Archaeologists Find Athenian Naval Base

[Minimalist]

Yes, but Banjo is correct about the mechanism of the change.  Before the 2d Punic War there were relatively few slaves in Italy, south of the Po.  This was Roman dominated territory and the military was drawn in classes based on citizen wealth.  Most were farmers and after planting and before harvest there was always plenty of men who wanted a little adventure and maybe a chance to pick up some loot with the army.  But the 2d Punic War was effectively a world war by the time it ended and Roman armies were kept in the field for far longer than they had been before.  After the 3d Punic War, with any possible threat of Carthage eliminated we began to see large numbers of slaves brought to Italy.  As noted, the Patricians bought out the small farmers and combined the plots into large estates and worked them with slaves.  The displaced farmers moved to the city and formed the basis of the urban mob.  They soon went through the money they had been paid and were destitute. Unable to meet the demands of the censors they dropped in class and were no longer designated to serve as one of the major formations of the republican army - Hastati, Principes, Triarii, Equites.  People did notice what was going on.  Famously the Gracchi brothers, Tiberius and Gaius, agitated for land reform but the nobility found it easier to kill them.

After the Battle of Arausio the state found itself unable to replace battle losses because there were no yeomen farmers to draw from.  Marius stepped forward to reform the army but he quickly learned that they other uses than fighting barbarians.  Twenty years later Marius and L. Cornelius Sulla were using their personal armies to slaughter each other.  And the republic was doomed.