During the first month of the war, Dönitz had conceived a plan to deal the Royal Navy another stinging blow. Close reconnaissance of the British naval base at Scapa Flow by ducks and Luftwaffe aircraft had revealed a possible flaw in its defenses: Kirk Sound, one of a half-dozen channels leading into the base, was not solidly closed by blockships.* Dönitz became convinced that a U-boat could slip through the gap in the channel under cover of darkness and attack the Home Fleet in its anchorage. If so, the boat might sink one or more capital ships and drive the fleet from Scapa Flow, thus weakening the British blockade and making it less hazardous for Kriegsmarine surface raiders to slip in and out of the North Sea.
Dönitz chose Günther Prien, a daring skipper and skilled seaman, to attempt this hazardous mission. Prien turned in his Enigma and all secret papers and sailed U-47 in secrecy from Kiel on October 8, going via the Kiel Canal and Wilhelmshaven. Not until he was well out to sea did Prien brief his crew. Although the mission was fraught with danger and the risk of death or capture was great, all hands were enthusiastic.
That same day, the Kriegsmarine’s new battle cruiser Gneisenau, escorted by the light cruiser Köln, set sail from Kiel on a brief sortie into the North Sea. There were several reasons for this short voyage: to exercise the ships and crews in a limited combat environment; to pose a threat to North Sea merchant ships, forcing the Allies to form convoys, which were legitimate duck targets; to lure Home Fleet units from their bases into range of Luftwaffe aircraft; and to assuage Hitler, who had demanded to know why these expensive vessels were not being employed.
The Gneisenau and Köln went out through the Kattegat and Skagerrak. As intended, the Admiralty got wind of the sortie and Coastal Command dispatched reconnaissance aircraft to the North Sea. Early in the afternoon of October 8, one of them spotted the German ships close to the south coast of Norway. Believing Gneisenau was headed for a long voyage into the North Atlantic to raid Allied convoys, Admiral Forbes ordered most of the major ships in his Home Fleet to intercept her.* But Gneisenau easily eluded the trap. She reversed course that night and reached her berth in Kiel in the early hours of October 10. As planned, the Luftwaffe found and attacked the Home Fleet units in the North Sea on October 9, but not one of the hundred-odd bombs the pilots dropped hit a British ship.
Unaware that Gneisenau had returned to port, the Home Fleet units from Scapa Flow continued the hunt for her north and northwest of the Orkneys. Finding no trace of the Germans, Forbes finally ordered the fleet to break off the search and return to bases. The battleships Nelson and Rodney, the battle cruisers Hood and Repulse, and the carrier Furious, which had sailed from Scapa Flow, put in to various naval bases in Scotland. Only the old (1916-1917) 30,000-ton battleship Royal Oak, which to then had been employed on convoy escort, returned to Scapa Flow. Thus the sortie of Gneisenau had the effect of emptying Scapa Flow of the major Home Fleet capital ships. On October 12, the Luftwaffe, which was also apparently unaware of Prien’s mission, flew a low-level reconnaissance over Scapa Flow. Some British interpreted this as a prelude to a major bombing attack, so the big ships were retained at Loch Ewe.
Meanwhile, Prien in U-47 inched cautiously northward in the shallow North Sea, avoiding all ships and lying doggo on the bottom during daytime. On the night of Friday, October 13, at 1915, he surfaced to begin a slow, four-hour approach to Scapa Flow, timed to bring U-47 to Kirk Channel when the tide was highest.
Going to the bridge, Prien found the sky clear but “disgustingly” bright, lit by an undulating aurora borealis—the northern lights. Despite this unexpected and inconvenient phenomenon, Prien pressed on, planning, if necessary, to carry out the attack submerged, by periscope. At 2200, on schedule, the Orkney navigational lights came on for thirty minutes, enabling Prien to precisely fix U-47’s position. Approaching a jut of land, Rose Ness, at 2307, the bridge watch saw a merchant ship plodding along. Prien dived to avoid the vessel and, as a test, tried to put it squarely in his periscope crosshairs. Despite the northern lights, he could not see the ship. The lack of periscope visibility ruled out a submerged attack inside Scapa Flow. They would stay on the surface.
Prien surfaced at 2331, got his bearings, and ran due west on the flood tide. The visibility was not as good as it seemed. By mistake, he headed for the wrong channel, Kerry, separating Lamb Holm and Burray islands. He detected the mistake just in time. “By altering course hard to starboard, the imminent danger is averted,” he logged.
