After Rome left Britain around 410 CE, Germanic tribes—the Angles, Saxons, and Jutes—migrated in and formed competing kingdoms. Viking invasions in the 800s destroyed most of them. Wessex, under Alfred the Great, survived. He defeated the Danes at Edington in 878, built fortified towns (burhs), and created England’s first navy. His grandson Athelstan united the English kingdoms by 927. England now functioned as a single state, with royal mints, written laws, a national land tax called the geld, and royal officials to collect it.

In 1016, the Danish king Cnut invaded and seized the English throne after years of fighting between his forces and those of Edmund Ironside. Cnut kept England’s administrative system intact and ruled through existing laws and institutions. When his sons died without heirs, the English throne returned to the old royal line with Edward the Confessor in 1042. Edward was English by birth but had spent about 25 years in exile in Normandy during the Danish period, and he brought Norman advisers into his court, which caused resentment among the Anglo-Saxon nobility.

When Edward died childless in 1066, England’s council (the Witenagemot) chose Harold Godwinson—earl of Wessex and the leading English noble—as king. But Duke William of Normandy claimed Edward had promised him the crown years earlier. William gathered an invasion force of about 7,000 men and landed at Pevensey in September 1066. On October 14, at the Battle of Hastings, Harold’s army fought from a hill behind a shield wall that held for most of the day. William’s cavalry and archers eventually broke it—possibly after Harold was killed, according to later sources, by an arrow to the face or eye. William advanced on London; the English leaders submitted, and he was crowned king on Christmas Day 1066 in Westminster Abbey. Over the next twenty years, he crushed uprisings, devastated the north so severely that the Domesday Book of 1086 still listed much of it as “waste,” and replaced nearly every Anglo-Saxon noble with Norman barons. Norman French became the language of government. England now had a foreign ruling class and a king who was also Duke of Normandy—a vassal of the French crown. This dual role would create centuries of conflict between England and France.

William’s heirs expanded their French possessions. Henry I conquered Normandy in 1106. His grandson Henry II, crowned 1154, married Eleanor of Aquitaine and ruled an empire stretching from Scotland to the Pyrenees—England, Normandy, Anjou, Maine, Touraine, Aquitaine, and Gascony. Henry II and his sons Richard I and John spoke French and spent most of their time in France, governing England through local sheriffs and royal justices while fighting to defend their French lands. In 1204 King John lost Normandy, Anjou, and Maine to Philip II of France. Many English nobles had owned land on both sides of the Channel; once those territories were gone, they had to choose which king to serve. Most kept their English estates and swore loyalty to the English crown, giving up their holdings in France. Over the next generation, these nobles began to see themselves as English rather than Norman. The English crown, however, still held Gascony and Aquitaine.

When the French king Charles IV died in 1328 without sons, the closest male relative was Edward III of England—his mother, Isabella, was Charles’s sister. French jurists rejected Edward’s claim under Salic Law, which barred inheritance of the crown through the female line, and they crowned Philip VI of Valois instead. Edward, still young and facing war in Scotland, accepted this for a time. But Philip later supported rebels in Gascony and asserted French jurisdiction there. In 1337 he declared Gascony forfeit. Edward responded by claiming the French crown himself and beginning the Hundred Years’ War (1337–1453).

The war came in long phases. English armies won major early victories—Crécy (1346), Poitiers (1356), and Agincourt (1415)—thanks to disciplined infantry and the longbow. Under Henry V, England gained control of northern France and secured a treaty naming him heir to the French throne. But after his death in 1422, the French rallied under Charles VII and Joan of Arc. Through steady reconquest, France retook its territory, capturing Bordeaux in 1453 and ending the war. England kept only Calais. The conflict permanently ended the dual monarchy problem created by the Norman Conquest: England became an independent island kingdom, and France a unified continental state.