Achilles among the daughters of Lycomedes

Apollodorus - The Library
The early life of Achilles

When Achilles was nine years old, Calchas declared that Troy could not be taken without him, but Thetis - who knew in advance that he was fated to be killed if he joined the expedition - disguised him in woman's clothing and entrusted him to Lycomedes in the semblance of a young girl.

While he was growing up at his court, Achilles had intercourse with Deidamia, the daughter of Lycomedes, and a son, Pyrrhos, was born to him, who was later called Neoptolemus.

Achilles' whereabouts were betrayed, however, and Odysseus, searching for him at the court of Lycomedes, discovered him by causing a trumpet to be sounded.

And so it came about that Achilles went to Troy.