Normandy, French Normandie, historic and cultural region of northern France encompassing the départements of Manche, Calvados, Orne, Eure, and Seine-Maritime and coextensive with the former province of Normandy. It was recreated as an administrative entity in 2016 with the union of the régions of Basse-Normandie and Haute-Normandie. (Read Sir John Keegan’s Britannica entry on the Normandy Invasion.) The Seine and Eure valleys were inhabited from Paleolithic times. Their Celtic inhabitants were conquered by Julius Caesar in 56 bce, and the region eventually became the Roman province of Gallia Lugdunensis Secunda. Its inhabitants were Christianized in the 3rd and 4th centuries