The German invasion of Denmark ( `` Operation Weserübung '' ) was the German attack Attack on Denmark on 9 April , 1940 , during the Second World War .

The attack was a prelude Process_start to the main attack Attack against Norway ( `` Weserübung Nord '' ) .

The term `` Weserübung '' means `` Weser-exercise '' in English , named Name_conferral after the river Weser in northwestern Germany .