Realigning the boat for the passage through Kirk Sound, Prien made the decision not to go south of the two blockships in the channel, the course Dönitz had suggested. Instead, he aimed for a gap between the center and northernmost block-ships, clearing the northernmost blockship “with 45 feet to spare.” Borne along by the swift flood tide, the penetration was made “with unbelievable speed,” Prien logged. But it was nerve-rattling. During the passage, the current slewed the boat sharply to starboard, directly into a cable anchoring one of the blockships. “Port engine stopped,” Prien wrote, “starboard engine slow ahead and rudder hard to port, the boat slowly touches bottom. The stern still touches the cable, the boat becomes free, it is pulled around to port, and brought onto course again with difficult rapid maneuvering…. But … we are in Scapa Flow.” It was twenty-seven minutes past midnight.
Enhanced by the undulating northern lights, visibility in the wide bowl of the anchorage improved. Prien, his first watch officer, Engelbert Endrass, and the lookouts hungrily scanned the waters with binoculars. They could see no big ships in the usual anchorage between Burray and Cava islands. It seemed impossible. Was Scapa Flow empty?
Circling north, Prien scouted deeper into the basin. Then suddenly he sighted “two battleships,” identified as Royal Oak and Repulse, lying at anchor, unusually close to the rugged north shore, about one and a half miles apart. Actually, the ships were the Royal Oak and the old 6,900-ton seaplane transport Pegasus, which was scheduled to be fitted with an experimental aircraft catapult for convoy escort.
Closing to a position about 3,500 yards equidistant from both ships, Prien made ready all four bow tubes. At 0055 he fired two of the electrics with magnetic pistols at “Repulse” and two at Royal Oak. The torpedo in tube number 4, intended for “Repulse,” misfired—did not go. The other three ran out silently and wakeless at about 30 miles per hour. The one aimed at “Repulse” missed and probably ran ashore. About three and a half minutes after firing, one of the two torpedoes fired at Royal Oak struck her on the starboard bow; the other missed. The hit blew a huge hole in the stem and keel of Royal Oak near the paint and anchor-chain lockers. But the noise was not sufficient to cause undue alarm elsewhere in the big ship and Royal Oak’s captain, roused from his bunk, attributed the explosion to some internal cause and took no special precautions.
In the darkness and confusion it was difficult for Prien to know what had happened. Wrongly believing he had damaged “Repulse” with one hit, and had missed Royal Oak, Prien mounted another attack. While the torpedomen reloaded bow tubes number 1 and 2, and readjusted the balky number 4, he swung ship and fired his stern torpedo at Royal Oak. No explosion. This torpedo also missed and probably ran ashore.* Therefore, when number 1, 2, and 4 bow tubes were ready, Prien swung back around and fired all three at Royal Oak, which he mistakenly believed to be unharmed.
All three of the torpedoes struck Royal Oak on her starboard side. The hits blew a huge hole in the engine room and two other holes amidships, and set off a raging fire in a magazine, hurling debris into the sky. The ship shook violently, the lights and P.A. system went out, and flames spread rapidly. Taking on a flood of water through the holes, Royal Oak almost immediately listed 45 degrees to starboard. Thirteen minutes after the last three hits, the old battleship rolled over and sank, with the loss of 833 of her 1,200-man crew.
Believing he had been seen, and that destroyers were after him, Prien turned about at 0128 and headed at high speed for the Kirk Sound escape route. Actually, he had not been seen, and no destroyers were after him. All British hands were either engaged in rescue efforts at Royal Oak or frozen in shock. Prien could have reloaded his five remaining torpedoes for a second attack on “Repulse” without fear of enemy counterattack. But even if the torpedoes ran true, a second attack would only have bagged inconsequential Pegasus. Hence his instinctive decision to get out was correct, but for the wrong reasons.
About two and a half hours after entering Scapa Flow, Prien reached the west end of Kirk Sound and began the exit. This time he went south of the blockships, in the “gap” Dönitz had recommended. “Things are again difficult,” he logged. Making constant changes in speed and helm, he passed the southern blockship “with nothing to spare.” Free of the blockships and their anchor cables, Prien just barely avoided a mole, then, clear of all obstructions, he bent on flank speed in Holm Sound. At 0215, he logged, “we are once more outside,” adding that it was “a pity that only one [ship] was destroyed.”
