The Military Reforms of Caius Marius

Oscar Vancea, Lake Ginninderra College, 2007

Caius Marius
Caius Marius
Marius, seven times Consul of the Republic, is best remembered for his dramatic reforms to the Roman military system. Having distinguished himself early in his career as an excellent soldier, Marius used this influence to secure multiple consulships. He was first elected consul in 107 BC and used the power of this office to enact fundamental changes to Roman military practice. Allowing any citizen to enlist, Marius increased the army’s size considerably, boosting its effectiveness and reliability. Additionally, he improved weapons and tactics, making them more consistent. His reforms provided the Romans with a new, more effective and skilled military force.

In 107 BC, after being elected consul, with the special task of defeating the African king Jugurtha, Marius saw the dire need to increase the number of men available for the legions. Until this time, the standard requirements to become a Roman soldier were very strict. To be considered, a soldier in the service of the Republic had to be a member of the fifth census class or higher, owning land worth at least three thousand sesterces in value. Originally, recruits were also expected to provide their own arms and uniforms. Marius relaxed the recruitment policies by removing the necessity to own land, and allowed all citizens entry into the legions, regardless of social class. According to Plutarch;

Marius was triumphantly elected (consul) and at once began to raise troops. Contrary to law and custom, he enrolled in his army poor men with no property qualifications, a class of people who used not to be accepted by commanders in the past, who gave arms, like other honours, only to those in the right income groups – the idea being that the possession of property guaranteed a man’s loyalty to the state. (Plutarch,1920)

The benefits to the army were numerous, as unemployed masses enlisted for service alongside the more fortunate citizens. Poorer citizens were attracted to life-long service, as they were rewarded with the prospect of a grant of land. These settlements of retired veterans also ‘Romanized’ the newly subjugated provinces, reducing unrest and lowering the chance of revolt against the Roman government. (Polfer,1999). The new Roman army, its numbers vastly bolstered by lower class citizens whose fortunes were tied to their permanent career, was able to provide reserves of manpower in times of disaster. In addition, the growth of the army ensured continued military success.

As well as increasing the size of the army, Marius also sought to improve organization among his troops. An active, experienced soldier himself, he improved and standardized weaponry and its manner of use on the battlefield. The most apparent change in the army’s weaponry was the modification of the standard Roman missile weapon, the pilum. Marius redesigned the spear so that it would break on impact and become unusable:

They say that it was in preparation for this coming battle (with the Cimbri) that Marius first altered the construction of the pilum. Before this time, the shaft was fastened into the iron head by two nails of iron; now Marius, leaving one of these nails as it was, removed the other and put in its place a weak wooden pin, the idea being that on impact with the enemy’s shield the wooden pin would break and, instead of the pilum sticking straight out, the shaft would twist sideways and trail down, though still firmly attached to the iron head. (Plutarch, 1920)

Until this change, the pilum’s usefulness had been tarnished by the fact that enemy soldiers could re-use the ones thrown at them. Along with this change, Marius standardized the use of missiles on the battlefield. The deployment of lightly armed skirmishers, the velites, was abolished, along with their characteristic arms of light spears and small bucklers. This meant the pilum became the standard throwing weapon and was used by all members of the legion.

Related Article: Lucius Cornelius Sulla and Gaius Marius
Another influential tactical reform of Marius was to encourage an innovative and flexible approach to military strategy. Marius abolished routine tactics in favour of a more unpredictable style, taking into account both differences in terrain and the nature of the adversary. Despite this new flexibility, the Roman army under Marius lost none of its severe discipline: "The exemplary steadiness of the Roman troop... virtually decided the Jugurthan War.” (Cary & Scullard, 1935: p.216)

Marius also turned his reforms to the individual soldier. He improved the self-reliance of his soldiers by forcing them to complete long route marches, carrying all their equipment. He streamlined the cumbersome baggage trains which slowed the army. He also compelled the soldiers to prepare their own meals, increasing their individual independence.

After he had set out for the front, he gave his army an intensive course of training while on the route. There was practice in running and in long marches; and every man was compelled to carry his own baggage and prepare his own meals. This was the origin of the expression ‘one of Marius’ mules’, applied to any soldier who was a glutton for work and obeyed orders cheerfully and without grumbling. (Plutarch, 1920)

Marius also went on to re-organise the legion, creating ten cohorts in place of the earlier thirty maniples. The new organization was thus made up of sixty centuries, each eighty men strong and led by a centurion. It was now grouped into ten cohorts, comprising of six centuries each. Furthermore, Marius broke with earlier practice and gave Roman citizenship to his Italian allies, even though this provoked criticism:

He granted the rights of citizenship to as many as a thousand men of (the town of) Camerinum for their gallantry in the war…His action being considered illegal, he was called to account for it. He replied that the din of warfare had drowned the voice of the law and he could not distinguish Roman from ally. (Plutarch, 1920)

This action further improved the army’s effectiveness by converting three separate types of soldier into one standard Roman soldier, based on the model of the principes, originally the middle ranks of the old legion organization of hastati, principes, and triarii.

To add additional unity to his army, Marius gave each legion a symbolic eagle-standard, to symbolize its collective spirit. The standard was carried into battle by an aquilifer, second only to the senior centurion in rank. This change not only worked to increase the loyalty and devotion of the soldiers to their unit and their commanders, but it was also reflective of the merging of the old class divisions within the army.

Gaius Marius utterly reformed the army of the growing Roman Empire, rearranging it and improving its effectiveness. His reforms abolished class bias, dramatically increased the size of Rome’s military force, standardized weapons and improved their use. He replaced predictable, routine tactics with a more flexible system of battlefield practice. He improved overall discipline and streamlined organization. For the individual soldier, he instigated demanding training regimes that emphasized self-reliance. Finally, he created a new structure for the legion, and a new focus in the symbol of the Roman eagle.

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Carney, T, (1961), A Biography of C. Marius, Proceedings of the African Classical Association, Supplement Number 1.

Carney, T, (1970), A Biography of C. Marius, Argonaut Press, Chicago.

Cary, M, & Scullard, H. H., (1935), A History of Rome, Macmillan Press, London.

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Plutarch (1920), 'The Life of Marius', The Parallel Lives Loeb Classical Library edition. Accessed at*.html 16/6/2011.

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