| Conflict: | Battle of the Harpasus |
| Date: | 229 BC |
| Place: | Harpasus river, Caria (modern-day Turkey) |
| Result: | Pergamese victory |
| Combatant1: | Kingdom of Pergamon |
| Combatant2: | Seleucid Empire |
| Commander1: | Attalus I |
| Commander2: | Antiochus Hierax |
The Battle of the Harpasus was fought in 229 BC between the Pergamese and Seleucid armies on the banks of the Harpasus River, a tributary of the Maeander River in Caria. The battle on the Harpasus was the last battle of the war between King Attalus I of Pergamon and the Seleucid prince Antiochus Hierax over dominion of western Anatolia.[1] Attalus won a decisive victory and Hierax started a failed campaign in Mesopotamia that would lead to his defeat and later death at Egypt.[2]