Encyclopedia

Ancient warfare

How the Greek, Roman, Persian and Egyptian worlds made war — formations, armies, ships, siege engineering, logistics and command, with every claim carrying the level of evidence that supports it.

37 topics · 18 battles

Ancient warfare is written about more confidently than the evidence allows. The numbers are rhetorical, the tactical reconstructions are inferences from a handful of passages, and the most familiar details — the drill of the Roman line relief, the mechanics of the hoplite push, the routine of decimation — are frequently repeated and thinly attested.

This encyclopedia therefore attaches an evidence level to every substantive claim, and it does so most insistently where the temptation is greatest. No troop figure on this platform appears as a bare number. Each one carries the source that gives it and an assessment of what it is worth, so that Herodotus’s 1,700,000 Persians and the modern reconstruction that replaces them can sit on the same page without being confused.

Describing how an army worked is not endorsing what it was for. Sparta’s military system rested on the permanent subjection of the helots; Rome’s manpower rested on conquest and slavery. Those facts belong in the description.

Civilization

c. 700 – 323 BCE
Greek warfare
Citizen infantry, the phalanx, and a way of fighting bound to the political community that produced it.
c. 400 BCE – 476 CE
Roman warfare
An army that won by organisation, engineering and the capacity to lose battles and continue — and that changed shape repeatedly across eight centuries.
c. 550 – 330 BCE
Persian warfare
An imperial military system built on cavalry, archery, road communications and the mobilisation of subject contingents across three continents.
c. 3000 – 30 BCE
Egyptian warfare
Three thousand years of military practice, from Old Kingdom levies to the chariot armies of the New Kingdom and the mercenary forces of the late period.

Formations and troop types

c. 700 – 300 BCE
The hoplite
The armoured citizen spearman of the Greek city-states, defined less by his weapon than by the shield he carried and the man beside him.
c. 700 – 168 BCE
The phalanx
A line of heavy infantry in close order — the dominant formation of Greek and Macedonian warfare, and two quite different things under the same name.
c. 400 BCE – 5th century CE
The legion
Rome's principal formation across eight centuries, and an institution that changed its organisation, recruitment and equipment more than once.
4th century BCE
The Companion cavalry
The heavy cavalry of the Macedonian kings, and the arm that decided every one of Alexander's major battles.
c. 550 – 330 BCE
The Persian Immortals
The royal guard corps of the Achaemenid kings, known by a Greek name that may rest on a mistranslation.

Armies

c. 700 – 371 BCE
The Spartan army
The only full-time infantry force in classical Greece, produced by a social system resting on the permanent subjection of a subject population.
359 – 323 BCE and after
The Macedonian army
The combined-arms system Philip II built and Alexander used to destroy the Achaemenid empire: pikemen to fix, heavy cavalry to decide.
c. 400 BCE – 5th century CE
The Roman army
Four distinct institutions under one name, separated by recruitment, terms of service and their relationship to the state.
c. 550 – 330 BCE
The Persian army
The military system of the Achaemenid empire: a professional core, provincial levies, and a reliance on cavalry and massed archery.
c. 3000 – 332 BCE
The Egyptian army
From district levies to a standing professional force built around the chariot, across a span longer than the whole of Greek and Roman history.

Naval warfare

c. 600 – 300 BCE and after
The trireme
A light, fast oared warship rowed by 170 men on three levels, and the instrument of Athenian power.
c. 700 BCE – 400 CE
Naval warfare
Ramming, boarding and the problem of keeping a fleet supplied — sea power in a world of oared warships that could not stay at sea.
c. 260 BCE – 4th century CE
The Roman navy
A service Rome built twice from nothing, used to make the Mediterranean an internal sea, and then largely forgot.

