1940 is the year when Norway becomes drawn into World War II. On 9 April Nazi Germany invades the country which, however spared many of the atrocities which befell other nations, remains occupied until 8 May 1945. See the article Occupation of Norway by Nazi Germany for a full exposition of World War II in Norway.
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.
German invasion of Norway: German air-landed soldiers land at and capture the airport at Fornebu near Oslo.
10 April - German invasion of Norway: Germans set up a Norwegian government under Vidkun Quisling, former minister of defence.
11 April - Norwegian Campaign: First Battle of Narvik, British destroyers and aircraft successfully make a surprise attack against a larger German naval force. A second attack on 13 April will also be a British success.
13 April - Norwegian Campaign: British and French troops begin landing at Namsos and Harstad in Norway. The landings are aimed at recapturing Trondheim and Narvik, respectively.
10 May - Norwegian Campaign: The Hurtigruten steamer Nordnorge is sunk at Hemnesberget while being used as a German troop ship.
24 May - Norwegian Campaign: The British make a final decision to cease operations in Norway.
27 May - Norwegian Campaign: Most of Bodø was destroyed during a Luftwaffe attack. 6,000 people were living in Bodø at that time, and 3,500 people lost their homes in the attack.
28 May - Norwegian Campaign: Norwegian, French, Polish and British forces recapture the Norwegian harbour-city Narvik which was of great strategic importance to Germany. This is the first allied infantry victory of World War II.
7 June - Norwegian Campaign: The Norwegian Royal Family and the Norwegian Government was evacuated from Tromsø on board the British cruiser Devonshire which later on arrived safely in London where Haakon VII and his cabinet set up a Norwegian government in exile.
8 June - Norwegian Campaign: The last of the Allied troops leave Norway.
10 June - Norwegian Campaign: Mainland Norway surrenders to German forces.