'Rheinübung' was the German naval commerce-raiding foray into the North Atlantic by the battleship Bismarck, accompanied by the heavy cruiser Prinz Eugen, and leading to the sinking of Bismarck (18/27 May 1941).

During both world wars, as an island nation the UK was largely dependent upon merchant shipping for the export of British goods and the import of food and essential raw materials, and the protection of this strategic lifeline was one of the highest British priorities. The Germans well knew that the severance of this lifeline would require the UK either to sue for peace, through either an armistice or a surrender, or to abandon the British Isles as a base of operations to blockade the sea approaches to Western Europe. This would effectively yield to Germany complete mastery of Western Europe.

Germany’s naval leadership, under Generaladmiral (from 1 April 1939 Grossadmiral) Erich Raeder, at the time firmly believed that a defeat of the UK by blockade was achievable. However, the Germans were divided into two camps about the best way to achieve this object. Konteradmiral (from 1 September 1940 Vizeadmiral) Karl Dönitz, commander of the U-boat arm, believed that this objective was attainable most effectively by his submarine force, while Raeder believed that the primary method to achieve this objective was the use traditional commerce-raiding tactics using surface combatants (battleships, battle-cruiser, cruisers and armed merchant raiders) supported by submarines. Regardless of the method or manner, Raeder convinced the Oberkommando der Wehrmacht and Adolf Hitler that if the German could cut this British lifeline, the UK would be defeated, regardless of any other considerations.

'Rheinübung' was the latest in a series of raids on Allied shipping carried out by surface units of the Kriegsmarine in the first years of World War II, and had been preceded by the very successful 'Berlin' (i) sortie by the battle-cruisers Scharnhorst and Gneisenau ending in March 1941.

By May 1941, Scharnhorst and Gneisenau were at Brest, the major naval base on the north-western corner of German-occupied France, and from this base posed a continued and major threat to the UK’s convoys in the Atlantic Ocean. As a result the two ships were frequently and heavily bombed by the RAF, but only with inconclusive results. The original plan for 'Rheinübung' was to have both of these ships involved in the operation together with Bismarck and Prinz Eugen, but Scharnhorst was undergoing major repairs to her engines, and Gneisenau had just suffered a torpedo hit which put her out of action for six months. This left the German navy with just the two new warships, namely the battleship Bismarck and the heavy cruiser Prinz Eugen, with which to consider a commerce-raiding cruise by major warships. The Kriegsmarine did also have available three light cruisers, but none of these possessed the endurance necessary for a lengthy operation in the Atlantic.

In the spring of 1941 both Kapitän Ernst Lindemann’s Bismarck and Kapitän Helmuth Brinkmann’s Prinz Eugen were in the Baltic Sea completing the process of working up to operational capability. Raeder believed that a commerce-raiding cruise into the Atlantic would be the best way for the two vessels to cut their operational teeth. The British were aware that the two ships had been completed, and that they might sortie with the pocket battleship Lützow and light cruisers Emden and Köln, so giving the German navy an exceptionally powerful Atlantic raiding squadron. Therefore the British put substantial forces on full alert, and intensified both air and sea patrol operations between Iceland and Norway, the area through which any German squadron would have to sail to reach the Denmark Strait between Greenland and Iceland, or the Færoes/Iceland gap to break out into the North Atlantic and its convoy routes.

In fact only Bismarck and Prinz Eugen were earmarked for the sortie ordered by Raeder on 2 April 1941. As noted above, the original plan was for the two battle-cruisers to sortie from Brest at the same time on a diversionary raid, but both of these ships had been damaged and were thus not available to participate even though the raid had to be postponed after Prinz Eugen had suffered mine damage in the Baltic on 23 April. Admiral Günther Lütjens, the Flottenchef and designated commander of 'Rheinübung', requested that Raeder delay 'Rheinübung' long enough either for Scharnhorst's engine repairs to be completed and the ship be declared combat-capable so as to rendezvous at sea with Bismarck and Prinz Eugen, or for Bismarck‍ '​s sister ship, Tirpitz, to accompany them. Raeder refused as Scharnhorst would not be ready until a time early in July, and the crew of the newly completed Tirpitz was not yet fully trained. Over Lütjens’s protests, therefore, Raeder ordered 'Rheinübung' to be implemented. Raeder’s principal reason for pressing ahead with 'Rheinübung' was his knowledge of the forthcoming 'Barbarossa', in which the Kriegsmarine was to play only minor and supporting role, and his desire to score a major success with a battleship before 'Barbarossa' in order to impress on Hitler the advisability of not cutting the budget for capital ships.

