Barbarian invasions into the Roman Empire of the 3rd century

Barbarian invasions of the 3rd century
Part of Roman-Germanic wars
The barbarian invasions of the 3rd century
Date 212 - 305 Location Limes Germanicus and Danubian Limes Result Raids that subsided after 268
Belligerents
Roman Empire	Germanic and Sarmatian peoples
Commanders and leaders
Caracalla Severus Alexander Maximinus Thrax Gordian III Philip the Arab Decius Trebonianus Gallus Gallienus, Claudius Gothicus, Aurelian Marcus Aurelius Probus Diocletian Maximian	Cannabaudes of the Goths, Cniva of the Goths, Gabiomarus of the Quadi, Genobaud of the Franks, Igillus of the Burgundians or Vandals, Naulobatus of the Heruli, Ostrogotha of the Goths, Semnon of the Lugii
Strength
At least 23 legions and about 150/200 auxiliary units involved, totaling 200/250,000 armed men	Numerous peoples, amounting to a few hundred thousand armed men

The barbarian invasions of the third century (212-305) constituted an uninterrupted period of raids within the borders of the Roman Empire, conducted for purposes of plunder and booty^[1] by armed peoples belonging to populations gravitating along the northern frontiers: Picts, Caledonians, and Saxons in Britain; the Germanic tribes of Frisii, Saxons, Franks, Alemanni, Burgundians, Marcomanni, Quadi, Lugii, Vandals, Juthungi, Gepids and Goths (Tervingi in the west and Greuthungi in the east),^[2] the Dacian tribes of the Carpi and the Sarmatian tribes of Iazyges, Roxolani and Alans, as well as Bastarnae, Scythians, Borani and Heruli along the Rhine-Danube rivers and the Black Sea.

Since the time of Marcus Aurelius during the Marcomannic Wars (166/167-189), Germanic-Sarmatian tribes had not exerted such strong pressure along the northern borders of the Roman Empire.

The growing danger to the Roman Empire of Germans and Sarmatians was mainly due to a change from previous centuries in the tribal structure of their society: the population, constantly growing and driven by the eastern peoples, needed new territories to expand, or else the weaker tribes would become extinct. Hence the need to aggregate into large ethnic federations, such as those of the Alemanni, Franks and Goths, in order to better attack the neighboring Empire or to defend themselves against the irruption of other neighboring barbarian populations. For other scholars, however, in addition to the pressure of outside populations, it was also the contact and confrontation with the Roman imperial civilization (its wealth, language, weapons, and organization) that prompted the Germanic peoples to restructure and organize themselves into more robust and permanent social systems, capable of better defending themselves or seriously attacking the Empire.^[3] Rome, for its part, had been trying since the first century A.D. to prevent the penetration of the barbarians by entrenching itself behind the limes, that is, the continuous line of fortifications extended between the Rhine and the Danube and built precisely to contain the pressure of the Germanic peoples.^[4]

The breakthrough by the barbarian peoples along the limes was also facilitated by the period of severe internal instability that ran through the Roman Empire during the third century. In Rome, there was a continuous alternation of emperors and usurpers (the so-called military anarchy). Not only did the internal wars unnecessarily consume important resources in the clashes between the various contenders, but – most seriously – they ended up depleting precisely the frontiers subjected to barbarian aggression.

As if this were not enough, along the eastern front of Mesopotamia and Armenia from 224 onward the Persian dynasty of the Parthians had been replaced by that of the Sasanids, which on several occasions severely engaged the Roman Empire, forced to suffer attacks that often joined the less strenuous but nonetheless dangerous invasions carried out along the African front by the Berber tribes of Moors, Baquates, Quinquegentiani, Nobati and Blemmyes. Rome showed that it was in serious difficulty in conducting so many wars at once and almost collapsed two centuries early.

It was also thanks to the subsequent internal and provisional division of the Roman state into three parts (to the west the Empire of Gaul, in the center Italy, Illyricum and African provinces, and to the east the Kingdom of Palmyra) that the Empire managed to save itself from ultimate collapse and dismemberment. However, it was only after the death of Gallienus (268) that a group of emperor-soldiers of Illyrian origin (Claudius the Gothic, Aurelian, and Marcus Aurelius Probus) finally succeeded in reunifying the Empire into a single bloc, even though the civil wars that had been going on for about fifty years and the barbarian invasions had forced the Romans to give up both the region of the Agri decumates (left to the Alemanni in about 260) and the province of Dacia (256-271), which had been subjected to incursions by the Dacian population of the Carpi, the Tervingi Goths, and the Iazigi Sarmatians.^[5]

The invasions of the third century, according to tradition, began with the first incursion conducted by the Germanic confederation of the Alemanni in 212 under Emperor Caracalla and ended in 305 at the time of Diocletian's abdication for the benefit of the new tetrarchic system.^[6]