Duchy of Normandy
The history of the Bailiwick of Guernsey goes back to 933, when the islands came under the control of William Longsword, having been annexed from the Duchy of Brittany by the Duchy of Normandy. The island of Guernsey and the other Channel Islands formed part of the lands of William the Conqueror. In 1204 France conquered mainland Normandy – but not the offshore islands of the bailiwick. The islands represent the last remnants of the medieval Duchy of Normandy.