after which he was adopted by Eumenes I, the incumbent dynast. Attalus' mother, Antiochis, was related to the Seleucid royal family (being a granddaughter of Seleucus I Nicator) with her marriage to Attalus' father likely arranged by Philetaerus to solidify his power. This would be consistent with the conjecture that Attalus' father had been Philetaerus' heir designate, but was succeeded by Eumenes, since Attalus I was too young when his father died. Defeat of the Galatians According to the 2nd century AD Greek writer Pausanias, "the greatest of his achievements" was the defeat of the "Gauls" (). Pausanias was referring to the Galatians, immigrant Celts from Thrace, who had recently settled in Galatia in central Asia Minor, and whom the Romans and Greeks called Gauls, associating them with the Celts of what is now France, Switzerland, and northern Italy. Since the time of Philetaerus, the first Attalid ruler, the Galatians had posed a problem for Pergamon, indeed for all of Asia Minor, by exacting tributes to avoid war or other repercussions. Eumenes I had (probably), along with other rulers, dealt with the Galatians by paying these tributes. Attalus however refused to pay them, being the first such ruler to do so. As a consequence, the Galatians set out to attack Pergamon. Attalus met them near the sources of the river Caïcus and won a decisive victory, after which, following the example of Antiochus I, Attalus took the name of Soter, which means "savior", and claimed the title of king. The victory brought Attalus legendary fame. A story arose, related by Pausanias, of an oracle who had foretold these events a generation earlier: Pausanias adds that by "son of a bull" the oracle "meant Attalus, king of Pergamon, who was styled bull-horned". On the acropolis of Pergamon was erected a triumphal monument, which included the famous sculpture the Dying Gaul, commemorating this battle. Conquests in Seleucid Asia Minor 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