Attalus of Pergamon, ostensibly a vassal-ally of the dominant Seleucid dynasty, to which he is distantly related, consolidates power in western Anatolia.

Proving both a strong protector of the Greek cities of Anatolia and an opportunist in trying to expand Pergamon's territory and power, Attalus scores a major victory over the Galatians, the Celtic or Gaulish people of parts of Anatolia.

The Dying Gaul—also called The Dying Galatian or The Dying Gladiator—an ancient Roman marble copy of a lost Hellenistic sculpture thought to have been executed in bronze, may have been commissioned some time between 230 and 220 BCE by Attalus to celebrate his victory.

Several years after the first victory over the Gauls, Pergamon had again been 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 had defeated the Gauls and Antiochus at the battle of Aphrodisium and again at a second battle in the East.

Subsequent battles are fought and won against Antiochus alone: in Hellespontine Phrygia, where Antiochus is perhaps seeking refuge with his father-in law, Ziaelas the king of Bithynia; near Sardis in the spring of 228 BCE; and, in the final battle of the campaign, further south in Caria on the banks of the Harpasus, a tributary of the Maeander.

Attalus, as a result of these victories, gains control over all of Seleucid Asia Minor north of the Taurus Mountains.

He is able to hold onto these gains in the face of repeated attempts by Seleucus III Ceraunus, eldest son and successor of Seleucus II, to recover the lost territory, culminating in Seleucus III himself crossing the Taurus, only to be assassinated in 223 BCE by members of his army.

Achaeus, who had accompanied Seleucus III, had assumed control of the army.

He is offered and refuses the kingship in favor of Seleucus III's younger brother Antiochus III the Great, who then makes Achaeus governor of Seleucid Asia Minor north of the Taurus.

Achaeus within two years recovers all the lost Seleucid territories and assumes the title of king.