Antiochus Hierax, supported by his mother Laodice I, allies himself with the Galatians (Celts) and two other states that are traditional foes of the Seleucid kingdom. With the aid of these forces, he inflicts a crushing defeat on his older brother Seleucus II's army at Ancyra in Anatolia. Seleucus leaves the country beyond the Taurus Mountains to his brother and the other powers of the peninsula.