Final answer:
During significant historical crises such as World War II and plague outbreaks, millions were displaced with the amount varying on the event; in some cases, such as during World War II, about 10 million Europeans were displaced while during a plague outbreak, nearly a smaller fraction of the population perished without fleeing.
Step-by-step explanation:
The amount of people who fled during various historical events varies significantly. During the Plinian stage, typically associated with a volcanic eruption, there is no specific historical account detailing the amount of people who fled. However, in the context of World War II, which the provided passages seem to describe, displacement was considerable. The second passage indicates that about 10 million Europeans were moved from their homes during and after the war, while the fourth passage notes that nearly 50,000 died out of a population of fewer than 100,000 due to the plague, affecting those who did not flee. Additionally, the sixth passage references more than three million people in France and Belgium being displaced by the end of 1914.
The provided passages demonstrate that while some people fled due to war or disease outbreaks, others who did not flee either succumbed to the respective plagues of their time or faced numerous hardships such as protracted regional warfare or poor economic conditions.