[4] In the Middle Ages Mortain was the head of an important county (comté), reserved for the reigning house of Normandy.

On the accession of Richard I (1189) he granted it to his brother John, who was thenceforth known as count of Mortain until he ascended the throne (1199).

With his loss of Normandy the comté was lost, but after the recapture of the province by the House of Lancaster, Edmund Beaufort, a grandson of John of Gaunt, was created count of Mortain and so styled till 1441, when he was made earl of Dorset.

Salinger, who wrote The Catcher in the Rye, fought alongside the American forces, an experience that his daughter claims led to his post-traumatic syndrome.

The ruins of a castle was once the home of the cruel Sir Guillaume de Mortain and the site of the Gap of Goeblin.