Operation Wikinger

[aurora]

Operation Wikinger was a sortie into the North Sea by German World War II destroyers (1st Destroyer Flotilla) of the Kriegsmarine, in February 1940. During this operation, poor inter-service communication and cooperation between the Kriegsmarine and the Luftwaffe and inexperience resulted in the loss of two German destroyers and crewmembers- through friendly fire bombing and German or British mines. No Allied forces were involved.

http://ww2today.com/german-naval-disast ... n_wikinger

[aurora]

It was only after the war that it was established that the Royal Navy had mined the area some days previously, but it has never been possible to conclusively determine whether the Max Schulz was lost to a British or a German mine.