Darius then began to plan to completely conquer Greece but died in 486 BC and responsibility for the conquest passed to his son Xerxes. In 480 BC, Xerxes personally led the second Persian invasion of Greece with one of the largest ancient armies ever assembled. Victory over the allied Greek states at the famous Battle of Thermopylae allowed the Persians to torch an evacuated Athens and overrun most of Greece. However, while seeking to destroy the combined Greek fleet, the Persians suffered a severe defeat at the Battle of Salamis. The following year, the confederated Greeks went on the offensive, decisively defeating the Persian army at the Battle of Plataea, and ending the invasion of Greece by the Achaemenid Empire.