1. The expedition of Xerxes
After the destruction of a Persian expeditionary corps, in 490 B.C., at the shores of Marathon, it took Persia another ten years to rally her forces and try again to subdue the recalcitrant mainland Greeks who had supported the revolt of the Ionians in western Asia Minor against the Great King. A huge Persian army under the personal command of King Xerxes proceeded south along the coast of the Aegean. Meanwhile the free Greeks under Spartan and Athenian leadership managed to wield a defensive alliance. After a delaying action to defend the pass at Thermopylai, which cost the lives of 300 Lakedaimonians, the naval battle of Salamis dealt a decisive blow to the Persian advance. As the campaigning season had reached its end, the Great King travelled back to Asia and left his army in Greece under the command of Mardonios, who was one of Persia’s most experienced generals and a member of the inner circle of Xerxes’ noblemen. He was under orders, one way or the other, to subdue Greece.
2. Political implications around Mardonios' effort to subdue the Greeks
The army wintered in Thessaly, where the local nobles, imagining a bright future under the rule of the Great King, lent their wholehearted support to the Persian cause. In spring and early summer 479 B.C. Mardonios procrastinated and tried to negotiate Athens out of its alliance with the Peloponnesians. When diplomacy did not succeed, he advanced through Boiotia into Attica to pressure Athens into submission, again without success. When a Peloponnesian army advanced to the Isthmos of Korinth in approximately late July or August 479 B.C., Mardonios withdrew to Boiotia, where Thebes, governed by an oligarchy, and the Thebes-dominated Boiotian koinon also sided with the Persians. Boiotia’s medismos was obviously founded on the quite logical hope of gaining, in exchange, Persia’s support in securing the position of the oligarchy within Thebes. This would guarantee Thebes’ hegemony over Boiotia and bring a decisive advantage in the long running political and military contest with Athens, which had just recently turned to the worse for the Boiotians. It is likely that Thebes also hoped to be awarded the long-contested polis of Plataea and parts of NW-Attica after the anticipated Persian victory.
3. The opposing armies and tactics
The Persians established a palisaded encampment measuring 1.8 by 1.8 km in Theban territory (the size may have been slightly exaggerated by Herodot). This encampment was situated near the village of Skolos, at the northern bank of the Asopos river, south of modern Neochorion. The positions of the army extended west along the northern banks of the Asopos for several kilometres, opposite Erythrai, Hysiai and the eastern part of the Plataean territory. Herodot gives a number of 300.000 for Mardonios’ forces, which is, of course, highly exaggerated. It seems much more probable that the Persian general commanded a composite force of infantry and cavalry units of different ethic origins, totalling between 50,000 and 80,000 strong. In addition, Thessaly and other Greek provinces siding with the Persians provided hoplites, probably numbering about 15,000, who were stationed at the right (western) flank.
The Greek army consisted of 38,700 hoplites, and an equal or even larger number of light-armed soldiers, composed of contingents from many poleis. The largest units came from Sparta, Athens, Megara and Korinth. Overall command lay with the Spartan king Pausanias. The force crossed the Kithairon and established a position in the northern foot hills of this mountain range (present day Mt. Pastras), opposite to but at quite some distance from the Persian front (fig. 1). The Greek camp extended approximately from the vicinity of modern Erythres (conveniently but incorrectly named after the ancient place located further to the east) towards the east for about four kilometres, straddling Hysiai until the ancient settlement of Erythrai. This uphill position was almost impossible to attack.
A series of manoeuvres were initiated from this location which lasted the better part of two weeks. The Greeks obviously were uncertain as to how they should proceed. The usual way for them to solve military conflicts was to seek battle, and they were confident in the superiority of their own heavy infantry over anything Mardonios could muster, with the exception of the hoplites of his Greek allies. Nevertheless they could not arrive at a plan on how to cross the plain and the Asopos River without being decimated by the roaming Persian cavalry.
Mardonios, on his part, likely had the defeat of the Persian expeditionary corps at Marathon on his mind; although smaller in size, it had been composed in a way quite similar to his main force. He had already withdrawn from Attica to Boiotia because the Asopos plain was much more suitable for the deployment of his cavalry. It seems he was playing for time, hoping that he could either bring his foe to battle down in the plain where his cavalry could unfold or that dissent would affect the Greek command and the supply situation would make his enemy’s position untenable. In an effort to bring the Greeks nearer to the breaking point he ordered his cavalry to stage running attacks in a campaign of attrition against the Greek line.
