German development of coastal forts in Norway during the second World War - Janne Wilberg

The work on fortifying Norway commenced immediately after the attack in April 1940. The occupation powers used already existing Norwegian coastal forts, changed them somewhat and began the development partly in accordance with Norwegian plans from the interwar period. After extensive inspections during the spring and summer of 1940, original plans for the fortification of strategically important places were developed. The wish to control Norway was based on the need to secure the transportation of ore from Narvik, secure the access to the Atlantic from Germany and the need for bases for the German navy in Norway.