Historical background: In 480 BC, King Xerxes I of Persia commanded 500,000 troops and 1000 warships to attack Greece on a large scale. All the way south to the demobilization channel. The powerful Xerxes I also sent a letter of surrender to the Greek city-state, hoping that the small country would surrender without a fight. This naturally includes Sparta. As a result, Xue Xisi's emissary suffered greatly in the resistance of many Greeks. The messenger to Sparta was also killed. At this time, in order to resist the strong enemy, the brave Spartan King Leonidas led 300 Spartans and friendly troops who wanted to join on the road, and took the lead in heading for the hot spring pass, ready to rely on favorable terrain to resist hundreds of thousands of troops.

Since then, the Spartan army, together with friendly forces, has defeated the Persian army several times in a row, and its morale has greatly increased.

However, the Persian army, led by a deformed man who once wanted to take refuge in the Spartan army, went around the back through a secret passage. At this time, the Spartan army faced great challenges, so the friendly forces also withdrew from the battle and left the hot spring pass. Entrusted by Leonidas, Delios, a comrade-in-arms, left the hot spring pass and set foot on the road back to Sparta.