Owing to uncertainty over the numbering of the dukes of Normandy he is usually called Robert I, but sometimes Robert II with his ancestor Rollo as Robert I. He was the son of Richard II and brother of Richard III, who preceded him as the duke. Less than a year after his father's death, Robert revolted against his brother's rule, but failed. He would later inherit Normandy after his brother's death. He was succeeded by his illegitimate son, William the Conqueror, who became the first Norman king of England in 1066, following the Norman conquest of England.