 From 1941 to 1942, he worked at Marx & Mérei Scientific Instruments Plant, and from 1942 to 1945, he was employed by Hungarian Philips Works.In 1943, Biszku joined "Vasas Szakszervezet", the metalworker's trade union and participated energetically in organizing work.Biszku joined the Hungarian Communist Party (MKP) in 1944 and participated in the Angyalföld resistance movement that fought against the Nazi German occupation force and against the collaborationist pro-fascist Arrow Cross Party government during the end of World War II.