May 9/10, 1940 - The Kriegsmarine plays practically no part in the German western offensive against Holland, Belgium and France after sustaining heavy loses during Operation Weser Exercise. The battlecruiser Gneisenau is the only capital ship that remains operational. Only two U-boats patrol the northen approaches to the English Channel during the first week of the western offensive.

June 10, 1940 - Operation Weser Exercise ends with the surrender of the Norwegian troops. The German Naval High Command calls the use of major naval vessels against Norway "a serious strategical error." As a result, the German Navy is in no position to support a potential invasion of England and the delays in restoring damaged ships to operational readiness will have a detrimental effect. Great Britain, despite its defeat in Norway, acquires almost 90% of the enormous Norwegian Merchant Navy totaling 1,024 ships including two hgundred tankers.

(Sea War 1939 - 1945 ---- published in 1987, by Janusz Piekalkiewicz, ISBN:0713716657)