William I, or in German Wilhelm I (full name: William Frederick Louis, , 22 March 1797 – 9 March 1888), of the House of Hohenzollern was the King of Prussia (2 January 1861 – 9 March 1888) and the first German Emperor (18 January 1871 – 9 March 1888), as well as the first Head of State of a united Germany. Under the leadership of William and his Minister President Otto von Bismarck, Prussia achieved the unification of Germany and the establishment of the German Empire. Despite his long support of Otto von Bismarck as Minister President, however, William held strong reservations about some of Bismarck's more reactionary policies, including his anti-Catholicism and tough handling of subordinates. Contrary to the aggressive, domineering Bismarck, William was described as polite, gentlemanly, and while a staunch conservative, more open to certain classical liberal ideas than his grandson Wilhelm II.