Born Apr. 2, 1913, in Berlin. An activist in the German workers’ movement.
In 1929, Danelius joined the German Communist Party. From 1933 to 1945 he was an active participant in the antifascist struggle. From 1946 to 1962 he was a member of the Socialist Unity Party of Germany (SED). From 1948 to 1950 he was first secretary of the SED regional organization in Tempelhof, West Berlin, and then was first secretary of the regional committee of the SED in Friedrichshain, Berlin. In 1959 he became first secretary of the West Berlin organization of the SED. After the formation of the independent Socialist Unity Party of Germany and West Berlin in 1962, he became first secretary of its directorate. In May 1966 he became chairman and member of the secretariat of the directorate of the Socialist Unity Party of Germany and West Berlin, and in February 1969 he became chairman of the Socialist Unity Party of West Berlin (SEW). Since May 1970 he has been chairman of the SEW and a member of the bureau and secretariat of the party directorate.