The overall object of the undertaking was for Bismarck and Prinz Eugen to break into the Atlantic and attack Allied shipping. Raeder’s orders to Lütjens were that Bismarck's task was not to tackle and defeat British warships of equal strength, but to tie them down in a delaying action, while preserving Bismarck's combat capacity to the highest degree possible, in order to allow Prinz Eugen to engage the merchant ships in any convoy under attack, and that the primary objective of the operation was British merchant shipping, so that British warships were to be engaged only in furtherance of the of the primary objective and only when it could be done without excessive risk. Thus Lütjens was under strict instructions not to jeopardise his squadron in any way against superior naval forces or if there was no worthwhile convoy in the offing.

To support and provide facilities for the battleship and heavy cruiser to refuel and rearm, the Oberkommando der Marine organised a network of tankers and supply ships in the operational area designated for the operation: thus seven oilers and two supply ships were sent as far afield as Labrador in the west and the Cape Verde islands group in the south.

To meet the threat of a foray by German surface ships, the British had stationed at Scapa Flow in the Orkney islands group, the main base of Admiral Sir John Tovey’s Home Fleet, the new battleships King George V and Prince of Wales as well as the elderly battle-cruiser Hood and the newly commissioned fleet carrier Victorious. Elsewhere, Vice Admiral Sir James Somerville’s Force 'H' at Gibraltar could muster the elderly battle-cruiser Renown and the fleet carrier Ark Royal, and at sea in the Atlantic on various duties were the battleships Ramilles, Revenge and Rodney, as well as the battle-cruiser Repulse. Cruisers and air patrols provided the fleet’s 'eyes'. At sea, or due to sail shortly, were 11 convoys, including an important troop convoy.

A factor which the Oberkommando der Marine failed to take into account was the Royal Navy’s determination to destroy the German surface fleet. To ensure that Bismarck was indeed sunk, the Royal Navy ruthlessly stripped other theatres despite the fact that this would entail the denuding of valuable convoys of their escorts. The British ultimately deployed six battleships, three battle-cruisers, two fleet carriers, 16 cruisers, 33 destroyers and eight submarines, along with patrol aircraft, in their hunt for Bismarck and Prinz Eugen, and this was the largest naval force assigned to a single operation up to that point in the war.

At about 21.00 on 18 May Prinz Eugen departed Gotenhafen, followed about five hours later by Bismarck. Both ships proceeded under escort and separately to rendezvous off Cape Arkona on Rügen island in the western part of the Baltic. They then proceeded through the Danish islands into the Kattegat on 20 May, then proceeded into the Skagerrak, the strait between Jutland and southern Norway, and here they were sighted at about 13.00 by the Swedish light cruiser Gotland, which forwarded the sighting in a routine report.

On 21 May, the Admiralty was alerted by sources in the Swedish government that two large warships had been seen in the Kattegat, and was further alerted when a Norwegian told the British naval attaché in Stockholm on 20 May that he had been informed at a cocktail party that two major Germans warships had been seen moving to the north through the Kattegat. The ships entered the North Sea and took a brief refuge in a fjord near Bergen on 21 May, making a break for the Atlantic shipping lanes on 22 May. By this day the British had aerial photographs of the two German ships lying in the Korsfjord to the south of Bergen. There were suggestions that the German ships might be covering a German assault on Iceland, but Tovey remained convinced that the Germans were about to launch another major offensive by surface ships into the North Atlantic.

Tovey therefore strengthened the British patrols between the Orkney islands group and Greenland (via the Shetland islands group, the Færoe islands group and Iceland, among which the Færoes/Iceland gap was being patrolled by the light cruisers Arethusa, Birmingham and Manchester and five trawlers with the support of flying boats of RAF Coastal Command), and sent Vice Admiral L. E. Holland’s Battle-Cruiser Squadron (the elderly battle-cruiser Hood, new battleship Prince of Wales, and destroyers Achates, Antelope, Anthony, Echo, Electra and Icarus) to the Hvalfjörður in south-western Iceland as cover for the Denmark Strait.

Further aerial reconnaissance on 22 May showed that Bismarck and Prinz Eugen had departed the Korsfjord, and Tovey steamed from Scapa Flow at 22.45 with King George V, the fleet carrier Victorious, the light cruisers Aurora, Galatea and Kenya and the light anti-aircraft cruiser Hermione of Rear Admiral A. T. B. Curteis’s 2^nd Cruiser Squadron, and the destroyers Active, Inglefield, Intrepid, Lance (forced to turn back with damage), Nestor and Punjabi. This force was joined later by the battle-cruiser Repulse from the Clyde river and three destroyers from Admiral Sir Percy Noble’s Western Approaches Command.

