In early August 1915, several powerful units of the German High Seas Fleet were transferred to the Baltic to participate in the foray into the Riga Gulf. The intention was to destroy the Russian naval forces in the area, including the pre-dreadnought battleship, and to use the minelayer to block the entrance to Moon Sound with mines. The German naval forces, under the command of Vice Admiral Hipper, included the four and four s, the battlecruisers,, and, and a number of smaller craft.
Battle
On 8 August, the first attempt to clear the gulf was made; the old battleships and kept Slava at bay while minesweepers cleared a path through the inner belt of mines. During this period, the rest of the German fleet remained in the Baltic and provided protection against other units of the Russian fleet. However, the approach of nightfall meant that Deutschland would be unable to mine the entrance to the Suur Strait in time, and so the operation was broken off. In the meantime, the German armored cruisers and were detached to shell the Russian positions at the Sõrve Peninsula in the Saaremaa island. Several Russian destroyers were anchored at Sõrve, and one was slightly damaged during the bombardment. The battlecruiser Von der Tann and the light cruiser were sent to shell the island of Utö. On 16 August, a second attempt was made to enter the gulf. The dreadnoughts and, four light cruisers, and 31 torpedo boats breached the defenses to the gulf. On the first day of the assault, the German minesweeper T46 was sunk, as was the destroyer. On 17 August, Nassau and Posen engaged in an artillery duel with Slava, resulting in three hits on the Russian ship that prompted her withdrawal. 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. Throughout the operation, the German battlecruisers remained in the Baltic and provided cover for the assault into the Gulf of Riga. On the morning of 19 August, Moltke was torpedoed by the British E-class submarine ; the torpedo was not spotted until it was approximately away. Without time to manoeuver, the ship was struck in the bow torpedo room. The explosion damaged several torpedoes in the ship, but they did not detonate themselves. Eight men were killed, and of water entered the ship. The ship was repaired at Blohm & Voss in Hamburg, between 23 August and 20 September. Four large, flat-bottomed barges loaded with German troops attempted to land at Pernau on 20 August, but were repelled by small Russian warships. The Russian gunboat Sivuch was destroyed in an engagement with the German cruiser Augsburg and eight destroyers, while the damaged minelaying cruiser Albatross ran ashore on the neutral coast of Gotland before the Russian cruiser Rurik forced the remaining German units to retreat. Moltke was damaged by a British submarine torpedo before reaching port.
