Pope Gregory IX will mostly be remembered for the Papal inquisition, a process designed to start punishing people for the act of heresy, but he will also be remembered for instigating the great cat cull across Europe in 1232.
It was a time of great superstition in Europe which saw the spread the demonization of heretics, with the Church attributing lack of belief with devil worship. As black cats were widely used in heretic rituals at the time, Gregory declared all black cats diabolical and incarnations of the devil. The Pope’s declaration led to a mass extermination of cats across Europe, little did he know it would be to Europe’s detriment.
Over the next 100 hundred so many cats were exterminated across Europe, that by the time the bubonic plague started spreading across Europe in the mid-14th century, there were so few cats to stop the influx of rats that were carrying the disease, and as a result the bubonic plague had devastating effects wiping out a third of Europe’s population at the time.
It also gave rise to the black cat superstition, where originally defined, crossing a black cat’s path is to be in the presence of the devil.