Why did Rome fall? To be more precise, why did the Western Empire collapse in the course of the fifth century? Gibbon and some later historians blamed Christianity, which, they allege, not only weakened the manly spirit that had sustained the Empire but also diverted manpower and resources away from the defense and administration of the secular establishment towards the Church.
In addressing this question, we should first eliminate two potential distractions. The first is the argument, increasingly popular among Medievalists, that the social and cultural changes that take place during the “Dark Age” (roughly the period beginning near the end of the fifth century and lasting roughly to Charlemagne’s time) represented less a violent upheaval than a mere gradual transformation into a higher civilization. Peter S. Wells’ recent book, Barbarians to Angels: The Dark Ages Reconsidered, is a cautionary example of this sort of reasoning. Aware of the evidence presented, for example by Brian Ward-Perkins, Wells puts the best face on the situation. We have no proof the population of Rome plunged in late antiquity, he says.
That may be true, but it shrank disastrously in the course of the 6th century. Charlemagne built an impressive palace at Aachen. Yes, but the building materials were looted from Ravenna. The plain truth is that for the most part Roman technology—the manufacture of bricks and pottery, tiled roofs and large stone buildings—collapsed, and along with the technology went Roman standards in law and literature. The ability to tell a good story with a beginning, middle, and end all but vanishes, and with it the writing of coherent history. He cites evidence from the City of London Museum to indicate some continuity of urban civilization, but neglects to mention the grisly facts stated in that museum, namely, that the health of Londoners reached a peak in the Roman period that was not to be regained until the 20th century.
The second distraction is a preoccupation with analogies and big-picture theories about recurring cycles. Third century Romans fornicated and exposed their babies and lost their empire; modern Americans fornicate and have abortions, so they are doomed. Naturally, there are common elements, e.g. the Romans tended to welcome barbarian immigrants as cheap labor and good soldiers, and this certainly contributed to the collapse, but before considering any comprehensive or universal theory, it is necessary to make sure of what one actually knows.
Why does any empire fall? Nearly everyone has a theory. Some theories focus on external challenges. For example, the USSR is said to have collapsed under the pressure of the arms race that Ronald Reagan heated up; while others seek the cause in the changing character of the people: The tired and cynical Soviet elite had lost the will to rule; still others look at economic factors: The Soviet empire strangled itself on economic inefficiency.
The fall of the Roman Empire in the West has been interpreted by every imaginable variety of theoretical approach, from Gibbon, who blamed the Christians, to A.H.M. Jones who attributed the empire’s collapse to inflation and economic deterioration, to Walter Goffart who imagined there was no real collapse but only a gentle transition. Gibbon’s thesis has been examined by non-Christian scholars many times, and it does not hold water. As Peter Heather (anything but a Christian apologist) has pointed out, the economic resources used to build churches were not transferred from the military budget but from money used to build and refurbish pagan temples. Gibbon’s other argument, that talented men devoted themselves to religion instead of the empire, would apply to only a tiny handful of men (who, in any case, might have entered the bureaucracy and not the army). Before returning to this subject, we should look at other possible causes
Socio-economic factors cannot be easily eliminated. If not the cause, they were certainly a cause in the Empire’s decline. Late antiquity witnessed a gradual socio-economic revolution in which the rich quickly became much richer and more powerful, and the poorer free classes went into a steep decline. Mere citizenship no longer counted for much, compared with the citizen’s class status: The equestrian order more or less disappeared at the bottom, and a series of honorific titles marked a man’s ascent from clarissimi to spectabiles, to illustres, as he rose up through the ranks of the imperial bureaucracy. The inevitable grade inflation set in to the point that it meant little even to be clarissimus, and the rank of gloriosi took precedence over the illustres. These titles were not for show but reflected real power. Ordinary citizens might be tortured, but not the honorati of the upper grades.
The widespread use of slaves is often cited as a factor, usually by high-minded people who think that only Romans and Southerners owned slaves. On the contrary, every advanced society depends upon some form of slavery, and some legally free workers can be worse off than the slave who can be bought and sold. In fact, slavery fell into decay, partly because their supply was diminished when the Empire ceased to expand, and in part because other forms of labor exploitation began to be more profitable. In fact, the condition and position of slaves began to converge on that of free tenant farmers. This class of adscripti were serfs bound to the land, and even the Emperor Justinian said there was no difference between them and slaves, though ordination and consecration as a bishop wiped out any claims a proprietor might have been able to make.
The decline in the number of freeholders, during this same period, led to a shortage of draftable young men. The empire was so desperate for farmers, it did not allow conscription of coloni, and an attempt to levy tenants aroused a successful protest from Roman senate in 397. Farmers were in such demand that the Empire preferred to establish captured barbarians as coloni rather than to sell them as slaves—much less conscript them into the army. This on the eve of the successful Barbarian final push.
Labor shortage was only one of many problems. Barbarian raids and economic insecurity led to depopulation of some areas, and agri deserti—untilled and uninhabited lands–were spreading, increased, though much of the lost acreage was probably in the form of unproductive or even waste lands. Some deforestation and overtillage had taken place, though there was more forest in 400 than later. The Christian rhetor Lactantius blamed Diocletian’s swelling state establishment and rapacious taxation. Owners of land or the local government—the curial class—were still responsible for taxes, though the laws were modified and moderated. Diocletian did his best to curb inflation, but he could no more control the future than he could control prices, and the devaluation of currency in the West gradually reduced the people of Gaul and much of Italy to barter. In the East, the Byzantine solidus became the standard currency used around the world.
Rome had survived crises before. Why did it not survive the crisis of the 5th century? The most obvious cause, as Peter Heather argues, is to be sought among the barbarians themselves. The revived Persian empire under the Sassanian dynasty put tremendous pressure on the empire to defend its Eastern frontier. At virtually the same time, German improvements in agriculture (which they learned from the Romans) enabled them to increase their population—as well as their pressure upon the frontier—and encouraged the formation of larger and more formidable confederations such as the Allemani, the Visigoths, and the Franks. To make matters worse, the Huns succeeded in uniting their divided tribes while coopting the fighting forces of the Germanic and Iranian peoples they subjugated.
As the Romans lost North Africa to the Vandals and Spain to the Visigoths and Burgundians, the decline in tax revenues limited the size of their field armies and the effectiveness of their military response to each to barbarian invasion. Some provincial Roman landowners were willing to make deals with the invaders so long as they could secure at least a good chunk of their holdings, while even the most patriotic Roman generals had to make deals with the enemy, hiring the Huns as mercenaries (as Aëtius, “the last of the Romans” did) or acknowledging the political pretensions of barbarian commanders who came to play a key role in settling the western empire.
So, to take a broad middle way, one might say that the Western Empire fell because of the growth of bureaucracy, the over-conetralization of power, and an economic crisis that included loss of tax revenues that might have stiffened Roman resistance to the unprecedented threats posed by the barbarian invasions. The brave Romans who did try to resist the barbarians were nearly all Christians, and a series of tough Byzantine emperors destroyed the Persian kingdom, reconquered the Balkan lands that had been occupied by Slavic and Bulgarian peoples, and fought off Muslim Arabs.
Gibbon was a great historian and one of a handful of masterful prose-writers in English. His Decline and Fall is one of the best books in our language, but his thesis amounts to little more than his dislike for Christianity. Over two centuries later, no one who pretends to be interested in the question has any business repeating Gibbon’s exploded argument. Those who do are motivated by anti-religious bigotry that has been nursed on ignorance.