Agesilaus, king of Sparta, was the son of Archidamus II., and the successor of Agis II. in 898 B. 0. He was not the legitimate heir to the throne, but Leotychides, his nephew, being suspected of illegitimacy, was set aside on the death of Agis, by the influence of Lysander, and Agesilaus substituted for him. Agesilaus, having received only the ordinary education of a Spartan citizen, was very popular with the mass of his countrymen, but he was lame and of small stature. Objection was made to him on this ground when Lysander, the conqueror of Athens, proposed him for the succession, and an augur prophesied against him. Lysander replied that a lame-footed king was better than a man who was not of pure Heraclidan blood. Agesilaus submitted to the restraints of a constitutional king and paid court to the ephori. Soon after his accession an expedition against Persia was determined upon. Agesilaus, accompanied by Lysander, accepted the command, and was placed at the head of the council of war. He burst into Asia Minor, 396 B. C, and forced Tissaphernes, the Persian satrap, to beg for a three months' truce, which was sworn to by both parties. It was treacherously broken by Tissaphernes, but kept by Agesilaus from considerations both of principle and policy.

After many successes in Asia Minor, he marched his army into the government of the satrap Pharnabazus. In a two years' campaign he brought his troops into the highest state of efficiency, and never allowed them to desecrate the temples of the foreign gods. Having overcome all the satraps in the neighborhood, Agesilaus conceived the gigantic scheme of penetrating to the heart of the Persian empire, and meeting the king of Persia face to face, as Alexander afterward did. The money of the Persian monarch, freely used in Athens and Thebes, had meantime stirred up in Greece itself a coalition against Sparta and her allies, and the ephori sent a messenger to Agesilaus recalling him. He returned from Asia Minor by way of the Hellespont through Thrace, Macedonia, and Thessaly, fighting his way when he was opposed, and making the march in 30 days. Xenophon accompanied him. He met the anti-Spartan allies at Coro-nea in Bœotia (391), and won a well contested battle, in which he was severely wounded and many of his choice body guard of Spartans were slain.

He regretted the Corinthian war, because it weakened in a fratricidal struggle those forces which, in his opinion, should have been turned against Persia. His bitter animosity against Thebes led him to screen and support Phoebidas, the Spartan who treacherously seized the citadel of Thebes; and he also saved the life of Sphodrias, who made an equally unprincipled but less successful attempt upon the Piraeus. This conduct to states with which Sparta was at peace united Thebes and Athens, and they jointly declared war against the Lacedaemonians. Agesilaus was not present at the defeat of Leuctra (371), after which his state never regained its ancient ascendancy; but he defended the city of Sparta with success against Epaminondas and his allied army. His son Archidamus soon afterward gained an easy victory over the Arcadians, which revived the drooping courage of the Lacedaemonians. The impoverished condition of Sparta after Leuctra was partly remedied by the benefactions of Agesilaus, who gave up to the state all the money and presents which he had received from various oriental potentates. The last scene of his life was held by the Greeks to have been unworthy of his renown. He agreed to aid Tachos, an Egyptian revolter against the Persian monarch, with a band of Laconian mercenaries.

When he landed he slept on the shore on straw and under the open sky, though more than 80 years old. The Egyptians could hardly believe that the ill-clad, mean-looking little old man whom they saw before them was he who once held the destinies of Greece and Persia in his hands. Tachos would not give him the supreme control of the land forces, but offered him the post of second in command after himself. This disgusted the old soldier, and when Nectanabis revolted from Tachos he declared for the former. Nectanabis subjected him to new humiliations, but Agesilaus rescued him from a perilous position, and seated him firmly in power. The Egyptian gave him 220 talents for his services, with which he, in the winter of 361-360, hastened homeward to lay them at the feet of his beloved Sparta, then engaged in war. He never reached home, but died on the coast of Africa, whither he had been driven by a tempest, at the age of about 80, after a reign of 38 years. His body was embalmed in melted wax and taken to Sparta, where he was splendidly buried.