How the Romans Invented One of History’s Most Successful Armies

Myke Cole

4 mins

03 Dec 2018

Header image credit: An artist’s depiction of a phalanx-eye view of an approaching Roman legion. Artwork © Giuseppe Rava.

The word ‘legion’ is a byword for military might. In modern use, it evokes a horde, an unstoppable body of warriors bent on a singular purpose. The implication is well-earned. The word is from the Latin legere, ‘to choose’, and it is attached to the keystone unit in one of the most successful armies in human history.

The legion carried Roman civilisation across the farthest reaches of the ancient world, extending Roman imperial domination from Spain’s Atlantic coast to Persia in the east, from Britain to the entire North African coast.

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The Roman phalanx

In Legion Versus Phalanx, I explore the ‘Polybian’ Roman legion (Polybian, because we know of it largely from the description of the 2nd century BC historian Polybius) – the Roman army as it existed in the early days of the Republic, before Julius Caesar and before the far-flung ambitions of empire were a glimmer in a consul’s eye.

It’s ironic that the book explores how the legion fought against the phalanx – that Greek conception of how men should fight, made famous by the film 300, in which men encased in bronze armour stand shoulder-to-shoulder, bronze-faced round shields overlapping, spears pointing toward the enemy: the Roman legion got its start as a phalanx, back in the days of Rome’s ‘Regal period’ when it was ruled by kings.

A Greek phalanx. The early Roman legion was centred around the phalanx.

In the 6th century BC, the famous Roman monarch Servius Tullius authored his ‘Servian reforms’, which grouped Romans into two wealth classes – the classis who could afford the expensive arms and armour they would need to serve in the phalanx, and the infra-classem, who could not and thus served as the light troops needed to provide skirmishing support.

Fighting as a phalanx, the classis Romans were equipped much as Greek hoplítēs: with a round aspis shield, Greek-pattern helmets, bronze or linen cuirasses, and the Greek weapon of choice – the thrusting spear.

But this early form of the legion met its match against the Senones, a tribe of Gauls that swept south into Italy, overcoming the Romans at the Battle of the Allia in roughly 390 BC and going on to sack Rome.

The defeat cannot be conclusively said to be the reason the phalanx eventually became the legion described by Polybius, but there’s no doubt that it revealed flaws in the phalanx that the Romans innovated to overcome.

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Learning lessons from the Allia

We can see echoes of the Allia in the evolution of Roman military equipment in this period.  The Romans of the Polybian legion carried gear that showed both admiration for, and terror of, their Gallic adversaries – the new oblong scutum shield, much larger than the aspis, with a central iron boss that turned it into a 22-pound boxing glove.

This oblong shape is well suited to stopping slashing blows, like the kind that would have been delivered by the long swords favoured by Gauls. Further evidence that this design was a reaction to the Allia can be seen in the metal reinforcement of the shield’s top edge (Polybius straight-up says it’s to protect the bearer from ‘descending blows’).

Artist’s depiction of a Roman legion engaging an enemy. The men in the centre and left are using oblong scutum shields, notice the metal reinforcement of the shield’s top edge (© Giuseppe Rava).

Swapping spear for sword

The Greek-pattern helmets were exchanged for the reverse jockey-cap ‘Montefortino’ style, clearly copied from Gallic patterns. But most important was their new main weapon – the two-foot gladius hispaniensis (Spanish sword), also possibly derived from weapons first encountered among Celtic Iberians (whom the Romans would also have broadly classed as ‘Gauls’).

This short sword (really a long knife) paired perfectly with the massive shield and made the Roman the master of up-close-and-personal fighting, charging into his opponent’s face, delivering a devastating punch with the shield, followed by a sword blow (usually a thrust – Polybius says that was more likely to kill) from a distance practically close enough to kiss.

A reconstruction of the tactics of an individual princeps legionary. Artwork by Gerry Embleton © Osprey Publishing.

The pila

The hoplite was strictly a spearman, but the Roman legionary also added a missile capability to his arsenal. Each legionary carried two pila (javelins), one thick and one thin (per Polybius).

The two javelins were thrown just prior to closing to the two-foot sweet spot where the sword was best employed, and were designed to bend on impact so they could not be thrown back.

The pila were a brilliant innovation, allowing close-combat infantry a missile capability that could either wound their enemy, or force him to throw away his shield (which would become unwieldy with a bent javelin stuck in it) just prior to engaging in close combat.

Myke Cole is the author of Legion versus Phalanx: The Epic Struggle for Infantry Supremacy in the Ancient World, published by Osprey Publishing.