Prologue: From Marathon to Tegea
In the Greek reckoning, the war had begun with the Ionian Revolt. At the beginning of the 5th Century, the tyrant Aristagoras of Miletus had led a revolt against the Persian Empire of Darius I. As part of this revolt, he had sought the assistance of the Greeks of the mainland but was only granted the help of the Athenians and Eretrians. In the end, when the revolt was put down, Darius set about on a campaign of punishment against the Greeks, seeking to destroy those who had aided his enemies. In a campaign that swept through the Aegean, his forces were finally driven back in a massive victory for the fledgling democracy of Athens. 10 years later, Xerxes came seeking revenge for the defeat at Marathon, leading a host numbering in the hundreds of thousands.
In the Persian reckoning, as recorded in the extant Vergina inscription, Darius and Xerxes were merely responding to the cries for help of the impoverished peoples of Greece and the many enslaved peoples of the mainland, specifically including the 'broken and wearied Argives, the Messenians whose impositions by the Spartans have utterly ruined a once-proud state'. In this version, Darius and Xerxes were nothing short of would-be liberators of Greece, seeking to bring justice and peace to a war-torn country.
The truth is rather more simple. The Battle of Marathon, for all it was hyped in Greek memory, was actually little more than a glorified raid; Darius' campaign in the Aegean Sea was never actually intended to conquer Athens at all, not unless it was effectively handed to them. Instead, it is a good deal more likely that he had set out simply to secure the islands of the Aegean, something he actually achieved regardless of what happened at Marathon. When Xerxes invaded 10 years later, in 480, it was not as a campaign of revenge, nor was it as a liberator. His invasion of Greece was aimed solely at conquest, as Darius had done before him in Cyrenaica, Thrace, and India, and Cambyses before him, in Phoenicia and Egypt. Persia was a conquering empire, it pushed the boundaries of its territory time and again. Xerxes was simply continuing this policy.
In many ways, the war was never in doubt. A lot has been written about the comparative military forces of the Greeks and Persians, especially since many of our sources for the war are in fact Greeks (we don't see a 'historical tradition' in the same way for Persia until later and a lot of the sources that still survive over from the royal archives are administrative in nature). However, the fact of the matter is that the Persians led a highly organised, intricately structured army supported by the largest fleet of its day against a form of warfare that was superbly amateurish in a variety of ways. Greek infantry has often been hyped up, especially that of the Spartans, but the reality is that it was nothing special for its day; the 'hoplite' existed in a whole slew of societies, including in Persia, and most Greek soldiers were entirely untrained, rejecting the idea that training was something required by a soldier entirely. In fact, despite myths of Spartan excellence (largely through post-war mythmaking glorifying the defeat of the Spartans at Thermopylae), the only thing we can ascertain to have been different between Spartan and other Greek warfare was a basic sense of drill training and some degree of physical fitness.
The biggest advantage the Greeks had was their country. Greece is rocky and arid with few major rivers and a lot of mountainous areas, regions in which the Persian army was often unable to use its characteristic manoeuvrability as was the case at Thermopylae. While the Persians were only held for a few days, the Battle of Thermopylae had shown that the Persians often needed to fight in open areas to make the best use of their soldiers. Luckily for the Persians, the threat of another Thermopylae situation was rather far from being a reality for the next year or so. Once past Thermopylae, the Persian army swept down on Athens and sacked the city, only to find that the Athenian citizens had already fled to the nearby island of Salamis.
It was here that the problems really started for the Greeks. A disagreement over the disposition of the fleet broke out, the Athenian politician Themistocles arguing that the fleet needed to stay united and hold out in the Gulf of Salamis, learning from the naval battle at Artemision that the Persian ships were at their weakest in tight areas. On the other hand was the threat of the Isthmus of Corinth being turned; the Persian fleet offered Xerxes an opportunity to take the Isthmus and enter the Peloponnese, turning aside whichever army stood in his way. Famously, the disagreement went too far and several Peloponnesian contingents broke rank and began making their way for the Isthmus. Upon hearing this, the Persians made their move. A chunk of the fleet was sent to blockade the strait of Salamis, holding the ships there so as to prevent them from reinforcing the Peloponnesians while a larger group, some 400 ships, was sent to catch up to the Peloponnesian navy.
Sure enough, in the open seas off the coast of the Peloponnese, the Greek ships were utterly annihilated in a major battle. Unable to reinforce, the rest of the Greek navy was left fully isolated. Of course, Themistocles' fleet was still a major threat; the Athenians alone fielded as many as 200 ships, the majority of the Greek navy in operation at the time. But what the previous battle had shown was that the Persians, one way or another, now held effective control of the sea. Instead of risking battle, Xerxes settled in for a blockade, leaving some 3-400 ships to keep the remaining 2-250 ships trapped at Salamis while he and the rest of his navy made a beeline for the Isthmus of Corinth. Here, the Greeks began to retreat; without control of the seas, the Isthmus was rendered indefensible and the Greek armies began to fall apart, each moving to defend their own city and hoping to wait out the Persian assault until they were forced to winter.
