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Bismarck could not outrun new radar
Did Operation Rheinübung ever have a hope of success?
Impressive battleships continued to have a place in the naval imagination into the 1930s and 1940s, as the capital ships of their day. All the major nations were still building them. It simply appeared necessary to have ships that were at least as powerful as those of your potential foes.
There were those within the Kriegsmarine who had argued that Germany’s interests would be better served by more U-boats or smaller ships capable of ‘commerce raiding’. The navy could be designed so that she was capable of isolating Britain in any future war, by sinking the merchant ships supplying her. This strategy had been among the options offered to Hitler when he embarked on his re-armament programme. But the appeal of a truly modern battleship had led him to choose to build the Bismarck and the Tirpitz.
The Bismarck was undoubtedly an impressive ship, modern in every respect. Considered by some to be impregnable, an attitude summed up in the phrase:
“ We are faster than anything stronger and stronger than anything faster, so really nothing can happen to us, and our assignment is just like life insurance”. 1
She was most definitely able to project the image that Hitler wanted of a Germany as a reborn military power, a force to be reckoned with. Yet this notion of a prestigious capital ship contained a paradox. If you lost such a ship then the loss in propaganda terms was so much greater than merely the loss of the fire power that she represented.
More realistic assessments of how impregnable she really was suggested there was a considerable risk she could be lost. Such assessments had to look at how the ship would actually operate, and for what purpose.
The Kriegsmarine had pressed for a capital ships building programme but Bismarck was just the first off the line. To confront the Royal Navy they would need many more such capital ships and their support vessels. They planned for a building programme that would go through to 1946 in preparation for a war beginning around 1948. Hitler had consistently told Admiral Raeder, head of the Kriegsmarine, that he had no plans to go to war with Great Britain right up to the middle of 1939.
In 1941 the scenarios originally envisaged for her deployment no longer applied. Now that she was fully commissioned Hitler was, of course, impatient to see her utilised. So having built the Bismarck, at no small diversion of resources, the Germans were in something of a quandary as to how to use her.
Although powerful, Bismarck by herself could not be turned against the many and varied forces of the Royal Navy without serious risk of loss. Even if she were to successfully sink a British capital ship this would not really serve Hitlers strategic aims, however great a propaganda victory. He was no longer interested in invading Britain, if he ever really had been. His attacks on Britain had been helpful in diverting attention from his real aim in attacking Soviet Russia. Reducing the power of the Royal Navy might be useful but it was not a high priority.
So Operation Rheinübung, ‘Exercise Rhine’, was conceived. The Bismarck was sent off to sea under strict orders not to engage with the Royal Navy unless there was a good chance of success. Her objective was to strike at merchant shipping in the Atlantic. Hitler was only interested in striking British warships insofar as they were protecting the supply of goods across the Atlantic.
But more than that, this large impressive ship, designed to project power, had to depart in secret. She was to attempt to break out into the Atlantic unseen.
Such a notable ship was not going to move unnoticed by friend, foe or neutral. She would have to slide close past the coast of Denmark (occupied) and Sweden (neutral) and then refuel in Norway (occupied).
Even if the Bismarck could evade ground based observers (which events showed, she couldn’t) it was readily apparent by 1941 that aircraft were transforming the naval war. Both the Royal Navy Fleet Air Arm and the Luftwaffe were, at this time, hard at work changing the rules of naval warfare in the Mediterranean. And in the Atlantic it was the German Luftwaffe, with the use of the long range Kondor aircraft to locate convoys, who were demonstrating how difficult it was to go to sea unseen.
But there remained the hope that Bismarck might get away with it. Given the right weather she might well be able to evade observation by aircraft. She was located in Norway by the RAF but then there was a period of uncertainty. Was she still there or had she sailed? Another aircraft established that she had gone, but "where to?" was then a matter of making an educated guess. The deployment of the Home Fleet rested on such a guess.
The Bismarck might have the firepower to keep many a smaller ship at a good distance and the speed to outrun them. But could she really disappear over the horizon? When she was finally located in the Denmark Strait by the cruisers HMS Suffolk and HMS Norfolk this possibility was put to the test. The threat of her firepower certainty kept the two tracking ships at bay. The weather also allowed her to periodically disappear into rain squalls. She disappeared from sight at least. But there was now a new development that had not existed when she was on the drawing board at Blohm & Voss.
