The outbreak of World War II found the Gneisenau in Brunsbüttel, where on September 4, 1939, she was unsuccessfully attacked by British bombers. Four days later, along with the Scharnhorst, she sailed through the Nord-Ostsee channel to the Baltic Sea, where she began artillery drills. On completion of those, on October 5, 1939, she became the flagship of the Commander-in-Chief of the Kriegsmarine, Admiral Hermann Boehm. Her first combat mission was a sortie with the light cruiser Köln and destroyers against the ship routes between Great Britain and Norway. It was soon over and the ships arrived in Kiel. On the next mission the Gneisenau departed with the light cruisers Köln and Leipzig, as well as her sistership the Scharnhorst. During this sortie the force under command of Vice Admiral Wilhelm Marshall sank the British armed merchant cruiser HMS Rawalpindi. The battleship was damaged in the storm. The hull was leaking and the ship was taking on considerable amounts of water. The situation was dangerous enough to abort the mission. The necessary repairs were made in Kiel and then the ship was redeployed to the Baltic Sea to undergo the sea trials. In the middle of January 1940 the Gneisenau returned to Kiel, where she was being prepared for another commerce raiding sortie in the Atlantic Ocean. This action, known as Operation “Nordmark” was a failure. Later, along with the other warships of the Kriegsmarine, the battleship was being prepared for the invasion of Denmark and Norway as part of the planned Operation “Wesserübung”. Vice Admiral Günther Lütjens took command of the German task force and the Genisenau became the flagship of the Commander-in-Chief of the Kriegsmarine. During that operation, near the Lofoten Islands, the German ships engaged the British battlecruiser HMS Renown. In the course of the battle the German battleship was hit and had to disengage. The explosion of a 38 cm shell near the top of the forward superstructure and the foremast put the fire control system out of action. On account of the damage Lütjens decided to break off the engagement and head back to base with all the warships. In the evening of April 12 the German ships safely reached Wilhelmshaven.
Before the beginning of Operation “Juno”, on May 20, 1940, main and secondary batteries turret tops and slopes were painted yellow as a form of new aircraft recognition markings. The battleship left Kiel on June 4, 1940 as the flagship of the Commander-in-Chief of the Kriegsmarine, Admiral Wilhelm Marshall. The operation promised to be successful, as already at its onset, on June 8, the German ships sank the British aircraft carrier HMS Glorious and her escorts – destroyers HMS Ardent and HMS Acasta. Before she sank, the HMS Acasta managed to launch torpedoes, one of which struck the Scharnhorst and caused some serious damage. Despite the losses the British did not concede and decided to take revenge on the enemy. Submarines were deployed to attack the German battleships on their return route. Soon, on June 20, 1940, the Genisenau fell prey to British torpedoes launched by the HMS Clyde. Damaged, with significant amount of water in her hull, she arrived at Trondheim (Drontheim) were the repairs were commenced immediately. They continued ceaselessly from July 19 until July 20, 1940 and on their completion the ship underwent sea trials in the nearby fjord. These temporary repairs permitted the ship to sail safely to Germany, where it was possible to restore her to fully operational status. When the decision to redeploy the ship to Kiel was taken, the battleship headed for Germany on July 25. Escorted by the light cruiser Nürnberg and destroyers, she arrived safely in Kiel, where on July 28 she was dry-docked at the Deutsche Werke shipyard. Repairs continued until the second half of October and on November 14, the ship departed for the Baltic Sea, where she performed a series of planned exercises and sea trials. They lasted until the middle of December and then the battleship headed for Kiel, where she was dry-docked again and prepared for another operation under the codename “Berlin”. Admiral Lütjens took command over this sortie. First attempt to break out into Atlantic began on December 28, but it was aborted after two days. Second attempt was made on January 21, 1941, but due to the lack of destroyer and torpedo boat screen, as well as bad weather, which prevented safe passage, it was soon aborted. During the attempt to break through between Iceland and the Faroe Islands, on January 28, the German battleships were spotted by the cruiser HMS Naiad, patrolling that area. They turned back and tried another route – the Denmark Strait, between Iceland and Greenland. That attempt was successful and the German task force broke through to the North Atlantic, where it began its commerce raiding sortie.
