Realpolitik is defined as a set of activities that help organize individuals, systematically resolve disputes, and maintain order in society with the use of power.
Bismark
Otto Eduard Leopold von Bismarck was greatly responsible for the creation of the German Empire in 1871. He was a leading diplomat of the late 19th century, and he was known as the Iron Chancellor. Bismarck, first Prime Minister of Prussia and then the Chancellor of the German Empire, set about the "construction" of Germany through high politics assisted by war against Austria and France. Bismark was a true advocate of "Realpolitik" Bismarck used Realpolitik in his journey to achieve Prussian dominance in Germany. He manipulated political issues such as the Schleswig-Holstein Question to antagonize other countries and cause wars to attain his goals. Exemplary for this was also his willingness to adopt some social policies of the "liberals" such as employee insurance and pensions. While doing so he used small changes from the top down, to avoid the possibility of major change. Another example of Bismarck's Realpolitik is Prussia's illogical move of not demanding territory from a defeated Austria, a move that later led to the unification of Germany, an often-cited example of Realpolitik.
Cavour
Camillo di Cavour, was the Prime Minister of the Kingdom of Piedmont and Sardinia. He was greatly responsible for creating the nation of Italy. He made an alliance with France which meant that his kingdom got Lombardy as a reward for fighting along with the French against the Austrians. Then Garibaldi went to Sicily and overthrew the King of Naples. Because he was a radical republican Cavour moved quickly to welcome the liberated lands into what he now called the Kingdom of Italy. Cavour was another major advocate for Realpolitik, Cavour involved the kingdom on the British and French side of the Crimean War, using a peace conference to give international publicity to the cause of Italian unification. In 1858, he formed an alliance with France, that included a pledge of military support if necessary, against Austria, which is Italy's major obstacle to unification. Austria declared war against Sardinia in 1859 and was easily defeated by the French army. In return, France received Savoy and Nice from Italy. Which was a small price to pay for paving the way to unification.