Bahram Chobin was the most celebrated military commander of his era. His campaigns had brought fame that the Sasanian Shah Hormizd IV apparently could not tolerate. When Hormizd seized on a minor defeat at the Aras River to strip Bahram of his command, the general did not retire quietly. During the summer of 590, backed by loyal veterans, Bahram marched on Ctesiphon. He arrived to find the political landscape already reshuffled: Hormizd had been murdered in a palace coup, and his young son Khosrow II had been placed on the throne. It made no difference. Bahram's army was at the gates, and Khosrow fled. The general proclaimed himself king -- an extraordinary act for a man outside the royal dynasty.

Khosrow did not run far. Together with his uncles Bendoy and Bestam, he sought refuge at the Byzantine court of Emperor Maurice. Here was a chance no Byzantine strategist could refuse: a legitimate Persian claimant, desperate and willing to pay. Maurice agreed to restore Khosrow in exchange for territorial concessions that would have been unthinkable under normal circumstances. He provided an army of 40,000 warriors under generals John Mystacon and Narses. It was one of the largest Byzantine expeditionary forces deployed into Persian territory in living memory. During the summer of 591, this army marched toward Azerbaijan, where 12,000 Armenians under Musel II Mamikonian and 8,000 Persian loyalists under Bendoy and Bestam would join them.

Bahram understood the danger of letting his enemies consolidate. He set out from Ctesiphon with a smaller force, hoping to engage the Byzantines before they linked up with their allies. He arrived too late. Near the ancient city of Ganzak, in the hills of northwestern Persia, the combined armies of Khosrow, Byzantium, and Armenia faced him across a river plain. The fighting lasted three days. On the evening of the third, Bendoy delivered the decisive blow -- not with a sword, but with an offer. He promised pardons and safety to any of Bahram's soldiers who deserted. The tactic shattered what remained of the usurper's army. Bahram's camp was overrun and captured. The general himself escaped eastward with 4,000 men, eventually reaching the court of the Turkish Khagan at Nishapur. He would never return.

Khosrow paid dearly for his restoration. The territorial concessions he had promised to Maurice reshaped the Caucasus. The Sasanians returned the fortress cities of Dara and Martyropolis. They ceded a constellation of Armenian and Georgian strongholds -- Armavir, Manzikert, Ani, Kars, Bagaran, and others -- to Byzantine control. Most of the Kingdom of Iberia, including Mtskheta, Ardahan, and Dmanisi, became Byzantine dependencies. Byzantine influence in the Caucasus reached its historical zenith, a high-water mark that would not be matched until the reign of Basil II four centuries later. For a few decades, this arrangement held. But the seeds of its undoing were already planted: Khosrow's gratitude would not outlast Maurice's reign, and within twenty years, the two empires would plunge into a war so devastating that both would be fatally weakened when the armies of Islam arrived.