The last decades of the existence of praetorians

[comitatus (Marco)]

As conclusion of this topic: With the creation of tetrarchy in 293 the praetorians were split between Diocletian, Maximian, Constantius I and Galerius, and then were inherited for their respective successors. Parts of all ten cohortes remained in Rome for policing and symbolic reasons, and these praetorians elevated Maxentius in 306. Then Maxentius filled the ranks missing in the cohortes and so all the ten cohortes were present in the battle of the Milvian bridge, while the praetorians of the tetrarchs still existing outside Rome were transformed into new units after 312 (or before). So the Guard disbanded by Constantine would have been largely a newly-raised formation. Constantine's praetorians were (maybe) transformed in the Armigeri Propugnatores and Armigeri Defensores, while Licinius' praetorians were disbanded after the battle of Chrysopolis in 324, if not transformed already into other units before (what seems more likely).

[Nathan Ross]

Parts of all ten cohortes remained in Rome for policing and symbolic reasons

I wonder what the 'reasons' might have been? As far as I know, the praetorians had no 'policing' role in the city - that was the job of the vigiles and urban cohorts, who seem to have remained there. As guards of the emperors, they would have no duties connected to the senate either. Perhaps they were intended as guards for the imperial mint, which remained one of the most productive in the empire?

Constantine's praetorians were (maybe) transformed in the Armigeri Propugnatores and Armigeri Defensores

Well, perhaps... armigeri does seem to have been used as a general word for bodyguards throughout Roman history. Ammianus refers to the German who deserted before the battle of Strasbourg and gave information to the enemy as both armigerius and scutarius, implying that the Armigeri and Scutarii were the same body...

[Theodosius the Great]

I believe the walls of Rome were sufficient to deter both Flavius Severus and Galerius

Good point. And with a little help from daddy Maxentius was able to secure his position. I think their falling out ultimately weakened Maxentius' support among the populace.

I wonder what the 'reasons' might have been? As far as I know, the praetorians had no 'policing' role in the city - that was the job of the vigiles and urban cohorts, who seem to have remained there. As guards of the emperors, they would have no duties connected to the senate either. Perhaps they were intended as guards for the imperial mint, which remained one of the most productive in the empire?

I used to think of them as city's official garrison but couldn't find any strong evidence to support that view. Yes, the mint seems a likely reason to maintain a presence. Then there's their HQ, the Castra Praetoria which may have contained the "armory" mentioned in Tacitus (History, Book 1, 38):

He then ordered the armoury to be opened. The soldiers immediately seized the arms without regard to rule or military order, no distinction being observed between Praetorians and legionaries, both of whom again indiscriminately assumed the shields and helmets of the auxiliary troops.

aperire deinde armamentarium iussit. rapta statim arma, sine more et ordine militiae, ut praetorianus aut legionarius insignibus suis distingueretur: miscentur auxiliaribus galeis scutisque

So the Guard disbanded by Constantine would have been largely a newly-raised formation.

It seems like an unfitting end for the Praetorians having fought so vigorously for a usurper with no military background.

~Theo