After the outbreak of World War I at the end of July 1914, "München" was assigned to III Scouting Group, which was attached to the High Seas Fleet, Germany's primary naval unit, based in the North Sea. She was transferred to IV Scouting Group on 25 August, and the following day, she and her sister ship were transferred to the Baltic Sea in response to the loss of the light cruiser . This proved to be short lived, and already on the 28th, she had been returned to the North Sea. That morning, she and "Danzig" lay moored at Brunsbüttel at the western end of the Kaiser Wilhelm Canal, when the British Harwich Force attacked the German patrol line in the Helgoland Bight. During the ensuing Battle of Helgoland Bight, "München" and "Danzig" were recalled and ordered to steam to the mouth of the Elbe and wait for further orders. At 12:25, the two cruisers were ordered to move into the Bight and support the cruiser , but at 14:06, "München" was instead ordered to conduct reconnaissance out to the north-east of Helgoland.