Germany invaded both Norway and Denmark on 9 April 1940.[1] Norway was very important to Germany for two reasons: firstly as a base for naval units to harass Allied shipping in the North Atlantic and Arctic Oceans, and secondly to secure shipments of iron ore coming in from Sweden through the port of Narvik.[2] During Operation Weserübung, Denmark fell in less than a day, becoming the briefest invasion in recorded military history.[3] The Norwegians put up a stiffer resistance to the invading German forces.