Wilhelm I, also known as Wilhelm the Great (William Frederick Louis, German: de) (22 March 1797 – 19 May 1880) of the House of Hohenzollern was the King of Prussia (2 January 1861 – 19 May 1880) and the first German Emperor (18 January 1871 – 19 May 1880). Under the leadership of Wilhelm and his Chancellor Otto von Bismarck, Prussia achieved the unification of Germany and the establishment of the German Empire.