After the Allied invasion of Normandy (D-Day), Großadmiral Karl Dönitz transferred the bulk of the German surface fleet to the Baltic in order to support the seaward flank of the German Army. The heavy cruiser bombarded Red Army positions near Riga, and several U-boats infiltrated the Gulf of Finland, losing six boats to the Soviets. Of particular importance was the loss of , sunk by the Soviet submarine chaser MO-103, because the Soviets managed to recover the wreck (despite Axis efforts) with all her secrets (including its new acoustic torpedoes). Also, on 16 July 1944, German anti-aircraft cruiser Niobe was sunk by Soviet bombers, seventy of the crew of the Niobe died and a Soviet A-20 was downed. Furthermore, on 25 July 1944 minesweeper Vilppula and small Finnish coastal minesweeper Merkurius were both torpedoed by a lone Boston (Douglas A-20 Havoc) type bomber. Though these two ships were later re-floated they were not deemed to be worth of repairing.
