Watch 123Movies. The 300 Spartans is an account of the 480 B.C. Battle of Thermopylae, in which the Greek Spartan King Leonidas, played by Richard Egan, led a remarkably small number of Greek Sparta to victory over an invading Persian army led by evil King Xerxes that was thought to number over 25,000. This spectacular conflict gave the Grecians enough time to organize a force to ultimately repel the Persians, and thus change the course of Western civilization.