The peoples who took the western empire apart were a fraction of one per cent of its population, and any explanation of what happened has to start by facing how few of them there were.
The previous lesson left the empire administratively split in 395 with two incapable emperors, a church fused into the state, and the same frontiers Diocletian had reorganised. This lesson looks across those frontiers. It asks who the Goths and Vandals actually were, how many of them there were, and why a word like invasion fits the events badly enough to mislead.
Who was over there
The first difficulty is that we have no account written by any of them. Everything comes from Roman authors, and the best of them, Ammianus Marcellinus, is a Greek-speaking soldier from Antioch writing in Latin about people he mostly met in war.
The names in those sources are unstable. Tacitus in the first century lists dozens of small German peoples; by the third century the sources name a few large ones, the Goths, the Alamanni, the Franks; by the fifth, Visigoths, Ostrogoths, Vandals and Burgundians. The old view read this as migration, whole nations moving with their languages and customs intact from somewhere else. The evidence does not support it. Archaeology on the lower Danube and in Ukraine shows a mixed material culture with strong Roman elements and no sign of a population arriving en masse, and the written names correspond poorly to anything a spade can find.
The better model is that these were political groups rather than nations: coalitions formed around a successful war leader and a core of families carrying a tradition, which could absorb outsiders quickly and dissolve quickly. Some historians go further and argue the groups were essentially manufactured by contact with Rome, since a confederation is what you need in order to negotiate with, raid or serve an empire. The argument is unresolved and the honest position is that both processes were probably at work. What is not in doubt is that a Gothic army of 400 contained men whose grandfathers had not been Goths.
What the frontier did to them
Three centuries of living beside the empire changed them profoundly, and the changes ran the way the empire's own institutions pushed.
They traded. Roman goods, coins and prestige objects appear far beyond the frontier, and the Roman customs posts of an earlier lesson existed because there was traffic to tax. They were paid. Subsidies to friendly chiefs were standard Roman practice and a cheaper alternative to campaigning, and a chief who could distribute Roman gold to his followers had an advantage over one who could not, which is itself a force pushing towards larger and more stable groupings. And they served: whole units were recruited from beyond the frontier, and by the fourth century the Roman army in the west was full of them, with men of Frankish, Vandal and Gothic descent commanding it.
Example. Around the 340s a bishop named Wulfila, of Cappadocian descent from a family taken captive in a Gothic raid, was consecrated to work among the Goths, devised an alphabet for their language and translated most of the Bible into it. He worked while the imperial court held to non-Nicene formulas, and the Gothic church that resulted was Homoian, which later Roman writers called Arian. Trace the consequence.
The immediate consequence is that the Goths became Christians on the empire's terms, using an alphabet built from Greek and Latin letters, with a Bible whose vocabulary had to borrow Greek theological words. That is Romanisation, arriving through a missionary rather than through conquest. Wulfila is reported to have left the books of Kings out of his translation on the grounds that the Goths were warlike enough already, which if true tells you he was making choices about what kind of people he was forming.
The delayed consequence is the important one. The creed the Goths adopted was the imperial orthodoxy of the 340s and 350s, and the previous lesson showed that orthodoxy reversing under Theodosius. So the Goths were left holding a version of Christianity the empire had come to define as heresy, purely because of when they converted. For the next two centuries, Gothic and Vandal rulers in the western provinces were separated from their Roman subjects by a doctrinal line neither had chosen, which impeded intermarriage, gave Roman bishops a reason to look elsewhere for a protector, and turned religious difference into the marker of who was and was not a Goth. A quarrel over one Greek word in the 320s shaped the politics of Spain and Africa a century and a half later.
Now you. Ammianus says an attempt was made to count the Goths crossing the Danube in 376 and was given up, and he quotes Virgil on numbering the sands of the Libyan desert. How should the numbers in these sources be handled?
Answer
As orders of magnitude at best, and only when they are internally checkable. Ammianus's remark is unusually honest, because he is admitting that the Roman authorities on the spot, who had every reason to know, could not produce a figure. Every other total in the sources is worse: it comes from a writer at a distance, in a tradition where large hostile armies were a compliment to the general who beat them, using no method at all.
What can be done is to look for figures produced for an administrative purpose rather than a literary one, and to check them against constraints. A count made by a leader for distributing land or rations is worth more than a number in a battle narrative. Shipping capacity, food supply and the size of the area settled all put ceilings on how many people can be involved. The general finding, which the next section works through, is that the numbers that survive scrutiny are small, and that the older habit of imagining hundreds of thousands of migrants has no evidential basis. Treat any barbarian total in a Roman narrative as a claim about how the author felt, unless it can be tied to a logistical fact.
376, and the crossing
In 375 or 376 a Gothic group under pressure from the Huns arrived on the north bank of the lower Danube and asked to be admitted to the empire. The emperor Valens agreed. This was neither unprecedented nor foolish: settling defeated or displaced groups inside the frontier was old Roman practice, it produced taxpayers and recruits, and Valens was preparing a Persian campaign and wanted the manpower.
The administration of it was catastrophic. Ammianus, no friend of the Goths, describes Roman officers exploiting the refugees systematically: food withheld and then sold at extortionate rates, so that families traded their children into slavery for dog meat. Disarmament, which was the condition of admission, was not enforced because the officers were busy profiteering. Within two years the settlement had become a war.
