In 376 CE, the western half of the Roman Empire stretched from northern Africa north to Britain and from Libya in the east to the Iberian Peninsula in Spain. The Empire lost its preeminence in 476 CE through: immigration, a series of small scale wars, and ongoing struggles that created a power vacuum amongst the Roman elite that crippled its effectiveness throughout the century. The barbarian immigration/invasion that would develop over a 60 year span; and how the Romans reacted would lead to the fall of the Roman Empire. Through three separate elements; the Rhine crossing or “immigration,” and wars lead by Radagaisus and Uldin
The Rhine crossing in the year 406, were Gothic groups made up of Tevinigi and Greuthungi who were asking for asylum from Emperor Valens. The area in question where the first small groups of settlers were to ask permission to settle was along the Rhine River and the upper and lower Danube. This immigration was stretched over several generations, perhaps as many as 50 years and consisted of small illiterate groups or tribes who were being pushed south and east; by the leading edge of a large mass or swarm of the Hun migration from what is now considered southern Russia. The Huns had no distinct king or leader and appeared to lead through a monarchial chain of command as shown by various tribes of nomadic people; who were not unified in any way and seemed to be independent from each other and had separate goals. There is no written record from within the tribes themselves; the few accounts that have surfaced are based on fragmented and badly kept Roman interpretations; along with theories of chronological and geographical locations from other sources. In 395, approximately 20 years after the first Goths crossed, the bulk of the Huns were still far to the east moving towards Persia.
The next element came about in 408; Uldin a Hunnic leader (an ally to the Romans) headed a body of Huns; in 400 CE the main force of Uldin’s army appeared to be located closer to the lower Danube, east of the Carpathian Mountains in what today would be considered Romania. Uldin together with the Scirii as allies, in the paid service of the Romans, fought against the invasion of a large multi-racial force under Radagaisus. Radagaisus’ force of 12,000 was defeated and most were sold into slavery. There were so many slaves available after the defeat the slave market crashed. Radagaisus himself was captured and executed in August 406.
The third element was Uldin’s shift in allegiance and attempted invasion of Castra Martis in 408 which was repulsed fairly easily by the Romans. Most of his followers were tracked down and killed; Uldin was forced to retreat.
These three separate incursions into Roman territory allowed the immigrants to establish a foothold that would have dire consequences to the Roman Empire in the coming years. The first settlers abided by Roman rule and within the laws of the Empire. Whether being pushed from behind by the growing threat of the Huns or to be a part of their own clans; as more of the immigrants moved into the areas they started to carve out kingdoms for themselves and became autonomous, self supportive and self governing; causing the Romans to lose revenue from the taxes on food and goods. With the growth and rise of power of these groups and integration into the Roman hierarchy; the Empire was forced to adopt new policies concerning these groups. This change in procedure went against the very fabric of the Empire.
The Roman elite were still a powerful force that had to be shown obsequiousness. These local landowners were typically spread far apart and who were held in high esteem amongst their subordinates through the privileges of the being a Roman leader. The loss of substantial revenue from taxes could no longer keep up with the demands of funding a large army and rights/privileges and loyalties the landowners were used to. The Roman elite would switch loyalties to the strongest barbarian tribe their area; further working to undermine the Imperial state and as to no longer being needed.
In some areas of the western empire where these footholds had been growing, groups of usurpers; from Anglo-Saxons and Franks in Britain to the Vandals, Alans, and Suvei in Spain led to led to the Romano-British declaring independence. Constantius who was a senior general manager, over the course of ten years would bring some political stability back to the western Empire. Constantius’ death followed by the death of Emperor Honorius a few years later created a power vacuum that wouldn’t be resolved for nine years. Emerging from this power struggle in 433 was Ateius who like Constantius put more effort into resisting the usurpers and barbarians than fixing the real problems within. The constant revolts: Goths revolted in 425, 430 and 436; Frankish in 428 and 432; Alamanni in 430-431; Burgundians in 436-437. This chaos continued to break down the infrastructure from within as Ateius battled other powerful Roman elites who thought they could do it better. This uncertainty for the next forty years would lead to the eventual collapse of the Roman Empire in 476.
In 376 a small group of displaced people looking for protection from the Huns would cast the Roman Empire in a century long struggle with invasion and growth that it could no longer control. Three separate times outsiders stepped foot onto Roman soil; the Rhine crossing, wars lead by Radagaisus and Uldin allowed the barbarians to gain a foothold. To accommodate these groups the Empire was forced to make policy changes as the invaders gained power within the Roman hierarchy. Other subtle but no less important influences are the loss of loyalties form the Roman landowners in outlying provinces; continued power struggles within the Roman elite and constant revolts. The internal power struggles and strife along with the high cost of the constant wars may have lead to the Empire drawing in or down. With the major loss of tax revenue and not being able to support the army in areas or little or no opposition the Empire may have drawn these outposts down to skeleton crews to help offset cost. Seeing this drawdown could have been a cause for the neighboring countries to think the Roman Empire was at the point of collapse? A combination of factors that was a 100 years in the making lead to the collapse of the Roman Empire in 476.