Philoctetes
Many years afterwards, Philoctetes came with seven ships to join the Greek armada which Agamemnon led against Troy. An oracle had enjoined that, in the course of their voyage, the Greeks should offer sacrifice to a deity named Chryse, whose altar was on a small island in the Aegean. Philoctetes alone knew where this altar was; he had once visited it in company with Heracles: and he guided the Greeks thither. The altar of Chryse stood in a sacred precinct under the open sky. As Philoctetes approached it, followed by the Greek chiefs, he was bitten in the foot by a serpent. - Taken from "Philoctetes" written by Sophocles