General Belisarius under the walls of Rome, c. 538 AD.
The charge of overextension therefore implies a charge of strategic incompetence, or more simply a lack of ordinary common sense: having himself inherited a war with the perpetually aggressive Sassanians when he came to the throne, Justinian had to know that the Persian front had to be well guarded at all times, in peace as in war. What military strength was left would be needed for the ‘northern front’ of the empire, from Dalmatia to the Danube, which was not under attack in 533 but which was bound to be attacked sooner or later, as the turbulence of peoples continued beyond the imperial frontiers. That northern front was indeed the primary defence perimeter of the empire; it protected the valuable sub‐Danubian lands all the way to the Adriatic, and shielded Greece as well as Thrace and therefore Constantinople itself. The northern front also contained prime recruiting grounds for the imperial army, including the village near the fort of Bederiana where Justinian himself was born and lived his first years when he was still called Sabbatius.
To launch expeditions far away, even to conquer the rich grain fields of Africa and the hallowed first Rome, while neglecting the defence of the very hinterland of the imperial capital, was therefore a strategic error so gross that it betokens a foolish mind—not the mind of the Justinian we know. It is true, of course, that history is the record of the crimes and follies of mankind, and many a foolish war of conquest has been launched since 553.
But there is an altogether different explanation, based on evidence in part very old and in part very new—so new that it is not yet incorporated in the broader research on Justinian and his wars, let alone more general histories. Entirely new historical evidence of large significance is very rare, and almost always the product of fortunate digging. That is true in this case also, even if the evidence itself is neither epigraphic nor numismatic, or conventionally archaeological, for it consists of skeletal DNA and ice cores.
First the old evidence. In book 2, chapter 22, of the History of the Wars of Prokopios, we read:
During these times [from 541] there was a pestilence, by which the whole human race came near to being annihilated. Now in the case of all other scourges sent from Heaven some explanation of a cause might be given by daring men…But for this calamity it is quite impossible either to express in words or to conceive in thought any explanation…For it did not come in a part of the world nor upon certain men, nor did it confine itself to any season of the year, so that from such circumstances it might be possible to find subtle explanations of a cause, but it embraced the entire world…
It started from the Aegyptians who dwell in Pelusium. Then it divided and moved…And in the second year it reached Byzantium in the middle of the spring, where it happened that I was staying at the time.…With the majority it came about that they were seized by the disease without becoming aware of what was coming.…They had a sudden fever…And the body showed no change from its previous color, nor was it hot as might be expected when attacked by a fever, nor did any inflammation set in…It was natural, therefore, that not one of those who had contracted the disease expected to die from it. But on the same day in some cases, in others on the following day, and in the rest not many days later, a bubonic swelling developed…not only in [the groin]…but also inside the armpit, and in some cases also beside the ears…. there ensued for some a deep coma, with others a violent delirium…Death came in some cases immediately, in others after many days, and with some the body broke out with black pustules about as large as a lentil and these did not survive even one day but all succumbed immediately. With many also a vomiting of blood ensued…and straightaway brought death…
We come to the demographic consequences:
Now the disease in Byzantium ran a course of four months, and its greatest virulence lasted about three. And at first the deaths were a little more than the normal, then the mortality rose still higher, and afterwards [the number of] dead reached five thousand each day, and again it even came to ten thousand and still more than that…
Three months, or ninety days, of the greatest virulence at 5,000 a day comes to 450,000; if we take the 10,000 estimate, we reach 900,000, and Prokopios mentions a still‐higher daily mortality, yielding seemingly impossible numbers. When writing as a historian and not as a polemicist, Prokopios is generally deemed a trustworthy source by his modern colleagues, but on the subject of the pandemic he was wrongly suspected, for two different reasons. First, in an age without statistics there were no mortality figures to peruse and incorporate in a text, while impressionistic assessments of the effects of epidemics are notoriously misleading—anyone who read prose accounts of the early years of AIDS in the United States would never guess that it had insignificant demographic effects. The second reason acquired greater resonance with the advent of structuralist approaches to the study of texts. Like any sane person, Prokopios immensely admired Thucydides, and tried to write in his prose, by then a millennium removed from the common Greek of his day. Thucydides famously wrote of the plague of his own days most poignantly (in (p.75) book 2, as now edited) and Prokopios clearly strove to echo his prose. Hence his testimony is wrongly discounted.
