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If you are considering whether Operation Rheinübung could have been a success, and what changes that would require, let’s start by considering what exactly the mission of the Bismarck and Prinz Eugen was. Despite being two very powerful warships, and in May 1941 Bismarck was one of the most (if not the most) powerful warships in the world, their mission was not to directly challenge the Royal Navy, in fact they were to do just the opposite; they were to, wherever possible, avoid contact with the Royal Navy. They were, despite their enormous firepower, commerce raiders: their mission was to seek out and destroy the merchant convoys whose continued safe passage was essential for Britain’s survival.
The first and most obvious alternative scenario for Rheinübung is: what if the Germans had sent out a more powerful force? Not too surprisingly, this had been the original plan: the Scharnhorst and the Gneisenau were to join Bismarck and Prinz Eugen in the Atlantic and either rendezvous with them to form a single powerful raider force, or operate apart, the two raiding forces sweeping a larger area of the Atlantic for convoys and at the same time forcing the Royal Navy to either concentrate all of their resources against one group, ignoring the other, or dividing their forces to track down both raiding parties, and consequently not having enough forces to defeat either. Scharnhorst and the Gneisenau had conducted Operation Berlin in March ’41 with mixed success; the two battleships located convoys on three occasions and sank or captured more than twenty merchant ships, including four oil tankers, but they also sustained damage to both ships, mainly from wear and tear; Scharnhorst was expected to take ten weeks to repair, ruling it out for Rheinübung, while Gneisenau was expected to take four weeks to repair; which should have meant that it would be available in late April, in time for Rheinübung. However, on 4th and 6th April the RAF attacked the two German battleships while they were undergoing repairs in the port of Brest, and the Gneisenau sustained further damage, making her unavailable for a further ten weeks. Given the significant damage that the two Brest based warships had inflicted on British merchant shipping in March, had they been available for Rheinübung, the potential success of the operation would have been enormously increased.
Two other potential German combatants were the Admiral Hipper and the Admiral Sheer. Admiral Hipper was a heavy cruiser of the same class as Prinz Eugen and, like Prinz Eugen, lacked the range of the battleships; its involvement would have required the raiders to seek refuelling more often, or the Bismarck would have had to operate apart from Admiral Hipper anyway. Admiral Hipper had been the first of its class of heavy cruiser and as is often the case with the first of a new class of ship, suffered significantly more mechanical problems than the later ships did; it was undergoing repairs in Brest in May ’41, otherwise it could have taken part in the operation. An alternative Rheinübung might have seen both Gneisenau and Admiral Hipper put to sea from Brest in conjunction to Bismarck and Prinz Eugen leaving Norway. (Or if you want to make things particularly bad for the Royal Navy: Scharnhorst, Gneisenau, and Admiral Hipper all put to sea) Admiral Sheer was a heavy cruiser that had already been successful as a merchant raider, having been at sea continuously for five months in 1940, but that time at sea had taken its toll; in April ’41 it was reported that Admiral Sheer would not be available until mid-June; delaying Rheinübung, or accelerating repairs might have seen Admiral Sheer accompany Bismarck. Having Admiral Sheer accompany Bismarck instead of Prinz Eugen would have significantly improved the German situation; Admiral Sheer was armed with 6 x 280 mm main guns, as opposed to Prinz Eugen’s 8 x 203 mm main guns, meaning that Admiral Sheer could engage an enemy ship at greater range and with heavier shells. Admiral Sheer also had far greater operational range than Prinz Eugen, increasing mission flexibility.
The most powerful German ship available but not included in Rheinübung was the second Bismarck-classbattleship: Tirpitz. By May ’41 Tirpitz was fully operational. Tirpitz was not originally included in the planning for Rheinübung because the operation had been planned for mid-April. But Rheinübung had been delayed twice, initially by the attacks on the Gneisenau, and then because the Prinz Eugen sustained damage from a sea mine, repairs for which would not be completed until mid-May. On 5 May ’41, Hitler visited Gdynia specifically so that he could inspect his two prized battleships, Tirpitz and Bismarck. During the inspection, Tirpitz’s commander, Captain Topp, expressed his wish to the Fuhrer that his ship should be included in the upcoming operation; Tirpitz was now fully operational. Hitler deffered to his naval commanders: admirals Raeder, commander of the Kriegsmarine, and Admiral Lütjens, fleet commander for Rheinübung. Both admirals disagreed with Topp and thought the crew of Tirpitz needed more experience prior to embarking on a major operation. Here then is an opportunity for an alternative scenario; it would not have been the first time that Hitler overruled his admirals and criticized them as being too cautious; if the commander of one of his two most powerful battleships believed that his crew and ship were ready, then that ship was ready and should be included in the operation!
