The Black Death cut a vast swathe across the European continent, claiming the lives of almost 60 percent of the population. As one can imagine, this had a devastating impact on society. Most people at that time lived off the land, and huge tracts of the countryside became depopulated in the wake of the plague. Among other things, this meant that landowners found it hard to find enough peasants to bring in the harvest. Whole villages emptied, not just as a result of death and disease but also from economic migration.
The decline of the countryside, combined with the growth of towns and cities, severely undermined the power of the nobles. In turn, this gave kings, princes, and other rulers much greater power and authority than they'd previously enjoyed. Prior to the Black Death, kings often found themselves entangled in bitter conflicts with their nobles. But the great plague that wrought such devastation on Europe changed all that, leading to the demise of feudalism and the rise of absolute monarchies.