Khosrow II (Khosrow Parvīz), son of Hormizd IV, was proclaimed king in 590 during intense internal conflict, including the challenge of the general Bahrām Chūbīn and a palace revolt that killed Hormizd IV.
A major internal revolt led by Khosrow’s uncle Vistahm destabilized the empire for years; widely cited reconstructions place the rebellion roughly in the early-to-mid 590s, highlighting the factional politics Khosrow faced even after his restoration.
Facing Bahrām Chūbīn’s usurpation, Khosrow fled to Byzantine territory and sought support from Emperor Maurice, setting the stage for Khosrow’s restoration and a major realignment of Roman–Sasanian relations.
With Byzantine military backing, Khosrow defeated Bahrām Chūbīn and regained the throne in 591, concluding a settlement with Byzantium that ended the immediate crisis and restored Khosrow’s rule from Ctesiphon.
Khosrow’s armies pushed deep into Byzantine Syria; Antioch fell by 611, helping open routes toward the southern Levant and further weakening Byzantine defenses in the east.
By 613, Sasanian advances culminated in the capture of Damascus, accelerating the collapse of Byzantine control across the Levant.
In April–May 614, Sasanian forces and allies captured Jerusalem after a siege; major Christian relics, including what was believed to be the True Cross, were taken to Persia, making the war an intense ideological and political crisis for Byzantium.
Sasanian forces reached the Bosporus and held Chalcedon (across from Constantinople), underscoring how far Khosrow’s expansion threatened the Byzantine capital itself.
By 619, Sasanian forces occupied Egypt, a major blow to Byzantine finances and logistics (including grain supply), and a hallmark of the empire’s maximum westward reach under Khosrow II.
After rebuilding Byzantine forces, Emperor Heraclius launched a major counteroffensive in 622, shifting momentum and beginning a sustained campaign that would ultimately break Sasanian military dominance.
In 624–625, Heraclius campaigned in the Caucasus/Transcaucasia, attacking Sasanian-held regions and disrupting Persian strategic depth, helping set conditions for later decisive operations.
In June–July 626, an Avar-led siege coordinated with Sasanian forces at Chalcedon failed, largely because Byzantine naval control prevented effective Persian–Avar coordination across the Bosporus.
On 12 December 627, Heraclius defeated a Sasanian army near Nineveh in a climactic victory that accelerated political collapse around Khosrow II and made continued resistance increasingly untenable.
Khosrow II's Reign and the Empire at its Zenith (590–628)
