How was nationalism important in the defeat of Napoleon's Empire?

The spirit of French nationalism had made possible the mass armies of the revolutionary and Napoleonic eras. However, Napoleon's spread of the principles of the French Revolution beyond France indirectly brought a spread of nationalism as well. The French aroused nationalism in two ways. First, they were hated as oppressors. This hatred stirred the patriotism of others in oppostition to the French. Second, the French showed the people of Europe what nationalism was and what a nation in arms could do.