Moonsund Operation of 1915

Irbe operation, combat actions of the Russian naval forces of the Gulf of Riga to repulse the attempts of the German Navy to break through into the Gulf of Riga; it- was carried out from July 26 (August 8) to August 8 (21) in World War I (1914–18).

For the Moonsund operation the German command assigned the Baltic Fleet under the command of Vice Admiral E. Schmidt (seven battleships, six cruisers, 24 destroyers and torpedo boats, one minelayer, 35 minesweepers, and other craft). The operational cover was provided by part of the forces of the High Seas Fleet under the command of Vice Admiral F. von Hipper (eight battleships, three battle cruisers, five cruisers, 32 destroyers and torpedo boats, and 13 minesweepers). The aim of the operation was to break through the Strait of Irbe into the Gulf of Riga, to destroy the Russian ships, and to block the exit from Moonsund and Pernov (Parnu) harbor.

The Russian naval forces of the Gulf of Riga, under the command of Rear Admiral Bakhirev, included the battleship Slava, four gunboats, 36 destroyers, six submarines, and one minelayer. A minefield was laid in the Strait of Irbe. The German Navy’s attempted breakthrough on July 26 (August 8) failed. After stubborn fighting on August 3–4 (16–17), in which two German destroyers and three minesweepers were sunk and one battle cruiser, one light cruiser, one destroyer, and one minesweeper were damaged (the Russian Navy lost two gun-boats), the German ships entered the Gulf of Riga on August 6 (19), bombarded Arensburg (Kingisepp), and sank three ships at the exit from Pernov. But, afraid of exploding mines, fearful of submarine attacks, and lacking bases, the German ships left the Gulf of Riga on August 8 (21) without fulfilling their mission.