Gluck: Iphigenie en Aulide / Iphigenie en Tauride.

Before the Trojan War, Agamemnon gathered the Greek armies at the port of Aulis. The goddess Diane sent unfavorable winds to prevent the Greeks from sailing. Her oracle set a condition for Agamemnon: to earn the right to sail forth and destroy an innocent country, he would have to sacrifice his own daughter. Agamemnon accepted these terms and killed his young daughter Iphigénie on the altar. In his play Iphigenia in Tauris Euripides imagines that Diane plucked Iphigénie from that altar and delivered her to a temple in distant Tauride, where Iphigénie began to serve the enemy Scythians as Diane’s high priestess—all the while Iphigénie’s family believing her dead.