By September 1939, and the outbreak of the Second World War the era of the mighty Battleship had passed, though it remained a painful lesson yet to be learned.
Threatened from beneath the waves by ever more sophisticated submarines and from the sky by the prospect of tactical air strikes ships had never been more vulnerable; but this was on the high seas not at anchor in their home ports protected as they were, or so it was believed, by mines, nets, patrol vessels, blockade ships, and anti-aircraft guns.
Grand Admiral Karl Doenitz, Commander of the German U-boat Fleet thought otherwise.
A veteran submariner of the Great War he believed that the key to victory in the present conflict lay as it had in the last, in severing Britain’s trans-Atlantic lifeline to the United States and the trade routes to its Imperial possessions.
His superior Grand Admiral Erich Raeder whilst not disagreeing with the strategy remained committed to his surface fleet regardless of the fact that despite possessing some powerful warships it was no longer large enough to confront the Royal Navy at sea in any decisive engagement, nor did it have the sea-borne capacity to protect its ships from the air.
Doenitz remained deeply frustrated at a naval strategy that focused on the viability of surface raiders and did not take into account the changed circumstances of naval warfare. It was a strategy he believed was starving the U-boat service of the resources necessary to build a fleet large enough to bring Britain to heel and win the war.
On the day that Britain and France declared war on Germany, Doenitz had just 57 serviceable U-boats only 22 of which were ocean going and could remain at sea for an extended period of time.
Despite some early successes, the sinking of the liner Athenia within hours of the outbreak of hostilities and of the Aircraft Carrier Courageous later in the month, Doenitz had a point to prove. He intended to attack the Royal Navy at its very heart and where it felt most secure, its anchorage at Scapa Flow.
Scapa Flow in the Orkneys off the northern tip of Scotland provided a vast natural deep water harbour for the Home Fleet with easy access to the North Sea which had so proved essential in maintaining the blockade of Germany during the First World War. But made up of a series of small islands as it was Scapa Flow had seven different entrances providing multiple points of incursion for any U-boat and doubts over its security had emerged before.
Certainly, Sir John Jellicoe, Admiral of the Grand Fleet for much of the First World War had expressed his concerns and measures such as the sinking of block ships and deployment of booms had been taken but the subsequent failure of a German U-boat to successfully infiltrate the harbour (one had previously grounded and another had been sunk) may have led to some complacency.
The Commander at Scapa Flow in 1939 was Admiral Sir Wilfred French who now expressed similar concerns – there was an inadequate number of searchlights, the booms were too slow in closing, and more block ships were required - he had even volunteered to pilot a submarine through the gaps he had found in Kirk Sound to show that it could be done but it was felt that he was being too alarmist and when he requested 15 new patrol craft he received just 2.
But he was right to be concerned.
Doenitz had been planning an attack on Scapa Flow even before war had been declared and German aerial reconnaissance carried out at very great risk had provided detailed photographic evidence of Scapa Flow's weak spots and in particular the very same Kirk Sound that had so concerned Admiral French.
A successful attack upon Scapa Flow would not only dent the reputation of the Royal Navy, the pride of Britain’s Armed Forces, provide a great propaganda coup, and reassert the value of the U-boat it might also encourage the British to disperse their fleet to safer anchorages thereby weakening their hold on the Northern Approaches.
It would also be revenge for the scuttling of the High Seas Fleet at Scapa Flow in 1919.
The man who would lead Special Operation P was the 31 year old Commander of U.47 Captain Gunther Prien who by no means an experienced submariner (he had only received his first command in February) was chosen as much for his enthusiasm in volunteering as any high regard he was held in.
Indeed, as a member of the Nazi Party serving in a branch of the military that still drank a toast to the Kaiser and frowned upon those who expressed political affiliations he was not only an outsider but deemed of uncertain character; but he’d had a good war so far sinking three merchant ships in its first week.
Prien sailed from Kiel on 8 October and only mid-way through the journey to Scapa Flow did he deem it appropriate to himself ask for volunteers. Given the prospect of being abandoned in a dinghy in the middle of the freezing North Sea all did so.
