[2] In 2018, Dark Horse published Xerxes: The Fall of the House of Darius and the Rise of Alexander, also written and drawn by Miller, acting as a prequel and sequel to the events of 300, depicting Xerxes I's rise to the throne, and the subsequent destruction of the Persian Empire under his descendant Darius III, by Alexander the Great.

Miller's art style for this project was similar to his Sin City work, although the addition of consistent color is an obvious difference.

In what is likely a suicide mission, they and their allies plan to stop King Xerxes' invasion of Greece at the narrow cliffs of the "Hot Gates" (Thermopylae).

Before the battle starts, Ephialtes, a deformed Spartan, begs Leonidas to let him fight but is rejected due to his hunchbacked form, which prevents him from lifting his shield high enough to be of use for the phalanx.

Meanwhile, Ephialtes awakes from his suicide attempt and decides to betray the Greeks by telling the Persians about the existence of a small pass that allows Xerxes to attack them from behind.

The story then shifts about a year later and ends as now-Captain Dilios relates the heroic sacrifice of Leonidas and his Spartan comrades to his troops before the historic Battle of Plataea.

[4] Miller, in the letters page of the series, replied to accusations of homophobia from a reader regarding the phrase "Those boy-lovers": If I allowed my characters to express only my own attitudes and beliefs, my work would be pretty darn boring.

[5]Writer David Brin has also criticized 300 as being historically inaccurate, with particular reference to the bravery and efficacy of the non-Spartan Greeks: That Athenian triumph deserves a movie!

Miller never hints at the underlying reason for Leonidas's rant, a deep current of smoldering shame over how Sparta sat out Marathon, leaving it to Athenian amateurs, like the playwright Aeschylus, to save all of Greece.

[6]During the Battle of Marathon, ten years previous to Thermopylae, the Spartans had been obligated to honor the Carneia, a religious festival during which military engagements were forbidden.

It is impossible to know for certain whether this change in policy regarding the Carneia was based in shame about missing Marathon (as Brin suggests) or merely marked a reinterpretation of the military threat posed by the invading Persians.

All Herodotus tells us is that the Spartan officials did not think that the engagement at Thermopylae would be decided so quickly and intended the main part of their force to arrive before the fighting broke out.

In Sin City: The Big Fat Kill, Dwight McCarthy considers Leonidas' choice of "where to fight" and manages to loosely recreate the Spartan defense tactics by cornering the enemy gang in a tight alley; they then annihilate them with heavy gunfire and explosives.

It used greenscreen technology to capture the comic book feel; the film is in fact notable for remaining extremely faithful to its source material as a result.