In 1939, a Nazi Submarine Slipped into One of Britain's Biggest Bases and Sunk a Battleship
Staying on the surface, Prien first sailed toward the southeast across the Flow and toward the island of Hoy before realizing a navigational error had the submarine heading toward some dangerous shoals. Prien turned to the north, spotting what appeared to be several ships anchored in that area. (Fifty-one ships––18 of which were combat vessels––were reported to be in Scapa Flow at the time.)
“It was absolutely dead calm in there,” Prien later said. “The entire bay was alight because of bright northern lights.”
Sailing north between the sunken block ships Seriano and Numidian, U-47 grounded itself temporarily on a cable strung across the channel from the Seriano and was briefly caught in the headlights of a taxi onshore, but no alarm was raised in either incident.
As U-47 moved north, a lookout on the bridge spotted the Royal Oak about 4,400 yards to the north and correctly identified the ship as a battleship of the Revenge class. Mostly hidden behind her was a second ship, only the bow of which was visible to U-47. (Prien misidentified that second ship as a battlecruiser of the Renown class, but it was later determined to be the World War I seaplane tender Pegasus.)
The submarine quietly approached the Royal Oak and fired a three-torpedo spread, then turned quickly to escape.
One of the three torpedoes struck the Royal Oak’s bow at 12:58 am, and the dull thud and muffled explosions of its detonation confused the sailors onboard. Most thought the cause was an internal problem on the ship, perhaps in the paint locker. The hit caused little damage other than severing the Royal Oak’s starboard anchor chain.
When Prien realized there was no surface or air reaction to his attack, he fired a torpedo from his rear tube, but this torpedo also missed the battleship. He then turned U-47 back to the north and fired another array of three torpedoes, hitting the Royal Oak amidships at 1:06 am.
“There was a bang and the next moment the Royal Oak blew up,” Prien said. “The view was indescribable.” (Kept secret by the German naval command when it jubilantly announced the attack was that several of the torpedoes fired by Prien failed to strike the Royal Oak or to detonate because of long-standing problems with their depth steering and magnetic detonator systems. These problems continued to bedevil the German submariners.)
The Royal Oak heeled over from the force of the explosions, and its gun barrels shifted with the heel, pulling the ship even more quickly onto her side. All her lights went out as the power failed. Water poured in through the gaping hole in her side and through the hatches, which were all open at the time, standard practice for a ship in port.
Men asleep in their bunks or just lying there were trapped by the speed of the deluge. In minutes the Royal Oak was going down, and those few men who had been able to get on deck were in the freezing water swimming through a thick oil slick.
“It was so cold that I was told that it was colder than the inside of a fridge,” one survivor later said.
Meanwhile, U-47 turned away to the east and slipped out of Scapa Flow by the same channel it had used to enter the British anchorage. The Royal Oak continued to take on water and finally disappeared below the waves at 1:29 am, only 13 minutes after U-47’s second successful hit.
After the sinking, Prien and his crew reached the German North Sea port of Wilhelmshaven on October 17 and were immediately greeted as heroes. Hitler sent his personal airplane to ferry the crew to Berlin, where each man aboard U-47 was awarded the Iron Cross Second Class. Prien received the Knight’s Cross of the Iron Cross, Germany’s highest military award. It was the first time the award had been made to a German submarine officer.
Prien was later nicknamed “the Bull of Scapa Flow,” and his crew at one point decorated U-47 ’s conning tower with the painted image of a snorting bull, which later became the emblem of the 7th U-boat Flotilla. Prien also found himself in demand for radio and newspaper interviews, and his autobiography, ghost-written by a German journalist, was published the following year.
Of those men in the water who attempted the half-mile swim to the nearest shore, only a handful survived. Many more were rescued by the tender Daisy 2, which had been tied up for the night to Royal Oak’s port side.
When the Royal Oak was hit and began to list, Daisy 2’s commander, John Gatt, quickly cut his ship clear, snapped on his floodlights, and began picking up survivors, managing to pull 386 men from the cold water, including the Royal Oak ’s commander, Captain William Benn. Rescue efforts continued until nearly 4 am.
Out of the Royal Oak ’s complement of 1,234 men and boys, 833 were killed that night or died later of their injuries. Among that number were 126 “boy sailors,” young men under the age of 18 who were stationed on the ship.
“I was a very lucky man [to survive],” said survivor Bert Peacock, who was 17 years old at the time of the attack.
Immediately after the sinking, there was confusion—and sometimes wild speculation—as to what had caused the sinking. It was only when divers descended to the wreck and discovered the remains of a German torpedo that the cause was confirmed as having been a U-boat attack.
That confirmation was nonetheless followed by additional speculation including a rumor that a local German spy had paddled out into Scapa Flow and led the U-boat into the harbor, a rumor that was labeled “nonsense” by the authorities.
Winston Churchill, then First Lord of the Admiralty, announced the attack to the House of Commons, calling it “a remarkable exploit of professional skill and daring”––an indication of the more gentlemanly attitude taken by both sides at that stage of the war.