How Did the Persians Fight the Greeks?
Badly, at the level of tactics, and well, at the level of strategy, but on the wrong terrain. The Greek city-states, fighting on their own ground at the limit of Achaemenid logistical reach, were able to concentrate at the decisive point — Marathon in 490, Salamis in 480, Plataea in 479 — and the Persian army, drawn from forty-six subject nations and supplied by a logistical system that was stretched to its limit at the Hellespont, was never able to deploy the way it would have liked. The result was a series of Greek tactical victories that the Achaemenid state absorbed without breaking, and a strategic stalemate that lasted another century and a half until Alexander of Macedon.
The wider context of the Persian military is covered in the Persian Military and Warfare pillar and the Persian Immortals cluster, while the question of weapons and equipment is treated in the associated long-tail articles.
Two systems in collision
The Greek city-states, particularly Athens, Corinth, and Sparta, fought according to the doctrine of the hoplite phalanx: a dense formation of heavily armoured infantrymen, locked together shield to shield, advancing in a controlled line and deciding the battle at close quarters with the spear and the short sword. The Persian army, by contrast, was a multi-ethnic combined-arms force, drawn from dozens of subject peoples, relying on the composite bow, the wicker shield, and a tactical doctrine of missile fire, manoeuvre, and exploitation of terrain. The Greek sources, particularly Herodotus, often present the Persian army as a kind of mob, but the modern consensus — worked out by generations of Achaemenid historians from Briant to Konijnendijk — is that the Persian army was a sophisticated force well adapted to the conditions of the Near East, and that the Greek tactical victory was, in large part, a victory of the Greek terrain.
Marathon (490 BCE)
The Battle of Marathon was the first great battle between the Persian and Greek armies. The Persian force, commanded by the Median general Datis and the Persian Artaphernes, had been sent by Darius I to punish Athens and Eretria for their support of the Ionian revolt. The expedition sailed across the Aegean, captured Eretria, and landed at Marathon, on the coast of Attica, where it was met by the Athenian and Plataean hoplites under the command of Miltiades.
The Greek force, although outnumbered, defeated the Persian army by a combination of surprise, superior armour, and the close-order discipline of the phalanx. The Greek hoplites, fighting in a dense phalanx, were able to close with the Persian infantry and fight at close quarters, where the lighter-armed Persian soldiers were at a disadvantage. The Persian cavalry was not committed at the decisive moment — the Greek sources are not consistent on whether it was detached to round up stray horses, to water at a distant spring, or simply not committed at the right moment — and the Persian archers, although they inflicted some casualties, were not able to break the Greek line. The Persian army suffered heavy losses, and the expedition was a failure.
Thermopylae (480 BCE)
The Battle of Thermopylae was the second great engagement of the Greco-Persian Wars, and the one that has had the deepest hold on the modern imagination. The Persian army, commanded by Xerxes I in person, invaded Greece from the north, and a small force of Greek hoplites, under the command of the Spartan king Leonidas, took up a position at the narrow pass of Thermopylae to block the advance. The Greek force, which included the famous Three Hundred Spartans, held the pass for three days against repeated Persian assaults.
The Greek hoplites, occupying a narrow pass that neutralised the Persian advantage in numbers and cavalry, were able to hold off the Persian army for three days. The Persian Immortals, committed by Xerxes at the decisive moment, were not able to break the Greek line, and the Persian archers were not able to defeat the close-order Greek infantry. The Greek defeat, on the strict reading, was not a defeat of the hoplite doctrine but a defeat of Greek strategy: the Greek high command committed only a small force to the defence of the pass, and the pass was taken by the flanking movement of the Persian general Hydarnes through the Anopaea path — Ephialtes was the local guide, not the commander. The Persian army won the battle, but the stand of Leonidas and the Three Hundred gave the rest of the Greek world time to organise the defence.
Salamis (480 BCE)
The Battle of Salamis was fought at sea, in late September 480 BCE, and it was the decisive engagement of the war. The Greek fleet, under the command of the Athenian general Themistocles, took up a position in the narrow strait of Salamis, where the Persian fleet, much larger but less manoeuvrable, was unable to deploy. The Greek triremes, manned by experienced crews, were able to ram and disable the Persian ships, and the Persian fleet suffered a decisive defeat.
The Persian fleet at Salamis was, as I have argued elsewhere, not a Persian fleet in any meaningful sense: it was a federation of subject fleets, with the Phoenicians of Tyre, Sidon, and Byblos providing the largest single contingent, and the Ionian, Egyptian, Cypriot, and Cilician contingents providing the rest. The defeat at Salamis broke the political will of the Phoenician cities to risk their fleet for an empire that had just suffered a serious tactical reverse, and the consequence was visible in the 330s BCE, when the Phoenician fleet surrendered to Alexander after Issus.
Plataea (479 BCE)
The Battle of Plataea was the last great land battle of the Greco-Persian Wars. The Persian army, left in Greece by Xerxes under Mardonius, was defeated by a coalition of Greek hoplites under the Spartan regent Pausanias. The Persian army, although substantially larger, was outmaneuvered by the Greek coalition, and the Persian Immortals, committed at the centre of the line, were broken by the Greek hoplite charge. The defeat at Plataea was the effective end of the Persian invasion of Greece.
Herodotus describes the death of the Persian cavalry commander Masistius at Plataea (IX.20–25) in some detail; the killing of a single distinguished Persian was, in the Greek imagination, the turning point of the battle. Whether the loss of Masistius was, in fact, the tactical turning point is a question scholars still debate.
The long aftermath
The Greco-Persian Wars did not, in fact, end with the Greek victory at Plataea. The Persian empire withdrew from mainland Greece but continued to be a major power in the eastern Mediterranean, and Athens continued to wage war with Persia for nearly half a century after the great battles. The peace of Callias, traditionally dated to 449 BCE, marked a formal end to the Greek–Persian war, but the Persian presence in Cyprus, in Egypt, and in the Aegean continued to be a major factor in Greek politics. The Greek mercenaries who served the Persian kings, of whom the Ten Thousand of Xenophon are the most famous example, became a substantial component of the Persian military establishment. The Achaemenid state, in other words, lost the battles and won the peace, and the Persian-Athenian competition of the fifth century BCE, far from being a Greek triumph, was a long stalemate that both sides settled into.
The story resumes with Philip of Macedon and his son Alexander. The Macedonian conquest of the Achaemenid empire in 334–330 BCE is a separate question, and the Macedonian victory is, in my view, a victory of Macedonian combined-arms tactics over the Achaemenid system, not a victory of Greek over Persian. The Macedonians, after Issus and Gaugamela, deliberately incorporated Persian cavalry, Persian officers, and Persian logistical methods into their own forces, and the Seleucid empire that succeeded Alexander was, in administrative terms, a direct continuation of the Achaemenid state.