the true nature of Christ.

In the first and last years of a long reign, the emperor appears to be the slave of sloth, of pleasure, or of superstition, the careless and impotent spectator of the public calamities.

But the languid mists of the morning and evening are separated by the brightness of the meridian sun; the Arcadius of the palace arose the Caesar of the camp; and the honor of Rome and Heraclius was gloriously retrieved by the exploits and trophies of six adventurous campaigns.

Meanwhile, some of the Persian grandees freed Khosrow's eldest son Kavad II, who had been imprisoned by his father, and proclaimed him King on the night of 23–24 February, 628.

At first, when he was on horseback (shown above), the burden was too heavy, but after he dismounted and removed his crown it became miraculously light, and the barred city gate opened of its own accord.

[75] Some scholars disagree with this narrative, Professor Constantin Zuckerman going as far as to suggest that the True Cross was actually lost, and that the wood contained in the allegedly-still-sealed reliquary brought to Jerusalem by Heraclius in 629 was a fake.

In the third and fourth verses, the Muslim community is promised that the Byzantines will reverse their defeat into a victory and retake Jerusalem "in a few years' time".

Asked by Heraclius about the man claiming to be a prophet, Abu Sufyan responded, speaking favorably of Muhammad's character and lineage and outlining some directives of Islam.

[79][86][87] Later reportedly he wrote to a certain religious official in Rome to confirm if Muhammad's claim of prophethood was legitimate, and, after receiving the reply to his letter, called the Roman assembly saying, "If you desire salvation and the orthodox way so that your empire remain firmly established, then follow this prophet," to the rejection of the council.

[90] The Swahili Utendi wa Tambuka, an epic poem composed in 1728 at Pate Island (off the shore of present-day Kenya) and depicting the wars between the Muslims and Byzantines from the former's point of view, is also known as Kyuo kya Hereḳali ("The Book of Heraclius").

"[92] According to the Muslim sources reported by El-Cheikh, he tried to convert the ruling class of the Empire, but they resisted so strongly that he reversed course and claimed that he was just testing their faith in Christianity.

[96] El-Cheikh notes that these accounts of Heraclius add "little to our historical knowledge" of the emperor; rather, they are an important part of "Islamic kerygma," attempting to legitimize Muhammad's status as a prophet.

[51] Al-Waqidi recorded a story about a trader acting as a spy in Medina from the Lakhmid kingdom who reported the coming of the Muslim forces before The Battle of the Yarmuk.