Battle of Opis
539 BCE · Opis, Tigris River (modern Iraq)
The Battle of Opis was fought in 539 BCE in Opis, Tigris River (modern Iraq) between Achaemenid Persian Empire vs the Neo-Babylonian Empire; decisive Persian victory that opened the road to Babylon, which fell days later.
Battle of Opis: quick facts
- Date
- 539 BCE
- Location
- Opis, Tigris River (modern Iraq)
- Belligerents
- Achaemenid Persian Empire vs the Neo-Babylonian Empire
- Commanders
- Cyrus the Great vs Nabonidus
- Result
- decisive Persian victory that opened the road to Babylon, which fell days later.
- Era
- 🏛️ Ancient Egypt & Mesopotamia
- Quiz difficulty
- hard
What happened at the Battle of Opis?
Cyrus the Great confronted the Babylonian army under Nabonidus's son Belshazzar at the strategic city of Opis on the Tigris River. The Persians won a decisive victory, and the defeat shattered Babylonian morale. The nearby city of Sippar surrendered without a fight, and Babylon itself fell shortly afterward with minimal resistance. The battle effectively ended the Neo-Babylonian Empire and brought all of Mesopotamia under Persian control, creating the largest empire the world had yet seen.
Did you know?
The Battle of Opis opened the road to Babylon, which fell so quickly afterward that according to the ancient sources, some parts of the city did not even know it had been captured.
Sources and further reading
- Battle of Opis on Wikipedia for the full account, historiography and primary sources.
- How BattleGuess compiles and checks battle facts: see the About page.
Entry last reviewed 26 September 2026.