ship conducted live fire drills in the Baltic. At the outbreak of World War II in September 1939, the ship was still conducting gunnery trials. She was briefly used to patrol the Baltic, but she did not see combat, and was quickly returned to training exercises. In November 1939, the ship returned to the Blohm & Voss dockyard for modifications; these included the replacement of the straight stem with a clipper bow and the installation of the funnel cap. Sea trials in the Baltic resumed in January 1940, but severe ice restrained the ship to port. On 17 February, the Kriegsmarine pronounced the ship fully operational, and on the following day, Admiral Hipper began her first major wartime patrol during Operation Nordmark. She joined the battleships Scharnhorst and Gneisenau and the destroyers Karl Galster and Wilhelm Heidkamp in a sortie into the North Sea off Bergen, Norway. A third destroyer, Wolfgang Zenker, was forced to turn back after sustaining damage from ice. The ships operated under the command of Admiral Wilhelm Marschall. The ships attempted to locate British merchant shipping, but failed and returned to port on 20 February. Operation Weserübung Following her return from the North Sea sortie, Admiral Hipper was assigned to the forces tasked with the invasion of Norway, codenamed Operation Weserübung. The ship was assigned as the flagship of Group 2, along with the destroyers Paul Jakobi, Theodor Riedel, Friedrich Eckoldt, and Bruno Heinemann. KzS Heye was given command of Group 2 during the operation. The five ships carried a total of 1,700 Wehrmacht mountain troops, whose objective was the port of Trondheim; the ships loaded the troops in Cuxhaven. The ships steamed to the Schillig roadstead outside Wilhelmshaven, where they joined Group 1, consisting of ten destroyers, and the battleships Scharnhorst and Gneisenau, which were assigned to cover Groups 1 and 2. The ships steamed out of the roadstead at midnight on the night of 6–7 April. While steaming off the Norwegian coast, Admiral Hipper was ordered to divert course to locate the destroyer Bernd von Arnim, which had fallen behind Group 1. In the mist, the destroyer encountered the British destroyer ; the two destroyers engaged each other until Bernd von Arnims commander requested assistance from Admiral Hipper. Upon arriving on the scene, Admiral Hipper was initially misidentified by Glowworm to be a friendly vessel, which allowed the German ship to close the distance