The film was known as 300: The Battle of Artemisia for a while, and was originally thought to be based on Frank Miller’s upcoming Dark Horse miniseries Xerxes (itself a follow-up to his 1998 comic 300). Now we know that the film, which was written by 300 director Zack Snyder and Kurt Johnstad, takes place around the same time as the original, and sees Themistokles and his common-man soldiers facing off on the water against the Persian forces.