However, they sailed on, till at Aulis they were stopped by foul winds for many days, and Calchas told them it was because of Agamemnon’s broken vow.  He had sworn, one year, to sacrifice to Diana the fairest thing that was born in his house or lands.  The fairest thing that was born was his little daughter Iphigenia; but he could not bear to sacrifice her, and so had tried offering his choicest kid.  Now Diana sent these winds to punish him, and the other kings required him to give up his child.  So a message was sent to her mother, Clytemnestra, to send her, on pretence that she was to be married to Achilles, and when she came to Aulis she found that it was only to be offered up.  However, she resigned herself bravely, and was ready to die for her father and the cause; but just as Agamemnon had his sword ready, and had covered her face that he might not see her pleading eyes as he was slaying her, Diana took pity, darted down in a cloud, and in the place of the maiden a white hind lay on the altar to be offered.  Iphigenia was really carried off to serve as priestess at Diana’s temple at Tauris, but it was long before it was known what had become of her, and Clytemnestra never forgave Agamemnon for what he had intended to do.