On the death of his father (1026/27), Robert contested the duchy with his elder brother Richard III, legally the heir, until the latter's opportune death a few years later. A strong ruler, Robert succeeded in exacting the obedience of his vassals. On the death of Robert II the Pious, king of France (1031), a crisis arose over the succession to the French throne. The Duke gave his support to Henry I against the party favouring his younger brother; in reward for his services he demanded and received the Vexin Français, a territory not far north of Paris. A patron of the monastic reform movement, he died while returning from a pilgrimage to Jerusalem.


Robert I was Duke 1028-35. His wife is Estrith, sister of Canute the Great (no issue). Robert was called "Robert the Devil", accused of poisoning his brother (whom Robert succeeded as Duke); he sheltered the exiled English princes, Edward and Alfred; he died returning from a pilgrimage to Jerusalem.

References: [RFC],[Weis1],[Paget1],[MRL],[AR7],[CP]