The sinking of HMS Royal Oak

Just before midnight on 13th October 1939, a German submarine U47, commanded by Kapitänleutnant Günther Prien, penetrated the Royal Navy base at Scapa Flow, in Orkney and sank the British battleship HMS Royal Oak. Prien returned to Germany to instant fame. He was awarded the Knight's Cross of the Iron Cross, personally by Adolf Hitler, the first sailor of the U-boat service and the second member of the Kriegsmarine to receive this award. Prien received the nickname Der Stier von Scapa Flow ("The Bull of Scapa Flow"); the emblem of a snorting bull was painted on the conning tower of U-47 and soon became the emblem of the entire 7th U Boat Flotilla. 835 sailors died with HMS Royal Oak, including Rear-Admiral Henry Blagrove, commander of the 2nd Battle Squadron. Over one hundred of the dead were Boy Seamen, not yet 18 years old, the largest ever such loss in a single Royal Navy action.

Kept secret by the German naval command was the fact that Prien had fired a total of seven torpedoes at his target, of which five failed because of long-standing problems with their depth steering and their magnetic detonator systems. These problems continued to bedevil the German submariners for a long time and particularly during the German invasion of Norway, when the U-boats were unable to keep the Royal Navy at bay. Prien narrated the attack in the book Mein Weg nach Scapa Flow (1940, Deutscher Verlag Berlin).