Weserübung: der deutsche Angriff auf Dänemark und Norwegen im April 1940, Operationen des Zweiten Weltkrieges, 1, München : Oldenbourg, Roskill, S.W. The War at Sea, 1939-1945: The defensive. Vol. 1 (HM Stationery Office, 1961), official history of Royal Navy, covers 1939-41 External links Campaign in Norway at www.BritishMilitaryHistory.co.uk Halford Mackinder's Necessary War An essay by F. William Engdahl describing the political manoeuvers behind the Norwegian Campaign United States Department of State Foreign relations of the United States diplomatic papers, 1940. General Volume I p. 136 onwards provides original documents which show how the conflict began. Torpedo Crisis of the U-Boats During Norwegian Campaign Norwegian Campaign he:המערכה בנורבגיה