Prior to sailing off to war against Troy, Agamemnon had angered the goddess Artemis because he had killed a sacred deer in a sacred grove, and had then boasted that he was a better hunter than she was. When the time came, Artemis stilled the winds so that Agamemnon's fleet could not sail. A prophet named Calchas told him that in order to appease Artemis, Agamemnon would have to sacrifice the most precious thing that had come to his possession in the year he killed the sacred deer. This was his first-born daughter, Iphigenia. He sent word home for her to come (in some versions of the story on the pretense that she was to be married to Achilles). Iphigenia accepted her father's choice and was honored to be a part of the war. Clytemnestra tried to stop Iphigenia but was sent away. After doing the deed, Agamemnon's fleet was able to get under way.