Overthrow of Hormizd IV and accession of
Hormizd IV from the
Sasanian Empire with the word
farr written in a calligraphic style of
Middle Persian In 590, Hormizd IV had his prominent general
Bahram Chobin disgraced and dismissed. Bahram, infuriated by Hormizd's actions,
responded by rebelling, and due to his noble status and great military knowledge, was joined by his soldiers and many others. He then appointed a new governor for
Khorasan, and afterwards set out for the Sasanian capital of
Ctesiphon. The legitimacy of the
House of Sasan was based on acceptance that the halo of kingship, the
farr, was given to the first Sasanian emperor,
Ardashir I () and his family following the latter's conquest of the
Parthian Empire. This was now, however, disputed by Bahram Chobin, thus marking the first time in Sasanian history that a Parthian dynast challenged the legitimacy of the Sasanian family by rebelling. Meanwhile, Hormizd tried to come to terms with his brothers-in-law Vistahm and Vinduyih, who, according to the
Syriac language writer
Joshua the Stylite, both "equally hated Hormizd". The two brothers overthrew Hormizd in a seemingly bloodless palace revolution. They had Hormizd blinded with a red-hot needle, and put Khosrow II on the throne. Sometime in the summer of 590, the two brothers then had Hormizd killed, with at least the implicit approval of Khosrow II. Nevertheless, Bahram Chobin continued his march to Ctesiphon, now with the pretext of claiming to avenge Hormizd. Khosrow then took a
carrot and stick attitude, and wrote a message to Bahram Chobin, stressing his rightful claim to the Sasanian kingship: "Khosrow, kings of kings, ruler over the ruling, lord of the peoples, prince of peace, salvation of men, among gods the good and eternally living man, among men the most esteemed god, the highly illustrious, the victor, the one who rises with the sun and who lends the night his eyesight, the one famed through his ancestors, the king who hates, the benefactor who engaged the Sasanians and saved the Iranians their kingship—to Bahram, the general of the Iranians, our friend.... We have also taken over the royal throne in a lawful manner and have upset no Iranian customs.... We have so firmly decided not to take off the diadem that we even expected to rule over other worlds, if this were possible.... If you wish your welfare, think about what is to be done."
Flight Bahram Chobin, however, ignored his warning—a few days later, he reached the
Nahrawan Canal near Ctesiphon, where he fought Khosrow's men, who were heavily outnumbered, but managed to hold Bahram Chobin's men back in several clashes. However, Khosrow's men eventually began losing their morale, and were in the end defeated by Bahram Chobin's forces. Khosrow, together with his two uncles, his wives, and a
retinue of 30 nobles, thereafter fled to Byzantine territory, while Ctesiphon fell to Bahram Chobin. Bahram Chobin declared himself king of kings in the summer of 590, asserting that the first Sasanian king
Ardashir I () had usurped the throne of the
Arsacids, and that he now was restoring their rule. Bahram Chobin tried to support his cause with the
Zoroastrian apocalyptic belief that by the end of
Zoroaster's millennium, chaos and destructive wars with the Hephthalites/Huns and the Romans occur, and then a saviour would appear. Indeed, the Sasanians had misidentified Zoroaster's era with that of the
Seleucid Empire (312 BCE), which put Bahram Chobin's life almost at the end of Zoroaster's millennium, he was therefore hailed by many as the promised savior, Kay Bahram Varjavand. Bahram was to re-establish the
Parthian Empire and commenced a new millennium of dynastic rule. He started minting coins, on the front of which he is depicted as an exalted figure, bearded and wearing a
crenellation-shaped crown with two crescents of the moon, whilst the reverse shows the traditional
fire altar flanked by two attendants. Regardless, many nobles and priests still chose to side with the inexperienced and less dominant Khosrow II. In order to get the attention of the Byzantine emperor
Maurice (r. 582–602), Khosrow II went to
Roman Syria, and sent a message to the Sasanian occupied city of
Martyropolis to stop their resistance against the Byzantines, but with no avail. He then sent a message to Maurice, and requested his help to regain the Sasanian throne, which the Byzantine emperor agreed with; in return, the Byzantines would re-gain sovereignty over the cities of
Amida,
Carrhae,
Dara and Martyropolis. Furthermore, Iran was required to stop intervening in the affairs of the
Kingdom of Iberia and
Armenia, effectively ceding control of
Lazistan to the Byzantines.
Return to Iran In 591, Khosrow moved to
Constantia and prepared to invade Bahram Chobin's territories in Mesopotamia, while Vistahm and Vinduyih were raising an army in
Adurbadagan under the observation of the Byzantine commander
John Mystacon, who was also raising an army in Armenia. After some time, Khosrow, along with the Byzantine commander of the south,
Comentiolus, invaded Mesopotamia. During this invasion,
Nisibis and Martyropolis quickly defected to them, and Bahram Chobin's commander Zatsparham was defeated and killed. One of Bahram Chobin's other commanders, Bryzacius, was captured in
Mosul and had his nose and ears cut off, and was thereafter sent to Khosrow, where he was killed. Khosrow II and the Byzantine general
Narses then penetrated deeper into Bahram's territory, seizing
Dara and then
Mardin in February, where Khosrow was re-proclaimed king. Shortly after this, Khosrow sent one of his Iranian supporters, Mahbodh, to capture Ctesiphon, which he managed to accomplish. At the same time a force of 8,000 Iranians under Vistahm and Vinduyih and 12,000 Armenians under
Mushegh II Mamikonian invaded Adurbadagan. Bahram Chobin tried to disrupt the force by writing a letter to Mushegh II, the letter said: "As for you Armenians who demonstrate an unseasonable loyalty, did not the house of Sasan destroy your land and sovereignty? Why otherwise did your fathers rebel and extricate themselves from their service, fighting up until today for your country?" Bahram Chobin in his letter promised that the Armenians would become partners of the new Iranian empire ruled by a Parthian dynastic family if he accepted his proposal to betray Khosrow II. Mushegh, however, rejected the offer. Bahram Chobin was then defeated at the
Battle of Blarathon, forcing him to flee with 4,000 men eastwards. He marched towards
Nishapur, where he defeated a pursuing army as well as an army led by a
Karenid nobleman at
Qumis. Constantly troubled, he crossed the
Oxus river, where he was received honorably by the Khagan of the Turks, who was most likely Birmudha—the same Turkic prince that Bahram Chobin had defeated and captured a few years earlier during his wars against the Turks. Bahram Chobin entered his service, and was appointed as a commander in the army, achieving further military accomplishments there. Bahram Chobin became a highly popular figure after saving the Khagan from a conspiracy instigated by the latter's brother Byghu (conceivably an incorrect translation of
yabghu). Khosrow II, however, could not feel safe as long as Bahram Chobin lived, and succeeded in having him assassinated. The assassination was reportedly achieved through distribution of presents and bribes between the members of the Turkic royal family, notably the queen. What remained of Bahram Chobin's supporters went back to northern Iran and joined the
rebellion of Vistahm (590/1–596 or 594/5–600). ==Consolidation of the empire==