By 1848, people's effort to introduce constitutional monarchy came out as unsuccessful. Under such situation, the task to unify Germany was taken by Prussia and its chief minister Otto Von Bismarck who played an important role. He followed the policy of 'blood and iron"and managed to defeat Austria, France and Denmark by fighting three wars with them.Finally, in January 1871,the process of German unification ended and the Prussian King William I was declared as the German Emperor.