Britain’s Pearl Harbor - U-47's attack on the Battleship Royal Oak in Scapa Flow October 1939

By John Dudek 11 Jun 2015 0

Just after midnight on the cold moonless night of 14 October 1939, Captain Gunter Prien stood on the conning tower of his Type VII-B submarine U-47 as it cruised along the surface of the calm waters of England's primary naval base and anchorage, Scapa Flow in the Orkney Islands of northern Scotland.  In spite of the lack of any moonlight, the night skies were aglow with the ethereal, unworldly light of the Aurora Borealis' Northern Lights.  Prien silently cursed the unwanted illumination as his submarine closed in upon two large targets at anchor in the distance.  He judged them to be British battleships given their silhouettes against the gently lighted sky line behind them.  As he probed the surrounding waters further, no other ships were seen at anchor and he was surprised to find the fleet out of port and at sea. He'd hoped to turn Scapa Flow into a torpedo shooting gallery of sinking and exploding British warships. However, he was also satisfied that no threats lurked in the darkness. Prien turned to port and proceeded north along the coast towards the two anchored warships sighted earlier.  At 3,000 yards he fired his four forward torpedo tubes in a spread so as to hit both overlapping stationary targets.  Only three of the four torpedoes launched properly as the fourth remained hopelessly jammed in its tube. Three and a half minutes later, a single torpedo explosion was seen striking the northernmost ship at its bow.  Prien ordered his sub to come about, so as to fire its single stern torpedo tube at the now damaged battleship.  As the stern tube fired, the forward torpedo tubes were reloaded.  The stern shot too was a miss “Verdamnt!!" Prien cursed bitterly with impotent rage “What sort of fool goes to war with bad torpedoes!!?" He remembered all the dockyard talk and rumors he'd heard about faulty German torpedoes, but until now he'd paid them no heed.  Suddenly, his submarine stood outlined in the bright glare of a car's headlights from the nearby headland shore.  Recognizing the German U-boat submarine in these restricted waters, the car turned around and drove quickly towards the town of Scapa.  Prien knew he had little time and but one final chance of making telling hits upon the targets before patrolling British destroyers and other anti submarine craft arrived and quickly terminated his existence in the waters of this much storied British naval base.  He grimaced as he prepared to fire his final salvo of torpedoes.



Scapa Flow naval base held great significance to both Great Britain's Royal Navy and Germany's new Second World War Kriegsmarine.  It was here that Kaiser Wilhelm's German High Seas Fleet of 74 battleships, cruisers and destroyers were interned immediately following the end of the First World War.  As part of the Armistice and the later Versailles Treaty ending the war, Germany had to turn over its entire navy to the victorious Allies and promise to build no new warships as part of the hated document's "War Guilt Clause."  The shame and unfairness of this clause remained a painful bone in the throat of the German Navy long after the signing of the treaty.  However, in one last glorious and supreme act of utter defiance, the German crews still aboard ship scuttled their warships to prevent the Allies from seizing them.  While the British were able to eventually beach the German battleship BADEN along with two light cruisers and 18 destroyers, the remaining 52 warships were sunk in the murky waters of Scapa Flow.  Nine German sailors were killed when British sailors fired upon them as they scuttled their ship.  These were the last casualties of WWI.  Germany never forgot the shame, degradation and insult to their nation's honor and it proved to be a catalyst for war to future dictator Adolf Hitler.  One of Hitler's ardent followers who never forgot this insult to Germany's national honor was Grand Admiral Karl Doenitz.  He'd served in U-Boats during the First World War and was taken prisoner when his sub was sunk by British destroyers in the Mediterranean in 1918.  Doenitz remained in the post war German Navy and served in a variety of functions before being promoted to commodore and Commander of Submarines in January 1939.  Despite the many roles and responsibilities in Doenitz's new job, the idea of one audacious and gallant operation remained ever green in the back of his mind. It was the possibility of U-Boats infiltrating and attacking British warships in England's main naval base of Scapa Flow.  During WWI, two U-boats had attempted to do so but were sunk.  In spite of this, Doenitz remained adamant that such an operation could be successfully carried out with the right men and the proper moon and tidal conditions.  Soon after the start of the Second World War, German long range reconnaissance aircraft had flown over Scapa Flow, taking extensive photographs of the base's defences and the block ships of deliberately sunken ships at its channel entrances. The reconnaissance photos detailed its weaknesses and strong points.  Even with this information in hand, any submarine attack would need in Doenitz's words, men with "...nerves of steel and the highest level of skill to carry out this boldest of bold enterprises."  Not only would captain and crew have to overcome the bases anti-submarine defences, block ships, nets and booms at its entrances, they would also have to battle shallow uncharted waters and powerful, unpredictable currents that could carry a U-boat onto its rocky shore.



