Marian reforms

The Marian reforms were putative changes to the composition and operation of the Roman army during the late Roman republic usually attributed to Gaius Marius (a general who was consul in 107, 104–100, and 86 BC). The most important of those putative changes concerned the altering of the socio-economic background of the soldiery. Other changes were supposed to have included the introduction of the cohort; the institution of a single form of heavy infantry with uniform equipment; the universal adoption of the eagle standard; and the abolition of the citizen cavalry. It was commonly believed that Marius changed the soldiers' socio-economic background by allowing citizens without property to join the Roman army, a process called "proletarianisation". This proletarianisation was then supposed to have created a semi-professional class of soldiers motivated by land grants which in turn became clients of their generals, who then used them to overthrow the republic.

Belief in a comprehensive scheme of reforms under Marius emerged in 1840s German scholarship, which posited that any changes in the Roman army between the times of Polybius and Marius were attributable to a single reform event. This belief was spread relatively uncritically and was accepted as largely proven by the 1850s and through much of the 20th century. There is, however, little ancient evidence for any permanent or significant change to recruitment practice in Marius's time. The occurrence of such a comprehensive reform led by Marius is no longer widely accepted by specialists; 21st-century scholars have called the reforms a "construct of modern scholarship".

Other reforms to the army's operations and equipment, said to have been done by Marius, are also largely rejected by scholars. Few of them have any basis in the ancient and archaeological evidence. Others are wrongly dated or misattributed. Changes in the Roman army of the late republic occurred both later (during the Social War and following civil wars rather than at the end of the 2nd century BC) and emerged from circumstance rather than a reformist Marian vision.