Agesilaus II, king of Sparta, of the Eurypontid family, was the son of Archidamus II and Eupolia, and younger step-brother of Agis II, whom he succeeded about 401 BC. Agis had, indeed, a son Leotychides, but he was set aside as illegitimate, current rumour representing him as the son of Alcibiades. Agesilaus' success was largely due to Lysander, who hoped to find in him a willing tool for the furtherance of his political designs; in this hope, however, Lysander was disappointed, and the increasing power of Agesilaus soon led to his downfall. In 396 BC Agesilaus was sent to Asia with a force of 2000 Neodamodes (enfranchized Helots) and 6000 allies to secure the Greek cities against a Persian attack. On the eve of sailing from Aulis he attempted to offer a sacrifice, as Agamemnon had done before the Trojan expedition, but the Thebans intervened to prevent it, an insult for which he never forgave them. On his arrival at Ephesus a three months' truce was concluded with Tissaphernes, the satrap of Lydia and Caria, but negotiations conducted during that time proved fruitless, and on its termination Agesilaus raided Phrygia, where he easily won immense booty since Tissaphernes had concentrated his troops in Caria. After spending the winter in organizing a cavalry force, he made a successful incursion into Lydia in the spring of 395 BC. Tithraustes was thereupon sent to replace Tissaphernes, who paid with his life for his continued failure. An armistice was concluded between Tithraustes and Agesilaus, who left the southern satrapy and again invaded Phrygia, which he ravaged until the following spring. He then came to an agreement with the satrap Pharnabazus and once more turned southward. It was said that he was planning a campaign in the interior, or even an attack on Artaxerxes himself, when he was recalled to Greece owing to the war between Sparta and the combined forces of Athens, Thebes, Corinth, Argos and several minor states. A rapid march through Thrace and Macedonia brought him to Thessaly, where he repulsed the Thessalian cavalry who tried to impede him. Reinforced by Phocian and Orchomenian troops and a Spartan army, he met the confederate forces at Coronea in Boeotia, and in a hotly contested battle was technically victorious, but the success was a barren one and he had to retire by way of Delphi to the Peloponnese. Shortly before this battle the Spartan navy, of which he had received the supreme command, was totally defeated off Cnidus by a powerful Persian fleet under Conon and Pharnabazus.
Subsequently Agesilaus took a prominent part in the Corinthian war, making several successful expeditions into Corinthian territory and capturing Lechaeum and Piraeum. The loss, however, of a mora, destroyed by Iphicrates, neutralized these successes, and Agesilaus returned to Sparta. In 389 he conducted a campaign in Acarnania, but two years later the Peace of Antalcidas, warmly supported by Agesilaus, put an end to hostilities. When war broke out afresh with Thebes the king twice invaded Boeotia (378, 377), and it was on his advice that Cleombrotus was ordered to march against Thebes in 371. Cleombrotus was defeated at Leuctra and the Spartan supremacy overthrown. In 370 Agesilaus tried to restore Spartan prestige by an invasion of Mantinean territory, and his prudence and heroism saved Sparta when her enemies, led by Epaminondas, penetrated Laconia that same year, and again in 362 when they all but succeeded in seizing the city by a rapid and unexpected march. The battle of Mantinea (362), in which Agesilaus took no part, was followed by a general peace: Sparta, however, stood aloof, hoping even yet to recover her supremacy. In order to gain money for prosecuting the war Agesilaus had supported the revolted satraps, and in 361 he went to Egypt at the head of a mercenary force to aid Tachos against Persia. He soon transferred his services to Tachos's cousin and rival Nectanabis, who, in return for his help, gave him a sum of over 200 talents. On his way home Agesilaus died at the age of 84, after a reign of some 41 years.
Agesilaus was of small stature and unimpressive appearance, and was somewhat lame from birth. These facts were used as an argument against his succession, an oracle having warned Sparta against a "lame reign." He was a successful leader in guerilla warfare, alert and quick, yet cautious--a man, moreover, whose personal bravery was unquestioned. As a statesman he won himself both enthusiastic adherents and bitter enemies, but of his patriotism there can be no doubt. He lived in the most frugal style alike at home and in the field, and though his campaigns were undertaken largely to secure booty, he was content to enrich the state and his friends and to return as poor as he had set forth. The worst trait in his character is his implacable hatred of Thebes, which led directly to the battle of Leuctra and Sparta's fall from her position of supremacy.