Intelligence and the ‘Mindset’: The German invasion of Norway in 1940

Abstract

‘Weserübung’, the German invasion of Norway and Denmark on 9 April 1940, was a brilliantly successful surprise attack, both strategically and tactically. Strategic surprise was obtained because the idea that Germany was about to launch a major invasion of Norway was remote from any of the preconceived scenarios about Germany's next move. Germany's achievement of tactical surprise was also aided by bad weather in the North Sea. The main reason for the failure of both Norwegian and British policy-makers to comprehend what the Germans were up to lies in the importance of the ‘mindset’. On both sides of the North Sea the conventional wisdom was that Germany would not attempt an invasion of Norway against the supremacy of British sea power. Hence all incoming information was interpreted in Oslo in the light of the next mindset, namely that only a determined British attempt to take control of the Norwegian coast could trigger an armed German retaliation. In London, incoming intelligence was interpreted so as to conform to the Admiralty's preconceived scenario of a German naval breakout into the North Atlantic.