Xerxes
Part of this story is told through the point of view of Xerxes, the Persian King in charge of the army invading Greece. Although he wasn't actually there supervising the army, he was notified by messengers whenever something went wrong. Xerxes was known for being strong and powerful, but this book fictionally reveals some of his emotional weaknesses when it comes to battle.
The Persian Army
Two million strong, there is no way that one could give a detailed list of everyone in the Persian army. But, because they worked almost as one, they were like their own character. They were said to have been completely defeated by the Spartans, but this is merely a myth. It is true, however, that the Persian army was not equipped with weapons as sophisticated as those that the opposing Spartans used in battle.
The Spartans
About three hundred of them all together, the Spartan army was trained from youth to fight. Native to the Greek city-state of Sparta, the Spartans were originally enemies with Greece. However, they became allies when it came ot the Battle of Thermopolylae, and Sparta and Athens fought the strong Persians. It is said that the group of three hundred Spartans defeated the Persians by themselves, but this is likely far from the truth. It is true, however, that had Greece not won this battle and those like it, that world history would have taken a completely different course.