What makes something in the past important?
In 541, a great pandemic began. The deadly bacterium Y. pestis found its way to Pelusium on the eastern side of the Nile delta. It spread swiftly, devastating the Roman imperial capital of Constantinople within the year. Another year and it had reached Britain and Gaul. Although each outbreak petered out, plague returned again and again for over a century. Many hundreds of thousands died.
How to assess the pandemic is becoming one of the big historical fights of recent years.
Scientific evidence shows conclusively that it was Y. pestis and we know that Y. pestis is very deadly indeed. (For more on this see this post by Monica Green, where she highlights that how deadly it was is only one aspect of what this evidence shows us). There are some lively contemporary accounts of the plague and evidence has been collected to show that there were knock-on effects including – but not limited to – abuse of pricing at markets and the debasement of coinage. What does that all add up to?
For a given value of things, it has been accepted that the mortality and wider disruption was probably pretty significant for a while. Just recently, Mischa Meier has argued that it was a key factor responsible for “a process of cultural reconstruction that formed part of the transition from late antiquity to the early Middle Ages.” The decisive role of plague in other ways has been pushed hard by Michael McCormick and his erstwhile student Kyle Harper. In a number of publications, they have argued the pandemic was the crucial rupture point in the break between Roman past and medieval future – a trauma that led to serious structural change.
A key bone of contention is how much of a demonstrable link there has to be between cause and supposed effect. If lots of people died… then what? There is evidence of local effects but do these add up to the “end of empire”? Even agreeing that there was a lot of “cultural reconstruction” going on – well, wasn’t there always? Some historians have outright refused to take the pandemic seriously because it doesn’t seem to them to weigh heavily on the chronicles and legal records they generally use.
The argument has been given extra heat by a series of articles by Lee Mordechai, Merle Eisenberg, and a few others. In these, they have argued that that evidence does not prove that there was significant mortality. Some of it they remain sceptical about, particularly the written evidence which they consider mostly rhetorical. And if there was no significant mortality, in their view it cannot have been that important. Most of it, they argue, was “local and short term.” The pandemic was “inconsequential” to the Big Picture.
The fun as an outsider to the debate starts to come when you might want to consider who is right or to what degree they might be right. Quickly, one has to face the problems of scale and volume of evidence.
First, we have a fundamental problem that we can only guess at how many people were around. This also means that we have a very poor sense of population density, which is important because high density helps spread plague. In the Black Death in the fourteenth century, Y. pestis may have killed 50% of the population. But we assume in most areas the population was 2-4 times greater then than it was for the Justinianic pandemic. We also assume there had been significant urbanisation making density in some places much higher. (There is a lot of assuming here, yes). Many towns in the sixth century, in contrast, are supposed to have been in decline. The structures are too different to justify a straight comparison – not that that’s what people have done, but it does make it hard to know how to fill in the gaps.
We also have no good figures for how many people died in the sixth century pandemic. Procopius says nearly everyone died, which must have felt close to the truth if his figures of 5,000 deaths per day rising to 10,000+ deaths per day in Constantinople are even nearly accurate. But Constantinople was bigger and denser than most places. Other cities likely faired better. At the same time – and this is possibly important – since we don’t have figures for much of anything, that doesn’t mean the pandemic wasn’t deadly. All it actually means is that we can’t prove much either way, regardless of how sure we might feel in our reading of the evidence.
The second problem, relatedly, is that this is the sixth century and the volume of evidence is decidedly thin on the ground. For Gaul, for instance, a lot of weight is put on the testimony of Gregory of Tours, writing half a century after the plague broke out. One man. Half a century later. Did he know everything that happened in Gaul? Would he have written it all down if he had? We do not know. He doesn’t seem to have been detailing every last thing ever. And the more we get to grips with Gregory as a writer, the trickier he seems to get in his motifs, plots, and subversions. I think McCormick is right in his recent article on Gregory, however: I don’t think we can dismiss his evidence as mere rhetoric, as Gregory certainly seems to have thought it was serious and he wasn’t making it up. At the same time, his testimony does not prove much either way with regards to whether lots of people died everywhere or just here and there. His evidence can only be suggestive, not conclusive. So: a bit important?
Finally, what do we even mean by using words like ‘important’ or ‘inconsequential’? Let’s take just one example. One consequence of an outbreak of plague in Rome in 589-90 was that Pope Pelagius II died, which meant that Gregory the Great became pope. I may have been watching too much What if…?, but imagine if Pelagius hadn’t died and therefore Gregory never became an influential reformer or revered intellectual or… and just imagine… Rome never sent missionaries to Kent to convert the English. Lots of early medieval history would be very different indeed. Plague doesn’t have to kill half the population to change the world. That a lot of it was “local and short term” doesn’t mean it didn’t change things. One person can do it. Every death can be meaningful.
Ah, but I am also less interested in what brought down the (western) Roman Empire or what caused the biggest break between antiquity and the Middle Ages. These are classic Big Questions. I am a small historian, too interested in polyphonies of ideas and cultural intersections to get excited by numbers or to know really what the thing that changed everything was. Like the apocalypse, plague was probably everywhere and nowhere depending on who, when, and where you were. I suspect I haven’t taken it seriously enough for some things (apocalypse) and it doesn’t much affect others (hagiography). But then, the thing about history is that there are always a lot of factors in play. “Importance” depends very much on what past things you are trying to explain.
 A commonly cited turning point is P. Sarris, “The Justinianic Plague: origins and effects,” Continuity and Change 17.2 (2002): 169-82.
 M. Meier, “The ‘Justinianic Plague’: the economic consequences of the pandemic in the eastern Roman empire and its cultural and religious effects,” EME 24.3 (2016): 267-92 at 291.
 K. Harper, The Fate of Rome: Climate, Disease, and the End of an Empire (Princeton, 2017); M. McCormick, “Gregory of Tours on sixth-century plague and other epidemics,” Speculum 96.1 (2021): 38-96. See also Plague and the End of Antiquity. The Pandemic of 541-750, ed. L. Little (Cambridge, 2007).
 J. Haldon et al, “Plagues, climate change, and the end of an empire: a response to Kyle Harper’s The Fate of Rome,” History Compass 16 (12) (2018); L. Mordechai et al, “The Justinianic Plague: an inconsequential pandemic?,” PNAS 116(51): 25546-54; L. Mordechai & M. Eisenberg, “Rejecting catastrophe: the case of the Justinianic Plague,” P&P 244 (2019): 3-50.