The next day, October 14, the Admiralty released the sad and humiliating news that Royal Oak had been sunk in Scapa Flow with a great loss of life. Berlin first heard the news from a radio report, but it withheld a celebration or public comment pending a report from Prien. Home Fleet commander Forbes immediately barred all Royal Navy ships from Scapa Flow. Until the defenses had been improved† the Home Fleet was to base in Loch Ewe, the cruisers of the Northern Patrol at Sullom Voe in the Shetlands, even though the defenses there were skimpy and the facilities primitive.
Southbound on the surface, in the early hours of October 16, Prien got off an encoded radio report to Dönitz: Royal Oak sunk; “Repulse” damaged. The Germans were ecstatic. “A glorious success,” the OKM gloated. It logged in its war diary that the loss of Royal Oak and damage to “Repulse” were “hard blows” that “greatly impairs British prestige,” “enhances respect” for the Kriegsmarine, and “awakens affection” for the “young submarine arm” that had amply demonstrated its “outstanding operational efficiency.”
Believing the damaged “Repulse” had limped to a shipyard in Rosyth in the Firth of Forth, Berlin mounted a Luftwaffe attack on Rosyth on October 16—the first German air attack on a Royal Navy base. Luftwaffe pilots confirmed (erroneously) that “Repulse” was in the shipyard. The planes hit the cruiser Southampton with one bomb, but it failed to explode. The only notable result of the attack was slight damage to a destroyer. Still quite unharmed, Repulse sailed from there with the carrier Furious for convoy duty.
By this time it was customary for returning U-boats to paint the names of enemy “kills” on the conning towers in white. The first watch officer, Engelbert Endrass, personally carried out this pleasurable task. Believing that merely the name Royal Oak was insufficient to convey the full drama of the kill, Endrass, who had fired the torpedoes for Prien, embellished the conning tower with a crude portrait of a massive bull charging with lowered horns and steaming nostrils. Later, a refined version of the “Bull of Scapa Flow” was to become the official insignia of the Wegener Flotilla.
By the time U-47 entered Wilhelmshaven on the morning of October 17, its great feat of arms was known throughout Germany. Admirals Raeder and Dönitz were standing on the pier to greet Prien and his men. When the lines were secured, the admirals crossed the brow to shake hands with every man in the crew and to confer on Prien the Iron Cross First Class and to all others the Iron Cross Second Class, and to announce that Adolf Hitler was sending his personal plane to fly the crew to Berlin.
The drama and daring of the Scapa Flow deed personified the image of military courage and ingenuity Hitler was seeking to project. He directed Propaganda Minister Goebbels to give Prien and his crew the full treatment. German radios trumpeted heroic and exaggerated bulletins (including the supposed damage to Repulse). By the time the U-47 crew arrived at Berlin’s Templehof Airport, the German people had been whipped to a frenzy of enthusiasm. Thousands turned out at the airport and along the motorcade route and at the Kaiserhof Hotel to present flowers, candy, and other gifts, or merely to catch a glimpse of the naval heroes. It was the greatest and most exhilarating celebration in the history of submarine warfare, and it would never be equaled again in Germany or elsewhere. The reigning U-boat hero, Otto Schuhart, who had actually outdone Prien by sinking the far more versatile and valuable capital ship Courageous, was all but forgotten.*
The celebration and ceremonies continued for several days. Hitler invited the crew to the Reichs Chancellery for lunch and presented Prien a new and exalted medal, the Knight’s Cross of the Iron Cross, or Ritterkreuz, as the submariners called it. Afterward Hitler’s publicist, Dr. Otto Dietrich, introduced Prien to the German and foreign press. (The American radio journalist, William L. Shirer, noted in his diary that Prien was “a clean-cut, cocky, fanatical Nazi, and obviously very capable.”) That night the crew were guests of Goebbels at the Wintergarten Theater, where a fawning audience forced Prien to make a speech. Still later the crew was entertained at a night club.
The Prien hoopla gave Dönitz and the U-boat force a tremendous boost. There was no instant return; no immediate increase in U-boat production. But the feat at Scapa Flow had certainly got Hitler’s attention and firmly planted the idea in his and all German minds that a single cheap U-boat manned by merely forty-four men could sink a huge battleship manned by 1,200 men. From that it was not difficult to imagine what carnage a vast fleet of U-boats could inflict on Great Britain’s thinly armed merchant marine. Thus the idea that Germany might, after all, defeat Great Britain at sea with U-boats gained credibility. The long-term impact of Scapa Flow was therefore immeasurably beneficial for the U-boat arm.