'Schleswig' was a German unrealised naval plan for a sortie by heavy warships to an area beyond the Shetland/Norway line (29 February/April 1940).

There was constant disagreement about the details of the emerging plan between Grossadmiral Erich Raeder’s Oberkommando der Kriegsmarine and Generaladmiral Alfred Saalwächter’s Marinegruppenkommando 'West', so the implementation of the plan was initially delayed and then rendered obsolete by 'Weserübung'.