Kahrs was born in
Bergen,
Norway in 1918 into a family of German origins. He joined the
Nasjonal Samling in 1934. And around the same time he also joined the party's paramilitary wing, the
Hird, and from 1936 the
NS Battle Organization. After the outbreak of World War II, he volunteered for service in the
Norwegian Legion of the
Waffen-SS. In the summer of 1944 made acting battalion commander of the SS Ski Jäger Battalion "Norwegen". In 2013 Norwegian daily
Dagbladet's then correspondent in Germany said that "The Norwegian company commander failed—and fled the combat zone, while many were killed or captured". Kahrs disappeared early in the battle—later reappearing uninjured in the rear echelons, where he in his own report put himself in a positive light; thus avoiding court martial. Later he was put in charge of
Vidkun Quisling's bodyguard detail, known as the
Førergarde. ==Criminal conviction==