Located in the Orkney Islands north of Scotland, Scapa Flow was the main fleet anchorage of the Royal Navy and had been seen by most as something of an impregnable fortress, particularly against submarine attack. Indeed, The Flow had not been used as a base between the wars, with the defensive mines being exploded in 1919; the last ship from the Home Fleet to lower its flag left the following year. However by the late 1930s and the re-emergence of German naval power, Scapa Flow was given a new lease of life. However, the idea that the base was impregnable was not shared by Admiral Sir Charles Forbes, who in 1938 had carried out an inspection of the defences. There and then Forbes himself purchased a large concrete barge, one of 100 to serve as additional blockships, but his recommendations for securing the defensive loopholes that remained went unheeded. Nevertheless, the base was once again to become the home of the Home Fleet in September 1939, something that was confirmed with Churchill being appointed First Lord of the Admiralty.

With the latest aerial intelligence and other information firmly in hand, Doenitz decided the only way into the naval base would be through the waters of Holm Sound and that could only happen at night and during the proper tidal conditions.  He wrote:

"Holm Sound is protected exclusively by two apparently sunken ships lying obliquely in the navigable water of Kirk Sound, together with one ship lying on the north side. South of these obstructions as far as Lamb Holm there is a gap, 170 metres wide, 7 metres in depth up to the shallow water. Also north of the sunken ships there is a small gap. The shore on both sides is practically uninhabited. I hold that a penetration at this point on the surface at the turn of the tide would be possible without further ceremony. The main difficulty concerns navigation."

The final sticking point was finding the proper captain and crew to carry out the mission, given all the risks entailed in getting in and out of Scapa Flow.  Doenitz wrote:

"On this [intelligence] I decided to allow an attempt to be made. My choice fell upon Lieutenant-Commander Prien, the captain of U-47. He, in my opinion, possessed all the personal qualities and the professional ability required. I handed over to him the whole file on the subject and left him free to accept the task or not, as he saw fit."

Prien was given 48 hours to study the dossier file before making a final decision.  He later wrote:

"I felt a tremendous tension within me. Would it be possible to bring it off? My common sense calculated and questioned the chances, but by will had already decided that it could be brought off. At home, supper was already on the table. Absentmindedly I greeted my wife and child, for my thoughts were obsessed with the single idea of Scapa Flow."

"What do you think of it, Prien?" Doenitz soon asked.  Prien grinned as he nodded in the affirmative.  U-47 was readied for sea and given a load of new G-7 electric wakeless torpedoes.  Her sailing date was set as Friday the 13th of October.  Upon receiving this departure date, it was immediately changed to the preceding Sunday to ward off any old superstitions.  On the journey north to the Orkney Islands, maximum security conditions were practiced.  U-47 lay on the bottom during daylight hours and surfaced to run only during the night.  Strict radio silence was maintained.  After nightfall on 13 October U-47 slowly entered the restricted waters of Kirk Sound, cautiously maneuvering around the sunken block ships and booms.  In spite of all precautions, the U-boat ran aground in shallow shoal water and it took some time to break free.  At 0027 Prien wrote in his log book "Wir sind in Scapa Flow!"  (We are in Scapa Flow!)  The scene was now set for one of the most dramatic incidents of the war.  U-47 soon headed towards a pair of what appeared to be battleships in the distance.

HMS ROYAL OAK was one of five R (Revenge) class battleships built during the First World War.  A veteran of the Battle of Jutland, she lived a much storied career both during war and peacetime.  Although modernized a number of times during her 25 year lifetime, the ship fitters could not overcome and correct her lack of speed that all her newer sisters now possessed and she was relegated into secondary roles as a training and school ship for men and ship's boys.  In October 1939 ROYAL OAK had a complement of 1,234 men and boys aboard when she anchored in Scapa Flow for the last time.



The torpedo that struck the ship's bow at 0104 hours that morning shook the battleship and awoke its crew. Little visible damage was observed, though the starboard anchor chain was severed by the blast.  The chain clattered loudly to the bottom of the harbor. It was first suspected that there had been an explosion in the ship's forward inflammable stores up forward. A submarine attack was never considered given the impregnability and imperviousness of Scapa Flow's defences.  Aside from an announcement made over ROYAL OAK'S public address system to check on the temperatures in the forward magazine, nothing further was done. Many if not most of her sailors returned wearily to their hammocks, completely unaware that the ship was under attack.  At 0116 three more torpedoes slammed into the battleship amidships, blowing massive holes through her armor plate, flooding her engine room and causing immediate loss of power.  In addition, a magazine explosion sent a rolling fireball of cordite throughout the ships lower passageways.  Thirteen minutes after Prien's second full salvo of torpedoes were fired, ROYAL OAK rolled over and sank with 833 men and her admiral still aboard.  Over a hundred of her dead were Boy Seamen under the age of 18 years.



