As Spartan warriors refused to drop their weapons, the battle soon began. Spartans used the Hot Gates to their advantage as well as their superior fighting skills to take down many rows of the Persian army. During the battle, Xerxes personally approached Leonidas and tried to get him to surrender bribing him with wealth and power, but Leonidas acted as any Spartan would and declined. As Xerxes kept sending more waves of armies, including war elephants, Spartans continue to defeat their enemy. In the meantime, Ephialtes reveals a secret goat path to Xerxes in exchange for wealth and women. Once Arcadians learned of Ephialtes betrayal, they retreat, but the Spartan army stayed as Leonidas ordered injured but reluctant Dilios to return to Sparta to tell them what had happened, a "tale of victory". In Sparta, the Queen was influenced by the Spartan Council to send help to the battling 300 men. A corrupt Spartan politician, Theron, claimed to own the council then threatened the Queen and forced sexual demands in return for his help. After Theron disgraces the Queen in front of the council, she kills him in anger. As the Queen killed Theron, bags of Xerxes' gold falls from his robe showing his betrayal to the entire Spartan Council. Back in Thermopylae, the Persians, led by Ephialtes through the secret path, surrounded the Spartans. Xerxes general again demands surrender from Leonidas as he kneels in submission to allow Stelios to leap over him and kill the general. Xerxes orders his army to attack just as Leonidas throws a spear just missing Xerxes, the cut across his face reveals the God-Kings mortality. Leonidas and his army fight to the last man until they finally buckle to an arrow barrage. At the end of the movie, it showed a larger Greek army, led by about 10,000 Spartans, heading to take on the Persians inspired by King Leonidas.
The directors purpose of 300 is to show a glimpse of what the Battle of Thermopylae was like.