Seleucus II Callinicus
Several years after the first victory over the Gauls, Pergamon was again attacked by the Gauls together with their ally Antiochus Hierax, the younger brother of Seleucus II Callinicus, and ruler of Seleucid Asia Minor from his capital at Sardis. Attalus defeated the Gauls and Antiochus at the Battle of Aphrodisium and again at a second battle in the east. Subsequent battles were fought and won against Antiochus alone: in Hellespontine Phrygia, where Antiochus was perhaps seeking refuge with his father-in law, Ziaelas the king of Bithynia; near Sardis in the spring of 228 BC; and, in the final battle of the campaign, further south in Caria on the banks of the Harpasus, a tributary of the Maeander.