You think none of the land in modern-day Denmark was fought over at some point in its ~10,000 year history? Heck, less than 100 years ago it was conquered by the Nazis.
It was never conquered by the Nazis, it was occupied which isn't the same thing. In it's recorded history (1000+ years) there is (AFAIK) no instance of a foreign power taking over.
Schleswig-Holstein? Part of Denmark before the Iron Chancellor took them in the 1860s.