Against the advice of his officers, Lütjens had decided to break through the ice-narrowed 60-mile (95-km) Denmark Strait rather than 300-mile (485-km) gap between the Færoe islands group and Iceland, which would have given him more rapid access to the Atlantic against a mere three cruisers before the heavier ships of the Battle-Cruiser Squadron and the Home Fleet could close on him. As it was, the German squadron was detected by the radar of the heavy cruiser Suffolk at 19.22 on 23 May, and thereafter the Germans were shadowed by Suffolk and Norfolk of Rear Admiral W. F. Wake-Walker’s 1^st Cruiser Squadron, whose radio reports started the two British main forces closing on the anticipated position of the German squadron.

At 05.35 on 24 May Hood and Prince of Wales sighted the German ships and immediately altered course to close the range, possibly so that Bismarck would be unable to use long-range plunging fire to strike a mortal blow through the thin horizontal armour of the obsolescent Hood. At 05.52 Holland ordered his two ships to open fire on the leading German ship, which was now Prinz Eugen as the two had exchanged places during the night. However, Prince of Wales correctly identified Bismarck and fired on her. The crisis came at 06.00 just as Holland ordered a turn to port to bring his after guns to bear. A 380-mm (15-in) salvo from Bismarck struck Hood, which blew up and disappeared in three or four minutes, leaving just three survivors out of a complement of 95 officers and 1,324 men. The Germans then turned their attentions to Prince of Wales, which was suffering technical teething problems with her 14-in (356-mm) main guns, and soon landed four 380-mm (15-in) and three 203-mm (8-in) shells on the British battleship, one hit landing on the compass platform and killing or wounding everyone on it but the ship’s captain and a signaller. Captain J. C. Leach broke off the action at 06.13 as he was heavily outgunned. But Prince of Wales had nevertheless managed to hit Bismarck twice, one of the 14-in (356-mm) shells gashing open an oil bunker and so hampering the German flagship through loss of fuel (she had earlier refused to take the opportunity to top up her bunkers), which also left a telltale slick in the sea, and also causing contamination of the surviving fuel with sea water.

Lütjens therefore decided to abandon 'Rheinübung', and at 08.01 radioed his intention of making for St Nazaire on the west coast of German-occupied France.

Meanwhile the British were reassessing their position after Hood's loss. While Wake-Walker took Prince of Wales and the Battle-Cruiser Squadron’s destroyers under command and continued to shadow the German ships, the Admiralty set about increasing the strength of the forces opposing Bismarck and Prinz Eugen by calling from Gibraltar Somerville’s Force 'H' (battle-cruiser Renown, fleet carrier Ark Royal, light cruiser Sheffield, and destroyers Faulknor, Foresight, Forester, Foxhound, Fury and Hesperus) plus the battleship Rodney and destroyers Mashona, Somali and Tartar, which were escorting the troopship Britannic from the Clyde to New York; the destroyer Eskimo remained with Britannic.

Tovey by now appreciated that Lütjens might make for a French port or seek to return to Germany rather than continue with the original raiding scheme, and disposed his forces accordingly. The speed of the German squadron was still too great for Tovey’s liking, however, and during the night of 24/25 May an attack by Fairey Swordfish torpedo-bombers of the untried Victorious was launched. Lieutenant Commander E. Esmonde led his aircraft with great skill, and managed to score one torpedo hit on Bismarck: the torpedo failed to detonate, but all the aircraft managed to return to their carrier.

Matters now took a more ominous turn for the British, for Lütjens ordered Prinz Eugen to break off on an independent raiding mission, and Suffolk then lost radar contact with the German battleship at 03.06 as Bismarck turned to the south-east in the general direction of the French coast. Moreover, the British ships were running short of fuel and having to break away for replenishment (leaving in the Atlantic only King George V of the 22 ships which had sailed on 22 May), and a radio message from Bismarck was incorrectly triangulated, leading Tovey to believe that the German battleship was trying to return to Germany, so persuading him to turn to the north-west at 10.47 on 25 May.

