Mardonius stayed with his troops in Thessaly during the winter months. But in the spring of 479 b.c. he determined to win Athens from the league which she had formed with the other Greek states, or if he failed to do this, to drive the citizens once again away from their city and occupy it himself.
So he sent an ambassador to the Athenians to offer, in the name of Xerxes, not only to repair all the harm that the Persians had done to Athens and to the country round about the city, but to give them new lands and to treat them as independent allies, if they would make a treaty with the great king.
The Spartans were afraid that the Athenians would accept so generous an offer, and they knew that alone they could not hope to conquer the large Persian army which Mardonius commanded. So they sent to the Athenians to beg them to be true to the league, promising that if they were so, Spartan soldiers would be sent to help them against the attacks of the enemy.
But the Athenians did not need to be entreated to refuse the offer of the great king, for they loved their city and their liberty.
"Tell Mardonius," they said to the ambassador whom the Persian general had sent, "so long as the sun moves in his present course we will never come to terms with Xerxes."
After receiving this defiant message, Mardonius marched with his army against Athens. The Spartans, in spite of their promises, sent no troops to defend the city, and the Athenians were forced once again to take refuge at Salamis.
Then they reproached the Spartans, and in bitter anger they declared that if an army was not sent at once to Attica to attack Mardonius, they would be forced to make an alliance with the enemy.
Again the Spartans grew alarmed for their own safety. Without further delay they sent a force of five thousand citizens, each attended by seven helots. Other troops soon followed, and all were under the command of Pausanias, who was a relation of Leonidas, the hero of Thermopylae.
The Persians had reached the province of Boeotia and were encamped on the plain of Plataea, while the Athenians and the Spartans set up their camp on a hill above the enemy.
Masistius, the favourite and most famous officer of the Persians, led his cavalry against the cavalry of the enemy and soon a fierce conflict was raging. Only after their leader fell wounded from his horse and was slain, were the Persians repulsed. The armour of Masistius could not be pierced by any weapon, but a spear which was thrust into his eye caused his death. In vain the soldiers tried to recover the body of their general, again and again they were driven back.
"Then there was a great mourning throughout the army of the Persians, for all lamented for Masistius, shaving themselves and their horses, and their beasts of burden. And there was a great cry through all the host, and the sound of it went through all Boeotia, as for the death of one who next to Mardonius was of most note among the Persians and with the king."
As for the Greeks, after having driven the Persian cavalry from the field, they "became much more bold and cheerful, and putting the dead body of Masistius on a car, they drew it along their ranks; and so wonderful was it for its stature and its beauty, that the men left their places and came forward to look upon Masistius."
Pausanias now determined to lead his troops down to the plain. Here he encamped, opposite the Persians, with only the little river Asopus between the two armies.
The oracles had foretold that the side which began the attack would be conquered; so day after day passed, neither army daring to move.
But although the Persians dared not attack the Greeks, they did them all the harm that they could, for they filled up the springs to which the enemy went for water, and cut off several convoys with provisions.
Pausanias was in despair when the water supply was stopped, and he determined to withdraw and take up a position nearer to Plataea, where both food and water would be secure.
Discipline had grown slack in the Greek camp, and the retreat, which began at night, was carried out in a disorderly manner.
One company set off in haste, but did not halt where Pausanias had arranged that it should. The Spartans refused to move at all. One of their captains, "lifting a piece of rock with both hands and flinging it at the feet of Pausanias, cried, 'Thus do I cast my vote against the counsel of flying from strangers.' " Only when the retreat was nearly ended did the Spartans tardily obey the order to withdraw. This was how it happened that, when morning dawned, the Persians found that the enemy had disappeared, all but the Spartans, whose captain had delayed to follow the orders of Pausanias.
When Mardonius caught sight of the loiterers he ordered his men to set out in pursuit of them, and before the Spartans could get into position the Persians were upon them. But Pausanias soon learned what was taking place in his rear, and he hastened back with the troops that were with him to aid the disobedient Spartans.
The Persians had thrust their shields into the ground to form a rough barrier between them and the Spartans, while they sent shower after shower of arrows upon the loiterers. The Spartans soon tore down the breastwork of shields, and with their swords in their hands advanced upon the enemy.
Mardonius did all he could to encourage his men, but they had no armour to protect them from the blows of the Spartans, and they were forced back toward the river, throwing into confusion those of their own army who were still advancing.
In the thick of the battle Mardonius rode on a white horse, surrounded by ten thousand chosen Persians. He was easily known by his white charger, and many were the spears that were aimed at him by the angry Spartans. At length one smote him so that he fell dead to the ground. "Thus," says Herodotus, "Mardonius paid the recompence for the murder of Leonidas."
No sooner was their leader slain than the Persians fled in utter confusion, all but forty thousand who were led off the field by one of the generals, and these marching north reached the Hellespont and crossed over to Asia in safety.
Those who fled from the field took refuge in their camp, where the Spartans attacked them. But the barricades were strong, and the camp was not taken until the Athenians had returned and joined in the assault.
As the Greeks swarmed into the camp they slaughtered the enemy without mercy. So severe was the defeat of Plataea that the Persians were utterly crushed.
The spoil in the camp was enormous. Gold and silver dishes were there in abundance, rich carpets too, and weapons inlaid with precious stones. Horses, camels, mules were captured in great numbers.
It is told that the great king had left his own magnificent war camp for Mardonius to use.
When Pausanias saw it "all blazing with gold and silver and embroidered hangings, he commanded the cooks and bakers to make ready for him a banquet, as they had been used to do for Mardonius.
When all was ready, he saw couches and tables of gold and silver, all fairly spread and a banquet splendidly set forth; and then, marvelling at this magnificence and glory, he charged his own servants, by way of mockery, to prepare a Spartan feast.
So the meal was made ready, but it looked not much like the other, and Pausanias laughed, and sending for the generals of the Greeks, pointed to the two banquets, saying, "Men of Hellas, I have brought you together that ye may see the madness of the Medes, who faring thus sumptuously came to rob us of our sorry food."
While the battle of Plataea was being fought, the Greek fleet was lying at Delos, an island in the Ægean Sea. The Persian fleet was near Samos, which is not far from the coast of Africa, while close at hand, at Cape Mycale, the Persian land forces were encamped.
The Samians were afraid when they saw the Persian army, and begged the Greeks to come to their aid. This they readily agreed to do, and sailing to Cape Mycale they landed and attacked and burned the Persian camp. The victory would have been harder to win had not the Ionian Greeks who were with the Persians deserted and fought with those of their own race.
Both the victory of Plataea and that of Mycale were said to have been gained on the same day in August 479 b.c.
Bands of Persians had still to be driven from some of the islands of the Ægean and from some of the Greek cities in Asia. But the victory of Mycale freed the Ionians from the rule of the great king, ended the Persian war, and laid the foundations of the Athenian Empire.