"Helgoland", her three sister ships, and the four "Nassau"-class battleships were assigned to the task force that was to cover the foray into the Gulf of Riga in August 1915. The German flotilla, which was under the command of Hipper, also included the battlecruisers , , and , several light cruisers, 32 destroyers and 13 minesweepers. The plan called for channels in Russian minefields to be swept so that the Russian naval presence, which included the pre-dreadnought battleship , could be eliminated. The Germans would then lay minefields of their own to prevent Russian ships from returning to the gulf. "Helgoland" and the majority of the other big ships of the High Seas Fleet remained outside the gulf for the entirety of the operation. The dreadnoughts and "Posen" were detached on 16 August to escort the minesweepers and to destroy "Slava", though they failed to sink the old battleship. After three days, the Russian minefields had been cleared, and the flotilla entered the gulf on 19 August, but reports of Allied submarines in the area prompted a German withdrawal from the gulf the following day.