Which has been a direct effect of nationalism in europe

The split of the Austro-Hungarian Empire has been a direct effect of nationalism in Europe.

The Austro-Hungarian Empire was divided as a result of several ethnicities living in the empire with differing beliefs. Nationalism caused cultural groups to join their efforts and call for independence to create nation-states.

Nationalism is defined as identification with one's own nation and support for its interests, particularly to the exclusion or detriment of the interests of other nations.