The Black Death (or the Great Pestilence as it was known then) hit Peterborough. This is a terrible disease carried by the fleas on black rats, though at the time it was thought to have been caused by bad air.
Approximately a third of the townspeople and 32 of the 64 monks at the monastery perished in a matter of weeks, and many of those who died were buried in mass burial pits to the west of the town, in the burial ground of the leper hospital of St Leonard. A higher proportion of monks died perhaps because they were helping tend to the sick.
The plague returned to Peterborough on many occasions causing a great deal of death and suffering until the last outbreak in 1665.