Battle of Moon Sound The Battle of Moon Sound was a naval battle fought between the forces of the German Empire , and the then Russian Republic ( and three British submarines ) in the Baltic Sea from 16 October 1917 until 3 November 1917 during World War I . The German intention was to destroy the Russian forces and occupy the West Estonian Archipelago . The German Navy had 1 battlecruiser , 10 battleships , 9 light cruisers , 1 mine cruiser , 50 destroyers and 6 submarines while the Russians had only 2 pre - dreadnoughts , 3 cruisers , 3 gunboats , 21 destroyers and 3 submarines . Background . It was the Germans ' intention to destroy the Russian Army and occupy the West Estonian Archipelago ( Moonsund Archipelago ) . The Germans captured the archipelago , with its main islands of Saaremaa ( Ösel ) , Hiiumaa ( Dagö ) , and Muhu ( Moon ) during the Operation Albion in September 1917 . This left a Russian squadron consisting of the old Russo - Japanese War - era pre - dreadnought battleship s , and , together with cruisers and destroyers , stranded in the Gulf of Riga . The Russian fleet escaped on 17 October 1917 by way of the Suur Strait separating the island of Muhu from the Estonian mainland . Battle . At the start of the Battle of Moon Sound , there were two submarines in the Gulf of Riga . They were " C 27 " ( Lt . Sealy ) and " C 32 " ( Lt Satow ) . When the Germans got there , Captain Francis Cromie sent out another submarine called " C 26 " ( Lt Downie ) . On the night of the 16th of October , Lt Sealy shot two torpedoes at two German ships but missed at first . They shot two more and made contact . The C27 returned to Hanko when it was not needed . The unit C32 attempted to take out a German ship but was seen and bombed . In the afternoon of 16 October , Gruppe Behncke travelled to the south exit of the Suur Strait and dropped anchor around 8 : 30 pm . All German ships were anchored in a close line with a torpedo boat at each end . The Germans made significant progress on shore on 16 October . They took 120 officers and 400 men prisoner as well as 49 guns . By the end of the day , German forces were prepared to capture the West Estonian Archipelago and the navy was ready to attack in the Matsalu Bay and the Suur Strait . The Russian battle strategy was changed at 4 : 30 am on October 17 because of a mistake made in the transfer of an order . That morning , ships were on the move by 7 : 00 . The 3rd M . S . H . F was heading east while the 8th H . f . F . l . was heading north under command of Erich Koellner . At 7 : 20 , Russian battleships opened fire on the 8th H . f . F . l , the 3rd M . S . Dive and the Sperrbrecher . The 8th advanced but were under constant Russian fire . It was the 3rd M . S . H . F ' s duty to clear mines . At 8 : 00 am Adm . Behncke ordered that the cruisers stay put and not advance any farther . At this point , " König " and " Kronprinz " headed East by the 3rd M . S . H . F , both under the command of Georg von der Marwitz . " Slava " was advancing so that she came between Paternoster and Werder and started firing upon any east - bound German ship . While this was going on , the 3rd M . S . H . F . had reached Laura Bank and turned north , " König " and " Kronprinz " continued east and " Slava " was now heading north . Adm . Hopman was now heading west towards the Väike Strait . At 9 : 10 , two Russian ships that had returned south opened fire on the 3rd M . S . H . F . The Russians now understood that if they could stop the minesweepers , they could stop the entire German attack . At 9 : 40 , 3rd Ms . Dive was brought over to the east side of Russian minefields to assist the 3rd H . f . F . l . By 10 : 00 , the minesweepers were on the northern edge of the rectangular minefield . " König " and " Kronprinz " now went forward . Around 10 : 13 , " König " opened fire on " Slava " . By 10 : 17 , " Kronprinz " followed " König " ` s lead and opened fire on the battleship " Graschdanin " . " Bayan " was also attacked by " König " . " Slava " took many underwater hits , causing extensive damage . " Graschdanin " only got hit twice in all of the chaos . at 10 : 40 the Germans ceased fire . The Russians continued to fire on the 3rd M . S . H . F . Around 10 : 30 , Adm . Bachirev ordered all sea forces to withdraw to the northern Suur Strait . " Slava " was now fatally wounded , destroyed by Turkmerec Strauropolski . The Russians were determined to make the channel impossible to pass through so they laid out more mines and used damaged ships to their advantage . At 10 : 46 , the Werder Battery opened fire on the German battleships . At approximately 11 : 09 , two German battleships anchored while under fire at Võilaid . At 11 . 