4. The first skirmishes
Nevertheless this worked out in a way quite different from Mardonios’ intentions. A first success against a harassing Persian cavalry unit made the Greeks more confident: some archers belonging to the Athenian division managed to hit the horse of Masistios, the commander of the attacking Persian cavalry, who was thrown off by the wounded animal. The man, burdened by his heavy shirt of scale armour, was unable to escape and killed by Athenian hoplites. A cart containing his body was driven along the entire Greek position to make it clear to every soldier that the enemy cavalry was not invincible. Consequently the Greek command (composed of the Spartan king and the commanding strategoi of the allied contingents) re-assessed the danger posed by the Persian cavalry and advanced the army to a position several kilometres to the northwest, on low ridges and flat land near the Asopos, well within the territory of the polis of Plataea (fig. 2). In this location a much better water supply was provided by the river and a spring called Gargaphia and the area provided better ground for encampments. In addition, the terrain in front of the new line was perfectly suited for an infantry engagement. Mardonios followed suit and took up a position on the opposite bank of the Asopos.
This new position of the Greek army had one grave disadvantage: the last few kilometres of the supply line that came out from the passes of Mt. Kithairon were left uncovered and therefore open to harassing attacks by the Persian and allied cavalry. Despite this advantage it took the Persian cavalry a week until they managed to ambush a Greek supply train when it descended from the mountain passes. They slaughtered all the personnel that accompanied this supply train and much of the cattle and carrying animals. The remainder they drove away. Further supplies were blocked in the mountains and could not reach the Greeks. Mardonios now increased the scale and frequency of his cavalry attacks. This gained some immediate success when the Persians managed to block the Gargaphia spring which was, since days, the only remaining source of water for the Greeks. Persian missile attacks prevented the Greeks from accessing the water of the Asopos River and caused more and more casualties in the Greek infantry.
5. The battle
Mounting enemy pressure in tandem with the serious supply crisis which had developed made the position of the Greek army untenable. Consequently, its command decided to take up a new position at a terrain feature called he nesos (the island) formed by two tributaries of the Oeroe Creek that descended from the slopes of Mt. Kithairon. This was closer to Plataea and to Mt. Kithairon (fig. 3). The creeks would provide water and natural obstacles that would block both frontal attacks and attacks to the flanks by the Persian cavalry. This new Greek line would also shield the supply route across the mountain against further attack. In this position the army could wait for a chance to commence battle on favourable terms. Because of the manifest danger of enemy cavalry attacks on the withdrawing troops, the decision was made to stage a night move.
As may be expected, the night march went awry. At daybreak the contingents of the Greek army were dispersed over an extended area and had lost cohesion (fig. 4). In the southeast the Spartans, together with the hoplites from Tegea, occupied a position in the foothills of Mt. Kithairon. Further to the northwest the Athenians together with the Plataean hoplites were retreating through the plain, most probably south of a terrain feature now called the Pyrgos hill. The Greek centre had all but disintegrated; they retreated to a makeshift camp in front of the Heraion of Plataea, far beyond where they had been ordered to establish their front. The Greeks were in a terribly perilous position, and a well organized and quickly executed Persian attack would doubtlessly have spelled the end of their grand army.
At sunrise Mardonios received news of these movements. The cavalry force which had, as every day, fanned out to harass the Greeks, found the Greek positions deserted. They sent a message to the general and followed the Greeks along their route of withdrawal. Arriving from the Persian camp in the northeast, the troops most probably followed the draw between Makrya Rachi and Retsi which automatically limited their sight to the eastern Greek wing in front of them. The Athenians and Plataeans were hidden from their sight behind Retsi hill. It fell to the Greeks on the right wing of Mardonios to take care of them.
The cavalry attacked as soon as it reached the Spartans. Meanwhile, the Persian commander, still back in camp, obviously misinterpreted the unfolding developments (of which his cavalry units will only have conveyed to him the Spartan withdrawal, having completely lost sight of the Athenians and the Greek center) as a wholesale withdrawal of his opponent, aiming to escape across the Kithairon. He feared that many of the Greeks had already managed to escape and that the Spartans would follow suit. Mardonios rallied his infantry and led it in hot pursuit of the withdrawing Greeks, thereby committing a major mistake: he allowed his troops to advance in a haphazard stream instead of in a solid formation. When the Persians came up against the Spartans these had already established their phalanx in a position in the foothills of Mt. Kithairon. Now they presented a front which was impenetrable to the much more lightly armed Persian infantry. The Persians were forced to establish their own makeshift front behind a line of wicker shields opposite to the Spartans and Tegeates and started to launch arrows and javelins into the Greek formation. At the same time, the Persian center under the command of Artabazos advanced with a delay, thus forfeiting the chance to drive a wedge between the Athenian and the Spartan formations and advance upon the flanks of either one of them.
