Blitzkrieg Triumphant: The Fall of France and the Battle of Britain (1940)

Germany invaded Denmark and Norway on 9 April 1940 under Operation Weserübung, driven above all by the strategic need to secure the supply of Swedish iron ore transported through Norwegian ports. Denmark was occupied almost immediately, while Norway put up a more prolonged fight aided by British and French forces; King Haakon VII fled into exile in London, and a collaborationist government was installed under Vidkun Quisling, whose name subsequently entered the international vocabulary as a synonym for a traitorous collaborator.