The crucial moment came at about 10.30 on 26 May, when a Consolidated Catalina flying boat of RAF Coastal Command spotted Bismarck steaming to the south-east in the direction of Brest, now only 690 miles (1110 km) distant. A signal was flashed out, and it was immediately apparent that the Home Fleet could not intercept in the immediate future. Success for the British now rested with Force 'H', which at 14.50 launched an attack by Swordfish torpedo-bombers from Ark Royal, the pilots fully appreciating that they must slow Bismarck sufficiently for Rodney and King George V to intercept before they too had to break off for fuel. The attack was a disaster, for the pilots struck at Sheffield, which had been sent ahead by Somerville to shadow Bismarck. The torpedoes failed to work, however, exploding as soon as they hit the water.

A second attack was launched from the carrier at 19.10, the torpedoes carried on this occasion being fitted with contact rather than magnetic proximity detonators. A U-boat watched the take-off but could not interfere as it was out of torpedoes. Greater success attended the second attack, for between 20.47 and 21.25 on 26 May the Swordfish torpedo bombers scored two hits, the first striking the armour belt and causing no damage but the second impacting the stern, where the detonation of the torpedo’s warhead damaged the battleship’s propellers and jammed her rudders.

The fate of Bismarck was now sealed, for the ship was seriously slowed and could not steer efficiently. Bismarck circled twice and then slowly settled on a north-north-westerly course toward the two British battleships. First Bismarck ran into the destroyers Cossack, Maori, Sikh, Zulu and Free Polish Piorun of Captain P. L. Vian’s 4^th Destroyer Flotilla, but so accurate was the battleship’s gunfire that of the 16 torpedoes launched by the destroyers at long range in a very heavy sea, only two struck the battleship, causing no significant damage.

Meanwhile Norfolk was vectoring in King George V and Rodney, and at 08.47 on 27 June the two British battleships opened fire at a range of 25,000 yards (22860 m), soon closing to 16,000 yards (14630 m). At 10.15 Tovey had to break off for fuel, but by this time Bismarck was a blazing wreck without effective armament.

At 10.36 Bismarck sank: according to the British she was finished by two torpedoes from the cruiser Dorsetshire, but according to the Germans she was scuttled by her crew. A mere 110 survivors were plucked out of the water by Dorsetshire and the destroyer Maori, but after an hour, rescue work was abruptly ended when there were reports of a U-boat in the area. Another five survivors were picked up by U-74, and the German weather ship Sachsenwald. Some 2,190 other men had been killed or otherwise went down with their ship.

After separating from Bismarck, Prinz Eugen steamed farther to the south into the Atlantic, intending to continue the commerce raiding mission. On 26 May, with just 160 tons of fuel left, she made rendezvous with the tanker Spichern and refuelled, but on the following day developed engine trouble, which worsened over the next few days. After a further refuelling on 28 May from Esso Hamburg, Prinz Eugen abandoned her mission on 29 May and headed for Brest as, with her speed reduced to 28 kt, it was considered no longer feasible to continue. Thus Prinz Eugen abandoned her commerce-raiding mission without sinking any merchant ships, and made her way to Brest, arriving on 1 June.

In the action, just two U-boats had sighted the British forces, and neither was able to attack. In the aftermath, the British ships were able to evade the patrol lines as they returned to base; there were no further U-boat contacts. The Luftwaffe also flew sorties against the Home Fleet, but none of these was successful until 28 May, when aircraft of Oberstleutnant Johann Raithel’s Kampfgeschwader 77 attacked and sank the destroyer Mashona.

So ended 'Rheinübung', which had been a disaster for the Germans but also a great blow to the British. Apart from the loss of Hood and damage to Prince of Wales, the operation to sink Bismarck revealed the severe tactical limitations imposed on Atlantic operations by British ships in the absence of underway replenishment oilers, and also how dangerous the German fleet would have been had its 'Plan Z' construction programme been completed before the outbreak of war: the chase of one battleship and one heavy cruiser had required the British to use eight capital ships (two aircraft carriers and six battleships and battle-cruisers), 11 cruisers, 22 destroyers and six submarines.

'Rheinübung' had been a German failure, for the loss of the modern battleship Bismarck represented the loss of one-quarter of the Kriegsmarine’s capital ship strength. No merchant ships were sunk or even sighted by the German heavy surface units during the two-week operation Allied convoys were not seriously disrupted; most convoys sailed according to schedule, and there was no diminution of the delivery of cargoes to the UK. On the other hand, the Atlantic U-boat campaign was disrupted: boats in the Atlantic sank just two ships in the last weeks of May, whereas the tally had been 29 ships at the beginning of the month.

