Winston Churchill got authorization to mine the Norwegian Coast to protect against a German assault by way of the Atlantic shortly before the German invasion, yet I can't find anything that says whether or not the mines hampered the German plans at all. It seems like the Germans were able to drop troops wherever they pleased along the coast, which I'm assuming is what the mines were supposed to prevent. This is kind of a minor point in World War II history, but I'm wondering if anyone knows what happened?
*Oops, I meant 1940.
I can't answer the question directly, but I'm pretty sure this comes up in Henrik Lunde's Hitler's Pre-Emptive War which is a pretty exhaustive history of the Norwegian campaign.
I only have it in Audiobook form so I can't just grab it off the shelf and look, unfortunately...