28 there was a false submarine alarm followed by a legitimate one at 12 : 08 . Around 1 : 35 , Kolberg attacked Võilaid for approximately ten minutes but met no reply . At 3 : 45 , Adm . Hopman ` s flagleutnant Obltz Keln led a landing party to take over Woi . At 5 : 30 , white star shell could be seen which meant that the battery had successfully been taken but the guns were unservicable . By 3 : 00 , Kommodore Heinrich took V100 toward the channel that would lead them to the Suur Strait but were immediately under fire by gunboats under the control of Adm . Makarov . At 10 : 00pm , Kptlt Zander began to go forward to the Suur Strait . Marker boat " S 50 " took up her position . At the end of the day , German ' s were in control over the southern Suur Strait , the Väike Strait and the Matsalu Bay . On the night of October 17 , Russians gave up trying to capture the Suur Strait . Just after midnight on October 18 , " S 64 " was shaken by a mine detonation and was rendered unmanoeuverable . By 1 : 00 am , it was completely sunk . Come dawn , German torpedo boats took up patrol stations in the Matsalu Bay . The landing operations on Hiiumaa gained momentum between 7 : 15 and 8 : 00 am was able to take the area around Emmaste . By 8 : 30 , German minesweepers had worked forward to a mile south of the Viirelaid lighthouse . 766 sank after a mine detonation . At 8 : 00 , Behncke ' s group started east and went behind the 3rd M . S . H . F . Just after 10 : 00 , Behncke ordered Adm . Hopman to dispatch " Strassburg " and the 8th M . S . H . F . to the 3rd squadron while " Kolberg " , the torpedo - boats and Sperrbrecher would remain to the west . At 12 : 40 the 3rd M . S . H . F . and two boats of the half flotilla confirmed that " Slava " was sunk along with two freight steamers . The Germans could see Russian destroyers laying mines , the Russians had not yet detected the Germans , so the Germans opened fire , which was met with a reply . Two German torpedo boats opened fire as the Germans continued northward , two Russian gunboats and several destroyers took them under fire . They then turned south at high speed under the cover of a smoke screen . By the evening of the 18th , Kuressaare had been made a supply base , the southern part of Hiiumaa under control of the second Cyclist Battalion and the S - Flotilla landing section , Saaremaa and Muhu were now firmly in German hands . On October 19 the forces of the Gulf of Riga and numerous transport steamers and auxiliaries left the northern Suur Strait under the protection of minesweepers and destroyers . By mid - afternoon , the German forces had penetrated the strait . The German losses were seven minesweepers , nine trawlers and small boats as well as one torpedo - boat . The Imperial Navy had a total of 156 dead and 60 wounded . The navy had 54 dead and 141 wounded . The German Army captured 20 130 prisoners , 141 Russian guns including 47 heavy pieces and 130 machine guns . Aftermath . Casualties of the Battle were far more extensive for the Germans than the Russians . 300 German soldiers were killed , and 200 were wounded while the Russians suffered fewer than 100 deaths and around the same number of wounded . German destroyers " S 46 " , " S 64 " and the Russian destroyer " Grom " were sunk . All the four ships , " Slava " , " Citizen " , " König " and " Kronprinz " were damaged but " Slava " was in a bad condition . The German battleships " Bayern " and " Grosser Kurfürst " were badly damaged , destroyer " B 98 " was damaged , " A 32 " run aground , the auxiliary ship " Corsika " was damaged , 7 minesweepers and the destroyers " S 65 " and " S 66 " were sunk .