Battle of the Gulf of Riga

8–20 August 1915, Irbe Strait and Gulf of Riga

Russian defensive success

Hipper brought dreadnoughts and battlecruisers from the North Sea to force the Irbe Strait, destroy the old battleship Slava and mine the entrance to Moon Sound, to help the German army take Riga. The first attempt failed. The second broke into the gulf: Nassau and Posen fought Slava, and a German torpedo boat was lost in the minefields. But with British submarines about, and E1 having torpedoed Moltke, the Germans withdrew. Riga held until 1917.