SMS Ostfriesland was the second vessel of the Helgoland class of battleships of the German Imperial Navy. Named for the region of East Frisia, Ostfriesland's keel was laid in October 1908 at the Kaiserliche Werft dockyard in Wilhelmshaven. She was launched on 30 September 1909 and was commissioned into the fleet on 1 August 1911. The ship was equipped with twelve guns in six twin turrets, and had a top speed of . Ostfriesland was assigned to the I Battle Squadron of the High Seas Fleet for the majority of her career, including World War I.