One that stands out is During the first day of battle, as the Greek forces advance in phalanx formation into the teeth of Persian arrows, singing a battle hymn, then pick up the pace as they cover the last few feet, their spears swinging down in unison, Xerxes, observing the battle, leaps to his feet in concern for his men.
The third day of the battle, when a thunderstorm is raging overhead and the Greeks have finally been driven back over their defensive wall. It looks like they are beaten. Then, for whatever reason, the Persian forces pause in their charge, as if unable to believe they're really about to win. At that exact moment, a lightning bolt hits the cliffs just above, stunning both sides. Leonidas recovers first and yells, "Zeus Thunderer! Hellas and Victory!" He then leads the heartened Greeks back into the fray and they are able to drive the Persians back over the wall and off the battlefield for the night.