Operation Weserübung (German: Unternehmen Weserübung [ˈveːsɐˌʔyːbʊŋ], transl. Operation Weser Exercise) was the code name for Germany’s assault on Denmark and Norway during the Second World War and the opening operation of the Norwegian Campaign.
In the early morning of 9 April 1940 (Wesertag, “Weser Day”), Germany occupied Denmark and invaded Norway, ostensibly as a preventive manoeuvre against a planned, and openly discussed, Franco-British occupation of Norway known as Plan R 4 (actually developed as a response to any German aggression against Norway).
After the occupation of Denmark (the Danish military was ordered to stand down as Denmark did not declare war with Germany), envoys of the Germans informed the governments of Denmark and Norway that the Wehrmacht had come to protect the countries’ neutrality against Franco-British aggression. Significant differences in geography, location and climate between the two nations made the actual military operations very dissimilar.
The invasion fleet’s nominal landing time, Weserzeit (transl. Weser Time), was set to 05:15.