Achilles is the mortal son of the Nereid Thetis and the mortal Peleus. The Trojan War started because Paris decided who was worthy of the golden apple, and he picked a goddess. The Trojans were not happy about this, which lead to the war. Achilles was the greatest warrior in the Trojan War, fighting with the Greeks. The orcales prophesied that if Achilles fought in the war he would die.