Meanwhile Paris' sister Cassandra was faced with trouble. Apollo gave her the gift of prophecy while trying to make love to her, but she had taken a vow of chastity and resisted him. In anger Apollo turned his gift into a curse by making it so that no one would believe her. When Paris returned with Helen and stood before Priam to get his father's acceptance Cassandra came into the room, visualized all that would occur because of Paris and his lust, gave shrieks of despair, and railed at her immoral brother. Thinking Cassandra mad, Priam had his daughter locked in a palace cell.
When Menelaus returned to Sparta and found his wife Helen gone, he summoned the Greek leaders to go with him to conquer Troy and recover Helen. These leaders were pledged to aid Menelaus, for as they had courted Helen too they had taken an oath to avenge any dishonor that fell upon her future husband because of her. Thus Paris precipitated the Trojan War, which would fulfill the prophetic dream his mother had of giving birth to a firebrand that would destroy Troy.
The Greek chieftains assembled at Aulis under the leadership of Agamemnon, the brother of Menelaus. Most of the warriors were glad to go, eager to burn and sack Troy. But two heroes were reluctant. An oracle told Odysseus that he would be twenty years from home if he went, so he feigned madness when the Greek leaders came for him. Palamedes exposed the ruse, and Odysseus had to go. Since Troy could not be taken without the help of Achilles, the Greeks went to Scyros to fetch him. Achilles was practically invulnerable as a fighter, for his mother, the nymph Thetis, had dipped him in the River Styx at birth, rendering him immortal everywhere but in his heel, where she had held him. Tutored by Chiron, he became an incredibly swift and fearsome warrior. Knowing he would have a short but glorious life if he went to Troy, Thetis disguised her valiant son in women's clothing at the Scyrian court. However, Odysseus discovered Achilles by a trick, and he too consented to go.
