The correct answer is "The impact of nationalism."
The unification of Germany under Otto von Bismarck and Italy under Camillo di Cavour demonstrates the impact and power of nationalism.
The unification of Italy and Germany was masterminded by strong leaders who relied on realpolitik. The main leaders were Otto von Bismarck in Germany and Camilo Benso, Count of Cavour, in Italy. These leaders used nationalism to unite people in supporting their aims.
Camilo Benso, Count of Cavour, directed the unification of Italy after so many years of the Austrian government. He led the Piedmont Army and as the good diplomat he was, he made alliances with the French.
The one who led the unification of Germany was Prussian leader Otto von Bismarck. He didn't fear using weapons to get the unification done and also used realpolitik, the concept of using practical ideas instead of fighting for elusive ideals.
