When the Germans launched Operation Weserübung, an invasion of Denmark and Norway on 9 April 1940, one of their principal objectives was the port of Narvik in Northern Norway, through which iron ore was exported to Germany during the winter months. Part of the German 3rd Mountain Division commanded by "Generalleutnant" Eduard Dietl occupied the port, but were isolated when the destroyers and ships which had transported them and much of their supplies were destroyed in the First and Second naval battles of Narvik.