Both Bismarck and Cavour were superb diplomats who relied on promises from other nations to either assist or at least to not intervene in unifying their respective countries. Both were experts at that which Bismarck called realpolitik. Bismarck perhaps best expressed the philosophy shared by both in his famous statement:
It is not by speeches and majority resolutions that the great questions of the time are decided – that was the big mistake of 1848 and 1849 – but by blood and iron.
Cavour had hoped to build a constitutional state in Italy centered in Sardinia and had hoped to receive help from France under Napoleon III. He managed to unleash tremendous nationalism in Italy, even though Napoleon III eventually abandoned him. When unification appeared to be complete under the more radical Guiseppe Garibaldi, Cavour organized a plebiscite whereby the people of southern Italy united with Sardinia. Italy thus became a united Kingdom under King Victor Emmanuel. Cavour became Italy's first Prime Minister.
Bismarck cared little for public opinion, and was inclined to accomplish his goals by military means if need be. His primary aim was to unite Germany under Prussian leadership and exclude Austria from the new German nation. He did so by provoking a war with Austria after first securing France's neutrality, again under Napoleon III. He offered Austria generous terms at the end of the war, and then attacked France. This was the famous Franco-Prussian War. At the end of the war, Bismarck publicly humiliated Napoleon III, and had Frederick Wilhelm I crowned Emperor of Germany at Versailles. Germany thus became an Empire, with Bismarck as its first chancellor.