Plataea was the last battle to be fought in Greece during the Second Persian War. It was fought on the isle of Attica between the combined forces of the Spartans, Athenians and allies, against the mighty Persian forces of Xerxes in 479 BC. It is an interesting battle, not in the daring or uniqueness of it, but in that it was the battle that almost lost the war for the Greeks. Had luck not been on their side, Greece could have become yet another province of the mighty Persian Empire.

Hitherto, Great King Xerxes I of Persia had managed to conquer much of northern Greece and the islands of the Aegean, as his father, Darius I, had. Things were different this time around, however, and far more in Xerxes' favour. The Persian force was almost twice what Darius' was, and not only that, but large portions of southern Greece had medized,1 such as Argos and Thebes. The Persians had been halted at Thermopylae, and defeated at Salamis, but the Persian war path was far from over. Xerxes had managed to avenge his father's loss at Marathon, succesfully invading Attica and sacking Athens. After the battle of Salamis, Xerxes withdrew and left Mardonius in charge of the assault.

Athens had been left to rebuild, and Mardonius approached them with an offer. The offer was well beyond what the Athenians could have hoped to receive; the Persians offered to restore Athens to its former Empire, and to allow it to take any lands it wanted in conquest, if it would work beside Persia rather than against. Despite this, the Athenians refused, and they paid for it. Mardonius landed a fresh Persian force in occupied Attica, marched on Athens and sacked it again. The Athenians withdrew without a fight and took up a fortified position at the mountain of Cithaeron in Boeotia, while the Persians took their positions in the plain of Plataea. They sent for aid from Sparta, and while reluctant to come, they eventually sent five thousand of the best Spartan troops to aid the Athenians.

Mardonius realised that the Greeks were not coming down from their high ground, and so sent a cavalry charge against them. The cavalry were routed and forced to retreat. Emboldened by their victory, the Greeks resolved to make the move to meet the Persians upon the plain. As they made their march, the Greeks were joined by their allies, and by the time they took their positions upon the plain they were 110,000 strong. Unfortuneately for the Greeks, the Persian force was 300,000 strong; making the odds here even worse than the battle of Marathon. The forces were set out roughly as follows:

---------- --------------------------------------------------------- ----------
|Persian | |                 Main Persian Body                     | |Persian |
|Cavalry | |                  Including Sacae                      | |Cavalry |
---------- --------------------------------------------------------- ----------
_______________________________________________________________________________________________
_________________________________River_Asopus__________________________________________________

               ----------------------- -----------------------     
               |     Athenians       | |      Spartans       |        Spring of Gargaphia 
      -------->|     & Allies        | |      & Allies       |     ___/   (Main Greek water
      |        ----------------------- -----------------------    /  /\             supply)
      |                                                           | / |
      | Greek supply route                                        \___/
      |                                                            
 /\/\/\  /\/\  /\  Cithaeron
/  \/  \/  \ \/  \                                                

Mardonius first move was to cut off the Greek supply and reenforcements coming across Cithaeron from Tegea. He dispatched the cavalry on the right wing and sent them around the river, behind the Greek hoplites, and slaughtered the pack mules carrying food and water for the army. He blockaded the pass known as Three Heads, preventing any more reenforcements from coming through. There was a sudden stalemate, with neither side willing to make the first move. For two days the Persians tried to provoke the Greeks by moving right up to the river, but the Greeks did not budge, and the Persians never crossed. This entire time the Persian cavalry continued to blockade the Greek's supply route and harrass the army, moving in to launch their arrows, then fleeing before an engagement could break out.

This continued for ten more days, and an alternate route was found for more reenforcements to join the Greeks. The Persian cavalry continued to harass the Greeks, and they were under strain, especially with their supply under blockade. Still, no moves were made on either side, and Mardonius was anxious to force an engagement. He did not have the full support of his commanders, but seeing as he was appointed high commander by Xerxes, he received no opposition. He began by being more agressive with his cavalry, forcing brief engagements rather than just harrassing the Greeks. He also moved to spoil the spring of Gargaphia, thus cutting off the Greek's water supply.

Now the Greeks began to suffer serious attrition without food or water. They attempted to create an alternate supply route via the Peloponnese, but the Persian cavalry quickly moved to cut this line off as well. The Greeks were under duress and realised they could not win the battle. They began making plans to withdraw under the cover of night. The Athenians left first, marching over Cithaeron and taking the low valley out towards the isthmus2. The Spartans were delayed by an argument in the army, one commander wishing to stay true to the Spartan ethos and not retreat, but eventually they marched off after the Athenians. With dawn not far off, the Spartans chose to take the high slopes of Cithaeron for greater protection, and surely enough when the sun rose, Mardonius saw the fleeing Greeks and immediately decided victory was his, sending his army off to harass the retreating troops.

The fast moving Persian force quickly fell upon the Spartans, but had no idea about the Athenians. The Spartans turned to face the onslaught and dispatched a messenger to request the Athenians return to aid them in the battle. Things were not going well, the Spartans were pressed to breaking point, and the Athenians still a ways off:

                -----------
                |Athenians| (In valley on opposite side, marching to meet Spartans)
               /-----------
 /\/\/\  /\/\ //\ 
/  \/  \/  \ //  \ Cithaeron
    --------/-
    |Spartans|
    ----X-----
--------X-----------
|     Persians     |
--------------------

Persian victory seemed assured; the Spartans were almost routing, but they managed to hold out just long enough for the Athenians to join the battle. When they did, it renewed the Greek spirit, and the battle was reinvigorated, despite the Spartan's losses. They began to push back against the Persians with ferocity, and the tide began to turn. The Greeks were not winning yet, but they were no longer losing. Pausanias, the Spartan commander, took charge of a force personally and pressed hard at the centre of the Persian force, the Persian Sacae,3 including Mardonius. They seemed to be locked in a stalemate, until Mardonius was slain. The Sacae were demoralised, and the tide turned very quickly. The Sacae were broken and turned to flee, and with the core of the Persian army routed, the rest followed quickly. The entire Persian army broke formation and fled towards Thebes, the Greeks pursuing and harassing them.

The Persians managed to reach the fortification (a wooden fort) they had made in Thebes, and took up a defensive position. They repelled the Spartans, who had no experience in siege, but the Athenians easily overcame the defenses. They broke into the fort and opened the gate so that the entire Greek army could enter. The Persian forces erupted into utter chaos, and all semblance of a fighting force was lost. The fact that they were caught within a small space spelled disaster for the Persians; the entire army was slaughtered, while Greek casualties only numbered at 159.4

After this, the Persians never regained a foothold in Greece. The Thebans and Argives were defeated and forced back under the Greek banner. Over the following years, the Greeks eventually forced the Persians from Thrace and recaptured Ionia.

1 Term meaning a Greek person or city state that betrays their kin to join the Persians. Derived from Medes; Persians commonly referred to as Medes, or Persians and Medes.
2 The strip of land between Attica and the Peloponnese. It was heavily fortified at this stage, recently done so by the Spartans.
3 Persian Sacae were the 1000 cavalry elite. They formed the personal guard of the commander of the army.
4 This only counts those lost during the battle in the fort at Thebes, not during the time on the field of Plataea, nor on the mountainside of Cithaeron.

Sources:
Herodotus Histories
Plutarch Lives