Of course, it is universally accepted that there was a pandemic, and a very severe one, not only because Prokopios was trusted that far, but also because other extant contemporary texts concur. One such is by Evagrius Scholasticus of Antioch; he too refers to Thucydides. But uncontaminated sources also depict an unprecedented catastrophe, notably the Chronicle of Pseudo‐Dionysius of Tel‐Mahre, which was written in Syriac (late eastern Aramaic), in eighth‐century Mesopotamia, but which preserves a lost contemporary text on the pandemic specifically written by the prelate and historian John of Ephesus. Under the Seleucid year 855 (= 543/4) the text reads, ‘there was a great and mighty plague in the whole world in the days of the emperor Justinian’. The chronicler then lists the affected provinces of the empire: all the Egyptian provinces and Palestine as far as the Red Sea, Cilicia, Mysia, Syria, Iconium (Konya, central Anatolia), Bithynia, Asia (western Anatolia), Galatia, and Cappadocia.
This is no mere literary emulation but rather the recollection of a demographic catastrophe. And it would also have been an institutional catastrophe: when half the soldiers of cohesive army units become casualties, those units do not lose half their combat capability but all of it, or almost. All components of the imperial military system—tax collection offices, central administrative commands, weapons workshops, supply depots, fortress construction teams, warships and fleets, and army units everywhere—would have been in the same predicament, with their surviving personnel much more likely to have scattered to flee the pandemic or to tend to sick survivors, or simply shocked into immobility, or weakened by the disease, or just demoralized, so that 50 per cent mortality would have caused more than 50 per cent incapacitation.
The old narrative evidence would thus immediately explain why Justinian’s military capabilities declined so drastically from 541, irremediably ruining his ambitious plans. But that evidence could not be conclusive because it was devoid of credible, comprehensive figures. Hence it has been said that Prokopios exaggerated. In the account of Justinian in the latest edition of the most authoritative survey of late antiquity, the principal evidence is presented—including fiscal legislation necessitated by the death of many taxpayers—but the implication is that it was just another disaster (‘there were other disasters, notably earthquakes, one of which destroyed the famous law school at Berytus’) whose consequences were incremental: ‘Justinian’s difficulties were increased by a severe outbreak of bubonic plague…’.
The new evidence, which comes in two parts, definitely proves that Prokopios was accurate: it was not just another outbreak of disease, not just another disaster soon assuaged, it was a historically unprecedented pandemic that may well have killed even more than one‐third of the population, radically altering the strategic situation.
First, a study published in 2005 contains the first definitive DNA evidence that the disease of Justinian’s pandemic was caused by an exceptionally virulent and exceptionally lethal biovar of Yersinia pestis, the bubonic plague.38 That is an entirely different disease from the plague narrated by Thucydides or any other malady known until then. When Yersinia pestis reappeared as the agent of the Black Death from c.1334 in China and from 1347 in Europe, some residual acquired immunity would have persisted, but for the populations of the empire in 541 it was an entirely new pathogen against which none had acquired any immunity, as opposed to much less prevalent natural resistance.
Hence the pathogen was exceptionally virulent; that is, its ability to cause the disease was very high—a single bite from a flea carrying Yersinia pestis in 541 was enough to infect, which is certainly not the case with established pathogens, because many people have acquired immunities against them. Infection rates of 90 per cent or more were therefore possible for people in contact with fleas, which meant practically everyone in antiquity. Justinian contracted the disease, as did our witness Evagrius among other survivors. To be sure, virulence is one thing, lethality another. Actually, for obvious reasons, highly virulent diseases are not usually highly lethal: common influenza biovars kill minimal numbers of their many victims. But that was not true of the biovar of Yersinia pestis in 541 because it was entirely new for the affected population—a lethality of 30 per cent or even as much as 50 per cent was thus very likely, at least in well‐connected parts of the empire, though not in remote backwaters of course.