As a result of Bismarck‍ '​s sinking, Hitler forbade any further Atlantic sorties, and Tirpitz, Bismarck‍ '​s sister ship, was despatched to Norway. The Kriegsmarine was never again able to mount a major surface operation against Allied supply routes in the North Atlantic, where its only weapon was now the U-boat.

After the end of 'Rheinübung' proper, the Royal Navy made a major effort to locate and destroy the German supply ships deployed to refuel and rearm the 'Rheinübung' ships, and at the same time to intercept Axis blockade-runners. The British undertaking was considerably aided by the fact that German Enigma coding machines and code books had been captured when the weather observation ship München was captured in 'EB' on 7 May and U-110 was seized three days later, as later were the supply ships Gedania and Lothringen. This made it possible for the British to decode and read current German radio traffic.

On 28 May the 3,290-ton blockade-runner Lech, homebound from Rio de Janeiro, had to be scuttled by her crew in the South Atlantic when a British warship came into sight. Then, on 29 May, the weather ship August Wriedt becomes a victim of the British search operations.

On 3 June the 6,367-ton tanker Belchen, which had replenished U-111 and U-557 in the Davis Strait, was sunk by the British cruisers Aurora and Kenya between Greenland and Labrador, their survivors being rescued by U-93.

On 4 June the 8,923-ton tanker Gedania was hastily abandoned when the auxiliary warship Marsdale was sighted, and the ship was then captured. An aeroplane from the carrier Victorious, proceeding to Gibraltar with the cruiser Hermione, sighted the 4,000-ton patrol ship Gonzenheim to the north of the Azores islands group: the German ship was able to escape from the auxiliary cruiser Esperance Bay but then had to be scuttled when the battleship Nelson and light cruiser Neptune, summoned to the area, hove into view: Neptune torpedoed the burning wreck.

On 4 and 5 June, respectively, the 9,949-ton tanker Esso Hamburg and 9,798-ton tanker Egerland were scuttled by their crews in the German rendezvous and supply area associated with attacks on the convoy route linking Freetown and Natal route after being approached by the heavy cruiser London and destroyer Brilliant.

On 6 June the 9,179-ton blockade-runner Elbe, homebound from eastern Asia, was sunk by aircraft from the carrier Eagle near the Azores islands group.

Two days later, the battle-cruiser Renown, carrier Ark Royal, cruiser Sheffield and six destroyers of Force 'H' departed Gibraltar to the west in order to avoid anticipated Vichy French air attacks (in reprisal for the 'Exporter' invasion of Lebanon and Syria) and at the same time to intercept German supply ships and blockade-runners. On 9 June the ships of Force 'H' met the carrier Victorious and cruiser Hermione coming from the north. Sheffield started to return to the UK, and on 12 June encountered the homebound 10,397-ton tanker Friedrich Breme in the North Atlantic at a position to the west-north-west of Cape Finisterre, inducing the captain of the tanker to scuttle his ship.

On 15 June the supply ship Lothringen, earmarked to replenish U-boats operating off Freetown, was sighted in the central Atlantic by an aeroplane from Eagle and captured by the light cruiser Dunedin, which gathered some highly classified Enigma cipher machines that the German ship was carrying. The Royal Navy then adapted Lothringen as the fleet oiler Empire Salvage. Dunedin went on to take three Vichy French vessels, namely the 5,598-ton Ville de Rouen off Natal, 4,993-ton Ville de Tamatave to the east of the St Paul’s Rocks, and 7,291-ton D’Entrecasteaux.

As the British search groups were replenishing and Force 'H' was operating in the Mediterranean in the course of 'Tracer' (ii), the patrol ship Kota Pinang, supply ships Ermland and Spichern, Italian blockade-runners Atlanta and Todaro coming from the Canary islands group and the German Regensburg homebound from eastern Asia passed through the blockade and reached ports in western French.

During the afternoon of 22 June, British air reconnaissance sighted the 3,039-ton supply ship Alstertor homebound from the Indian Ocean, and the auxiliary Marsdale and the destroyers Faulknor, Fearless, Forester, Foxhound and Fury were deployed for a surface search. On 23 June, off Cape Finisterre, Alstertor spotted the British warships and her captain decided to scuttle his ship: the crew and 78 British prisoners from the auxiliary cruiser Atlantis were rescued.

In the meantime the spotting of the cruiser London persuaded the captain of the 4,422-ton blockade-runner Babitonga, homebound from Brazil, to scuttle his ship in the South Atlantic.

In little more than a fortnight, therefore, seven of the nine tankers and supply ships assigned to 'Rheinübung' had been sunk or taken, with serious consequences for future German surface operations.