The Marian Reforms and the Fall of the Roman Republic

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Gaius Marius (157-86 BC) was a Roman politician and general. Through his military reforms of 107 BC, Maris played a crucial role in reshaping the Roman army, opening recruitment to the capite censi – the landless poor – for the first time. Although envisioned as a practical measure to solve recruitment issues, the Marian reforms would have a profound socio-economic and political legacy. They led to the growth of larger standing armies with poorer soldiers, who relied entirely on their generals for their retirement prospects. As a result, legions increasingly shifted their allegiance away from the senate and towards individual commanders, becoming political instruments in the hands of ambitious men such as Sulla and Caesar. The erosion of senatorial power and the collapse of the republic can therefore, in large part, be traced back to Marius’s reforms.

Prior to the Marian reforms, only those with a net worth above four thousand asses were able to join the army. Most owned property and everyone had to supply their own equipment. Military service was therefore considered a state duty of the propertied class, who had a vested interest to defend the land they owned. Crucially, landed soldiers did not rely on the military for their retirements plans, as they could always return to their farms once campaigning was over. The pre-Marian army was arranged into five classes: the poorest and most inexperienced of the propertied classes joined the skirmishers, known as velites; the rank above joined the medium infantry or hastati; those in peak physical condition joined the heavy infantry known as principes; and older men were assigned to triarii, another category of heavy infantry. Finally, the most prosperous landowners were part of the equestrian class, as they could afford the upkeep of horses. The capite censi were generally not allowed to serve except in exceptional cases when there was a complete shortage of manpower.

As a result of these restrictions, pre-Marian military campaigns tended to be much shorter. The campaigning season spanned from March to October, which ensured that soldiers could return to their farms in time for harvest. Soldiers also had the prospect of acquiring loot on campaign to compensate for the time spent away from their estates, tempting many landowners to enlist. However, as the Roman Empire expanded over time, these campaigns inevitably became longer. This placed strain on farms that could not be tended to while soldiers were absent, as their families could not afford to maintain them. Many struggling farms were sold to neighbours as a result. In addition, much of Roman public land, such as in Campania, was sold to senators and wealthy equestrians who created vast farms worked by thousands of slaves to produce cash crops. This damaged the business of smaller farms, making landowners less willing to enlist. This increasing shortage of men was compounded by the fact that, as the empire grew, Rome’s armies only needed to grow larger. All these factors led to recruitment issues that culminated at the end of the 2nd century BC.

As a highly capable general, Marius was acutely aware of the issues faced by the Roman Army. When he obtained the consulship of 107 BC, he set about implementing his vision of military reform. First, he improved the training undertaken by soldiers, and equipped all soldiers with the short sword to make the army more uniform. He also instituted the universal adoption of the eagle or aquila as the army’s sole standard. The cohort also replaced the maniple as the basic unit in the Roman legions. Finally, Marius eliminated the land requirement for joining the army. With this last stroke he revolutionised the military system, significantly increasing Rome’s recruitment pool. However, the capite censi relied on the military for their retirement; lacking land or livelihood of their own, they required benefits such as land grants once their service was completed.

These reforms were received ambivalently by the senate. Most notably, it refused to create retirement programmes for veterans of the capite censi. This precipitated a radical shift in loyalties, as wealthy generals superseded the state as the guarantors of their soldiers’ future livelihoods. Marius effectively opened the door for popular generals to use legions as private armies, instead of treating them as armies of the state.

These impacts were first illustrated by Sulla’s rise to power. Sulla, like Marius, had proven his mettle as an able general during the Social War (91-87 BC). In 88 BC he became consul, and took command of the war against Mithridates, King of Pontus, who was wreaking havoc in Rome’s eastern provinces. Marius, envying this position, used a sympathetic tribune to transfer the command to himself. Furious, Sulla turned his army around and marched on Rome – a treasonous act, as it was illegal to enter the city without relinquishing one’s military imperium. While his officers were reluctant, Sulla’s troops obeyed this unprecedented order – evidence of the effect of Marius’s reforms decades earlier. Sulla’s capture of the city also set a new standard; from now on ambitious commanders saw fit to use their armies as political instruments.

When Sulla set off again to command the war against Mithridates, an ally of Marius named Cinna rose to power, marching on Rome in 86 BC to secure the position of consul. Declaring Sulla an enemy of the republic, Cinna raised an army to fight him only to be killed by his own soldiers in a mutiny. Sulla and his loyal army captured Rome once again – sending a pertinent message to future generals of the value of cultivating personal loyalty among their troops. Indeed, when Sulla returned to power he issued proscription lists of his opponents in the Roman aristocracy and had them killed. Much of their land was then redistributed to his troops for their retirement.

Sulla was the first but certainly not the last to use such means to achieve political success. Julius Caesar relied heavily on the legacy of the Marian reforms in his rise to power. As the consul of 59 BC, he passed laws to win the support of soldiers, including provisions to redistribute public land to veterans, providing debt relief for some soldiers and granting Roman citizenship to the province of Cisapline Gaul – the source of many of his troops. Appointed to the governorship of Gaul, Caesar led his soldiers in the successful Gallic wars, conquering vast new lands and riches – which secured the personal allegiance of his soldiers. In 50 BC, growing tensions with a Pompey-controlled senate resulted in Caesar being issued an ultimatum to abandon his command and return to Italy. But thanks to Marius’s reforms Caesar’s troops stood by him as he took the final step that would plunge the republic into civil war – crossing the Rubicon and marching on Rome.

Recent years have seen some revisionist historians doubt the reality of the Marian reforms. It is argued that many of the changes attributed to Marius likely took place over a number of decades, and cannot be pinpointed to a single programme of reform. However, it is clear that over the course of the late 2nd and early 1st centuries BC there was a dramatic shift in Roman military organisation, with the ‘proletarianisation’ of the legions leading to larger and poorer armies – and it would seem that Marius certainly played a role in this change. As a result, the Marian reforms will continue to be seen as one of the primary causes of the turmoil and destruction that led to the fall of the Roman Republic.