Son of Archidamus III., of the Eurypontid line, commonly called Agis III. He succeeded his father in 338 BC, on the very day of the battle of Chaeronea. During Alexander's Asiatic campaign he revolted against Macedonia (333 BC) and, with the aid of Persian money and ships and a force of 8000 Greek mercenaries, gained considerable successes in Crete. In the Peloponnese he routed a force under Corragus and, although Athens held aloof, he was joined by Elis, Achaea (except Pellene ) and Arcadia, with the exception of Megalopolis, which the allies besieged. Antipater marched rapidly to its relief at the head of a large army, and the allied force was defeated after a desperate struggle (331) and Agis was slain.