 William I, German Emperor

William I or Wilhelm I (; 22 March 1797 – 9 March 1888) of the House of Hohenzollern was King of Prussia from 2 January 1861 and the first German Emperor from 18 January 1871 to his death.William was the first head of state of a united Germany, and was also de facto head of state of Prussia from 1858 to 1861, serving as regent for his brother, Frederick William IV.