In 107BC Gaius Marius instigated a series of reforms to the structure of the Roman army that, among other things, shifted the allegiance of soldiers towards their generals as apposed to Rome itself. This is widely accepted by modern historians as being a contributing factor to the frequent civil wars that brought an end to the republic, but I cannot find any reference to this dimension of the reforms in the works of ancient Roman Historians. Did they never consider the potentially destabilising effect of the reforms?
This is widely accepted by modern historians as being a contributing factor to the frequent civil wars that brought an end to the republic
Is it widely accepted? I was unaware of that. Wouldn't Sulla's establishment of promagisterial commands in the provinces for all praetorians and consulars be more significant to the establishment of what used to be called "private armies?" The abolition of the property requirement (which was by Marius' time essentially nominal in any case) had very little long-term effect on the composition of the army. And nothing about Marius' legislation provided for multi-year armies led by the same commanders. Most political historians think of the abolition of the property requirement as no more significant than our texts indicate. Plutarch and Sallust both mention it, but mostly incidentally--both authors only bring it up to point out that the army that marched into Africa (which was, specifically, the one that we are told included the capite censi) was made up of men who had no property and therefore no legitimate stake (at least the way such things were often thought in antiquity) in the state's defense. I can't think of any political scholar of any importance in the last forty or fifty years who ascribes any great significance to the abolition of the property requirement--I'm sure there are some, but off the top of my head nothing comes to mind.