The problem was that that risked isolating them. Corinth lay right on the other side of the Isthmus, one of the biggest cities still left standing in the Hellenic League and at risk of being captured before winter came. If the Greeks didn't offer a pitched battle at Corinth, then they simply risked the city falling and leaving the door to the Peloponnese wide open. Once again, the war councils fell into debate; should they risk an open battle with the Persians on the fields of Corinth, or should they retreat and try to hold the mountainous passes of the inner Peloponnese? It wouldn't have mattered, really, anyway. While the Corinthian army did take the field, it was quickly annihilated by the Persians and within weeks the city had surrendered to Xerxes, opening the gates and being spared the same sack that had awaited Athens.
However, time was wearing on and once winter came it would be a lot harder to sustain the Persian army in the field. Taking stock at Corinth, Xerxes resolved to return with the larger part of his army to the Persian Empire, leaving Mardonius to finish up his conquests in the region. Before he did so, however, Xerxes set about tying up a few loose ends. The first of these was the coalition of ships still trapped in the straits of Salamis. Simply put, neither he nor the Athenians could really risk a long winter blockade; their ships would rot and be utterly useless for the next season to come. He wouldn't even have an advantage; the Athenians were in the sheltered strait, his ships would be vulnerable to storms that could carry off thousands of men. On the other hand, he also couldn't leave the Athenians just sitting on Salamis ready to harass the coastline. They either had to be conquered, or brought into the fold via diplomacy.
Leaving Mardonius to wrap up in Corinth, Xerxes marched back to Attica and took up camp in the ruins of Athens, inviting the leaders of the Athenian demos to a conference. Here they were offered the chance to return to Attica, to rebuild Athens however they wanted and to retain their democracy on the condition that the Greek fleet at Salamis be turned over and submission given. As proof of his generosity, he brought statues that had been left on the Parthenon when it was sacked, restoring them to the Athenians. Also present at the conference were several other Greek envoys, those who had already sided with the Persians; Thebans, Thessalians, Macedonians and, more recently, Argives.
Back in the Peloponnese, Mardonius was conducting his own propaganda campaign. As mentioned, Argos had been quick to side with the Persians once Corinth fell and, in the weeks that followed were able to turn over most of the Argolid to Persian rule. Shortly after Xerxes left, Mardonius moved to consolidate Argolis, touring the countryside and bringing gifts to the Argives to welcome them into the empire. At the same time, several envoys were sent into Achaea, attempting to win over the local cities with mixed success. Still, the whole thing was enough to be considered something of a victory; the Argives were long-term enemies of the Spartans and a major city in the Eastern Peloponnese. What's more, the capture of both Corinth and Argos left Mardonius able to possibly take winter quarters here in the Peloponnese without needing to return to either Attica or even Boeotia.
With news of the defection of Argos, the ships that had been supporting Mardonius now returned to Salamis, putting further pressure on Themistocles' forces. After weeks of deliberation, the Athenians finally agreed to surrender in late 480, their ships being led to Attica and disarmed by Xerxes and his men. There, the king personally received Themistocles and made a very public display of returning a statue of Athena to the Acropolis before finally leaving for Persia. Much of the fleet was either brought back to Persia with him or else was beached in Macedonia for repairs. Meanwhile, Mardonius settled in for winter in the Peloponnese continuing to shore up his control of the region as he did so.
The result was that, come Spring, the Persians could move quickly. In March, Mardonius' army took to the field again and swept down on Mantinea, taking the city quickly and opening the route down to Tegea, another major city still in the Hellenic League and one currently under Spartan influence. Importantly, Tegea lay upon a road leading into Laconia, should the city fall then there seemed to be little that the Spartans or their allies could do to keep the Persians out. At the same time, however, Mardonius had already begun to capitalise on the biggest instability of the Spartan political system... the Helots. Agents, most likely loyal Greeks, had been sent into Messenia over the winter and there had begun to foment revolt amongst Sparta's slave population.
This all came together when, in late March or early April, the Spartans mobilised everything they could against the Persians. We are told of at least 10-15,000 hoplites, and likely a good deal more in the way of light infantry, slaves, and other hanger-ons attached to the army. In addition, there were at least 4000 Tegean hoplites and perhaps another 1000 light infantry from the city. It wasn't much, it wasn't even nearly enough but it was all that was left after a winter of defections and sieges had sapped Greek fighting strength. Against them, the Persians fielded a freshly rejuvenated army, bolstered with new contingents from Argos and Corinth.
The battle of Tegea was hard-fought, famously so. It just wasn't enough. Outside Tegea, the Persian army utterly routed their Greek counterparts and took the city in a rapid assault. From there, it was just a case of marching South to Sparta. As he went, Mardonius received envoys from dozens of Greek cities across the Peloponnese, including from the Messenians to whom he sent a delegation of Persian soldiers to officially declare their freedom from the Spartans. By the end of April, Mardonius had entered Sparta and received the official surrender of their kings. Traditionally, this is where the Second Greco-Persian War is said to have ended, with the surrender of Sparta and the declaration of Messenian freedom. This is where the story, for us, begins. With Mardonius' victory at Tegea, the Greeks had been utterly defeated and the route was open for the Persians to set about securing their dominion in Greece.
