Achilles was born in Ancient Greece to Peleus, the King of the Myrmidons, and Thetis. In an attempt to make Achilles invulnerable, Thetis dipped him in the River Styx, but accidentally left a small part of his heel exposed, which later became his vulnerability. Before the Trojan War, Achilles received a prophecy predicting that if he participated in the war, he would become the most formidable warrior, killing many enemies including the Trojan prince Hector. However, the prophecy also foretold that he would die at the age of 25 by an arrow to his heel. Alternatively, if he decided not to join the war, he could remain in his kingdom as a prince and eventually die of old age.