Warfare History Network
London feared death by torpedo.
In October 1939, illuminated by the northern lights, the German submarine U-47 threaded its way through sunken barriers and slipped into the British anchorage at Scapa Flow, a 125.3-square-mile natural port off the northern coast of Scotland, in the Orkney Islands.
Penetrating the anchorage had long been an unrealized German dream, one that U-boats had attempted twice in World War I; both times they had failed. One U-boat had been rammed and run aground and the second destroyed with all hands.
But now, at last, a German submarine slid quietly across its surface.
U-47 and its 31-year-old captain, Günther Prien, moved across the anchorage from the east where they had entered and then turned toward the north, searching for targets. Prien was surprised at how few British ships were in the area.
He had expected hundreds and was unaware that Sir Charles Forbes, commander in chief of the British Home Fleet, had become concerned by German aircraft recently spotted in the area and had ordered most of the fleet to disperse.
Finally, a lookout on U-47’s bridge spotted a small cluster of ships including the 1914 battleship Royal Oak silhouetted against the northern lights.
Unknown to Prien and the crew of U-47, the 29,000-ton Royal Oak had just returned to Scapa Flow after a battering from storms in the North Atlantic. Some of her smaller caliber guns had been rendered inoperable by flooding and many of her life rafts had been seriously damaged. Because of her condition, Forbes had decided to keep the Royal Oak in Scapa Flow to provide added antiaircraft fire if needed.
In the darkness, U-47 slid toward the big ship.
The Royal Oak, like Scapa Flow itself, was a veteran of World War I, but by the outbreak of World War II, the 25-year-old ship was no longer considered fit for modern combat. She had been launched in 1914, had seen battle in 1916 at Jutland, and had later served as part of Britain’s Atlantic, Home, and Mediterranean Fleets.
At the end of World War I, Royal Oak had also served as escort to several German vessels that had surrendered and were interned at Scapa Flow, which had been used by ships since prehistory.
In 1904, in response to the German naval action, British naval planners had decided a northern base was needed to control access to the North Sea. Scapa Flow was chosen, and the area was reinforced with minefields, artillery, and concrete barriers.