How much did the crisis of the 3rd century denude the Rhine Danube frontier?

Nov 2014
340
ph
#1
How much did the crisis of the 3rd century and the constant civil wars affect the external defenses of the Roman Empire? It seems that the barbarians did make some sucessful raids, but there was no permanent collapse of the frontier and permanent massive losses in territory like what happened after Manzikert, how many troops did the Romans like behind to guard the limes during their constant civil wars during that period? How denuded were the frontier defenses during this period relative to say, the mid 2nd century?
 
#2
I imagine parts of the frontier were indeed pretty denuded due to the repeated imperial campaigns against usurpers and foreign enemies. Emperors repeatedly failed to convince the armies of their legitimacy, and different armies competed to raise their own emperors. The failure of emperors to achieve longevity meant that no dynasty could take hold. Foreign enemies form a major part of this picture. Their aggression created anxiety among the armies and provincials. The Sassanian Persians penetrated deep into the eastern provinces, twice sacked Antioch and numerous other cities, defeated Roman armies and captured an emperor. The Goths and Heruli raided far and wide in the Balkans and the eastern Mediterranean, on and off, for almost three decades. The Alemanni and Iuthungi invaded Italy three times and caused anxiety in the city of Rome itself. Frankish raiders devastated parts of Gaul (Armorica suffered from the collapse of economic and social structures) and they reached Britain and Spain as well. But with that all being said, the Persians alone sought to hold territories permanently, and their ambitions in that regard appear to have been limited to Mesopotamia and Armenia (despite their ideological claim that they intended to retake all that the Achaemenids once possessed). The Goths sacked cities but never sought to hold them.
 
#3
Also, the concept of the Roman Empire was bigger than any one emperor. This is another reason why the empire did not collapse. Both the Gallic emperors and the rulers of Palmyra were not separatist rulers, but rather framed their rule in Roman terms. And no matter what happened regarding the power struggles at the very top, the Roman Empire (for the most part) kept on chugging along. That being said, the armies and their officers were clearly very invested in the imperial leadership, thus their trigger-happy behaviour, and again, civil war must have effected the amount of men guarding the frontiers.
 
Likes: Kevinmeath

authun

Ad Honorem
Aug 2011
5,039
#4
How much did the crisis of the 3rd century and the constant civil wars affect the external defenses of the Roman Empire? It seems that the barbarians did make some sucessful raids, but there was no permanent collapse of the frontier and permanent massive losses in territory like what happened after Manzikert, how many troops did the Romans like behind to guard the limes during their constant civil wars during that period? How denuded were the frontier defenses during this period relative to say, the mid 2nd century?

There were many changes, expanding northwards from the south and eastwards from the west, and then back again. This map shows the expansion from the Odenwald Limes, based on the Neckar to the the upper german raetian limes, its most easterly extent by the 3rd century. Later it retreated further west when the Rhine became the frontier and in the south the retreat was to the Danube. I shall look for a map which shows the 3rd and 4th centuries. In the north and the south east, it was stable, but you can see the area which was in a stat of flux.

 
Last edited:
#6
There were many changes, expanding northwards from the south and eastwards from the west, and then back again. This map shows the expansion from the Odenwald Limes, based on the Neckar to the the upper german raetian limes, its most easterly extent by the 3rd century. Later it retreated further west when the Rhine became the frontier and in the south the retreat was to the Danube. I shall look for a map which shows the 3rd and 4th centuries. In the north and the south east, it was stable, but you can see the area which was in a stat of flux.

Oh yes, I forgot that this period was when the Romans permanently abandoned the Agri Decumates (and perhaps temporarily abandoned the Swiss Rhine).

Here are snippets of a discussion by John Drinkwater (1987, The Gallic Empire: Separatism and Continuity in the North-Western Provinces of the Roman Empire, AD 260-274, pp. 218, 224-227): '(Exceptional here is the (archaeological) evidence for the final collapse of the Upper German limes and the loss of the Agri Decumates c. 259/60, and for the permanent settlement of the area by the Alamanni no earlier than the fourth century.) … The Upper German limes, which protected the Agri Decumates, were probably breached in 260 by the invasions which resulted from the capture of Valerian. … the Alamanni took many years to settle the region … the Agri Decumates seem to have become a no-man’s land … The Gallic Empire had no need to control the Agri Decumates; indeed, any expedition across the Rhine in an attempt to restore the limes would have risked not only barbarian attack, but also a Central imperial thrust against its exposed right flank. … Postumus could scarcely attempt to hold the Swiss Rhine when he could not trust the Central imperial forces in Raetia not to take advantage of such a move. (The Central Emperors would, of course, have faced a similar dilemma in respect of the Gallic Empire.) Indeed, … it may well have been that … central Switzerland was a no-man’s-land during the period of the Gallic Empire.’
 
#7
It was also during the late third century that the Romans, under Aurelian, permanently abandoned Dacia. Here a two quotations from Alaric Watson 1999, Aurelian and the Third Century.

p. 55: ‘The resounding victory (over the Goths in 271) restored not only the Danube frontier, but the flagging morale of the region’s defence forces. But that was not enough. … Aurelian could not spare the men and matériel that would be required to restore the transdanubian bulwark and the Dacian limes. He knew that, if he was to defeat the Palmyrenes (in the following year), he needed to take with him to the east a sizeable army, one much larger than he had brought with him from Italy. He fully intended to levy more troops while in the Balkans, but raw recruits would be insufficiently reliable for the task in hand. But to deplete the already over-extended Danube army could be costly. For two decades the armies of Rome had been forced to defend the eastern Balkans from almost constant Gothic invasions. Aurelian himself had personally witnessed these bloody conflicts over the last four years. Nothing short of a drastic rethink of regional strategy would do.
Aurelian’s solution was as radical as it was bold. He ordered the complete withdrawal of all the legionary forces stationed in Dacia and redrew the defensive line along the Danube, thereby greatly reducing the length of the frontier to be guarded. Furthermore, he evacuated from Dacia a sizeable proportion of its more important citizens and resettled them south of the river in a newly constituted province of Dacia Ripensis.’

pp. 155-157: ‘From the reign of Philip on, the province had known little respite from barbarian raids. Gallienus had been unable to spare the resources to expel the barbarians and indeed had even transferred part of the two Dacian legions, the V Macedonica and the XIII Gemina, back across the Danube to Poetovio (Ptuj) in Pannonia Superior. …
It is highly improbable that (Aurelian) attempted a mass evacuation of the entire population of the old province of Dacia. … the epigraphic evidence, which points to the survival of Daco-Roman civilization north of the Danube for more than two centuries after Aurelian, strongly argues against the wholesale removal of the population. This inference is further supported by the continuation of the Latin language in the region, of which modern Romanian is a direct descendant. …
It is possible that two new provinces were created simultaneously, one along the Danube, called Ripensis, and the other to the south, chiefly comprising the region of Dardania, called Dacia Mediterranea. …’

Also, from David Potter 2014, The Roman Empire at Bay AD 180-395, 2nd. ed., p. 266: ‘Unlike Valerian (Aurelian) was not devoted to the world of the early third century, but rather to rationalizing the empire that he now ruled. … But still, it was a dangerous move, and one that Aurelian attempted to obscure by carving two new provinces of “Dacia” out of Upper Moesia. The last emperor to surrender Roman territory had been Hadrian, and, necessary though Hadrian’s action had been, it had many critics.’
 
Feb 2011
1,006
Scotland
#8
As I understand it, the rise of separatist Roman Empires such as the Gallo-Roman under Postumus and his successors, resulted from the desire of the local landowners and other powers-that-be in the area not to see the defence forces pulled away to crises in other parts of the Empire for unforeseen lengths of time, leaving them open to incursions from their own local problem tribes. The Franks and Alamanni represented (so I understand) increasing tendencies for German tribes to form confederations (themselves under Roman pressure) - and there must also have been a ripple effect from the impact of arrival of Goths and Vandals onto the scene about this time.
 
#9
As I understand it, the rise of separatist Roman Empires such as the Gallo-Roman under Postumus and his successors, resulted from the desire of the local landowners and other powers-that-be in the area not to see the defence forces pulled away to crises in other parts of the Empire for unforeseen lengths of time, leaving them open to incursions from their own local problem tribes. The Franks and Alamanni represented (so I understand) increasing tendencies for German tribes to form confederations (themselves under Roman pressure) - and there must also have been a ripple effect from the impact of arrival of Goths and Vandals onto the scene about this time.
Regarding the Franks, Alemanni and Goths, I have indeed read scholars make such interpretations. As for the Gallic Empire, the immediate cause for Postumus' usurpation was the fact that Gallienus' son and Caesar Saloninus was stupidly attempting to reclaim booty that Postumus had distributed among his troops, but it is certainly very plausible that the landed aristocracy supported the Gallic emperors for the reason you cite. We can add the officers and soldiers themselves to that equation - they wanted a present emperor and plenty of support in their attempts to defend the frontier and by extension their property and families. The fact that Frankish raiders reached Spain in the late 250s attests to serious problems.