Born in Berlin to Danish parents, Hentschel was hired on 4 July 1934. During the last days of the Third Reich, he was responsible for the machine room in the Führerbunker and he stayed in the bunker after almost everyone else had either committed suicide or left, as the field hospital in the Chancellery above needed power and water. He surrendered to the Red Army as they entered the bunker and was released four years later, on 4 April 1949. Hentschel died in 1982 in Achern, West Germany.