A second stream of new evidence indicates that what could have happened, did in fact happen. Climatology is now infected by partisan polemics, but ice‐core studies that show rising carbon dioxide levels in the atmosphere over the last 10,000 years are undisputed. According to an ‘anthropogenic’ explanation offered by an eminent climatologist with much persuasive evidence, agricultural deforestation, which replaces natural greenery with bare planted fields and increasing livestock herds, especially methane‐producing cattle, has measurably contributed to rising levels of carbon dioxide over the last several thousand years. In any case, carbon dioxide levels in the ice show two abrupt and drastic declines, one of which correlates with c.541, providing independent evidence of an unprecedented demographic collapse, which would have caused the widespread reversion of cleared fields to natural greenery, and the predation of abandoned cattle—imperial territories still had populations of wolves, bears, lions, and cheetahs, and also Caspian tigers in eastern Anatolia. The climatological evidence is more decisive than the archaeological evidence, but the latter is perfectly consistent. A recent overview concludes: ‘the expansion of settlement that had characterized much of rural and urban Syria in the fifth and early sixth centuries came to an abrupt end after the middle of the sixth century. There is evidence that housing starts almost ceased.’
Taken together, the new biological evidence and the climatological theory compel a reassessment of the realism of Justinian’s ambitions. He could have been as successful in his military ambitions as he was in his jurisprudential and architectural ambitions. It was not overextension but Yersinia pestis that wrecked the empire, drastically diminishing its military strength as compared to that of enemies less affected. The invaders were less infected because they were less urbanized, or simply less organized to begin with, hence less vulnerable to institutional breakdown.
Quite suddenly, with frontiers denuded of their defenders (the post‐541 disappearance of coinage from Byzantine military sites on the frontiers of Syria and Arabia has long been attested, if misunderstood), with strongholds abandoned, once prosperous provinces desolate, and its own administrative machinery greatly enfeebled, the empire found itself in a drastically altered world, in which the nomads of the steppe and the desert were greatly favoured as compared to empires, and in which the less urbanized Persian empire was relatively favoured also.
Still, what Justinian did would not have been done by his successors. It was his policy to destroy totally the power of the Vandal conquerors of Africa, and he succeeded. Therefore, when the native tribes started raiding from the desert and the hills of the Aurès, there was no pliant Vandal militia to resist them, let alone a functioning Vandal client state, so the overburdened imperial army had to fight them instead. Likewise, there were promising opportunities for a negotiated acquisition of Italy instead of an invasion followed by all‐out war to destroy the Ostrogothic power. The landing of Byzantine troops from reconquered Sicily to the mainland of Italy in 535 was preceded by secret negotiations with King Theodahad. One proposal would have retained him as client ruler of a dependent state, another would have seen him off with the award of landed estates yielding 86,400 solidi a year, the income of 43,200 poor men. Justinian’s successors would have found such a compromise solution, but he rejected all compromise—before the pandemic. After it, Justinian too had no other choice but to revert to the embryonic Theodosian strategy of avoiding war by paying off enemies if necessary.
When the Turkic Kutrigurs of the Pontic steppe under their leader Zabergan mounted raids in 558 that penetrated Greece and approached Constantinople, indulging in the usual outrages that allowed Agathias Scholasticus to indulge himself and his readers (‘well‐born women of chaste life were most cruelly carried off to undergo the worst of all misfortunes, and minister to the unbridled lust of the barbarians’, etc. etc.), Justinian called out Belisarios from retirement (he was 53) to repel them with ceremonial palace guards, 300 veterans, and a mob of volunteers, but then took more decisive action by enlisting the aid of the leader of the Utrigurs. The alternative of waging war could be very successful tactically and operationally, but even in total victory the only definite result would be the cost of it, while the benefit would only be temporary, as the demise of one enemy merely made room for another. It is hard to imagine that the empire could have overcome the ensuing century of acute internal crises and devastating invasions without its new strategy. It generated disproportionate power by magnifying the strength obtainable from greatly diminished forces, and by combining that military strength with varied means and techniques of persuasion.