Answer: Bismarck's ultimate goal was the unification of the German states into a single, powerful German Empire, and this was achieved through a combination of military victories and political maneuvering. The event that allowed Bismarck to finally achieve his ultimate goal was:
D. Winning the Franco-Prussian War
The Franco-Prussian War, which lasted from 1870 to 1871, resulted in the defeat of France by the forces of the North German Confederation under Prussian leadership. The war not only solidified German unification but also led to the proclamation of the German Empire in 1871, with King Wilhelm I of Prussia becoming the German Emperor (Kaiser). This marked the realization of Bismarck's ultimate goal of a united German nation under Prussian leadership.