“[The movie Xerxes] takes on the exact same three days as Thermopylae. There was a sea battle, called the Battle of Artemisium. And in that battle the Persian fleet met a small fleet of Greek ships and over three days they battled. In the same exact three days. Even though the Greek fleet was destroyed, the Persians were turned back from that advance. It’s a similar story. It centers around a character called Themistocles, who really was a democratic and free cat from Athens who was into true democracy, not Spartan democracy. So, it’s his story. He survives that battle, unlike Leonidas, and is able to regroup his forces at Salamis. And Salamis is at the end of the movie where Salamis is the final defeat of the Persian fleet. It kind of starts a bit before ‘300’ and goes a little passed that.”
Director Zack Snyder
Director Zack Snyder also added that the movie Xerxes will keep the visual style of 300.