War began before Scharnhorst's modification work was completed. Her first wartime operation was a sweep into the Iceland-Faroes passage in late November 1939, in which the British armed merchant cruiser Rawalpindi was sunk. In the spring of 1940 the battleship and her sister, Gneisenau, covered the conquest of Norway. They engaged the British battlecruiser Renown on April 9, 1940, and sank the carrier HMS Glorious and two destroyers on June 8. In the latter action, Scharnhorst was torpedoed. She was further damaged by a bomb a few days later and was under repair for most of the rest of 1940.
From January 22 until March 22, 1941, Scharnhorst and Gneisenau operated in the Atlantic, sinking several ships and severely threatening British seaborne supply lines. While at Brest, France, following this operation, the German ships were the targets of repeated air attacks. The resulting damage kept them non-operational into late 1941, when it was decided to concentrate German surface naval power in the Norwegian theater as a result of the Commando raid on Vaagso. Since it was too risky to attempt the redeployment via the North Atlantic, on February 11-13, 1942, the two battleships and heavy cruiser Prinz Eugen made a daring "dash" through the English Channel to reach Germany. Caught off guard, the British were unable to stop the ships with air and surface attacks, though both Scharnhorst and Gneisenau were damaged by mines during the latter part of the voyage.
Repair work, a grounding and her always troublesome steam powerplant kept Scharnhorst out of action until March 1943, when she went to northern Norway to join the battleship Tirpitz and other German ships threatening the convoy route to the USSR. Training exercises over the next several months climaxed in a bombardment of Spitzbergen on September 8, 1943.
On Christmas day, 1943, Scharnhorst and several destroyers put to sea to attack a convoy northwest of Norway. Unfortunately for the Germans, their orders were decoded by the British, who sent a superior force to intercept. The Royal Navy cruisers Belfast, Norfolk, and Sheffield effectively kept Scharnhorst away from the convoy until the reinforcements arrived. Realizing the futility of their mission, the Germans attempted to return to their base, but Scharnhorst was cut off by the British battleship Duke of York and her escorting cruisers and destroyers. In a three-hour battle in the frigid Arctic seas, the German battleship was battered by gunfire and sunk by torpedoes. There were 36 survivors of her crew of some 1968 men.
Scharnhorst's wreck was located and photographed by a Norwegian Navy underwater exploration group in the year 2000.
''Originally from http://www.history.navy.mil/photos/sh-fornv/germany/gersh-s/scharn2.htm, a public domain publication of the Naval Historical Center, Department of the Navy.''