One of the main reasons that europe fell in defeat was because of the anonymous disease that was going around known as "The Black Death" or "The Bubonic Plague". Most of the population fell as more than 7500 people would die each day and would be kept laying on the street. People were forced to move to a certain island with all those that have any symptom or anything even related to this disease. Over 75,000,000 people died from this disease in total. This also meant a good thing for peasants. If a knight or vassal that owned land with its own peasant died the peasants would take that as an opportunity to escape from the land for freedom but were also in risk of spreading the disease to other places if they travel without even knowing they have it because of their strong immune system.