The Objective

The British naval base at Scapa Flow on the Orkneys was the main fleet anchorage of the British Isles. Needlessly to say that base usually held some very tempting targets for the U-boats. (During WWI the U-boat UB-116 under Oblt. Hans Joachim Emsmann attempted in October 1918 to slip into Scapa Flow, but the boat was lost with all hands to a mine). But of course the British knew this and had fortified the area heavily and Scapa Flow was regarded as very safe. Preparations

Dönitz had always wanted to slip a U-boat into these waters and give the British a powerful punch that would really hurt them for years to come (it took 3-4 years to build a battleship and work it up). This sort of mission required skill, some luck and excellent intelligence. On September 26, 1939 Luftwaffe, the German air force, managed to get excellent photographs of the base and U-14 brought valuable information about the Scapa Flow approaches from a patrol in September 1939. On Sunday Oct 1 Dönitz called in one of his most energetic and daring U-boat commanders, Günther Prien of U-47 and offered him the mission of slipping into Scapa Flow. Dönitz made it clear that Prien was to take this voluntarily and he could say no without any damage to his career. Prien took the plans home for the night and studied them carefully before returning the next day and accepting the task. The Attack

The first hint the crew of U-47 got that something very special was going on was when the stores that had been put on board were removed and replaced with supplies for much shorter mission than usual. U-47 then put out from Kiel on October 8, 1939, sailed through the Kaiser-Wilhelm-Kanal into the North Sea, where they absolved south of Helgoland the usual dive trials. On the route to Scapa Flow, U-47 avoided any vessels that might report his position.

U-47 leaves Kiel for Scapa Flow on October 8, 1939.

Note the old emblem which the famous Snorting Bull replaced on the way home. Late in the evening (at 2331 hours) of October 13, Prien started his run into Scapa. The strong currents coming through the entrance channels forced Prien to time his attack very carefully and using slack water (period between high tide and low tide). He carefully took his boat on the surface between the vessels the British had sunk in the channels to prevent such an attack and at one time was so close to the shores that U-47 was illuminated by highlights of a passing car. Just after midnight on October 13/14, U-47 was inside Scapa Flow and the commander wrote at 0027 in the KTB (War diary) Wir sind in Scapa Flow!!! (We are in Scapa Flow!!!). Once inside the harbour Prien started to scan the area looking for targets and after a while he spotted 2 large vessels to his north and fired at 0058 hours a spread of 3 torpedoes at the overlapping targets. After 3 and a half minute one explosion was heard but incredibly seemed to attract no attention from the British. Then the boat turned and fired the stern torpedo without success. Frantically Prien's crew re-loaded the tubes and then fired at 0122 hours 3 torpedoes. After run of three minutes explosions tore through the massive hull of the 31,100 ton battleship HMS Royal Oak, which sank in 13 minutes taking with her 24 officers and 809 men. There were only 375 survivors. This was the second largest vessel sunk by a German U-boat in the war and one of only 2 British battleships lost (the other being HMS Barham sunk by Tiesenhausen's U-331). U-47 Returns

Despite heavy incoming currents, U-47 managed to slip away from the now-alerted British destroyers and at 0215 hours slipped out of Scapa Flow and headed home (the British announced that they had sunk the offending U-boat). The BBC announced on October 14, 1939: