Wilhelm I of Germany
Because his brother Frederick William IV of Prussia had a stroke in 1857, Wilhelm became Prince Regent and actual ruler. His brother died in 1861 and Wihelm became King. When Wilhelm was king of Prussia, he and his prime minister, Otto von Bismarck, worked on the unification of Germany, from a large group of smaller German countries. Winning the Franco-Prussian War allowed the start of the German Empire.