Did a plague cut short Justinian's dream of rebuilding Rome?

Possibly, but historians genuinely disagree about how much. In 541 plague reached the Byzantine Empire, the eastern Roman state ruled from Constantinople by the emperor Justinian. It spread around the Mediterranean until 544 and lingered in northern Europe and Arabia until 549. Justinian himself caught it, according to his court historian Procopius, and recovered in 542, while the epidemic killed about a fifth of the people in his capital.

The story historians tell goes like this. Justinian's armies had nearly retaken all of Italy and the western Mediterranean coast, a step toward reuniting the old Roman world. Plague, in this account, weakened the empire at a critical point: farmers could not tend their crops, grain prices rose in the capital, and tax revenue fell just as the empire was paying for wars and great churches such as Hagia Sophia. In 568 the Lombards invaded northern Italy, beat the small Byzantine army left there and founded their own kingdom, and the reunion did not last long.

But other scholars push back. Lee Mordechai and Merle Eisenberg argue that the plague may have killed many people in particular places without causing a wide demographic decline across the Mediterranean. Peter Sarris criticises their methods and handling of sources. The plague's severity and impact remain debated.

One thing is no longer in doubt: in 2013 researchers confirmed that the cause was Yersinia pestis, the same bacterium behind the Black Death.