Here’s what Frank Miller said about Xerxes:
But there is something I don’t really understand. The battle of Marathon was fought between the citizens of Athens and a Persian force commanded by Datis and Artaphernes. It was the culmination of the first attempt by Persia, under King Darius I, to subjugate Greece. But despite the numerical advantage of the Persians, the hoplites proved devastatingly effective against the more lightly armed Persian infantry, routing the wings before turning in on the centre of the Persian line. Darius was Xerxes’ father.
So Xerxes, who is Darius’ son, wasn’t much involved in the battle of Marathon… Or did I miss something?
Anyway hope to get more information more about the movie Xerxes soon!