While still conducting experiments with the FI 282 in September 1941, "Köln" provided gunfire support to ground troops attacking Soviet positions on Dagö in the Gulf of Riga. She also bombarded Soviet positions on Ristna. She joined the battleship , "Admiral Scheer", "Nürnberg", and several destroyers and torpedo boats formed the Baltic Fleet, which was intended to block any Soviet warships from fleeing the eastern Baltic. No Soviet vessels attempted to do so, however. On 13 July, the Soviet submarine tried to attack "Köln", but the cruiser's escorts forced the Soviet submarine to break off the attack.