In the early 1030s Alan III , Duke of Brittany began expanding his influence from the area of Rennes and appeared to have designs on the area surrounding Mont Saint-Michel After sacking Dol and repelling Alan 's attempts to raid Avranches , Robert mounted a major campaign against his cousin Alan III .
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 .