Cunaxa (kyōōnăk´sə), ancient town of Babylonia, near the Euphrates River, NE of Ctesiphon. It was the scene of a battle (401 BC) between Cyrus the Younger and Artaxerxes II, described by Xenophon in the Anabasis.Clearchus, Spartan mercenary leader under Cyrus, chose to attack the Persian left wing (under Tissaphernes), which he completely routed and pursued. When he and his Ten Thousand returned, they found that Cyrus had fought hard in the center, had broken Artaxerxes' bodyguard, but in the moment of victory had been killed. Cyrus' army, demoralized, had broken up, and the Persians had taken the field. The retreat of the Ten Thousand northward is the most famous feature of the campaign.