Source A: Ancient account by Herodotus

'In 480 BC, the Persian king Xerxes launched a massive invasion of Greece. The Greek city-states united to oppose him, and the Spartans, under King Leonidas, chose to make a stand at the narrow pass of Thermopylae. The battle began on the 17th of September, and the Greek forces, though vastly outnumbered, fought bravely for three days. On the third day, a Greek traitor revealed a secret path to the Persians, leading to the eventual Greek defeat.'

Source B: Timeline of the Battle

• September 17, 480 BC: The Greek allies arrive at Thermopylae.
• First three days: The Spartans and allies hold off the Persians.
• Day three: The traitor reveals the secret path.
• Final day: The Persians flank the Greeks, leading to their defeat.

Source C: Historical analysis by Professor Jones

'The stand at Thermopylae, although a defeat, was a crucial moment in the Greco-Persian Wars, inspiring Greek unity and resistance.'