Our knowledge of the preparations made for this invasion by Xerxes comes from Herodotus.[2] He may have exaggerated some things in his account, but his history was written for the Greeks of his own time and he wanted to make clear to them how great was the difference between the East and the West; how much better their freedom and independence were than the slavery endured by states which were ruled by the Great King. For these states had no voice in the affairs of the Empire; if the King went to war, they had to follow him and lay down their lives for causes in which they had no concern, and which generally only ministered to the greed and avarice of their rulers. Having decided on the invasion of Greece, Xerxes sent heralds throughout the Empire proclaiming the war and bidding all fighting men make ready and join the King at Sardis. There the troops were mustered, and in the spring of 480 B.C. ten years after the battle of Marathon, Xerxes and his army were ready to set out. They were to march to the Hellespont, and then, by way of Thrace and Macedonia, to descend into Greece. The fleet was to join the army at the Hellespont, and by sailing close to the shore, to keep in constant touch with the army on land. At last all was ready and the day came for the army to leave Sardis. First the baggage-bearers led the way together with their horses, and after these, {139} half the infantry of all the nations who followed the Great King. Then a space was left, after which came the King himself. Before him went first a thousand horsemen, chosen from amongst the noblest Persians, and then a thousand spearmen; these were followed by ten sacred horses with rich trappings, and behind the horses came the sacred chariot of the great Persian god, drawn by eight horses, with the reins held by a charioteer on foot, for no human creature might mount upon the seat of that chariot. Then followed Xerxes himself, attended by spearmen chosen from the best and most noble of all the Persians. They were in turn followed by a body of men known as the Immortals, of which there were always ten thousand. They bore this name, because if any one of them made the number incomplete, either by death or illness, another man filled his place, and there were never either more or fewer than ten thousand. These were the very flower of the Persian army; nine thousand of them carried spears ending with silver pomegranates, and the spears of the thousand who guarded the front and rear were ornamented with pomegranates of gold.