In a new study (2019) Alan Raven highlights the innovative use of radar, recently installed on the cruiser Suffolk:
The Bismarck episode was the first instance in history where extended tracking of surface targets was made by radar, and not by a dedicated surface-warning set, but by a gunnery set fitted on the Suffolk. This ship had very recently become operational after a ten-month repair, at the end of which, she was fitted with a Type 279 air-warning set, and a Type 284 gunnery set. The aerials for Type 284 were attached to the roof of the main director, which had to sweep to allow the radar set to perform a search. Although not designed to operate in a search mode to allow radar coverage, this could be done, but in a judicious manner, because constant training of the director would have a negative effect on its mechanism.
On the 23rd, before making contact with the Bismarck, the Type 284 set was being used as a navigational aid, allowing a patrol distance to be maintained within 24,000 yards off the ice shelf, when visibility ranges were less than eight miles. Although the first sighting was at 1922, it was not until 1934 that radar contact was made. Of the six initial sighting reports sent to Admiralty, five were based upon data from the Type 284 radar.
From 2043 to 2154, Bismarck was within visual range that varied from 15 to 18 miles. At 2154 Bismarck entered a rainstorm at a speed of 28 knots and was tracked and held by the 284 until visual touch was regained at 2258.
The above will give the reader an idea of how effective Type 284 radar was for tracking targets in very poor weather, in spite of not having automatic all-round sweep ability, as many later surface-warning sets had. When the Bismarck was in visual contact, the radar was not used for tracking in order to reduce the wear on the training mechanism of the director. Shadowing by a combination of visual and radar continued until about 0326 on the 25th, when radar contact was lost. From the time of first sighting at 1922 on the 23rd to 0326 on the 25th when contact was lost, the Bismarck was at no greater a distance from Suffolk than 18 miles.
The use of Suffolks radar was not only the first time that radar had been used for an extended period of time for tracking surface targets, but also the longest ever recorded! Throughout, the set performed well, without any breakdowns, and was a superb example of tactical use made without any prior training or written procedure laid down.
The use of Type 284 in its designed function was mixed, but when Bismarck tried to ambush the Suffolk between 1805 and 1855 on the 24th, Suffolk made use of her Type 284, first to avoid, and then when firing her 8in guns in return fire, she obtained a straddle at a range of 20,700 yards using radar ranges.
The successful use of this set highlights well the somewhat poor performance of Type 286m radar as was fitted in Norfolk. This had been installed in the ship at the end of the first week of May. There had been problems in getting Type 286m to properly perform; all the spare valves had been used and as a consequence, when the ship sailed from Scapa Flow to patrol the Denmark Strait, this set had to be ‘nursed’, meaning that it had to be shut down periodically.
In addition to being nursed, the range on a large ship was only about 14,000 yards, compared to the 26,000 yards of Type 284, but its greatest deficiency was the fixed aerial array that was fitted at the masthead. In order to track a target the ship itself had to be steered in the direction of same, so that when Bismarck made turns, especially toward the ship, contact would of course be lost when the tracking vessel had to turn away. Also, its poor resolution made it unsuitable for gunnery purposes.
In many respects the very concept of a "Battleship" might appear to be out of date by this time. Since the turn of the century torpedoes, submarines and aircraft had revealed their vulnerabilities. But naval strategists had clung to the notion of invincible ships, now with ever thicker armour and a wide range of countermeasures to deal the new threats.
The Bismarck episode illustrates how evolving technologies were challenging these ideas. She was located and tracked first by radar and then by aircraft.
With the benefit of hindsight we can see that it was the combination of radar and naval air power that saw the end of the battleships. The outcome of Operation Rhinubung was just the proof that they could not outrun the new realities.
But can we assess the likelihood of a successful outcome on what the Germans knew before the Bismarck set sail?
Was it was ever a realistic proposition for the Bismarck to make a surprise break out into the Atlantic, suddenly appearing to wreak devastation on merchant ships? It was even more unlikely that she could safely return to Germany once she had broken cover. She would have had to fight her way back past the Royal Navy on full alert and ready for vengeance, either up the English Channel or back down the North Sea.
Ultimately the Bismarck was the wrong ship to send on a raid on commercial shipping. She would inevitably become a high priority target wherever she roamed. But Nazi Germany didn’t really have another role for her.
See ‘British Cruiser Warfare’ for a day by day history of the individual actions of cruisers during this period, and much additional material on naval warfare at this time.
This excerpt by kind permission of Seaforth Publishing and Pen & Sword Books Ltd. Copyright remains with the author.
The magnificent volume Battleship Bismarck will be the subject of my next newsletter.
I am having difficulty pinning down the original source for this oft quoted phrase.