That indeed is the case. 300 is based on Frank Miller’s over-dramatized, overtly-biased comic book, which is itself based on Herodotus’ (aka. The Father of Lies) overtly-biased account of the Battle of Thermopyle, in which the Persian destroyed the tiny Spartan army of 300 madmen on the Greek land.
Spartans are depicted as free men in the movie, whose courage and strength is meant to incite admiration amongst the crowd. It turns out, as modern historians acknowledge, Spartans were nothing less of a Fascist state in the ancient world who hated and fought the “democratic” Athenians constantly (except that one time they fought and lost to Persians). Every Spartan soldier had 7 slaves in the battle of Thermopyle, and Spartans were known throughout history for taking their neighbors as slaves.
This article by the American historian Alex Beam sheds some light on how misleading the movie has been in showing what really happened. Speaking of Spartans, he states,
In his book “The Peloponnesian War,” Yale’s Donald Kagan edges close to describing Sparta as a fascist place, “subordinating individual and family to the needs of the state.” In a similar vein, Thermopylae is often hailed by military dead-enders as an evocative triumph of the few over the many. Even if Xerxes’s army didn’t number 2 million, as contemporaries believed, it did number 400,000, which put the Spartans at well over 1,000-1 underdogs.
But, as the classicist Victor Davis Hanson points out, the Spartans didn’t win. Hanson calls Thermopylae “perhaps the greatest loss in the history of Panhellenic operations, and one of the few times in history that an Asian army would defeat a Western force inside Europe.”
Persians are being assaulted on every front!