How did nationalism change the Italian and German states?

Nationalism basically created the Italian and Germany states in the nineteenth century. Both were a patchwork of principalities and independent kingdoms prior to the mid-nineteenth century. The early nineteenth century, however, saw the rise of romantic nationalist movements, largely led by young intellectuals. They argued that German and Italian "nations," characterized by shared histories, cultures, and languages existed, and that the boundaries of the state ought to reflect these realities. One especially influential leader in Italy was Giuseppe Mazzini, whose "Young Italy" movement helped to build momentum for the creation of an Italian nation. Nationalism was a key cause of the revolutions of 1848, and though these revolutions did not end with the unification of either Germany or Italy, they helped keep these movements going. Both of these nations were unified through a process of statecraft and wars (both foreign and civil), but the leaders of the unification process, including political elites like Count Cavour and Otto von Bismarck, were motivated in no small part by a desire to harness the powerful popular forces of nationalism for their own purposes.