Oscarsborg Fortress is best known for sinking the  German heavy cruiser named for the Prussian victor of what?
Oscarsborg Fortress: Oscarsborg Fortress (Norwegian: Oscarsborg festning ) is a coastal fortress in the Oslofjord, close to the small town of Drøbak. Oscarsborg Fortress:  The fortress is best known for sinking the German heavy cruiser "Blücher" on 9 April 1940. German cruiser Blücher:  Named for Gebhard Leberecht von Blücher, the Prussian victor of the Battle of Waterloo, the ship was laid down in August 1936 and launched in June 1937.
i don't know