Agamemnon gathered the reluctant Greek forces to sail for Troy. Preparing to depart from Aulis, which was a port in Boeotia, Agamemnon's army incurred the wrath of the goddess Artemis.

There are several reasons for such wrath: in Aeschylus' play Agamemnon, Artemis is angry for the young men who will die at Troy, whereas in Sophocles' Electra, Agamemnon has slain an animal sacred to Artemis in her sacred forest, and subsequently boasted that he was Artemis' equal in hunting.

Confronted by the goddess for his transgression, Agamemnon bargains for his own life to be spared, promising the goddess that he will sacrifice instead the next living creature he encounters -- which he is horrified to find is his own daughter Iphigenia.