| Conflict: | Battle of Ganzak |
| Partof: | the Byzantine–Sasanian War of 602–628 |
| Date: | June 624 |
| Place: | Ganzak |
| Result: | Byzantine victory |
| Combatant1: | Byzantine Empire |
| Combatant2: | Sasanian Empire |
| Commander1: | Heraclius |
| Commander2: | Khosrow II |
| Strength1: | unknown |
| Strength2: | 40,000 |
| Casualties1: | unknown |
| Casualties2: | unknown |
The Battle of Ganzak was a clash between the Byzantine and Sasanian armies. The emperors of both empires personally took part in this battle. As a result, the Persians suffered a crushing defeat, and Khosrow fled leaving his army. As a result of this, Heraclius was able to move deeper into Persia.
After Khosrow refused the peace treaty, sending an insulting letter in response. Using Khosrow's letter as a tool of inspiration and propaganda for his army, Heraclius marched on Caucasus. Already on the way, he learned that Khosrow was with 40,000 soldiers in Ganzak.
Khosrow's letter looked like this:
Heraclius sent the faithful Arabs forward, who defeated the guards of the Sasanian king. After this, Khosrow fled to the south, and Heraclius killed the remnants of his troops.
Khosrow fled south to Dastagard, where his army finally dispersed. At this time, Heraclius took Ganzak, and after that he burned the famous temple Takht-i-Suleiman. Heraclius raided the region of Atrpatakan, as far as the King's residence at Gayshawan and continued his campaign.