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Scapa Flow Log Book

U-47's Scapa Flow Mission Logbook

After the war, the British Admiralty acquired a copy of Prien's log book (Kriegstagebuch, or KTB) covering the mission to Scapa Flow, which provided a concrete breakdown of the events leading to the sinking of the Royal Oak. This information, along with a report submitted by the Admiralty, was then made into an official report. This document was then passed to the Office of Naval Intelligence in the US at the Naval War College.

The Report on the sinking of "Royal Oak" was eventually declassified by US Naval Intelligence in May 1967, almost thirty years after the sinking of the British battleship. The log book extracts covering the period 8 to 17 October 1939 below are copied "as is", direct from the official document.

To download a zip file containing a scan of Prien's original logbook map, click here (file size 1.05MB, dimensions 1404x1347px).

(Thanks to Captain Jerry Mason, USN for providing me with a facsimile of this report).

Position, Wind etc.
Heligoland Bight.
Wind SE 1. Cloudy.
Left port (Kiel) on special operations, Operation Order North Sea No. 16, through Kiel Canal, Heligoland Bight, and Channel 1.
Exact positions cannot be given as under special orders all secret documents were destroyed before carrying out of order.
South of Dogger Bank.
Wind SSE 4-5.
Overcast, very dark night.
Lying submerged. After dark, surfaced and proceeded on our way. Met rather a lot of fishing vessels.
North of Dogger Bank.
Wind ESE 7. Overcast.
During day lay submerged; at night continued on course.
Devil's Hole.
Wind ESE 7-8, overcast.
As on previous day.
Wind SE 7-8, overcast.
During day lay submerged off Orkneys. Surfaced in the evening and came in to the coast in order to fix exact position of ship. From 2200 to 2230 the English are kind enough to switch on all the coastal lights so that I can obtain the most exact fix. The ship's position is correct to within 1.8 nautical miles, despite the fact that since leaving Channel 1 there was no possibility of obtaining an accurate fix, so that I had to steer by dead reckonings and soundings.
E. of Orkney Islands.
Wind NNE 3-4, light clouds, very clear light, Northern Lights on entire horizon.
At 0437 lying submerged in 90 metres of water. Rest period for crew. At 1600 general stand-to. After breakfast at 1700, preparations for attack on Scapa Flow. Two torpedoes are placed in rapid loading position before tubes 1 and 2. Explosives brought out in case of necessity of scuttling. Crew's morale splendid. Surfaced at 1915. After warm supper for entire crew, set course for Holm Sound. Everything goes to plan until 2307, when it is necessary to submerge on sighting a merchant ship just before Rose Ness. I cannot make out the ship in either of the periscopes, in spite of the very clear night and the bright lights. At 2331, surfaced again and entered Holm Sound. Following tide. On nearer approach, the sunken blockship in Skerry Sound is clearly visible, so that at first I believe myself to be already in Kirk Sound, and prepare for work. But the navigator, by means of dead reckoning, states that the preparations are premature, while I at the same time realise the mistake, for there is only one sunken ship in the straits. By altering hard to starboard, the imminent danger is averted. A few minutes later, Kirk Sound is clearly visible.
It is a very eerie sight. On land everything is dark, high in the sky are the flickering Northern Lights, so that the bay, surrounded by highish mountains, is directly lit from above. The blockships lie in the sound, ghostly as the wings of a theatre.
I am now repaid for having learnt the chart beforehand, for the penetration proceeds with unbelievable speed. In the meantime I had decided to pass the blockships on the Northern side. On a course of 270 I past the two-masted schooner, which is lying on a bearing of 315 in front of the real boom, with 15 metres to spare. In the next minute the boat is turned by the current to starboard. At the same time I recognise the cable of the northern blockship at an angle of 45 degrees ahead. Port engine stopped, starboard engine slow ahead, and rudder heard to port, the boat slowly touches bottom. The stern still touches the cable, the boat becomes free, it is pulled round to port, and brought on course again with difficult rapid manoeuvring, but we are in Scapa Flow.
