In with the new

[Watchman]

It's not like one day people just decided to seriously redo their whole military system of course. Especially the "Camillian-Polybian" shift was just a normal gradual evolution of equipement, tactics and organisation. It was always a rather lenghty process naturally - with the "Marian" developement the old citizen milita eventually became an increasingly unsustainable system, with ever more men simply hired and equipped by their employers to make up the balance... until you basically had the Republic full of "strong men" with their own private armies. Augustus was the guy who was left standing after the brown stuff hit the fan over than, and he understandably consolidated the multifarious more-or-less private forces into a rather more manageable, dependable and affordable core of standing "national" armies.

[Gaivs]

The late Polybian troops were all uniformly equipped (pretty much) by the time Marius arrived, he just formalised it all, his major change was the capite censi soldiers.

[zooeyglass]

The late Polybian troops were all uniformly equipped (pretty much) by the time Marius arrived, he just formalised it all, his major change was the capite censi soldiers.

and the very name "polybian" only refers (although correct me if i'm wrong) to polybius' description of the changing style of the roman "army", not an actual "reform" per se. So any changes described by him are "polybian" although he himself did not implement such a change, but only provides us with an understanding of said change....

re: Augustan era reformation:
Augustus' move to formalise private forces into a "national" army was also a product of his own dynastic leanings, and an understanding that military force must enforce the ruling man's position. By aligning the army and his family into the position that was central of government (that is to say, the power behind ruling, and the rulers), he not only removed others' opportunities to rise up against him (they lacked the man power/armed forces) but also consolidated his own desire for keeping power in one man, and one family.

[Disciple of Tacitus]

It's not like one day people just decided to seriously redo their whole military system of course. Especially the "Camillian-Polybian" shift was just a normal gradual evolution of equipement, tactics and organisation. It was always a rather lenghty process naturally - with the "Marian" developement the old citizen milita eventually became an increasingly unsustainable system, with ever more men simply hired and equipped by their employers to make up the balance... until you basically had the Republic full of "strong men" with their own private armies. Augustus was the guy who was left standing after the brown stuff hit the fan over than, and he understandably consolidated the multifarious more-or-less private forces into a rather more manageable, dependable and affordable core of standing "national" armies.

@ Watchman

Which - you might say - are one (among many) reason why the Eastern Roman Empire hung around for so long. It's been a while since I read the History of the Byzantium Empire, but this "reform" seems to have done the Eastern Roman Empire some good. Certainly stayed around for a few more centuries. I was unaware that it's "origin" could be traced back to Augustus. Comments, good sir?

[Watchman]

Are you referring to the themes ? That's a whole different and far later issue. AFAIK - with the caveat that the Late Roman period isn't my strong suit by any measure - the Eastern Empire military was for a long time only marginally less ad hoc than the Western one after the whatwasitnow, 4th century AD quakes.