'Sommerreise' was the German movement of the heavy cruiser Lützow (ex-pocket battleship Deutschland) from Gotenhafen in the Baltic Sea to Norwegian waters (10/13 June 1941).
The ship had been moderately damaged by the fire of Norwegian coastal batteries during her involvement in 'Weserübung' on 9 April 1940, and during her passage back to Germany had been further and more severely damaged by a torpedo from the British submarine Spearfish. After lengthy repairs, in which her stern had been rebuilt, the German cruiser was recommissioned for service on 31 March 1941, after which the Kriegsmarine initially planned to send the ship on the commerce raiding operation planned the previous year. Her sister Admiral Scheer was to join Lützow for the operation, and during the afternoon of 10 June she departed for Norway with an escort of destroyers.
From a time early on 11 June, 'Ultra' decrypts of Enigma signals to the Luftwaffe and Lützow's escorts, had made the Government Code and Cypher School at Bletchley Park aware of this movement, and the information led to the Admiralty’s Operation Intelligence Centre to decide that Lützow was about to attempt a break-out into the North Atlantic on a commerce-raiding operation. At 04.30 on the same day, therefore, the Home Fleet at Scapa Flow in the Orkney islands group was brought to one hour’s notice.
At 01.27 on 12 June the battleship King George V, the light cruisers Arethusa and Aurora, and the destroyers Bedouin, Eskimo, Nestor and Punjabi departed Scapa Flow to provide heavy cover for the vessels of the Northern Patrol.
Just before 24.00 on 12 June, moreover, information forwarded from the Operational Intelligence Centre allowed the Royal Air Force to launch an attack force of five Bristol Beaufort Mk I torpedo bombers of No. 22 Squadron from Wick and nine Beaufort Mk I machines of No. 42 Squadron from Leuchars in Scotland. At 00.15 on 13 June a patrolling Bristol Blenheim of the RAF’s No. 114 Squadron sighted Lützow and reported her location, course and speed. At 02.25, off Egersund, one of the Beaufort warplanes torpedoed Lützow on her port side in the no. 2 motor room, disabling her electrical system and rendering the ship motionless. Lützow took on a severe list to port, and her port shaft was damaged. The crew managed to effect emergency repairs, and by 04.45 the German warship had abandoned her mission and was making for Kiel. At 05.25 the Operational Intelligence Centre was aware that Lützow had been hit and crippled.
The repair work in Kiel lasted for six months, and it was only on 10 May 1942 that Lützow was finally pronounced ready for action once more.