Plutarch, Quaestiones Graecae
Frank Cole Babbitt, Ed.

Why do the people of Tanagra have before their city an Achilleum, that is, a place bearing this name? For it is related that Achilles actually had more enmity than friendship for the city, since he carried off Stratonicê, the mother of Poemander, and slew Acestor, the son of Ephippus.¹

While the territory of Tanagra was still inhabited in village communities, Poemander, the father of Ephippus, had been besieged by the Achaeans in the place called Stephon, because of his unwillingness to join their expedition.² But he abandoned that stronghold by night and fortified Poemandria.³ [p. 221] Polycrithus the master-builder, however, who was present, spoke slightingly of the fortifications and, in derision, leaped over the moat. Poemander was enraged and hastened to throw at him a great stone which had been hidden there from ancient days, set aside for use in the ritual of the Nyctelia.⁴ This stone Poemander snatched up in his ignorance, and hurled. He missed Polycrithus, but slew his son Leucippus. According to the law, therefore, he had to depart from Boeotia and become a suppliant at a stranger's hearth. But this was not easy, since the Achaeans had invaded the territory of Tanagra. Accordingly he sent his son Ephippus to appeal to Achilles. Ephippus, by his persuasive words, brought to his father Achilles, as well as Tlepolemus, the son of Heracles, and Peneleös, the son of Hippalcmas, all of them interrelated. Poemander was escorted by them to Chalcis, and there at the house of Elephenor he was purified of the murder. Therefore he honoured these heroes and set apart sacred precincts for them all, and of these the precinct of Achilles has still kept its name.