Prien later wrote:

"There is a loud explosion, roar, and rumbling. Then come columns of water, followed by columns of fire, and splinters fly through the air. The harbor springs to life. Destroyers are lit up, signalling starts on every side, and on land 200 metres away from me cars roar along the roads. A battleship has been sunk and the other three torpedoes have gone to blazes. All the tubes are empty. I decide to withdraw, because:

(1) With my periscopes I cannot conduct night attacks while submerged.

(2) On a bright night I cannot manoeuvre unobserved in a calm sea.

(3) I must assume that I was observed by the driver of a car which stopped opposite us, turned around, and drove off towards Scapa at top speed.

(4) Nor can I go further north, for there, well hidden from my sight, lie the destroyers which were previously dimly distinguishable.

At high speed both engines we withdraw. Everything is simple until we reach Skildaenoy Point. Then we have more trouble. It is now low tide, the current is against us. Engines at slow and dead slow, I attempt to get away. I must leave by the south through the narrows, because of the depth of the water. Things are again difficult. Course, 058, slow - 10 knots. "

Behind him air raid search lights along the shore snapped on, probing the heavens with brilliantly bright shafts of light, looking for German bombers.  Everyone ashore still believed a German submarine attack here to be impossible.  Prien and U-47 faced one last obstacle between them and the open ocean, a line of sunken block ship wrecks.  Fighting the strong current and keeping a constant wary eye as to the closeness of the nearby wrecks, Prien somehow managed to make the passage with the aid of his experienced helmsman.  He wrote this in his log:

"Things are again difficult. Course, 058, slow - 10 knots. I make no progress. At high speed I pass the southern blockship with nothing to spare. The helmsman does magnificently. High speed ahead both, finally 3/4 speed and full ahead all out".



Soon after U-47 reached open sea and with no destroyers in pursuit, captain and crew could finally relax.  Prien saluted the men as they stood down from their battle stations and he ordered a shot of rum to be passed out to every crewman.  Their mission had succeeded beyond everyone's expectations. They were now on their way home. U-47 arrived at Wilhelmshaven on 17 October to a hero's welcome.  Captain and crew were flown to Berlin to meet with Adolf Hitler, where they were all awarded the Iron Cross for their gallant exploits during the Scapa Flow operation. For the next several days U-47's crew were treated and feted like grand celebrities before an adoring public.



The attack by U-47 on the Royal Oak was without doubt one of the most significant actions of the war, in that the threat posed by Prien and his colleagues finally received the complete attention of the British high command and the then First Lord of the Admiralty Winston Churchill. Churchill, who in an announcement made after the attack grudgingly described Prien's feat as "a remarkable exploit of professional skill and daring", had always been aware of the "U-boat peril"; it was this change in general attitude that was to play a significant role in turning the tide against the U-boats.

Perhaps it was fortuitous that only ROYAL OAK was in Scapa Flow and sunk by U-47 that night.  Had the fleet been in harbor, perhaps Prien's idea of a torpedo shooting gallery of sinking and exploding warships could have indeed occurred and the Royal Navy war against the U-boat menace been handed a major strategic setback.  Faulty torpedoes would continue to plague the German Kriegsmarine for another year before the problems were finally corrected.

During a later war patrol in April 1940, Prien and U-47 encountered an armed convoy of cruisers, and fully loaded troop transports at anchor in a Norwegian fjord.  Lining up for a point blank shot at two of the stationary troop transports, Prien fired a spread of four torpedoes at them.  None of the "eels" hit the troop ships although one did explode after hitting rocks along the shore.  Four days later, he fired two salvos of torpedoes at the British battleship WARSPITE with zero results.  After firing ten dud torpedoes, Prien returned to base with four of his 14 torpedoes still aboard.  As he explained to Doenitz "I could hardly be expected to fight a war with a dummy rifle."  In spite of often times faulty torpedoes, Prien became one of the highest scoring U-boat aces in the German Navy, sinking 30 commercial ships, while damaging eight others. In addition, he also damaged the heavy cruiser NORFOLK.  Captain Gunter Prien and the crew of the U-47 went missing on 7 March 1941 after attacking Convoy OB-293.  It is not known for sure how U-47 met her end and some speculation has been given that perhaps she was the victim of a faulty circular running torpedo.  In any event the gallant Captain and crew remain forever more on "Eternal Patrol."



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