At the start of World War II, "Monte Rosa" was allocated for military use. She was used as a barracks ship at Stettin, then as a troopship for the invasion of Norway in April 1940. She was later used as an accommodation and recreational ship attached to the battleship "Tirpitz", stationed in the north of Norway, from where "Tirpitz" and her flotilla attacked the Allied convoys en route to Russia. In 1942, she was one of several ships used for the deportation of Norwegian Jewish people, carrying a total of 46 people from Norway to Denmark, including the Polish-Norwegian businessman and humanitarian Moritz Rabinowitz. Of the 46 deportees carried on "Monte Rosa", all but two died in Auschwitz concentration camp.