What were the major empires in europe prior to world war 1 and why did nationalism threaten the stability of europe

1. The major empires in Europe before the World War I are the following:
Britain, France, Italy, Germany, Austria-Hungaria, and Russia.  These countries aimed to colonize a big portion of the world. They conquer cities and countries and put them under their power.

2. Nationalism had threatened the stability in Europe because it gave the citizens a sense of belongingness to their country. Nationalism had led people to rebel against their colonizers and stage wars to acquire independence from these imperial states.