Including Tirpitz in Rheinübung, in addition to immediately doubling the potential firepower of the German squadron, would have meant that the operation could have taken place earlier; Tirpitz could have been fully provisioned and ready to depart before Prinz Eugen’s repairs were even complete. The earlier that Operation Rheinübung can take place, the better the German chances of breaking out into the Atlantic shipping routes undetected are; the later that the operation takes place, the more hours of daylight and the better the flying conditions for RAF aircraft to locate the German surface will be. If Bismarck and Tirpitz had embarked without Prinz Eugen they could have maintained a higher cruising speed; while Prinz Eugen could cruise as fast as Bismarck and could sprint faster, it could not do so without severely curtailing its range before refueling. Therefore, to extend their operational range, both ships maintained a cruising speed dictated by the Prinz Eugen; replace Prinz Eugen with Tirpitz and the squadron could cruise faster, go farther and deliver a more powerful punch if encountered the Royal Navy. If Reader and Lütjens had been presented with the stark choice of either taking Tirpitz or cancelling Rheinübung, they would almost certainly have chosen the former; the shear cost of building the two battleships would demand their use. So if repairs to Prinz Eugen had been further delayed, Lütjens may have taken Bismarck and Tirpitz to sea, with all other conditions at the outset of Rheinübung remaining the same. The squadron would have put to sea from Gdynia on 18 May 1941.
Immediately things would have gone better for the Germans; the British were first informed that the German warships might be active by Swedish contacts on the 20th, as they made the run north through the Kattegat between Denmark and Sweden. Lütjens’ plan, prior to departure, was to skirt the coast of Norway heading north to rendezvous with the fleet oiler Weissenburg, waiting in the far north near the island of Jan Mayen to top up the warships tanks, after that, and with full oil on board, he could make a high speed run for the Atlantic via either the Denmark Strait between Greenland and Iceland, or between Iceland and the Faeroe Islands. Historically, Lütjens changed his plans when he reached the Norwegian port of Bergen, he stopped in the Bergen Fjord to allow the Prinz Eugen to top up its tanks in preparation for making a break for the open Atlantic immediately afterwards rather than continuing north to the rendezvous with Weissenburg; he had received reports from the Luftwaffe that the weather in the Denmark Strait would be favourable for the next few days. It was while in the Bergen Fjord that an RAF reconnaissance aircraft photographed the two warships on the 21st May, confirming that the Bismarck was on the prowl, after which the Royal Navy’s Home Fleet was alerted. Bismarck didn’t take on oil in Bergen; with its much greater range it had more than enough fuel on board without needing to top up at this stage. Being an identical ship, Tirpitz also would not have needed to refuel before the run for the Denmark Strait. The two German battleships could have continued north and west, passing through the Denmark Strait in the bad weather on the 22 May; the British Admiralty would not be certain if any German warships were at sea, what ships they might be, or where they were headed.
If Lütjens’ squadron had managed to make the run through the Denmark Strait on the 22nd May, they may well have done so undetected; the weather conditions were perfect at the time for Lütjens, low clouds and rain shrouded the Straits. In addition, icebergs and fog banks further reduced visibility. Waiting in the Strait were the two Royal Navy cruisers, Norfolk and Suffolk. Both ships were more than 15 years old and in terms of firepower, were completely outclassed by the German battleships. In the very poor visibility prevailing on the 22nd, both would have been relying heavily on their radar sets. Suffolk’s radar set was one of the best available to the Royal Navy at the time, which unfortunately wasn’t saying much, it had a range of only 12 nm (23 km); this was less than the range of the Bismarck and Tirpitz’s main guns, and considerably less than the range of the more sophisticated German shipboard radar sets; Lütjens could have altered course to avoid the RN ships before they were even aware that he was there.
Once through the Denmark Strait, the battleships would be in the open Atlantic and would then have the task of intercepting and destroying British convoys, all the while trying to avoid the Royal Navy, who would probably be alerted to their location as soon as they attacked their first merchant ship. ‘Probably alerted’ rather than ‘certainly alerted’ because during Operation Berlin in February and March 1941, the Scharnhorst and Gneisenau were able to sink several merchant ships before one was able to raise the alarm.
On the 23rd May, there were two convoys due south of the Denmark Strait; SC31 inbound for the British Isles with 32 merchant ships was just south of the Strait, while HX126, also inbound, with 20 merchant ships, was a little further south than SC31. Heading into the same area were the outbound convoys OB323 and OB324, with 35 merchant ships each. There were also three more convoys just departing the British Isles: WS8B, OB325 and OB326, with a further 71 merchant ships between them. HX127 had also just departed Halifax with 56 merchant ships; unless it was redirected south it would enter the danger zone within the next few days.
More to follow...
