Battle of the Atlantic · United Kingdom vs Germany
Sinking of HMS Royal Oak
14 October 1939
Gunther Prien's U-47 slipped through the blockships at Kirk Sound into Scapa Flow and torpedoed the battleship Royal Oak at anchor. 835 men died. The Home Fleet was dispersed to west-coast anchorages until the defences were rebuilt.
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Day by day
— Kirk Sound
U-47 came in on the surface through Kirk Sound at about 00:30, squeezing between the blockships on a rising tide. Most of the Home Fleet had left for Loch Ewe; Prien found Royal Oak at anchor in the north-east corner of the Flow and fired at 00:58 and again at 01:16. The battleship capsized in thirteen minutes with 835 of her 1,234 men. U-47 went out the way it had come and was back in Wilhelmshaven on the 17th.