It is disgustingly light. The whole bay is lit up. To the south of Cava there is nothing. I go farther in. To port, I recognise the Hoxa Sound coastguard, to which in the next few minutes the boat must present itself as a target. In that event all would be lost; at present south of Cava no ships are to be seen, although visibility is extremely good. Hence decisions: South of Cava there is no shipping; so before staking everything on success, all possible precautions must be taken.
Therefore, turn to port is made. We proceed north by the coast. Two battleships are lying there at anchor, and further inshore, destroyers. Cruisers not visible, therefore attack on the big fellows. Distance apart, 3000 metres.
(time queried in pencil, 0058 suggested)
Estimated depth, 7.5 metres. Impact firing. One torpedo fixed on the northern ship, two on southern. After a good 3 1/2 minutes, a torpedo detonates on the northern ship; of the other two nothing is to be seen.
(queried to 0102) (suggested time 0123, in pencil)
About! Torpedo fired from stern; in the bow two tubes are loaded; three torpedoes from the bow. After three tense minutes comes the detonation on the nearer ship. 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 harbour 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, a second damaged, 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. (See experience on entering.)
(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. 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. Free of the blockships - ahead a mole! Hard over and again about, and at 0215 we are once more outside. A pity that only one was destroyed. The torpedo misses I explain as due to faults of course, speed, and drift. In tube 4, a misfire. The crew behaved splendidly throughout the operation. On the morning of 13/10, the lubricating oil was found to have 7-8% water in it. All hands worked feverishly to change the oil, i.e. to get rid of the water and to isolate the leaking point. The torpedo crews loaded their tubes with remarkable speed. The boat was in such good form that I was able to switch on to charge in the harbour and pump up air.
Set SE course for base. I still have 5 torpedoes for possible attacks on merchantmen.
57 58' N
01 03' W
Lay submerged. The glow from Scapa is still visible for a long time. Apparently they are still dropping depth charges.
ENE 3-4, light clouds, occasional rain, visibility bad towards land, otherwise good.
Off again, course 180. This course was chosen in the hope that we might perhaps catch a ship inshore, and to avoid U-20
56 20' N
0 40' W
Submerged and lay at 72 metres. From 1000 onwards, depth charges were dropped from time to time in the distance. 32 depth charges were definitely counted. So I lie low, submerged, until dusk
Wind NE 5, sea 4, swell from E, cloudy, visibility good.
Surfaced. On surfacing, Norwegian steamer "METEOR" lies ahead. W/T traffic from the steamer is reported in error from the W/T office; I therefore fire a salvo far ahead of the steamer which is already stopped. The steamer is destined for Newcastle on Tyne, with 238 passengers. Steamer immediately allowed to proceed. It is reported later by the W/T office that the steamer did not make any signals.
54 57' N
2 58' E
Wind NNW 2-3,
visibility good.
General course 180. Submerged on the Dogger Bank. 3 drifting minds sighted, 54 58' N, 2 56' E. No measures taken, owing to the proximity of fishing vessels. Proceeded submerged throughout the day.
54 51' N
3 21' E
Wind NW 2, light clouds, visibility good.
Surfaced. Course 128. Steered course of 128 into Channel 1.
Channel 1 passed. From 0404 to 0447 chased fishing escort ship no. 808; gave recognition signal eight times - no reply received. This fool did not react until V/S was used at a distance of 500-600 metres. With such guardships, an incident such as my operation could occur in our waters also.
Entered port - Wilhelmshaven III.
Tied up.
Crew flown to Kiel and Berlin.
Crew returned.
Sailed for Kiel.
Met an armed fishing trawler at anchor with riding lights in the stretch between Elbe I and Elbe II. I pass him with darkened ship at a distance of 40 metres. Apparently he sees nothing, because no call for recognition is made.
Tied up at Brunsbüttel Lock.
Tied up at Holtenau Lock. Operation Completed.

On 17 October, Kapitänleutnant Prien and the crew of U-47 were flown to Berlin, where the following day they were met by Adolf Hitler. They returned to the boat almost immediately, setting out again on the 20th before returning to the home dock at Kiel at 1300 on the 21st. Prien's log, therefore, cited this time as being when the operation officially ended.

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