Bismarck, Otto Eduard Leopold von

German politician, prime minister of Prussia 1862–90 and chancellor of the German Empire 1871–90. He pursued an aggressively expansionist policy, waging wars against Denmark (1863–64), Austria (1866), and France (1870–71), which brought about the unification of Germany. He became Prince in 1871.

Bismarck was ambitious to establish Prussia's leadership within Germany and eliminate the influence of Austria. He secured Austria's support for his successful war against Denmark then, in 1866, went to war against Austria and its allies (the Seven Weeks' War), his victory forcing Austria out of the German Bund and unifying the northern German states into the North German Confederation under his own chancellorship in 1867. He then defeated France, under Napoleon III, in the Franco-Prussian War 1870–71, proclaimed the German Empire in 1871, and annexed Alsace-Lorraine. He tried to secure his work by the Triple Alliance in 1881 with Austria and Italy but ran into difficulties at home with the Roman Catholic Church and the socialist movement and was forced to resign by Wilhelm II on 18 March 1890.