Institutional military command structure of the Roman Republic?

Any modern national army has some kind of institutional command structure that endures from one war to the next; it ties together at the top, under one CinC or a board; and usually it is under the real or nominal supervision of a civilian government agency, a Department of Defense or Ministry of War.

Did the Roman Republic have anything of the kind? From what I’ve read I’ve gotten the impression, never explicitly stated, that each legion was an autonomous entity, whose commander might hold command by virtue of being an elected magistrate, a consul or praetor, but who was not answerable to anything analogous to the Pentagon or the Joint Chiefs or the DoD. And that seems to have held true even after the Marian Reforms.

I think you’re right. The Senate would grant “imperium” of an area to a commander (usually a Consul, or later, a Legate), and that commander would have control of the legions in that area. He wasn’t answerable to anyone during the term of his office.

In some cases two Consuls would be in the same area, and either each lead their own armies or, if there was only one army, alternate days of leadership.

Was there no DoD-equivalent under the Empire either?

There was the Emperor. There was also the Commander of the Pretorians, who tended to serve as an unofficial army staff chief.

Eh. Roman Republic not Empire. Yes know it was never officially abolished.

A person could be named commander of a certain region, like Ceaser was in Gaul or Crassus in the East or Pompey all over the Med in the anti-Pirate campaign.

Well, did he, really? That is, did the Commander of Praetorians have any administrative or operational or command authority, real or nominal, over the legions on the frontiers, or any general authority over legionary administration and finances, or anything?

Well, that’s very mission-specific; I’m looking for something like a Roman Pentagon.

The late Empire had a fairly developed military bureaucracy, with centralized command and finance posts set above the regional commands.

Prior to that, the system seemed to basically vary with the whim of the Emperor. As already mentioned, the Praetorian Prefect often served as a sort of Chief of Staff, but this varied with the personalities involved.

As a practical matter, there’s only so much Command and Control you can exercise if you’re limited to iron-age communication technology and have armies spread across most of Europe and the Mediterranean basin. This was one of the reason Diocletian tried to establish a hierarchy of four Emperors, trying to run multiple armies from one central location was too hard, while trying to temporarily give large armies to local commanders had a tendency to backfire when those commanders declined to give them back.

I assume that authority took the form of “I am authorized by the emperor to issue the following orders”, or that he and his collection of desk jockeys would write up the orders, and pass them to the emperor for signature/seal before distribution?

More like an ad hoc cabinet post and office of “Secretary of Defense” than a formal pentagon?

Which would be the process for almost any form of large-scale administration of any such government task - delegate.

Probably not. The idea of a military staff was developed by the Prussians centuries later. Prior to that, a military commander was expected to handle both the battlefield direction and all of the administrative work involved in keeping a force in existence. At most, there might be a quartermaster who was in charge of buying supplies. But nobody who was supposed to be making plans and issuing orders on a commander’s behalf - it was basically a situation where if a commander wanted something done, he had to do it himself.

The Roman tax system and public works, from what I’ve read, involved basically a franchise system. The reviled tax collector (Matthew?) was given an area or group from which he collected taxes and remitted to his higher-up, minus his commission. The governor or local administrator was responsible for public works in his area, from the taxes he collected. Some were gradiose monuments, some were necessary - aqueducts, temples, roads…

I assume the armies worked the same. The local commander would know how much bread and wine his troops needed, what new arms, to where, and what was the most efficient means of buying and delivering. I doubt anyone above the area commander would be telling him garrison size of his troops go to each of fort A, B, and C along the frontier.

Yes but that is the philosophy from the sophist emperor and senate… how did it REALLY work ?

The upper ranks of the of the army would be from the equite and patrician classes.
Thats where the permanent structure is …

The equite class was the public service of the roman empire.

“The bulk of non-agricultural activities were in the hands of non-senatorial equites. As well as holding large landed estates, equites came to dominate mining, shipping and manufacturing industry. In particular, tax farming companies (publicani) were almost all in the hands of equites.”

It would be best to inherit if you had become a knight. If the family hadn’t produced enough cavalry and knights, there would be pressure to take the industry off that family… So each family and each town, etc would have a permanent system to produce cavalry and knights, to train and test them… to record the information gleened.The equite - the cavalry - were the spies for their superiors in the army AND for their home town…