Answer:
Rise of Nationalism.
Step-by-step explanation:
The rise of Nationalism create the sense of pride of a country that historically have been used to justify the bad actions that being done to another countries. For example, the will of European countries to be the strongest country led to the colonization of other countries in an effort to take up the resources necessary to build their military's. Nationalism can be tied directly to several wars that led to the death of millions of people (Such as World War I & II).
Industrial revolution had a great impact on world's history occurred , but periods of colonization and wars have occurred even before the industrial revolution has started.