Into Scapa Flow
By David Lippman
October 2012

Studying his maps and the Luftwaffe’s reconnaissance reports in the early days of World War II, Karl Dönitz, commander of the German submarine force, believes there is a gap in the channels around Scapa Flow, Britain’s prime naval base in the north of Scotland, and a determined U-boat captain can sail through the gap, attack the Home Fleet in its anchorage, and retire safely. Such an attack would have a damaging impact on British morale, not to mention Home Fleet strength, and buoy German morale.

Dönitz assigns the project to one of his better U-boat skippers, the hard-charging Günther Prien, captain of U-47. Prien turns in his Enigma machine and all secret papers from U-47 before setting sail from Kiel, going by the Kiel Canal to Wilhelmshaven. The risk for this mission is great, but all hands are enthusiastic. At 7:15 p.m. on Friday October 13th 1939, U-47 surfaces to begin a slow, four-hour approach to Scapa Flow, timed to bring the submarine to Kirk Channel when the tide is at its highest.

On the bridge, Prien finds the sky clear but “disgustingly” bright, lit by an undulating aurora borealis – the northern lights. Despite the unexpected and inconvenient phenomenon, Prien sails on, determined to make the attack.

At 10 p.m., right on schedule, the Orkney navigational lights come on for 30 minutes, enabling Prien’s navigators to fix their U-boat’s position. Approaching a jut of land, Rose Ness, at 11:07 p.m., the bridge watch sees a merchant ship plodding along. Prien dives to avoid the vessel, and as a test, puts it in his periscope crosshairs.

Despite the northern lights, he can’t see the ship. The lack of periscope visibility means the attack at Scapa will have to be done on the surface.

At 11:31, Prien surfaces his U-boat and gets his bearings. Visibility is not as good as it seems, despite the Northern Lights. By mistake, he heads for the wrong channel, Kerry, separating Lamb Holm and Burray islands. He detects the mistake just in time. “By altering course hard to starboard, the imminent danger is averted,” he logs.

Prien re-aligns his submarine for the passage through Kirk Sound, deciding not to go south of the two blockships in the channel. Instead, he aims for a gap between the center and northernmost blockships, clearing the northernmost blockship with “45 feet to spare.” Borne along by the swift flood tide, the submarine races along. U-47 gets slewed by the current to starboard, right into a cable anchoring a blockship.

U47 sets out on patrol.

“Port engine stopped,” Prien logs. “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.”

At 12:27 a.m., Prien and First Watch Officer Engelbert Endrass study the scene with their binoculars, from the bridge of U-47. The fabled harbor, where the British Home Fleet is based, seems empty. Then Prien spots two “battleships” parked near the rugged north shore, about one and a half miles apart. He correctly identifies the first as Royal Oak, incorrectly the second ship as the battle cruiser Repulse. It’s actually the less glorious 6,900-ton seaplane tender Pegasus, being fitted with an experimental aircraft catapult for convoy work.

Prien sets up to shoot at 3,500 yards equidistant from both ships, using all four bow tubes. At 12:55 a.m., he fires two torpedoes with electric fuses at Pegasus and two at Royal Oak. The torpedo in Tube 4 misfires and does not go. The other three whoosh toward their target silently and wakelessly at 30 miles per hour.

The fish aimed at Pegasus misses and goes ashore. The other two, aimed at Royal Oak, keep going. One misses. The last torpedo hits Royal Oak on the starboard bow, blowing a huge hole in the stem and keel of the battleship near her paint and anchor-chain lockers. The noise is not sufficient to cause undue alarm elsewhere in the big ship. Royal Oak’s captain, roused from his bunk, assumes the explosion is due to an internal cause, not external. On the bridge, everyone looks to the sky, wondering if it’s an air attack.

The battleship’s XO, Cdr. C.H.A. Harper, throws on a coat, and runs on deck. Nobody can tell him what’s happened. Harper heads up to the forecastle where there is an acrid smell. “I could see by the light of a faint aurora that the stopper on the starboard cable had parted and the cable run out to a ‘clinch.’ Evidently the trouble was below in the cable locker flat where I found the Captain and the Engineer Commander. It seemed an explosion had occurred in the inflammable store and a man was going down in a smoke helmet to investigate.”

Royal Oak Stoker Herbert Johnson remembers: “At midnight I went down below to the refrigerating room on watch and just before 1 a.m. I put the readings in the engine room register (they had to go in every hour). A moment or two afterwards there was a terrific explosion. I thought we’d blown up, I thought we’d hit a mine, and then I decided that there had been an air-raid, so I closed down the machinery, shut the doors and the hatches and went up on the main deck.” Many crewmembers are awake and alert already, as the drifter Daisy II, bringing the ship’s mail, is late, and are up and about, waiting for the morale-boosting letters from home.

In the darkness and utter confusion, Prien is a disgusted man. He thinks he’s only damaged “Repulse” and missed Royal Oak. While the torpedo-men reload bow tubes 1 and 2, and readjust the balky tube 4, he swings ship, and fires his stern torpedo at Royal Oak. The torpedo misses and runs ashore, enabling the British to recover it later.

David H. Lippman, an award-winning journalist and graduate of the new School for Social Research, has written many magazine articles about World War II. He maintains the World War II Plus 55 website and currently works as a public information officer for the city of Newark, N.J. We're always pleased to add his work to our Daily Content.