 SMS "Oldenburg", the final vessel, was built by Schichau in Danzig; she was laid down 1 March 1909, launched 30 June 1910, and commissioned on 1 May 1912.The "Helgoland"-class ships operated as a unit in the High Seas Fleet; they served as I Division of I Battle Squadron.The ships of the class participated in several fleet operations in the North Sea, including the sortie on 31 May 1916 that resulted in the Battle of Jutland.