Marius Creates a Private Army Summary

  • Last updated on November 11, 2022

The general Gaius Marius created a private army composed of volunteers rather than conscripts, thereby revolutionizing the organization of the Roman army.

Summary of Event

Marius’s reforms of the Roman army were the culmination of developments arising out of Rome’s emergence as an imperial power. These reforms marked the beginning of developments that led to the civil wars of the late first century and the end of the Roman Republic. Marius, Gaius

From the earliest period, the Roman army was recruited on an ad hoc basis for specific campaigns. Levies were held in each year in which military operations were proposed; recruits were conscripted from free-born citizens whose properties enabled them to provide their own arms. Although the property qualifications for military service were often loosely observed, and although the extended campaigns required from the First Punic War onward brought about the institution of military pay for soldiers, the armies of Rome were still thought of, and in large part were still treated as, a citizen militia rather than a professional force. Possession of property, regarded as a pledge of good faith and a commitment to the nation, remained a requirement for eligibility to serve.

Gaius Marius.

(Library of Congress)

During the third and second centuries b.c.e., the traditional system of recruitment was subjected to increasing strain. The requirements of empire created a need for larger numbers of troops recruited for longer periods of time. Small landholders, who made up the bulk of the army, found it increasingly difficult to maintain their farms while fulfilling their military responsibilities. The importation of cheap grain from conquered territories created additional hardships for small farmers, whose small holdings fell more and more into the hand of large landowners. These prosperous landowners operated their tracts with the help of slaves and tenants who were disqualified, by lack of property, from army service. In short, the need for troops was increasing while the class of citizens who supplied that need was diminishing.

The reforms of Tiberius and Gaius Sempronius Gracchus, designed to reestablish the small farmer class, failed to achieve their purpose while creating a climate of mutual suspicion and hostility between the ruling senatorial order and the rest of the Roman population. When Gaius Marius, an experienced soldier unconnected with the senatorial order, offered to remove the conduct of the Jugurthine War (111-105 b.c.e.) from the hands of the senate-appointed generals, he was elected to office by a large popular majority. Furthermore, over the objections of the senate, Marius was entrusted with the African campaign. Seeing the difficulties of raising an army in the traditional way, and less bound by tradition than generals of higher birth, Marius refused to order a conscription. Instead, he called for volunteers, accepting all who appeared to be physically fit, with no consideration of property qualifications.

Marius’s action, superb in its simplicity, solved once and for all the problems of recruiting military forces. Although the Roman countryside had been depleted of small farmers, the propertyless masses of the city had grown large. From these urban residents and from the large rural population of tenant farmers, Marius forged an army of volunteers who regarded military service not as a civic obligation but as a means of earning a living.


The change from a citizen militia to a professional army, however, created difficulties of a new kind. Thereafter, the Roman army was not a force raised by the state, but one that had attached itself to a particular commander. Soldiers fought not to protect their possessions but to earn a living. Their advantage lay not in a quick resolution of a specific campaign but in the continuation of military action. The commander of these forces had to guarantee their pay and booty; he also had to ensure them some form of pension, usually a small landholding, at the end of their service. To offer such guarantees, he had to maintain a high degree of control over Roman policies, both foreign and domestic. So Rome came under the twin threats of civil war and military dictatorship, a situation that was not resolved until the collapse of the Roman Republic, when military and civil government were combined under the emperors.

With the creation of a truly professional army came extensive reorganizations in tactics and equipment. The Roman legion, regarded as a standing force, was given an identity symbolized by a permanent name and a legionary standard. Armor and pack were improved and standardized; training and discipline received greater attention. The maniple, a tactical unit of approximately 120 men of proven maneuverability against the larger and tighter Greek phalanx, was replaced by the cohort. This tactical unit of six hundred men proved itself more effective against the non-Greek forces that had become more common as Rome’s opponents. Whatever its unfortunate effects upon the republican form of government, the professional army created by Marius served the Roman Empire well for centuries of conquest, occupation, and defense.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Goldsworthy, Adrian. The Roman Army at War: 100 b.c.-a.d. 200. New York: Oxford University Press, 1997. An overview of the organization and operation of the Roman imperial army. Gives both practical and theoretical examples and contrasts the Roman army with its major oppositions.
  • citation-type="booksimple"

    xlink:type="simple">Keppie, L. J. F. The Making of the Roman Army: From Republic to Empire. 1984. Reprint. Norman: University of Oklahoma Press, 1998. A survey of the historical development of the Roman army, tracing changes in strategy and organization as a result of political as well as military factors.
  • citation-type="booksimple"

    xlink:type="simple">Le Bohec, Yann. The Roman Imperial Army. New York: Routledge, 2000. One of the best studies of the Roman army, divided into sections on its organization, its activities and functions, and its role in the maintenance of the empire.
  • citation-type="booksimple"

    xlink:type="simple">Peddie, John. The Roman War Machine. Stroud, Gloucestershire, England: A. Sutton, 1994. A good general introduction to the evolution of the Roman army and navy.
  • citation-type="booksimple"

    xlink:type="simple">Santosuosso, Antonio. Storming the Heavens: Soldiers, Emperors, and Civilians in the Roman Empire. Boulder, Colo.: Westview Press, 2001. Focuses on how the military was itself a source of antagonism and disorder within Roman society and contributed to the instability of imperial Roman politics.
Related Articles in <i>Great Lives from History: Ancient World</i>

Gaius Marius. Marius, Gaius;private army of

Categories: History Content