Iphigenia at Aulis by Euripides

When the Greeks were detained at Aulis by stress of weather, Calchas declared that they would never reach Troy unless the daughter of Agamemnon, Iphigenia, was sacrificed to Diana. Agamemnon sent for his daughter with this view, but repenting, he dispatched a messenger to prevent Clytæmnestra sending her. The messenger being intercepted by Menelaus, an altercation between the brother chieftains arose, during which Iphigenia, who had been tempted with the expectation of being wedded to Achilles, arrived with her mother. The latter, meeting with Achilles, discovered the deception, and Achilles swore to protect her. But Iphigenia, having determined to die nobly on behalf of the Greeks, was snatched away by the Goddess, and a stag substituted in her place. The Greeks were then enabled to set sail.