After the battle of Salamis, Xerxes, much terrified, immediately hastened to the Hellespont. But Mardonius was left with the most serviceable part of the army, about three hundred thousand men, and was a formidable enemy, confident in his infantry, and writing messages of defiance to the Greeks: "You have overcome by sea men accustomed to fight on land and unskilled at the oar; but there lies now the open country of Thessaly; and the plains of Boeotia offer a broad and worthy field for brave men, either horse or foot, to contend in."But he sent privately to the Athenians, both by letter and word of mouth from the king, promising to rebuild their city, to give them a vast sum of money, and constitute them lords of all Greece on condition they would not engage in the war. The Lacedaemonians receiving news of this, and fearing, dispatched an embassy to the Athenians, entreating that they would send their wives and children to Sparta, and receive support from them for their superannuated. For, being despoiled both of their city and country, the people were suffering extreme distress. Having given audience to the ambassadors, they returned an answer, upon the motion of Aristides, worthy of the highest admiration; declaring, that they forgave their enemies if they thought all things purchasable by wealth, than which they knew nothing of greater value; but that they felt offended at the Lacaemonians, for looking only to their present poverty, without any remembrance of their valor and magnanimity, and offering them their victuals, to fight in the cause of Greece. Aristides made this proposal, brought back the ambassadors into the assembly, and charged them to tell the Lacaemonians that all the treasure on earth or under it was of less value with the people of Athens than the liberty of Greece. And, showing the sun to those who came from Mardonius," as long as that retains the same course, so long," said he, "shall the citizens of Athens wage war with the Persians for the country which has been wasted, and the temples that have been profaned and burnt by them." Moreover, he proposed a decree, that the priests should anathematize him who sent any herald to the Medes, or deserted the alliance of Greece.
When Mardonius made a second incursion into the country of Attica, the people passed over again into the isle of Salamis. Aristides himself went to Lacedaemon, and reproved them for the delay and neglect in abandoning Athens once more to the barbarians; and demanded their assistance for that part of Greece which was not yet lost. The Ephori, hearing this, made show of sporting all day, and of carelessly keeping holy day (for they were then celebrating the Hyacinthian festival), but in the night, selecting five thousand Spartans, each of whom was attended by seven Helots, they sent them forth unknown to those from Athens. And when Aristides again reprehended them, they told him in derision that he either doted or dreamed, for the army was already at Oresteum, in their march towards the strangers; as they called the Persians.
Aristides answered that they jested unreasonably, deluding their friends, instead of their enemies.
Being chosen general for the war, he repaired to Plataea, with eight thousand Athenians, where Pausanias, general-issimo of all Greece, joined him with the Spartans; and the forces of the other Greeks came in to them. The encampment of the barbarians extended all along the bank of the river Asopus, their numbers being so great, there was no enclosing them all, but their baggage and most valuable things were surrounded with a square bulwark, each side of which was the length of ten furlongs.
The Tegeatans, contesting the post of honor with the Athenians, demanded, that according to custom, the Lacedaemonians being ranged on the right wing of the battle, they might have the left, alleging several matters in commendation of their ancestors. The Athenians being indignant at the claim, Aristides came forward and said: "To contend with the Tegeatans for noble descent and valor, the present time permits not: but this we say to you, O you Spartans, and you the rest of the Greeks, that place neither takes away nor contributes courage: we shall endeavor by maintaining the post you assign us, to reflect no dishonor on our former performances. For we are come, not to differ with our friends, but to fight our enemies; not to extol our ancestors, but to behave as valiant men. This battle will manifest how much each city, captain, and private soldier is worth to Greece." The council of war, upon this address, decided for the Athenians, and gave them the other wing of the battle.
At this juncture, Mardonius made trial of the Grecian courage, by sending his whole number of horse, in which he thought himself much the stronger, against them, while they were all, except the Megarians, encamped at the foot of Mount Cithaeron, in strong and rocky places. They being three thousand in number, had pitched their tents on the plain, where the cavalry charged and made inroads upon them from all sides. They sent, therefore, in haste to Pausanias, demanding relief, not being able alone to sustain the great numbers of the barbarians. Pausanias, hearing this, and perceiving the tents of the Megarians almost hidden by the multitude of darts and arrows, and themselves driven together into a narrow space, was at a loss how to aid them with his battalions of heavy-armed Lacedaemonians. He asked, therefore, as a test of emulation and love of distinction, to the commanders and captains who were around him, if any would voluntarily take upon the defense and succor of the Megarians.