Early 480 BC: Thrace, Macedonia, and Thessaly Having crossed into Europe in April 480 BC, the Persian army began its march to Greece, taking 3 months to travel unopposed from the Hellespont to
Therme. It paused at
Doriskos where it was joined by the fleet. Xerxes reorganized the troops into tactical units replacing the national formations used earlier for the march. The Allied 'congress' met again in the spring of 480 BC and agreed to defend the narrow
Vale of Tempe on the borders of Thessaly and block Xerxes's advance. However, once there, they were warned by
Alexander I of Macedon that the vale could be bypassed and that the army of Xerxes was overwhelmingly large, thus the Greeks retreated. Shortly afterwards, they received the news that Xerxes had crossed the Hellespont. At this point, a second strategy was suggested by Themistocles to the allies. The route to southern Greece (
Boeotia,
Attica and the
Peloponnesus) would require the army of Xerxes to travel through the narrow pass of
Thermopylae. This could easily be blocked by the Greek hoplites, despite the overwhelming numbers of Persians. Furthermore, to prevent the Persians bypassing Thermopylae by sea, the Athenian and allied navies could block the straits of
Artemisium. This dual strategy was adopted by the congress. However, the Peloponnesian cities made fall-back plans to defend the
Isthmus of Corinth should it come to it, while the women and children of Athens were evacuated to the Peloponnesian city of
Troezen.
August 480 BC: Battles of Thermopylae and Artemisium Xerxes's estimated time of arrival at Thermopylae coincided with both the Olympic Games and the festival of
Carneia. For the Spartans, warfare during these periods was considered sacrilegious. Despite the uncomfortable timing, the Spartans considered the threat so grave that they dispatched their king
Leonidas I with his personal bodyguard (the
Hippeis) of 300 men. The customary elite young men in the Hippeis were replaced by veterans who already had children. Leonidas was supported by contingents from the Allied Peloponnesian cities, and other forces that the Allies picked up on the way to Thermopylae. The Allies proceeded to occupy the pass, rebuilt the wall the
Phocians had built at the narrowest point of the pass, and waited for Xerxes's arrival. When the Persians arrived at Thermopylae in mid-August, they initially waited for three days for the Allies to disperse. When Xerxes was eventually persuaded that the Allies intended to contest the pass, he sent his troops to attack. However, the Allied position was ideally suited to
hoplite warfare, the Persian contingents being forced to attack the Greek
phalanx head on. The Allies withstood two full days of Persian attacks, including those by the elite
Persian Immortals. However, towards the end of the second day, they were betrayed by a local resident named
Ephialtes who revealed to Xerxes a mountain path that led behind the Allied lines, according to Herodotus. Herodotus has often been dismissed as a 'story teller', by Aristotle himself among others, and this may be a piece of folklore to create a more engaging narrative. In any case, it is impossible to determine with absolute certainty the legitimacy of Ephialtes' involvement in the battle. The Anopoea path was defended by roughly 1000 Phocians, according to Herodotus, who reportedly fled when confronted by the Persians. Made aware by scouts that they were being outflanked, Leonidas dismissed most of the Allied army, remaining to guard the rear with perhaps 2,000 men. On the final day of the battle, the remaining Allies sallied forth from the wall to meet the Persians in the wider part of the pass to slaughter as many Persians as they could, but eventually they were all killed or captured. Simultaneous with the battle at Thermopylae, an Allied naval force of 271 triremes defended the Straits of
Artemisium against the Persians, thus protecting the flank of the forces at Thermopylae. Here the Allied fleet held off the Persians for three days; however, on the third evening the Allies received news of the fate of Leonidas and the Allied troops at Thermopylae. Since the Allied fleet was badly damaged, and since it no longer needed to defend the flank of Thermopylae, the Allies retreated from Artemisium to the island of
Salamis.
