The Wikipedia article of the day for November 17, 2019 is HMS Royal Oak (08).
HMS Royal Oak was one of five British Revenge-class battleships built for the Royal Navy during the First World War. Launched on 17 November 1914, the ship first saw combat at the Battle of Jutland. On 14 October 1939, she was torpedoed by the German submarine U-47 while anchored at Scapa Flow in Orkney, Scotland; 835 were killed that night or died later of their wounds. The loss of the outdated ship—the first of the five Royal Navy battleships and battlecruisers sunk in the Second World War—did little to affect the numerical superiority enjoyed by the British navy and its allies, but the sinking had a considerable effect on wartime morale. Günther Prien, the U-boat commander, became the first German submarine officer to be awarded the Knight's Cross of the Iron Cross. Demonstrating that the German navy was capable of bringing the war to British home waters, the raid resulted in rapid changes to dockland security and the construction of the Churchill Barriers around Scapa Flow.