Contemporary sources and modern historiography present a mixed view of Kavad II, with some of the latter criticizing him for his fratricide, considering it to have heavy consequences for the empire.

However, Byzantine sources do not report that Maurice had a daughter named Maria, much less that he gave her in marriage to a member of the Sasanian dynasty.

During the two-decade war, Khosrow II was initially successful, conquering the Byzantine provinces in the Near East, including Egypt.

[7] However, by 627 the tables had turned against the Sasanians, with the Byzantine emperor Heraclius (r. 610–641) seizing chunks of Adurbadagan (in present-day northwestern Iran) and laying waste to the temple of Adur Gushnasp.

[6] The nobles had grown weary of Khosrow II's policies, with some of them possibly already starting to form an opposition against him following the failed siege of Constantinople in 626.

Sheroe soon sent a letter, in which he promised to replace Khosrow II as the shahanshah, make peace with the Byzantines and the Western Turkic Khaganate, and increase the rank of the conspirators and the income of the army.

[3] Having convinced the conspirators with his letter, Sheroe continued to correspond with them through his foster brother, who made it possible for the two parties to plan their actions for the upcoming coup d'état.

[14] The palace guards were made aware of the situation by the ruckus coming from Veh-Ardashir, and several of them crossed the bridge to join the rebels.

After consolidating his position, Kavad II had turned to the Sasanian Empire's most influential constituency—the noble estate—for formal permission to begin peace negotiations with the Byzantines.

This was easily gained, as the coup against Khosrow II owed its success to the extensive war-weariness and vehement dissatisfaction at many of the policies implemented in order to prolong the war effort.

Arguments could be made in favor of all of the several frontiers that had separated their lands since the resurgence of Iranian authority in the middle of the 3rd-century, due to the lack of any evident topographical, ethnic, or cultural line of boundary south or north of the Armenian Taurus Mountains.

By using the word "brother", Kavad II made it clear right away that he acknowledged the Byzantine Empire as legitimate and equals of Iran.

Kavad II was doing everything in his power to avoid supporting the idea that the war had been a religious conflict by omitting mention of the divinities in Zoroastrianism.

[29] He claimed that he intended to free every individual held in jail, including political opponents of his father and prisoners of war, as a sign of his commitment to doing whatever could be helpful and in the service of mankind.

Instead, Chosdaï had to relay the Sasanian offer to withdraw from Byzantine territory verbally, and Heraclius had to respond in writing with precise suggestions on how to fix the borders.

[30] The English historian James Howard-Johnston suggests that the rest of Heraclius' letter was a general statement, in which he said that he was prepared to make peace, along with some indication of what he thought should be a fair boundary to draw between the two empires.

The Byzantine writer Nikephoros I claims that in the letter Heraclius called Kavad II his "son," thus declaring superiority over the Sasanian Empire.

Howard-Johnston dismisses this claim, amongst other things arguing that due to the weakened Byzantine military, Heraclius was in no position to make such an assertion.

He gave orders for a letter to be written, telling Shahrbaraz to assemble his troops and head back to Iranian land, which he refused.

[32] However, the Iranologist Parvaneh Pourshariati suggests that Shahrbaraz's noncompliance was due to his concern of the collaboration of the other factions of Iran, who were managing the affairs of the state while he was still in Byzantine territory.

However, for the time being, Heraclius and his men could march home in peace, assured that the protracted conflict was finished, while the Iranian military could start preparing operations against the Turks in the South Caucasus.

According to the modern historian Michael Bonner, epidemic sickness would have quickly swept throughout Mesopotamia's crowded and densely populated communities.

He died in late summer or early autumn,[36] and was succeeded by his seven-year-old son Ardashir III, who was supervised by Mah-Adhur Gushnasp as his regent.

[6] A passage of the Chronicle of Edessa identifies "Anzoy the Roman" as the wife of Kavad II and mother of Ardashir III.

[40] According to Guidi's Chronicle, Boran was also Kavad II's wife, demonstrating the practice in Zoroastrianism of Xwedodah, or close-kin marriage.

This may have caused a growing disconnection between the army and the shahanshah, which gave military commanders (such as Bahram Chobin and Shahrbaraz) the opportunity to challenge the shahanshah—something which never happened in earlier Sasanian history.

[44] Some sources such as al-Tabari consider Kavad II to be a bad ruler, while others such as the Chronicle of Seert paint a more favorable picture of him.

[6] Schindel suggests that if Kavad II had lived longer, he might had been able to prevent the disintegration of the Sasanian political structure and the impending Arab-Islamic conquest of Iran.

The Jews of Palestine had great hopes for a Messianic verdict in history when the Iranians took control of Jerusalem, and thus despised Kavad II for his murder of his father and subsequent peace with Heraclius.