The primary cause for the major drop in the English population beginning in 1350 was the outbreak of the Black Death, also known as the Bubonic Plague. This devastating pandemic was caused by the bacterium Yersinia pestis, which was spread by fleas that infested black rats. The disease spread rapidly through fleas and rats, as well as through human-to-human transmission. It is estimated that the Black Death wiped out approximately 30-50% of the English population during this time period.