The Spartans and Tegeates were weathering the hail of missiles behind their large hoplite shields, but casualties began to mount. Still, the sacrifices delivered omens which indicated that Pausanias should not attack, but the Tegeates had had enough of passive suffering from enemy fire; they attacked on their own. When this happened, the Spartans followed suit and the Greek hoplite phalanx made contact with the Persian shield line.
Unfortunately for the Persians, their infantry had gradually amassed behind the front and this now prevented any kind of movement which would have been their best chance of winning the battle. Instead of maximizing the assets of lightly armed troops (i.e. their mobility in attack and withdrawal) they had to stand fast against the heavily armed hoplites. These were provided with optimum protection against all kinds of enemy weapons – arrows, javelins, spears and swords – by large aspides (shields), kranoi (helmets) and, in many cases, thorakes (breast plates) and knemides (shin protectors). At the same time their dory (hoplite spear) gave them a vital margin of offensive outreach against the shorter spears of the Persian infantry soldier, who were lacking effective protective armour as well. This difference in offensive and defensive capabilities was soon evident as casualties in the massed, immobilized formation of Mardonios’ soldiers were mounting, despite the heroic efforts of individuals and small groups to fight and even counterattack the Greeks. Mardonios perished in the mêlée and soon after the Persian formation broke and its members started a headlong escape back across the Asopos into their fortified camp (fig. 5). Artabazos, upon receiving news of these developments, withdrew his unengaged troops to Thebes.
When the Persian cavalry had started their attack against the Spartans, Pausanias had sent a messenger to the left flank of his ragged Greek formation to summon the support of the Athenians, and the Plataians marching with them. Nevertheless an Athenian movement towards the right in response to this request was stopped by the right wing of the Persian formation, consisting of the Theban phalanx, which attacked the Athenians. As a result a separate phalanx engagement developed in which the Athenians succeeded, with difficulties, to push back the Thebans and dissolve their battle line, inflicting 300 casualties. Higher losses of the defeated Thebans were avoided by an expertly fought delaying action of the Boiotian cavalry in their support. This unit also managed to inflict the most serious blow the Greeks would suffer in this battle. When information reached the dispersed Greek center at the sanctuary of Hera that battle had commenced and was going well, these troops belatedly rallied and rushed to the support of their victorious comrades. They split up, with one part, mainly the Corinthians and their neighbors, going to the aid of the victorious Spartans and Tegeates. The other part, among them the Megarians and Phleiasians, advanced in the direction of the fleeing Thebans without preserving their marching order and ran into the Boiotian cavalry. In what must have been a vicious cavalry battle, they lost up to 600 men to the furiously attacking riders who wished to protect the retreat of their compatriots. In the meantime the Spartans had reached the Persian camp in pursuit of the retreating foe. At first the palisades protecting the camp stopped their advance. When the Athenians arrived after they had disengaged from the Boiotians, a couple of them managed to scale and break open the palisade. The Greeks poured into this breach, and indiscriminate massacre ensued.
6. The aftermath
The Greeks had lost approximately 1360 men in the battle. Persian casualties numbered into the thousands – Herodot writes that of those trapped in the camp only 3000 survived. The booty was enormous. Portions were allocated to Delphi, where the sum was used to fabricate the famous tripod, to Olympia, where a large bronze statue of Zeus was dedicated, and to Isthmia, where a statue of Poseidon was erected. The rest was distributed among the soldiers. The Greek contingents buried their dead in tumuli, and, ten days after their victory, advanced to Thebes so as to punish the town for supporting the Persian enemy. After a siege of three weeks the political leaders of Thebes surrendered. They were transported to Korinth and executed there on the order of Pausanias.
This spectacular defeat ended every possible chance of Persia to impose its will on Greece. A victory – allegedly won at the same day – by the Greek fleet and amphibious troops at Cape Mycale in Ionia made the whole Persian position in the Aegean untenable. From this day on, the Greeks, and shortly thereafter the Athenians and their allies in the Delian League, advanced in the Aegean, along the western coast of Asia Minor and along its southern coast until the Eurymedon. Plataea and Mycale had, on the same day, broken the back of the Persian land army and of the Persian navy. It would take ninety years and the Peloponnesian War, the most destructive armed conflict the Greek world had yet to experience, to restore the rule of the Great King over the territories which Kyros the Great had once conquered. But not even these dreadful developments could nullify the consequences of this historical double-victory which had secured the independent development of Greek cultural and political institutions from which western civilization has inherited so much. The battle of Plataea may thus be regarded as one of the key events along the line of development of European, and indeed global civilization, as we know it today.