September 480 BC: Battle of Salamis Victory at Thermopylae meant that all
Boeotia fell to Xerxes; Attica was then open to invasion. The remaining population of Athens was evacuated, with the aid of the Allied fleet, to Salamis. The Peloponnesian Allies began to prepare a defensive line across the
Isthmus of Corinth, building a wall, and demolishing the road from
Megara, abandoning Athens to the Persians. Athens thus fell to the Persians; the small number of Athenians who had barricaded themselves on the
Acropolis were eventually defeated, and Xerxes then ordered the
destruction of Athens. The Persians had now captured most of Greece, but Xerxes had perhaps not expected such defiance; his priority was now to complete the war as quickly as possible. If Xerxes could destroy the Allied navy, he would be in a strong position to force an Allied surrender; conversely by avoiding destruction, or as Themistocles hoped, by destroying the Persian fleet, the Allies could prevent conquest from being completed. The Allied fleet thus remained off the coast of Salamis into September, despite the imminent arrival of the Persians. Even after Athens fell, the Allied fleet remained off the coast of Salamis, trying to lure the Persian fleet to battle. Partly because of deception by Themistocles, the navies met in the cramped Straits of Salamis. There, the Persian numbers became a hindrance, as ships struggled to maneuver and became disorganised. Seizing the opportunity, the Allied fleet attacked, and scored a decisive victory, sinking or capturing at least 200 Persian ships, therefore ensuring the safety of the Peloponnessus. According to Herodotus, after the loss of the battle Xerxes attempted to build a causeway across the channel to attack the Athenian evacuees on Salamis, but this project was soon abandoned. With the Persians' naval superiority removed, Xerxes feared that the Allies might sail to the Hellespont and destroy the pontoon bridges. His general Mardonius volunteered to remain in Greece and complete the conquest with a hand-picked group of troops, while Xerxes retreated to Asia with the bulk of the army. Mardonius over-wintered in Boeotia and Thessaly; the Athenians were thus able to return to their burnt-out city for the winter.
June 479 BC: Battles of Plataea and Mycale . 19th century illustration. Over the winter, there was some tension among the Allies. In particular, the Athenians, who were not protected by the Isthmus, but whose fleet was the key to the security of the Peloponnesus, felt that they had been treated unfairly, and so they refused to join the Allied navy in the spring.
Mardonius remained in Thessaly, knowing an attack on the Isthmus was pointless, while the Allies refused to send an army outside the Peloponessus. Mardonius moved to break the stalemate, by offering peace to the Athenians, using
Alexander I of Macedon as an intermediate. The Athenians made sure that a Spartan delegation was on hand to hear the Athenians reject the Persians' offer. Athens was thus evacuated again, and the Persians marched south and re-took possession of it. Mardonius now repeated his offer of peace to the Athenian refugees on Salamis. Athens, with
Megara and
Plataea, sent emissaries to Sparta demanding assistance, and threatening to accept the Persian terms if they were not aided. In response, the Spartans summoned a large army from the Peloponnese cities and marched to meet the Persians. When Mardonius heard the Allied army was on the march, he retreated into Boeotia, near
Plataea, trying to draw the Allies into open terrain where he could use his cavalry. The Allied army, under the command of the regent
Pausanias, stayed on high ground above Plataea to protect themselves against such tactics. After several days of maneuver and stalemate, Pausanias ordered a night-time retreat towards the Allies' original positions. This maneuver went awry, leaving the Athenians, and Spartans and Tegeans isolated on separate hills, with the other contingents scattered further away near Plataea. Seeing that the Persians might never have a better opportunity to attack, Mardonius ordered his whole army forward. However, the Persian infantry proved no match for the heavily armoured Greek hoplites, and the Spartans broke through to Mardonius's bodyguard and killed him. After this the Persian force dissolved in rout; 40,000 troops managed to escape via the road to Thessaly, but the rest fled to the Persian camp where they were trapped and slaughtered by the Greeks, finalising the Greek victory. Herodotus recounts that, on the afternoon of the
Battle of Plataea, a rumour of their victory at that battle reached the Allies' navy, at that time off the coast of
Mount Mycale in Ionia. Their morale boosted, the Allied marines fought and won a decisive victory at the
Battle of Mycale that same day, destroying the remnants of the Persian fleet, crippling Xerxes's sea power, and marking the ascendancy of the Greek fleet. While a number of modern historians doubt that Mycale took place on the same day as Plataea, the battle may well only have occurred once the Allies received news of the events unfolding in Greece. ==Greek counterattack (479–478 BC)==