Atlantic: BATTLESHIP ROYAL OAK SUNK (833 dead) in ‘impregnable’ anchorage of Scapa Flow, Orkney Islands, by U-boat U-47 from Guenther Prien. British Home Fleet subsequently retires to Loch Ewe (West Scotland).
Polish submarine Orzel reaches British waters after amazing escape from Baltic.
General Gamelin, French CinC, issues melodramatic Order of the Day predicting a massive German offensive ‘at any moment’.
Finland: Military mobilization.
Escaped Polish Intelligence team resume code-breaking operations with their highly secret replicas of the German Enigma machine in France. The Poles had supplied one replica each to Britain and France on July 25.