cities of perioecic status. In 420, Elis left the League because Sparta recognised the independence of perioecic Lepreon. Sparta had to wait until the end of the Peloponnesian War to turn against Elis in the Elean War c.400. Victorious, Sparta forced Elis back into the league, as well as to release all its perioecic cities, which presumably formed two federal states and joined the Peloponnesian League. Elis defected again in 370 after Leuctra. Mantinea defected from the League in 421, but rejoined after its defeat against Sparta in 418. It left again after Leuctra to found the Arcadian League. Orchomenus (Arcadian) was forced to temporarily defect in 418 by the coalition of Elis, Mantinea, Argos and Athens, but rejoined after the battle of Mantinea. The situation in the rest of Arcadia is difficult to track, with many small communities organised in tribes and leagues of their own. However, all of these communities were members of the Peloponnesian League, which they left in 370 to found the Arcadian League around the city of Megalopolis. Later additions (after c.504 BC) Mycenae joined after the battle of Sepeia in 494, when Argos was defeated by Sparta. However, c.460 Argos took advantage of the Helot Revolt in Sparta to reconquer and destroy Mycenae. Tiryns probably joined after Sepeia in 494. It was recaptured some years after 468 and destroyed. The Boeotian League was already an ally of Sparta at the end of the 6th century, but apparently not a member of the Peloponnesian League. It more probably joined the League in the years between the Thirty Years' Peace in 446 and the beginning of the Peloponnesian war in 431, "as a single unit". Thebes and other members of the Boeotian League left in 395 at the beginning of the Corinthian War (398–387), of which Thebes was a key player against Sparta. Thebes likely returned to the League after the King's Peace of 387. Thebes left the Peloponnesian League for good in 378. The Phocians probably joined the league as a single unit at the same time as the Boeotians, between 446 and 431. The Eastern Locrians probably joined the league as a single unit at the same time as the Boeotians, between 446 and 431. The Acarnanian cities of Ambracia, Leucas, and Anactorium, possibly joined between 446 and 431. They certainly joined the League in 389/8, after their defeat against Sparta. They left in