Unknown to both Doenitz and Prien there were few ships anchored at Scapa Flow as reports of a threatened air raid had seen most of the fleet put to sea or disperse to other ports with the exception of a small number of Cruisers and support vessels, the only ship of any significance was the battleship Royal Oak.
HMS Royal Oak, a veteran of the Battle of Jutland was a Revenge Class Battleship, a sister ship of the Renown and Repulse that had seen better days.
Still possessed of a formidable armament including four 15” guns and with a compliment of around a 1,000 men she was nonetheless old, slow, difficult to manoeuvre, and prone to flooding. As the First Lord of the Admiralty would remark of many of the Royal Navy’s ships of that era – she was too old to fight and too slow to run away – as such she had been assigned to patrol home waters and provide anti-aircraft cover for the anchorage.
Sailing on the surface U.47 arrived off Scapa Flow at around midnight on 14 October on what was a bitterly cold but still night with the winds that are such a feature of the barren Orkneys landscape less than might have been expected but the currents remained strong, and it was dark, very dark.
Prien approached Kirk Sound with trepidation aware that he could be spotted at any time, and he was indeed caught in the headlights of a car driving along the shoreline. At that moment it must have crossed his mind to abandon the mission but if the driver saw anything he declined to report it.
Manoeuvring his vessel at slow speed and with great caution was problematic enough but so was finding Kirk Sound itself and he initially mistook it for another entrance becoming snagged on a cable strung between two block ships only avoiding catastrophe by putting the boat into a speedy reverse.
Kirk Sound was 600 yards across, 33 feet deep at high tide and protected by three block ships but there was a 140 foot gap between the northern most block ship and the shore and no other defences.
With patience and skill it could be penetrated.
At 00.27 Prien wrote excitedly in U.47 log book that he had gained access to the harbour but rather than see the British Home Fleet spread out before him he struggled to see any ships at all and it was a lookout on the bridge who after some delay alerted him to a large figure looming out of the darkness some 4,400 yards distant – it was the Royal Oak.
Approaching to within 3,000 yards Prien ordered his men to battle-stations and prepared to attack.
At 00.58 he launched four torpedoes, one failed to discharge and two missed their target but the fourth struck the bow of the Royal Oak with it was remembered more of a thud than an explosion but it was enough to cause the ship to shudder violently and waken the crew from their slumbers.
There was some initial confusion but no indication that they were under attack and minds were put to rest when the message – take all magazine temperatures – was received over the tannoy system.
It seemed there might have been a small problem in one of the ships four magazines, but it was being dealt with and so most of the men returned to their bunks.
In the meantime, Prien believing he had failed and expecting a swift retaliatory response was seeking to make a quick getaway but there were no sirens, no searchlights and no patrol boats on the horizon.
It soon became evident that U.47’s presence had not been detected and thanking his good fortune Prien reversed course - he would try again.
At 01.13 he launched three torpedoes at the still unaware and inert Royal Oak nervously glancing at his watch as the torpedoes sped through the still waters towards their target - this would be his last opportunity but by this time he had found his range.
At 01.16 all three torpedoes smashed into the starboard side of the Royal Oak almost simultaneously.
Those near the blasts were almost certainly killed as the cordite from the magazines ignited causing a huge fireball to sweep through much of the ship which began to list almost immediately, a process hastened as water flooded in through open portholes.
Chaos ensued as dazed and still barely awake men scrambling from their bunks were suddenly plunged into darkness by a failure of the electricity followed minutes later by the ship rolling onto her side throwing off-balance and confusing even further those desperately trying to avoid the flames and each other to reach the upper-decks.
At 01.29 the Royal Oak capsized . . . ten minutes later she sank.
Still no alarm had been sounded, order received to abandon ship, or lifeboats launched and hundreds of men now jumped into the dark waters where many still in their nightclothes quickly froze whilst all choked on the thick, toxic, and foul-smelling oil and gasoline fuel.
Of those who attempted to swim the 800 metres or so to shore, few made it.
Moored alongside Daisy II, the Royal Oak’s tender had escaped the carnage and was the only boat on the scene to attempt a rescue and skippered by John Gatt, who was to be awarded the Distinguished Service Cross for his actions it worked throughout the early hours picking up survivors most of whom owed their lives to him and his crew.
