Vespasianus had become Emperor after the chaos of the post-61 Nero years and the 'Year of the Four Emperors'. A successful general who treated the Senate with respect (if not deference), he restored stability to the throne and order to the Empire's workings. He also ensured that the succession worked smoothly. His son Titus was well prepared and passed through the proper cursus honorum, including consulships and military commands. In 79 he became Emperor. He gave gifts and military donatives upon his accession, and treated the Senate well. He also administered disaster relief, a key example being in the aftermath of Mt. Vesuvius' eruption in 79-90. In 80, Rome burned again, necessitating more disaster relief, which was distributed loyally. In 81 CE Titus died.
His younger brother Domitian (r. 81-96) succeeded him. The succession went off without a hitch, and the army was loyal throughout. He was, though, clearly different from the other Flavians (the dynasty name is take from one of Vespasianus' names). He had been kept in the background by his father, and did not gain Titus' education or experience, and thus did not acquire the latter's political savvy, especially as regards his attitude towards the Senate. Domitian was good at administration and retained the favor of the army, but he was abrasive. He increased the heavy reliance on the equites in imperial administration. Equestrians replaced freedmen as Principate secretaries, gradually even moving into governor slots in senatorial provinces, at times even leading legions. Both of the latter two were usually prerogatives of senators. Equestrians were also added to the Emperor's council—a sort of law court in which senators could even find themselves judged by the (assumedly) lower social status equites. Thus, while at first Domitian-Senate relations were characterized by irritation, the Emperor eventually gave up on them and ruled without even the appearance of consulting them.
Senate historians blackened Domitian's name and devoted little attention to his period. Thus, we know little of his actions. He was an autocrat, and had some grandiose eccentricities, such as trying to name a month after him. He did, however, accomplish some reasonable things. First, he attempted to bolster the frontier. He took the Agri Decumantes along the Danube, which shortened the line of the frontier. Second, Domitian was active near the Danube. The northern bank was increasingly congested with Barbarians. There were three main groups. On the middle and upper Danube were the Marcomanni and Quadi, while downstream were the Sarmatians, hedged by the Roxolani of the western Ukraine. Wedged between these groups were the Dacians, of Transylvania. They were the most advanced of the Barbarians, with a kingdom ruled by Decebalus. A strong warrior, he was able to lead large forces by example. In 85, he invaded Moesia (Bulgaria), on the Roman side of the Danube, plundering heavily. Domitian collected his legions and went to war from 86-88. While the Romans did drive out the Dacians, the campaigns were not very satisfactory, and Domitian elected to make a treaty in 88-89, whereby he recognized Decebalus as a client king, and undertook to send subsidies—yearly protection money. Decebalus in turn promised peace. Domitian's measure, while popularly accepted an acceptable tactic in the eastern reaches of Roman lands, was seen by Romans as a defeat when employed on the Danube. Around the same time, L.A. Saturninus, an imperial legate from the upper Rhine area, revolted. He had allied with the Barbarian Chatti across the Rhine, but as the river thawed early that spring, they were unable to cross to assist him. The revolt turned out to be a short- lived fiasco. Yet despite its meagerness, the revolt convinced Domitian he could no longer trust the senatorial aristocracy, which had provided several legates. Further, after a time lag, a new Tiberius-style terror commenced, in 93. Fearing conspiracies, the Emperor used treason charges to judicially murder his enemies. He was able to destroy a healthy chunk of the old senatorial aristocratic clans through exile, execution, and expropriation of their material basis. Around this time, writers began to refer to him as psychologically unbalanced—Tacitus called him a paranoid monster. If this is true at all, it only began after 93. Indeed, perhaps he was justified in his paranoia: in 96 he was assassinated by his wife, the praetorian prefect, and a palace visitor. Domitians death marked the end of the Flavians, and the Roman mob rioted at the prospect of a new power vacuum.
As events during Domitian's rule suggest, around this time the German Barbarians were becoming an unavoidable element in the Rhine-Danube areas. Caesar first observed them in 51 BCE. German tribes were clan-based, with blood-loyalty the basis for all bonds. Living intermittently in settled forest clearings called hamlets, they engaged in mixed subsistence cultivation of crops and animals. Cultivation was rudimentary given the hard clay soil and use of implements more suited to Mediterranean areas. There were no surpluses, so population remained small, around one million. Without much occupational specialization, they were an iron-age culture emphasizing war.
For the first century CE, they were not a real danger to Rome: 1)Poverty ensured poor armor and weapons, and 2) they had limited tactics, consisting of ambushes and a mass charge. 3) Divisions into numerous small tribes meant a lack of political cooperation. 4) There was no real, continual government beyond the clan. In peacetime, tribal assemblies made up of all free men and warriors decided issues of peace and war. They would elect temporary war chiefs, whose legitimacy ended after hostilities.
Tacitus described the Germans again about 100 CE. After Caesar had taken Gaul up to the Rhine, expansion space was curtailed for the nomadic tribes, causing demographic pressure on the borders. Some Germans began to come into contact with Roman civilization at border garrisons. They greatly admired the material aspects of Roman culture, such as arms, domestic wares, etc. Small numbers were accepted for service with Roman legions, and small scale German-Roman trade relations emerged involving cattle and slaves developed.
Gradual, changes occurred in the next 250 years: A) Though kinship remained the primary bond, a new kind of political formation evolved: the Comitatus. Older, successful warrior chieftains took in younger aspirants, who then raided and shared the booty with each other. A kind of professional, more lethal warrior group came about, where bonds were now between man and lord, the latter signaling the beginning of a small aristocracy. B) At the same time, tribes began electing fewer, longer serving war-chiefs, as inter-tribe conflict increased, spurred by the desire to partake of Roman material culture. C) Eastern German tribes, Goths and Vandals, gradually migrated from North Poland to the Ukraine, pressuring the Danube frontier and settling north of the Black Sea, to the West of the Huns. D) Around 200, small tribes began to coalesce into supra-tribal groups. Southern Germans came together into the Alamanni, while middle Rhine groups incorporated into the Franks, as the North Germans coalesced as Saxons. By the 300s there was a continual belt of barbarian tribes all along the Roman borders from the North Sea to the Black Sea. E) Increasing numbers of Germans began to serve as Roman auxiliary forces just beyond the Roman borders, learning new tactics, acquiring better materials, coming to admire Roman society even more. Some even underwent a process of partial Romanization.
It was the gradual, at times explosive migration of Germanic Barbarians into Roman territory that would end the placidity of the early part of Marcus Aurelius' reign (r. 161-180). The migrations have come to be known as the volkerwanderung, 'wanderings of the peoples.' What set off this very unfortunate demographic avalanche was not Barbarian anti-Roman animosity. To a certain extent, it was predetermined: a defining aspect of ancient and Medieval history was the inability of settled, sedentary peoples to avoid encroachment by neighboring nomadic, transhuman groups. Beyond that, the sheer demographic pressure of the piling up of different Barbarian tribes served to encourage expansion: unsettled, roving societies traditionally do not tolerate population pressure. Thus, in the fundamental division of antiquity between an urbanized, agrarian-based, Latin civilization whose core was the Mediterranean basin, and a rural, pastoral, nomadic, non-literate Barbarian world emerging from the steppe lands, these tribes represented the citadel of Barbarism ready to move.