To try and stop the trade of iron ore between Norway and Germany the British Navy started to lay mines on April 8, 1940.
On April 9, 1940, the German military began the invasion of Norway code named Operation Weser. Kriegsmarine took troops in to Norway's major harbors and the Luftwaffe dropped and landed paratroopers on key installations. Even with the assistance of the British and French forces, Norway fell to the Germans.
The Norwegian royal family and gold supply made it to Britain where the Norwegian government in exile was formed.