Final answer:
Otto von Bismarck is the younger brother of Bernhard von Bismarck. He was the first Chancellor of Germany and a key figure in its unification, known for his Realpolitik approach to politics.
Step-by-step explanation:
The younger brother of Bernhard von Bismarck, who sank in 1893 and died five years before his younger brother, is Otto von Bismarck (a). Otto von Bismarck played a significant role in European history as the key figure in the unification of Germany. He served as the first Chancellor of the German Empire, orchestrating the unification through a series of wars and strategic diplomatic initiatives. Known for his policy of Realpolitik, Bismarck placed practicality and pragmatism at the forefront of his political decisions. Bismarck's influence on European politics was profound, as he navigated the complexities of inter-state relations and internal politics to position the German Empire as a major European power.