By the time of Marius, the Roman army had long been a citizen militia. The rich provided the cavalry, middling men were the heavy infantry, and the poorest and youngest acted as lightly armed skirmishers. Citizens too poor to afford their own equipment (proletarii) were dispensed from military service, except as rowers for the fleet (Polybius 6.19-21). Many historians believe that in 107, Gaius Marius permanently abolished the minimum property qualification for military service and opened the ranks of the legions to proletarii, who saw military service as a trade rather than a civic duty. The sources most often quoted to support this theory come from Sallust and Plutarch.
Sallust (Jugurthine War 86.2-4) has: He himself in the meantime enrolled soldiers, not according to the classes in the manner of our forefathers, but allowing anyone to volunteer, for the most part the proletariat. Some say that he did this through lack of good men, others
