Miniature from the Toggenburg Bible (Switzerland), 1411. The disease is widely believed to be the plague, although the location of bumps and blisters is more consistent with smallpox. Between 1347 and 1353, Europe was gripped by the most catastrophic pandemic in its history: the Black Death. Killing many millions, the plague wiped out between one-third and a half of Europe’s population. In some cities, mortality rates were as high as 80%.