1065 Battle of Dinan

Conan 2 vs William the bastard in the Breton-Norman war
Before the invasion of England, William the bastard of Normandy sent word to Brittany, warning them against attacking his lands, because he was backed by the Roman pope.
Conan 2 of Brittany said to William the bastard that he would take the opportunity to invade, so William's Norman army set out for battle. Outside the monastery of Mont Saint-Michel, two Norman soldiers became mired in quicksand, but Harold Godwinson, at that time allied with Normans saved their lives.William the conqueror`s army chased Conan  from Dol-de-Bretagne to Rennes and the Britons finally surrendered at Château de Dinan.
William ordered the construction of ships
An unexpected ally came to Harald Godwinson. King Harold’s brother Tostig had been deprived of his earldom in Northumbria by Edward in October 1065