Timeline of the Norwegian campaign

The Norwegian campaign, lasting from 9 April to 10 June 1940, led to the first direct land confrontation between the military forces of the Allies—the United Kingdom and France— against Nazi Germany in World War II. == January 1940 == 27: German planners assign the code name Weserübung to the operation. == February 1940 == 5: Using assistance to Finland as rationale, the Allied Supreme War Council decides on intervention in Norway.

Source: Wikipedia — Timeline of the Norwegian campaign (CC BY-SA 4.0)