On 13 April 1940 eleven Ju 52s landed on frozen Hartvig Lake to fly in a mountain artillery battery for the German troops in Narvik. Only one could take off again. Norwegian forces drove the Germans from the lake and tried to prepare three of the Ju 52s for their own use. Despite empty fuel drums strapped underneath the aircraft selected by the Norwegians, all ten Ju 52s on the lake eventually sank. Five were salvaged in good condition in the 1980s and 6821 is preserved in Speyer.