(1) Son of Eurysthenes, founder of the royal house of the Agiadae (Pausanias iii. 2.1). His genealogy was traced through Aristodemus, Aristomachus, Cleodaeus and Hyllus to Heracles (Herodotus 7, 204), and he belongs rather to mythology than to history. Tradition ascribed to him the capture of the maritime town of Helos, which resisted his attempt to curtail its guaranteed rights, and the institution of the class of serfs called Helots.
(2) Son of Archidamus II., Eurypontid, commonly called Agis I. He succeeded his father, probably in 427 BC, and from his first invasion of Attica in 425 BC down to the close of the Peloponnesian War was the chief leader of the Spartan operations on land. After the conclusion of the peace of Nicias (421 BC) he marched against the Argives in defence of Epidaurus, and after skilful manoeuvring surrounded the Argive army, and seemed to have victory within his grasp when he unaccountably concluded a four months' truce and withdrew his forces. The Spartans were indignant, and when the Argives and their allies, in flagrant disregard of the truce, took Arcadian Orchomenus and prepared to march on Tegea, their fury knew no bounds, and Agis escaped having his house razed and a fine of 100,000 drachmae imposed only by promising to atone for his error by a signal victory. This promise he brilliantly fulfilled by routing the forces of the Argive confederacy at Mantinea (418), the moral effect of which was out of all proportion to the losses inflicted on the enemy. In the winter 417-416 a further expedition to Argos resulted in the destruction of the half-finished Long Walls and the capture of Hysiae. In 413, on the suggestion of Alcibiades, he fortified Decelea in Attica, where he remained directing operations until, after the battle of Aegospotami (405), he took the leading part in the blockade of Athens, which was ended in spring 404 by the surrender of the city. Subsequently he invaded and ravaged Elis, forcing the Eleans to acknowledge the freedom of their perioeci (citizens of cities conquered by Sparta, who were given some privileges) and to allow Spartans to take part in the Olympic Games and sacrifices. He fell ill on his return from Delphi, where he had gone to dedicate a tithe of the spoils, and, probably in 401, died at Sparta, where he was buried with unparalleled solemnity and pomp.
3) Son of Archidamus III., of the Eurypontid line, commonly called Agis II. 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.
(4) Son of Eudamidas II., of the Eurypontid family, commonly called Agis III. He succeeded his father probably in 245 BC, in his twentieth year. At this time the state had been brought to the brink of ruin by the growth of avarice and luxury; there was a glaring inequality in the distribution of land and wealth, and the number of full citizens had sunk to 700, of whom about 100 practically monopolized the land.
Though reared in the height of luxury he at once determined to restore the traditional institutions of Lycurgus, with the aid of Lysander, a descendant of the victor of Aegospotami, and Mandrocleidas, a man of noted prudence and courage; even his mother, the wealthy Agesistrata, threw herself heartily into the cause. A powerful but not disinterested ally was found in the king's uncle, Agesilaus, who hoped to rid himself of his debts without losing his vast estates.
Lysander as ephor proposed on behalf of Agis that all debts sbould be cancelled and that Laconia should be divided into 19,500 lots, of which 4500 should be given to the Spartans, whose number was to be recruited from the best of the perioeci and other foreigners, and the remaining 15,000 to perioeci who could bear arms. The Agiad king Leonidas having prevailed on the council to reject this measure, though by a majority of only one, was deposed in favour of his son-in-law Cleombrotus, who assisted Agis in bearing down opposition by the threat of force.
The abolition of debts was carried into effect, but the land distribution was put off by Agesilaus on various pretexts. At this point Aratus appealed to Sparta to help the Achaeans in repelling an expected Aetolian attack, and Agis was sent to the Isthmus at the head of an army. In his absence the open violence and extortion of Agesilaus, combined with the popular disappointment at the failure of the agrarian scheme, brought about the restoration of Leonidas and the deposition of Cleombrotus, who took refuge at the temple of Apollo at Taenarum and escaped death only at the entreaty of his wife, Leonidas's daughter Chilonis.
On his return Agis fled to the temple of Athene Chalcioecus at Sparta, but soon afterwards he was treacherously induced to leave his asylum and, after a mockery of a trial, was strangled in prison, his mother and grandmother sharing the same fate (241). Though too weak and good-natured to cope with the problem which confronted him, Agis was characterized by a sincerity of purpose and a blend of youthful modesty with royal dignity, which render him perhaps the most attractive figure in the whole of Spartan history.