A phalanx was a dense rectangular formation of heavy infantry standing shoulder to shoulder with overlapping shields and levelled spears. Presenting a wall of points, it was almost unbreakable from the front and dominated ancient warfare for centuries.

What is the difference between a Greek and a Macedonian phalanx?

The Greek hoplite phalanx used a large round shield and a spear around 2 to 3 metres long, usually eight ranks deep. The Macedonian phalanx of Philip II and Alexander used a much longer two-handed pike, the sarissa, up to about 6 metres, with a smaller shield and deeper ranks, so several rows of points reached the enemy at once.

What was the weakness of the phalanx?

It was formidable head-on but clumsy. On rough ground it lost cohesion and gaps opened, and its flanks and rear were highly vulnerable. An enemy who could turn its flank or fight it on broken terrain could destroy it.

Why did the Roman legion beat the phalanx?

The legion was more flexible. Its smaller units could manoeuvre over broken ground, exploit gaps in the pike line, and get inside the reach of the sarissas with sword and shield. At Cynoscephalae and Pydna in the 2nd century BC, Roman flexibility overwhelmed the rigid phalanx.

What Was a Phalanx? The formation that ruled antiquity

For centuries, one shape decided battles in the ancient world: a solid block of men, shields locked and spears levelled, moving forward as one. The phalanx was less a unit than a machine, and understanding it explains half the battles of antiquity.

Key points

A phalanx was a dense block of infantry fighting shoulder to shoulder behind a wall of shields and spears.
The Greek hoplite version used a large round shield and a spear about 2.4 metres long.¹
Philip and Alexander's Macedonian version swapped it for the sarissa, a pike up to six metres long.
Almost unstoppable from the front, it was vulnerable on the flanks and on broken ground.

The Greek hoplite phalanx

The classic phalanx was built from hoplites, citizen-soldiers who armed themselves². Each carried a large round shield, the aspis, and a thrusting spear about two to three metres long. Standing shoulder to shoulder, usually eight ranks deep², they overlapped shields so that each man protected the one to his left³, and presented a hedge of spearpoints to the enemy. Head-on, packed this tightly, they were almost impossible to break, as the Persians learned at Marathon and in the pass at Thermopylae.

Ancient vase painting of two lines of hoplites with round shields and spears clashing — Hoplites with round shields and levelled spears advance in close ranks on the Chigi Vase, a Corinthian jug painted about 650 BC, now in the Villa Giulia museum in Rome. Public domain

The Macedonian pike phalanx

Philip II of Macedon and his son Alexander the Great turned the phalanx into something deadlier⁴. They swapped the spear for the sarissa, a two-handed pike up to about six metres long⁵, and a smaller shield slung from the shoulder. Ranks grew deeper, so the points of four or five rows projected ahead of the front man⁵ at once, an approaching thicket of iron. It pinned the enemy in place while Alexander's cavalry delivered the killing blow, as at Gaugamela.

Drawing of a square block of pikemen with long sarissas, front rows levelled and rear rows raised — A syntagma of the Macedonian phalanx, 256 men in a 16 by 16 square, each with a sarissa, drawn for Theodore Ayrault Dodge's history of Alexander (1890). The front ranks level their pikes while the rear ranks hold them upright. Public domain

Almost unbreakable from the front, and dangerously clumsy everywhere else.

The fatal weakness

The phalanx had one great flaw: it could only fight in one direction. On broken ground it lost cohesion and gaps appeared between files.⁵ Its flanks and rear were soft. An enemy who refused a head-on push and instead turned a flank could roll it up. That is exactly how the flexible Roman legion finally beat it in the 2nd century BC¹, getting inside the reach of the pikes with sword and shield. Explore the formation in action across the greatest battles of ancient Greece, or brush up on the terms in our military history glossary.

Line drawing of carved frieze panels showing Roman and Macedonian soldiers and horsemen fighting — Line drawing (1909) of the frieze from the monument of Lucius Aemilius Paullus at Delphi, which celebrated his victory over Perseus of Macedon at Pydna in 168 BC, where the legions broke the phalanx. Public domain

Sources and notes

Numbered notes in the text point to the works below.

World History Encyclopedia (Joshua J. Mark), “The Greek Phalanx” ↩ a b
Victor Davis Hanson, The Western Way of War: Infantry Battle in Classical Greece (Alfred A. Knopf, 1989). ↩ a b
Thucydides, History of the Peloponnesian War, Book 5, 71 (each hoplite shelters his unshielded right side behind the shield of the man on his right, so the line drifts rightwards). ↩
Ian Worthington, Philip II of Macedonia (Yale University Press, 2008). ↩
Polybius, Histories, Book 18, 24 to 26 (Cynoscephalae: an unnamed tribune with about twenty maniples falls on the rear of the victorious Macedonian right) and 28 to 32 (phalanx compared with legion: the sarissa, five pike-points projecting before each front-rank man at 18.29, the need for level, unbroken ground at 18.31). Loeb translation online at LacusCurtius: https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Polybius/18*.html. ↩ a b c
Wikipedia, “Phalanx”

What Was a Phalanx?