Operation Rainbow (Unternehmen Regenbogen) was a 1942 sortie into the Arctic Ocean by warships of the Nazi German Kriegsmarine (German Navy) during the Second World War. The operation culminated in the Battle of the Barents Sea.

Following the disastrous Convoy PQ 17 and the hard-fought Convoy PQ 18 battles in the summer and autumn of 1942 and the needs of Operation Torch in the Mediterranean, Allied convoys to the Soviet Union had been temporarily suspended. In December 1942 Arctic convoys resumed with a new JW/RA convoy series. The Kriegsmarine had concentrated a large force of surface vessels and U-boats, supported by the aircraft of Luftflotte 5 (Air Fleet 5) of the Luftwaffe.

Regenbogen was based on a plan to intercept the next Allied convoy to Murmansk. A patrol line of four U-boats was established off Bear Island and a surface force consisting of the cruisers Admiral Hipper and Lützow with six destroyers was assembled at Altafjord. When a convoy was spotted, the fleet would sail as two battle groups; one to engage the expected cruiser escort and the other to attack the convoy. The German force was handicapped by strict orders from Adolf Hitler not to take excessive risks with the capital ships, which led to a general loss of initiative. Regenbogen was also hampered by the intention to send Lützow into the Atlantic following the action, which meant that the ship should avoid damage.^[1]

On 22 December 1942 Convoy JW 51B sailed for Murmansk and was detected by U-354 on 30 December. The German flotilla sailed from Altafjord the same day. In the Battle of the Barents Sea, Regenbogen had some success; Hipper was able to draw off the escort as planned, allowing Lützow to close with the convoy. Excessive caution by the captain of Lutzow caused him to break off the attack having caused little damage.

The failure of the operation can be attributed to the spirited defence made by the convoy escort and the restrictive and contradictory orders given by Hitler to the force commander. Hitler was furious when he heard about the dismal performance of the Navy. He subjected Grand Admiral Erich Raeder, the head of the Kriegsmarine, to a 90-minute tirade, in which he berated the uselessness of the German surface fleet and announced a decision to scrap all its ships and use its guns and men as shore defences. Raeder felt unable to continue without the confidence of his leader and offered his resignation, which was accepted. Raeder was replaced by Admiral Karl Dönitz, the commander of the U-boat fleet.^[2]

Regenbogen ships^[3]

Ship	Flag	Type	Notes
Admiral Hipper	Kriegsmarine	Admiral Hipper-class cruiser	Sailed 30 December
Lützow	Kriegsmarine	Deutschland-class cruiser	Sailed 30 December
Z4 Richard Beitzen	Kriegsmarine	Type 1934-class destroyer	Sailed 30 December
Z6 Theodor Riedel	Kriegsmarine	Type 1934A-class destroyer	Sailed 30 December
Z16 Friedrich Eckoldt	Kriegsmarine	Type 1934A-class destroyer	Sailed 30 December
Z29	Kriegsmarine	Type 1936A-class destroyer	Sailed 30 December
Z30	Kriegsmarine	Type 1936A-class destroyer	Sailed 30 December
Z31	Kriegsmarine	Type 1936A-class destroyer	Sailed 30 December

• Blair, Clay (2000) [1998]. Hitler's U-Boat War: The Hunted 1942–1945. Vol. II (pbk. repr. ed.). Cassell. ISBN 0-304-35261-6.
• Roskill, S. W. (1956). The Period of Balance. History of the Second World War United Kingdom Military Series: The War at Sea 1939–1945. Vol. II. London: HMSO. OCLC 174453986. Retrieved 16 April 2020.
• Woodman, Richard (2004) [1994]. Arctic Convoys 1941–1945. London: John Murray. ISBN 978-0-7195-5752-1.

• Schofield, B. B. (1964). The Russian Convoys. British battles. London: Batsford. OCLC 930491299 – via Archive Foundation.