Rainer or Reginar III succeeded his father. With his brother Rodolfe he took the side of Louis d'Outremer, King of France, against Otto I, King of Germany. Rainer was forced to subdue Conrad, Duke of Lorraine, in 952, but after peace was restored he committed many acts of violence, even daring to seize lands possessed by the Dowager Queen Gerberga, widow of King Louis. King Lothair forced Rainer, in 956, to restore the lands he had taken from the Queen. The next year Rainer made war on Duke Bruno, Archbishop of Cologne and brother of King Otto, but was defeated and forced to submit to the prelate. Later he was deposed by Bruno in 958 and sent into exile. He married Alix, daughter of Hugo, Count of Dagsburg and Egisheim, and had Lambert, Count of Louvain, and Rainer or Reginar IV, Count of Hainaul.