10 January — World War II: Mechelen Incident: A German plane carrying secret plans for the invasion of western Europe makes a forced landing in Belgium, leading to mobilization of defense forces in the Low Countries.
German invasion of Norway: German heavy cruiser Blücher is sunk by gunfire and torpedoes from the Norwegian coastal fortress Oscarsborg in the Oslofjord. Of the 2,202 German crew and troops on board, some 830 died (at least 320 of them crewmen). Most either drowned or burnt to death in the flaming oil slick surrounding the wreck.
20 April - on his 51st birthday, Hitler orders the formation of a new SS regiment, containing Norwegians and Danes as well as Germans.
21 June — World War II: Vichy France and Germany sign an armistice at Compiegne, in the same wagon-lit railroad car used by Marshal Ferdinand Foch to accept the surrender of Germany in 1918.
14 July — World War II: Winston Churchill, in a worldwide broadcast, proclaims the intention of Great Britain to fight alone against Germany whatever the outcome.
19 July — World War II: Adolf Hitler promotes 12 generals to field marshal during the 1940 Field Marshal Ceremony following the swift victory over France, and makes a peace appeal to Britain in an address to the Reichstag. Lord Halifax, British foreign minister, flatly rejects peace terms in a broadcast reply on 22 July.
14 November — World War II: The city of Coventry, England is destroyed by 500 German Luftwaffe bombers (150,000 fire bombs, 503 tons of high explosives, and 130 parachute mines level 60,000 of the city's 75,000 buildings; 568 people are killed).
16 November — World War II: In response to Germany levelling Coventry 2 days before, the Royal Air Force begins to bomb Hamburg (by war's end, 50,000 Hamburg residents will have died from Allied attacks).
29 December — World War II: Luftwaffe carries out a massive incendiary bombing raid on London, UK, starting 1,500 fires. Many famous buildings, including the Guildhall and Trinity House, are either damaged or destroyed.
^Longerich, Peter (2010). Holocaust: The Nazi Persecution and Murder of the Jews. Oxford; New York: Oxford University Press. p. 162. ISBN978-0-19-280436-5.
^Hooton, E.R. (2007). Luftwaffe at War: Blitzkrieg in the West. London: Chevron/Ian Allan. p. 88. ISBN978-1-85780-272-6.
^Roy Hemming (1994). Discovering Great Music: A New Listener's Guide to the Top Classical Composers and Their Best Recordings. Newmarket Press. p. 248. ISBN9781557042101.