Original: He served as deputy chairman of the SPD party of Wuppertal, and was elected later on to the City Council (1964-1978), where he served as chairman of the SPD Group (1964-1967) and later as Mayor (1969-1970).
Simplified: He served on the City Council (1964-1978), where he was as chairman of the SDP Group (1964-1967) and later as Mayor (1969-1970).