Adrianople
Example. On 9 August 378, Valens attacked the Gothic force near Adrianople without waiting for the western army marching to join him. He was killed with, in Ammianus's account, two thirds of his army and thirty-five senior officers, and Ammianus compares the defeat to Cannae. Was it decisive?
Take the arithmetic first. A field army of the size usually reconstructed for this campaign, perhaps 20,000 men, losing two thirds, means something over 13,000 dead. Against a total imperial establishment of the order of 400,000 that is a bad afternoon, not a mortal wound, and the empire had absorbed worse: the comparison Ammianus reaches for, Cannae in 216 BC, was followed by Roman victory, as the earlier course on the Republic shows in detail. Rome went on for another 98 years in the west after Adrianople, and in the east for far longer.
What was lost that mattered was not the men but the settlement. Valens was dead, the eastern field army was wrecked at the moment it was needed against Persia, and the Goths were inside the empire, undefeated and unresettled, in provinces that could not feed them. Theodosius, appointed to deal with the problem, spent four years trying and failing to destroy them militarily, which is the real evidence of what the defeat cost. Adrianople was decisive in the sense that it removed the option of solving the problem by force, and that forced the treaty described next. Battles are rarely decisive because of casualties; they are decisive when they eliminate a choice.
Now you. In 382 Theodosius made a treaty admitting the Goths to Thrace as a body, under their own leaders, not distributed among landowners, and obliged to serve as allied contingents under their own commanders rather than being enrolled in Roman units. What was new about it?
Answer
That a group inside the empire retained its own leadership and its own military identity. Rome had settled barbarians on imperial soil many times, and had always broken them up: they were scattered across provinces, given land as individual farmers, and their fighting men were absorbed into Roman units under Roman officers, which within a generation left no group at all. The whole point of the older practice was dissolution.
The treaty of 382 did not dissolve them, because after four years of failure Theodosius had no means of imposing dissolution. That leaves a permanent armed community inside the frontier with its own leaders, and the interests of those leaders were not the empire's. Within twenty years one of them, Alaric, was using that force to bargain for a Roman generalship and supplies, moving between the two courts to see which would pay, and in 410, when neither would, he took Rome. Every later settlement in the west followed the shape of 382 rather than the older pattern, and the western provinces gradually filled with such groups. Notice that this was not a decision to change policy. It was an inability to enforce the old one, recorded as a treaty.
How many of them there were
The best figure we have for any of these groups comes from the Vandals. When Geiseric took his people from Spain to Africa in 429 he had them counted, and the number reported is 80,000, including women, children and slaves.
Example. Test that against the empire.
Against a population of perhaps 50 million by this date, 80,000 is 0.16 per cent, one person in six hundred. If one in five was a fighting man, which is generous for a group that includes families and slaves, the army is around 16,000. The late Roman establishment on paper ran to several hundred thousand men, so this force is perhaps four or five per cent of it.
With those 16,000, Geiseric took the richest provinces of the western empire, held them for a century, built a fleet, sacked Rome in 455 and destroyed the largest expedition the two empires ever mounted against him. The disproportion is the central fact of the fifth century and it is what makes the usual explanation useless: an empire of 50 million was not overwhelmed by 80,000 people. It has been argued that Geiseric inflated the figure to impress, which if true makes the point sharper still. Something other than numbers is doing the work, and the next lesson is about what.
Now you. Given all this, what is wrong with the word invasion?
Answer
Three things. It implies arrival from outside, when most of these groups were admitted by treaty, invited as allies, or already serving in the Roman army, and had been living within or beside the empire for generations. It implies a plan to conquer, when the demands recorded are consistently for land, supplies, subsidies and Roman military rank, which is what a group wants when it intends to stay inside a system rather than replace it. And it implies two sides, when the wars of the fifth-century west were mostly fought by mixed armies on both sides, commanded by men of barbarian descent holding Roman offices: Stilicho was of Vandal parentage and ran the western empire, and Ricimer and Aspar after him were of Suevic and Alan descent.
The alternative is not that nothing violent happened, because a great deal did, including sacks, massacres and the seizure of estates. It is that what happened is better described as the Roman state losing control of armed groups it had itself created, admitted and employed, at a time when it could no longer pay them. That formulation has the advantage of explaining the numbers. Sixteen thousand men cannot conquer an empire, but sixteen thousand men can take over an army that is not being paid, and the next lesson shows exactly how the western empire stopped being able to pay.
What this leaves to explain
Two facts now sit uncomfortably together. The peoples involved were few, familiar, partly Romanised and mostly admitted. And within seventy years of Adrianople the western provinces were governed by their kings.
Nothing in this lesson explains that, and it is important to see that nothing does. There was no barbarian population surge, no new military technology, no religious motive, and no evidence of any intention to destroy the empire; Gothic and Vandal kings issued Roman-style law, used Roman officials and dated by Roman consuls. The east faced the same peoples on the same river, and in the case of the Huns faced worse, and survived.
So the question the next lesson has to answer is not why the barbarians came but why the west could not absorb them when it had absorbed everything else for four hundred years, and why the east could. The answer turns out to be about revenue.