the elder son of Archidamus III., was the 20th king of the Eurypontid line. His reign was short, but eventful. He succeeded his father in B. C. 388. In B. C. 333, we find him going with a single trireme to the Persian commanders in the Aegean, Pharnabazus and Autophradates, to request money and an armament for carrying on hostile operations against Alexander in Greece. They gave him 30 talents and 10 triremes. The news of the battle of Issus, however, put a check upon their plans. He sent the galleys to his brother Agesilaus, with instructions to sail with them to Crete, that he might secure that island for the Spartan interest. In this he seems in a great measure to have succeeded. Two years afterwards (B. C. 331), the Greek states which were leagued together against Alexander, seized the opportunity of the disaster of Zopyrion and the revolt of the Thracians, to declare war against Macedonia. Agis was invested with the command, and with the Lacedaemonian troops, and a body of 8000 Greek mercenaries, who had been present at the battle of Issus, gained a decisive victory over a Macedonian army under Corragus. Having been joined by the other forces of the league he laid siege to Megalopolis. The city held out till Antipater came to its relief, when a battle ensued, in which Agis was defeated and killed. It happened about the time of the battle of Arbela. (Arrian, 2.13 ; Diod. 16.63, 68, 17.62; Aesch. c. Ctesiph. p. 77; Curt. 6.1; Justin, 12.1.)