Plutarch, Quaestiones Graecae
Frank Cole Babbitt, Ed.

Why is it that among the Coans the priest of Heracles at Antimacheia dons a woman's garb, and [p. 247] fastens upon his head a woman's head-dress before he begins the sacrifice?

Heracles, putting out with his six ships from Troy, encountered a storm ; and when his other ships had been destroyed, with the only one remaining he was driven by the gale to Cos. He was cast ashore upon the Laceter, as the place is called, with nothing salvaged save his arms and his men. Now he happened upon some sheep and asked for one ram from the shepherd. This man, whose name was Antagoras, was in the prime of bodily strength, and bade Heracles wrestle with him ; if Heracles could throw him, he might carry off the ram. And when Heracles grappled with him, the Meropes came to the aid of Antagoras, and the Greeks to help Heracles, and they were soon engaged in a mighty battle. In the struggle it is said that Heracles, being exhausted by the multitude of his adversaries, fled to the house of a Thracian woman ; there, disguising himself in feminine garb, he managed to escape detection. But later, when he had overcome the Meropes in another encounter, and had been purified, he married Chalciopê and assumed a gay-coloured raiment. Wherefore the priest sacrifices on the spot where it came about that the battle was fought, and bridegrooms wear feminine raiment when they welcome their brides.