How would events change if the Imperial German Navy's ships returned in 1939 and attacked the Nazi fleet?
Short answerThe fantasy premise destroys German naval options, may prevent the invasion of Norway, shifts Swedish ore toward Britain, and transforms naval politics.
NotesThe premise is explicitly fantastical: Imperial German ships return in 1939 and attack Nazi naval forces at Wilhelmshaven. Removing the Kriegsmarine could prevent the Norwegian campaign, leaving even a neutral Norway strategically harmful to Germany by constraining Atlantic access and exposing Swedish iron-ore traffic to British purchase. Britain could buy more high-grade ore than it immediately needed and turn it into armor, steel, and ships while denying the same resource to Germany. The returned fleet would also overwhelm later German capital ships and create political fear that mistreated warships might act on their own. That supernatural lesson could strengthen support for CVA-01 and other naval programs even though the scenario itself is not real history.