Engineering and siege

c. 700 BCE – 5th century CE
Siege warfare
The slowest and most expensive form of ancient war, and the one in which engineering, not courage, decided outcomes.
c. 399 BCE – 5th century CE
Catapults
Mechanical artillery from the tension-powered belly-bow to the torsion engines that could break masonry.
c. 3rd century BCE – 5th century CE
Ballistae and bolt-shooters
Torsion engines used as field and defensive artillery, and the one class of ancient weapon whose remains can be reassembled.
c. 1400 BCE – 5th century CE
Fortifications
City walls, frontier systems and field defences — the largest structures most ancient states ever built.
c. 300 BCE – 4th century CE
Roman military engineering
The capability that distinguished Roman armies more than any tactic: legions that could build faster than their enemies could react.
c. 200 BCE – 4th century CE
The Roman camp
A fortified enclosure built at the end of each day's march to a standard plan — the habit that made Roman armies almost impossible to surprise.
312 BCE – 4th century CE
Roman roads
Built for armies and used by everything else — the infrastructure that turned conquest into administration.

Operations

Throughout
Logistics
The constraint that determined where ancient armies could go, how large they could be and how long they could stay.
Throughout
Military supply
How armies were paid, fed and equipped as an administrative problem rather than a marching one.
Throughout
Strategy
Whether ancient states had strategy in any modern sense, and what they had instead.
Throughout
Battle tactics
What commanders could actually control once the lines met, which was less than the narratives suggest.

Institutions

Late 2nd century BCE
The Marian reforms
A set of changes traditionally credited to Gaius Marius that turned the Roman citizen levy into a professional army — and a label modern scholarship increasingly distrusts.
Throughout
Command structure
Who gave orders, on what authority, and what happened when the constitution put two men in charge of one army.
Throughout
Military discipline
Rewards, punishments and the deliberate construction of a body of men who would stand when standing was worse than running.
Throughout
Recruitment
Who served, on what terms, and what military service was worth to the person performing it.
Throughout
Training
Drill, weapons practice and route marching — and the difficulty of establishing what most ancient soldiers actually learned.

Arms and armour

Throughout
Weapons
Spears, swords, javelins and bows — and the reasons the spear mattered more than the sword almost everywhere.
Throughout
Armour
Bronze, linen, mail and plate — protection as a compromise between coverage, weight and cost.
Throughout
Helmets
The most protective and most restrictive item a soldier wore, and the one that changed most as tactics changed.
Throughout
Shields
The most important defensive item in ancient warfare, and in the Greek case the object that made the formation possible.

Battles

All 18 battles

490 BCE
Marathon
An Athenian and Plataean hoplite force defeated a Persian expedition on the coast of Attica, and the Greek world learned that a Persian army could be beaten.
480 BCE
Thermopylae
A Greek force held a coastal pass in central Greece for three days against the army of Xerxes, and was destroyed when the position was turned by a mountain path.
480 BCE
Salamis
A naval battle fought in the straits between Attica and the island of Salamis, and the engagement that broke the Persian campaign.
479 BCE
Plataea
The largest hoplite battle of the Persian Wars, which destroyed the Persian field army in Greece and ended the invasion.
371 BCE
Leuctra
A Theban army under Epaminondas broke the Spartan phalanx in open battle, and with it the assumption that Spartan infantry could not be beaten.
362 BCE
Mantinea (362 BCE)
The largest hoplite battle fought between Greek states, won by Thebes and rendered indecisive by the death of the commander who won it.

How to read the evidence labels

Evidence level: Documented: Supported by a named primary text or by excavated material evidence.
Evidence level: Probable: Supported by strong inference that most specialists accept.
Evidence level: Disputed: Substantial specialist disagreement exists; competing readings are stated.
Evidence level: Literary: Belongs to poetic or mythological construction rather than to history.
Evidence level: Mythological: Belongs to shared religious or mythic tradition rather than to any single text.
Evidence level: Unknown: The available evidence is insufficient to decide.

These labels describe the status of the evidence, not our confidence in a conclusion. A claim marked Literary is not a claim we doubt; it is a claim about what kind of thing a poem is.