Inaccuracies in his log book confuse the facts somewhat but entries indicate that Prien did not remain long to admire his achievement but beat a hasty retreat understandable in the circumstances, though his exit from Scapa Flow was in fact unimpeded and uneventful.
As dawn broke on the morning of the 15th October the scale of the tragedy became clear, the once mighty Royal Oak had gone with only an oil slick indicating where she had once been, taking 833 of her crew with her most still trapped inside her hull as the ship went down. Only 326 men had been plucked from the water.
The national trauma that would follow was made worse when it was revealed that 126 of 163 boy sailors aged between 15 and 17 years aboard had been killed.
It was a tradition in the Royal Navy that young recruits should complete their apprenticeship whilst on active duty but such was the outrage felt at this murder of the innocents that there was talk of ending it. Churchill opposed any such change and there were no formal moves to do so but the practice ceased nonetheless.
On 17 October, Winston Churchill in his capacity as First Lord of the Admiralty announced the loss of the Royal Oak to the House of Commons expressing his deep sorrow and regret but also emphasising that it in no way altered the balance of power regarding the war at sea. He also felt compelled to acknowledge the audacity, courage, and skill of the U-boat Captain and crew who had perpetrated the act.
Such nobility of considered admiration would soon cease as the war escalated in its intensity and savagery, as also would the swift announcement of further such incidents.
The same day that Winston Churchill made public the loss of the Royal Oak, U.47 and its crew, their achievement already broadcast on German radio and well-trumpeted by Joseph Goebbels and his propaganda machine, arrived back at Wilhelmshaven to a hero’s welcome.
Gunther Prien was awarded the Iron Cross First Class but Hitler wishing to embellish his heroic status even further ordered that the Captain and his crew be flown to Berlin where with the cameras rolling he would personally congratulate them, and so in an official ceremony Prien had the Knight’s Cross pinned to his increasingly be-medalled and puffed out chest.
The propaganda coup that was the attack upon the Royal Navy’s anchorage at Scapa Flow did not however change German naval strategy as Admiral Doenitz had hoped and resources continued to be withheld from the production of U-boats and their further development despite their continued success in sinking British and later Allied shipping – 1,299 vessels in 1941; 1,662 in 1942.
It wasn’t until the resignation of Admiral Erich Raeder in January 1943 and his replacement by Doenitz that he was able to fully implement the Wolf-Pack strategy (U-boats working in groups and coordinating their attacks on merchant shipping) that he believed would starve Britain into submission.
But by this time the Allies were adopting anti-submarine methods that were proving increasingly effective.
In 1943, Doenitz would come perilously close to winning the Battle of the Atlantic, in the end he would lose it for just as German missile technology came too late to alter the course of the war, so did improvements in U-boat design.
Gunther Prien, the ‘Bull of Scapa Flow’, the image of a snorting bull was by now painted on to U-47’s conning tower continued to claim victories but they would often prove to be pyrrhic ones and have tragic consequences and not just for the Allies - on 2 July 1940, he torpedoed the liner Arandora Star which sank with the loss of 868 lives almost all of them Italian and German prisoners-of-war on their way to internment camps in Canada.
In 15 months on operations Gunther Prien and U.47 sank 31 ships making him one of the leading U-boat aces but it was to be a short life and career.
On 7 March 1941, depth charged by HMS Wolverine U.47 was seen to be attempting to surface when it exploded and sank with the loss of all hands.
The horrifying death of those on the Royal Oak and other ships was also shared by many who were its perpetrators – during the war 768 U-boats were lost to accident and enemy action with 26,877 men killed.
Such was the fame of Gunther Prien his death was kept from the German people for some time.
In Britain meanwhile there remained the need, as there nearly always is in the case of disasters either natural or man-made, to find a scapegoat and on this occasion it was Admiral Sir Wilfred French who despite his oft repeated warnings and the arrival of the extra block ship he had requested to shore up Kirk Sound just hours after the Royal Oak had been sunk was deemed culpable and forced to resign and retire from active service.
With only 26 bodies ever recovered from the waters of Scapa Flow the final resting place of the Royal Oak is now a designated war grave.