What happened was that I, Mardonios, son of Gobryas, persuaded the Great King to embark upon a new campaign of conquest. I am quite proud of my speech to my cousin Xerxes - it went like this:

Master, you surpass not only all Persians that have been but also all that shall be; besides having dealt excellently and truly with all other matters, you will not suffer the Yauna who dwell in Europe to laugh at us, which they have no right to do. It would be strange indeed if we who have subdued and made slaves of Sacae and Indians and Ethiopians and Assyrians and many other great nations, for no wrong done to the Persians but of mere desire to add to our power, will not take vengeance on the Yauna for unprovoked wrongs. What have we to fear from them? Have they a massive population or abundance of wealth? Their manner of fighting we know, and we know how weak their power is; we have conquered and hold their sons, those who dwell in our land and are called Ionians and Aeolians and Dorians. I myself have made trial of these men, when by your father's command I marched against them. I marched as far as Macedonia and almost to Athens itself, yet none came out to meet me in battle. Yet the Yauna are accustomed to wage wars, as I learn, and they do it most senselessly in their wrongheadedness and folly. When they have declared war against each other, they come down to the fairest and most level ground that they can find and fight there, so that the victors come off with great harm; of the vanquished I say not so much as a word, for they are utterly destroyed. Since they speak the same language, they should end their disputes by means of heralds or messengers, or by any way rather than fighting; if they must make war upon each other, they should each discover where they are in the strongest position and make the attempt there. The custom of the Yauna, then, is not good; and when I marched as far as the land of Macedonia, it had not come into their minds to fight. But against you, O King, who shall make war? You will bring the multitudes of Asia, and all your ships. I think there is not so much boldness in Hellas as that; but if time should show me wrong in my judgment, and those men prove foolhardy enough to do battle with us, they would be taught that we are the greatest warriors on earth. Let us leave nothing untried; for nothing happens by itself, and all men's gains are the fruit of adventure.

Gaze upon my excellent rhetoric. Yes, if you are a boring old fart like Artabanos, son of Hystaspes, you might point out that I am not perhaps telling the truth about the Yauna and their way of war. But who cares about such details? The Great King will readily shape the world as he sees fit.