The Cotentin Peninsula, also known as the Cherbourg Peninsula, is a peninsula in Normandy that forms part of the northwest coast of France. It extends north-westward into the English Channel, towards Great Britain. To its west lie the Channel Islands and to the southwest lies the Brittany Peninsula.
The peninsula formed part of the Roman geographical area of Armorica. The town known today as Coutances, capital of the Unelli, a Gaulish tribe, acquired the name of Constantia in 298 during the reign of Roman emperor Constantius Chlorus. The base of the peninsula, called in Latin the pagus Constantinus, joined together with the pagus Coriovallensis centred upon Cherbourg to the north, subsequently became known as the Cotentin. Under the Carolingians it was administered by viscounts drawn successively from members of the Saint-Sauveur family, at their seat Saint-Sauveur on the Douve.
King Alan the Great of Brittany waged war successfully on the Norsemen. As the result of his conquests, the Cotentin Peninsula was included theoretically in the territory of the Duchy of Brittany, after the Treaty of Compiègne (867) with the king of the Franks. The Dukes of Brittany suffered continuing Norse invasions and Norman raids. Eventually the Cotentin Peninsula (and Avranchin nearby) was lost to Brittany after only 70 years of political domination. It became part of Normandy.
Meanwhile Vikings settled the Cotentin in the ninth and tenth century. They were followed by Anglo-Norse and Anglo-Danish people, who established as farmers. It became part of Normandy in the early tenth century. Many placenames there are derived from the Norse language. Examples include La Hague from hagi "meadow" or "enclosure" and La Hougue from haugr meaning a "hill" or "mound". Other names are typical: all those ending with -tot (Quettetot..) from topt "site of a house" (modern -toft), -bec (Bricquebec, Houlbec..) from bekkr "brook", "stream", etc. Until the construction of modern roads, the peninsula was almost inaccessible in winter due to the band of marshland cutting off the higher ground of the promontory itself. This explains occasional historical references to the Cotentin as an island.
In 1088 Robert Curthose, Duke of Normandy, enfeoffed the Cotentin to his brother Henry, later King Henry I of England. Henry, as count of the Cotentin, established his first power base there and in the adjoining Avranchin, which lay to the south, beyond the River Thar.
During the Hundred Years War, King Edward III of England landed in the bay of La Hogue, and then came to the Church of Quettehou in Val de Saire. It was there that Edward III knighted his son Edward, the Black Prince. A remembrance plaque can be seen next to the altar.
The town of Valognes was, until the French Revolution, a provincial social resort for the aristocracy, nicknamed the Versailles of Normandy. The social scene was described in the novels of Jules Barbey d'Aurevilly (himself from the Cotentin). Little now remains of the grand houses and châteaux; they were destroyed by combat there during the Battle of Normandy in World War II.
During World War II, part of the 1944 Battle of Normandy was fought in the Cotentin. The westernmost part of the D-Day landings was at Utah Beach, on the southeastern coast of the peninsula, and was followed by a campaign to occupy the peninsula and take Cherbourg.