The dynasty of Rollo’s heirs that conquered England in 1066 and ruled a cross-Channel Anglo-Norman realm until the civil war known as the Anarchy.
The dynasty began with Rollo, a Viking leader who, by the treaty traditionally dated to 911 at Saint-Clair-sur-Epte, received the lands around Rouen from the West Frankish king Charles the Simple in exchange for defending the Seine and accepting baptism. His descendants — William Longsword, Richard I, and Richard II — expanded and consolidated the territory that became the Duchy of Normandy.
Within a few generations the Northmen had become Normans: French-speaking, Christian, and organised around a powerful duke, castles, and a martial aristocracy. That combination of Scandinavian aggression and Frankish institutions made Normandy one of the most effective principalities in eleventh-century Europe.
William, an illegitimate son of Duke Robert I, survived a violent minority to master Normandy. When Edward the Confessor died childless in 1066, William claimed the English throne against Harold Godwinson. He crossed the Channel, and at the Battle of Hastings on 14 October 1066 Harold was killed and the English army destroyed.
The Norman Conquest replaced the English ruling class with a Norman aristocracy, introduced a network of castles, and produced the Domesday survey of 1086. William held England and Normandy together, ruling a cross-Channel realm whose politics would shape both countries for centuries.
William was succeeded in England by his son William II Rufus, a forceful and irreligious king killed by an arrow in the New Forest in 1100. His younger brother Henry I seized the throne, defeated their eldest brother Robert Curthose at Tinchebrai in 1106, and reunited England and Normandy.
Henry I was a formidable administrator who developed the Exchequer and royal justice. But the drowning of his only legitimate son, William Adelin, in the wreck of the White Ship in 1120 left him without a male heir and set the stage for a succession crisis.
Henry I named his daughter, the Empress Matilda, as his heir and had his barons swear to accept her. On his death in 1135 his nephew Stephen of Blois seized the crown instead, and the rival claims plunged England into nearly two decades of civil war known as the Anarchy.
Neither side could win outright. The Treaty of Wallingford in 1153 recognised Stephen as king for life but made Matilda’s son, Henry of Anjou, his heir. When Stephen died in 1154, the throne passed to Henry II, and with him the House of Plantagenet, closing the Norman royal line in England.
The Norman dynasty bound England to continental Europe and remade its ruling culture. It imposed a French-speaking aristocracy and a feudal tenurial system, covered the country in motte-and-bailey and stone castles, rebuilt cathedrals and abbeys in the Romanesque style, and left the Domesday Book as an unrivalled record of the conquered land.
The Anglo-Norman realm the dynasty created — an English kingdom whose kings were also great French princes — outlived the house itself and defined the political geography that the Plantagenets inherited, including the long entanglement with France that would culminate in the Hundred Years’ War.