Operation Weserübung began on 9 April 1940 with the invasions of Norway and Denmark. Denmark capitulated within the day; Norway continued to resist with British and French help. The campaign was not a "Blitzkrieg" of fast-moving armoured divisions supported by air power as the mountainous terrain ruled out close Panzer/Stuka cooperation. Instead, the Germans relied on paratroops transported by Junkers Ju 52s and specialised ski troops. The Ju 87s were given the role of ground attack and anti-shipping missions; they proved to be the most effective weapon in the Luftwaffe's armoury carrying out the latter task.