Robert gave shelter to Henry I of France against his mother, Queen Constance. The queen wanted her younger son Robert to succeed his father Robert II as king of France. For his help Henry I gave Robert the French Vexin. In the early 1030s Alan III, Duke of Brittany began to expand from the area of Rennes and appeared to have wanted the area around Mont Saint-Michel After raiding Dol and stopping Alan's attempts to raid Avranches, Robert mounted a major campaign against his cousin Alan III. However, Alan appealed to Archbishop Robert of Rouen (they were both his nephews). The Archbishop arranged a peace between Duke Robert and his vassal Alan III.