Xerxes I: The Achaemenid King Who Invaded Greece
In the spring of 480 BCE, on the narrow strait that separates Europe from Asia, an army crossed on a double pontoon bridge of boats lashed together by cables of flax and papyrus. The crossing took seven days and seven nights, according to Herodotus, and the army was so large that it drank the rivers dry. From the Hellespont, the army marched through Thrace and Macedonia, joined by contingents from the northern Greek tribes, and reached Thermopylae in the late summer of 480 BCE. The Persian fleet, meanwhile, took up position off Artemisium, on the northern coast of Euboea, opposite the Greek fleet. The expedition culminated in the battles of Thermopylae, Salamis, and Plataea, and ended in the Persian withdrawal from mainland Greece. The king who led the expedition is Xerxes I, called Khshayarsha in Old Persian, the eldest son of Darius I and Atossa, and the ruler under whom the Achaemenid state suffered the most consequential strategic defeat in its history.
The crossing itself is the right place to start, because almost everything we think we know about Xerxes is shaped by it. The Greek sources — Herodotus above all, but also Aeschylus in the Persians of 472 BCE — present the expedition as an act of hubris, a punishment sent by the gods, and the modern reception has been shaped by that reading. The standard modern treatment is Pierre Briant’s From Cyrus to Alexander (2002), chapter 13; the Greek evidence is collected in Amélie Kuhrt’s The Persian Empire: A Corpus of Sources from the Achaemenid Period (2007). I think the reading is partly right and partly wrong, and the partly wrong part is what the rest of this article is about.
The decision and the preparation
The decision to invade Greece has been debated since antiquity. Herodotus presents it as a complex process in which Xerxes was won over by a combination of personal ambition, Persian tradition, family honour, and the urging of his cousin Mardonius. The famous passage in which Xerxes has the Hellespont whipped for the loss of his first pontoon bridge is a recurring image of Persian arrogance in Greek literature, and the literary elaboration has tended to obscure the strategic logic. The destruction of the second pair of bridges is what provokes the whipping; Herodotus’ account is more carefully sequenced than the popular version.
Modern historians emphasise the strategic and economic dimensions. The Achaemenid state had been at war with the Greek world, in some form, since the Ionian revolt of 499 BCE, and the question was not whether to fight but how. The expedition of 480 BCE was a continuation of existing policy, carried out with the resources of the largest state of the ancient world. The unfinished business of Darius’ reign — the expedition against Athens and Eretria that had been defeated at Marathon in 490 BCE — was the immediate trigger, and the propaganda of the invasion emphasised the punishment of Athens for the burning of Sardis. The expedition was also, on the Persian calculation, a project of imperial expansion. The Aegean was a rich commercial region, and a successful invasion would have given the Achaemenid state control of the eastern Mediterranean.
The preparations were on an unprecedented scale. Herodotus puts the army at 2.6 million men and the fleet at 1,207 triremes, supported by a vast train of attendants, provisions, and ships. No serious modern historian accepts these numbers; the logistical impossibility is obvious. The consensus, after generations of argument, is somewhere between 60,000 and 200,000 effectives, with most scholars in the lower half of that range. W. Kendrick Pritchett’s The Greek State at War (vol. V, 1991) is the most thorough demolition of Herodotus’ figures. The army drew troops from at least forty-six subject nations, which is itself significant: this was a cooperative force, held together by pay, prestige, and the political culture of the farr (the royal charisma), not by ethnic homogeneity.
The Persian engineers also dug a canal through the isthmus of Mount Athos to allow the fleet to avoid the dangerous waters around the peninsula — a piece of infrastructure that Herodotus marvels at, and that has been confirmed by archaeological survey in the 1990s and 2000s. The work tells you something about the Achaemenid state: that it was willing to dig a 2-kilometre canal through solid rock to protect a fleet that had not yet been defeated, and that it had the engineering and administrative resources to do so.
The campaign in Greece
The Battle of Thermopylae was fought in August 480 BCE. A small Greek force — perhaps 300 Spartiates (Spartan citizens, the “300”) plus several thousand other Greeks from the Peloponnese, Phocis, Thespiae, and Thebes — held the narrow coastal pass against the much larger Persian army for several days, before a local Greek, Ephialtes, betrayed the existence of a path around the position. The Greeks were surrounded and overwhelmed, and the 300 Spartans, who refused to retreat, were killed to a man. The battle was, in military terms, a Persian victory, but it acquired a symbolic significance in Western memory that has endured: the stand of the 300 became a byword for courage in defence of freedom, and Thermopylae has been a touchstone of European self-understanding ever since.
The Greek fleet withdrew from Artemisium to the Saronic Gulf after Thermopylae fell, and the Persian army, marching south through Boeotia, entered and burned Athens. The Persian fleet followed the Greek fleet to the Bay of Salamis, off the coast of Attica, and there, in late September 480 BCE, the Greek fleet under Themistocles won the decisive naval battle. The Greek triremes, smaller and more manoeuvrable than the Persian vessels, and fought by skilled rowers and marines, rammed and boarded the Persian ships in the narrow waters of the bay. More than 200 Persian ships were sunk or captured. The Persian fleet was effectively destroyed. Xerxes, watching the battle from a throne on the shore, withdrew with the bulk of his army to Asia, leaving Mardonius in command of a reduced but still substantial force — perhaps 50,000–80,000 by most modern estimates — in Thessaly.
