2. Population loss: The war also caused a great deal of population loss in Europe. Millions of people were killed in the fighting, and millions more were displaced from their homes. This had a significant impact on the region's demographics, and created a large number of refugees who had to be resettled.
3. Economic disruption: The war also caused widespread economic disruption in Europe. Many factories and businesses were destroyed, and trade was disrupted. This led to a decline in production and a rise in unemployment. The war also left many countries with large debts, which made it difficult for them to rebuild.