He worked as a journalist during the Weimar Republic and he was a member of the liberal German Democratic Party.

After World War II, Bach was the co-founder of East German Christian Democratic Union in Thüringen and was elected in the provincial executive of the CDUD of Thüringen.

In 1947 he joined the Society for German-Soviet Russian Friendship (DSF) and he served as the vice-chairman of the DSF-Thüringen (1949).

A loyal supporter of the Communist SED regime, he helped push out those CDU members not willing to do the Communists' bidding, and led its formal transformation into a loyal partner of the SED in 1952.

After the death of Otto Nuschke, Bach was elected Chairman of the CDUD (as it was now known) in 1958.