The German occupation of Norway (1940–1945) during World War II made the Rjukan Line the area for a massive struggle in between the Norwegian resistance movement and the Third Reich. In February 1940, before the occupation, the entire Vestfjorddalen and the docks closed for foreigners. On 4 May 1940 German troops reached Rjukan, a month after the invasion of Norway had started. The ferries were camouflaged and by January 1941 lack of coal resulted in the steamships being fired by wood.