Roman Army before and after the Marius' Reforms

[Nathan Ross]

Legionaries in the time of Caesar, were military professionals... Pre-Marian Militia/levy men, who were not professional soldiers, but ordinary farmers who spent their lives working in the field, and occasionally went to war

I would think the troops of Caesar's veteran legions by the end of the civil wars, after 15 years of near-constant campaigning, were probably among the toughest and most experienced soldiers ever fielded by Rome.

However, we shouldn't assume that the soldiers of the earlier Republic were all that occasional - Spurius Ligustinus may have been exceptional, but his example proves that long service was certainly possible in the 2nd century BC.

Also, the vast majority of Romans of any means owned slaves (which is presumably how they kept their farms running while they were away at war) - a 'Roman farmer' wouldn't be doing all the hard work himself!