Herodotus and the dating of the battle of thermopylae
After this engagement, the Allied navy at Artemisium received news of the defeat at Thermopylae.
In Athens, however, the ambassadors were put on trial and then executed by throwing them in a pit; in Sparta, they were simply thrown down a well.
Xerxes decided that the Hellespont would be bridged to allow his army to cross to Europe, and that a canal should be dug across the isthmus of Mount Athos (rounding which headland, a Persian fleet had been destroyed in 492 BC).
The Athenians had also been preparing for war with the Persians since the mid-480s BC, and in 482 BC the decision was taken, under the guidance of the Athenian politician Themistocles, to build a massive fleet of triremes that would be necessary for the Greeks to fight the Persians.
This actually suggests that Herodotus might have done a reasonable job of being even-handed.
The prevailing modern view is perhaps that Herodotus generally did a remarkable job in his Historia, but that some of his specific details (particularly troop numbers and dates) should be viewed with skepticism.