The decisive land battle came in August 479 BCE at Plataea, in Boeotia. The Greek army, composed of contingents from the major Greek city-states and commanded by the Spartan regent Pausanias, met the Persian army of Mardonius and won a decisive victory. Mardonius was killed, the Persian army was broken, and the Greek force marched on Thebes, which had sided with Persia, and forced the Persian sympathisers to surrender. On the same day, by tradition, the Greek fleet defeated the remaining Persian fleet at Mycale, off the coast of Asia Minor. The war in mainland Greece was effectively over.
The second half of the reign
This is the part that the Greek sources underplay, and the part I want to dwell on. After the withdrawal from Greece, Xerxes returned to Susa and resumed the business of ruling. The eastern satrapies were untouched, the treasury was full, and the Great King retained control of Asia Minor, Mesopotamia, Egypt, and Iran. Xerxes devoted much of the rest of his reign to building projects, in particular the completion of the Persepolis complex that his father had begun. The Throne Hall of Xerxes, the Gate of All Nations, and the Harem of Xerxes are all dated to his reign, and the Persepolis inscriptions record the names of the peoples and workforces that contributed. The Treasury is also part of the Xerxes–Artaxerxes I building programme. The royal tomb of Xerxes, on the slopes of the Kuh-e Rahmat behind the terrace, completes the Achaemenid royal necropolis.
The reign was also marked by growing tensions at the court of Susa. The queen Amestris, the mother of the future Artaxerxes I, played a powerful role, and the court was riven by faction. The biblical book of Esther, traditionally set in the reign of Xerxes, gives a vivid picture of the court at Susa with its eunuchs, concubines, and feasts; the historicity of the specific Esther story is disputed, but the social world it describes is consistent with what we know from Ctesias and the Greek sources. Ctesias himself, who was a Greek physician at the Persian court, paints a still more dramatic picture of intrigue, poisoning, and murder. Whatever the truth, the court of Xerxes was a tense and dangerous place.
The Xerxes inscriptions at Persepolis are notably less confident than the Darius inscriptions. The Daiva Inscription, in which Xerxes records his suppression of a revolt in Babylon and his destruction of a cult, has been read as evidence of religious ferment, and the article by W. J. Vogelsang (in Achaemenid History VIII, 1994) is the best treatment. The king’s authority is real but is asserted rather than assumed, and the assumption is gone. Briant is right, in my view, to say that the post-Marathon reign is the moment at which the Achaemenid dynasty never recovered the strategic initiative against the Greek world. The Achaemenid state continued to function, but the energy of expansion had passed.
The death
In 465 BCE, after a reign of twenty years, Xerxes I was murdered in his bedchamber in Susa. Ctesias, the Greek physician at the Persian court, attributes the killing to Artabanus the chiliarch — the commander of the royal guard, not the king’s son — with the complicity of the heir Artaxerxes. Justin’s version names the assassin as Artabazanus. The two accounts are not easily reconciled, and the Achaemenid sources are silent; we have no Persepolis inscription that explains the transition from Xerxes to Artaxerxes I. The succession was troubled, and the troubles of the succession are the reason that the reign is more difficult to assess than the Darius or Cyrus reigns. The reign of Xerxes marks the moment after which the Achaemenid dynasty was on the defensive against the Greek world, and the troubles of the succession are the first internal sign of that.
The reputation, and what to make of it
The judgment of modern historians on Xerxes has been more sympathetic than the Greek tradition. The invasion of Greece was, in the strategic context, a reasonable enterprise, and the Greek victory was due as much to Athenian naval skill and Spartan military prowess as to Persian weakness. The Achaemenid tradition, as preserved in the inscriptions of Persepolis, presented Xerxes as a pious and legitimate king, the son and successor of Darius, the builder of the great palace, and the faithful servant of Ahura Mazda. The Greek tradition, beginning with Herodotus, often portrayed him as a model of royal hubris, a magnificent but ultimately foolish ruler. Both readings have their partisans.
My own view, for what it is worth, is that Xerxes is the most difficult Achaemenid king to assess because the evidence is the most unbalanced. We have detailed Greek sources for the invasion and a few Ctesias anecdotes for the rest. We do not have the kind of administrative record that the Persepolis Fortification Tablets give us for Darius, and we do not have the kind of royal inscription record that we have for Darius either. The Xerxes inscriptions at Persepolis are real, but they are mostly building inscriptions and dedications, not the kind of self-presentation that the Behistun Inscription is. The Xerxes we can read is the Xerxes the Greeks gave us, and the Greeks had an interest in making him a particular kind of king.
What can be said with some confidence: the invasion was the largest single military undertaking of the Achaemenid period, and it failed. The failure was not catastrophic. The Achaemenid state lost the western frontier for a generation, but it retained the rest of the empire and rebuilt. The Xerxes who came back from Greece and built the Persepolis Throne Hall was, in his own understanding, a successful king. The Greek tradition thought otherwise. Both readings are partial.
Where to go next
Briant (2002), chapter 13, is the synthesis. Wiesehöfer (1996), chapter 6, for the German tradition. Boardman (2000) for the visual and material evidence. The Ctesias material is in Llewellyn-Jones and Robson, Ctesias’ History of Persia (2010), which is more sceptical of Ctesias than the older translations. The relevant articles in Achaemenid History (Leiden, 1987–) are the place to look for current scholarship. For the naval side, Wallinga’s The Persian Wars and the Ancient Greek Navy (in Dutch, 2005) is the technical study.