 Achille, unaware of these events, cannot be dissuaded from his wish to marry Iphigénie and leave for Troy, even though it has been predicted that he will die there.In Achille's absence, Ulysse convinces Agamemnon that his daughter's sacrifice is necessary to avenge the honour of Helen of Troy and for the eternal glory of Greece.The arrival is announced of Clytemnestre and Iphigénie with Eriphile, a young girl in their charge, captured by Achille on the island of Lesbos, an ally of Troy