Iphigenia at Aulis is the last play written by the Greek Playwright Euripides and describes the scene in Greece before the armies of Agamemnon and Menelaus before they depart for the battle for Helen in Troy.
This play is one of the best Greek Tragedies in my opinion, but is considered to be one of Euripides' worst. The play shows us how the Greeks really believed in seers and how because the seer Calchas says that a sacrifice is needed for good wind to guide the fleets on to Troy. The sacrifice that is required is Agamemnon's daugter Iphigenia who is lured to Aulis under the false pretense of an impending marriage to Achilles.
Agamemnon changes his mind and the message that he sends to his wife Clytemnestra does not reach her warning of the real reason for summoning Iphigenia. When Iphigenia and her mother get to Aulis and she learns the true tragedy of her fate, she is first upset and does not understand why it has to happen, but then in the twist that makes it a true tragedy, she accepts her fate, that she has to be a sacrifice and shed her blood for the good of her country.
This play can be seen as the interlude to Aeschylus' The Oresteia.