The great-great-grandfather of current head of the House of Hohenzollern held what official title?
Georg Friedrich, Prince of Prussia:  He is the great-great-grandson and historic heir of Wilhelm II, the last German Emperor and King of Prussia, who was deposed and went into exile upon Germany's defeat in World War I in 1918. Wilhelm II, German Emperor: Wilhelm II or William II (German: "Friedrich Wilhelm Viktor Albert von Preußen", English: Frederick William Victor Albert of Prussia; 27 January 18594 June 1941) was the last German Emperor ("Kaiser") and King of Prussia, ruling the German Empire and the Kingdom of Prussia from 15 June 1888 to 9 November 1918.
i don't know