When muscle failed, they turned to their magic.
6 seconds sound clip from the 300 movie soundboard.
You can hear this line at 01:10:41 in the Blu-ray version of the movie.
Quote context
[...]
- Even the king allows himself to hope for more than glory. Such mad hope, but there it is...
- Dawn. Whips crack. Barbarians howl.
- Those behind cry, 'Forward!' Those in front cry, 'Back'!
- When muscle failed, they turned to their magic.
- One hundred nations descend upon us, the armies of all Asia.
- Funneled into this narrow corridor, their numbers count for nothing.
- We send the severed bodies and the fragile hearts back to Xerxes' feet.
- King Xerxes is displeased with his generals. He disciplines them.
[...]