Paris heard about Helen while he was in Troy after rejoining his family. Helen married King Menelaus in Sparta, but Paris heard of her, went to Sparta, and convinced her to run off with him. She was the wife Aphrodite had promised him.
King Melaneus came back to the palace after a hunting trip and found Helen to be missing. To find her, he called on the kings of other lands to help him. Achilles was not with the other war leaders though.
Thetis dipped Achilles in the River Styx as a baby so he would be protected from death in battle. A small part of his ankle wasn’t protected though because that was where Thetis was holding him in the water.
No. You have to be safe.
You have to stay for your protection.
I want to go to battle though.
Thetis was scared for Achilles because of his ankle. When the king called for him to find Helen, Thetis sent him to be disguised as a princess among the princesses on the Island of Sycros.
The Greek Army needed Achilles to win the war, so Odysseus went to the island with a pack of gifts for the princesses, including Achilles. In the pack was a huge, golden sword for Achilles, which he grabbed.