William the Conqueror's claim to England ran through Viking Normandy and exiled princes
Before he was the Conqueror, he was known as William the Bastard, the illegitimate son of a Norman duke and a woman from Falaise. He inherited the duchy as a child amid aristocratic chaos, took decades to control it, and then in 1066 crossed the Channel to seize the English crown.
Normandy itself began as a Viking settlement. Before 911 the French king Charles the Simple granted the lands around Rouen to the Norse leader Rollo, William's ancestor. Links with England deepened when King Æthelred married Emma, sister of the Norman duke, in 1002. Driven out by Danish invaders, Æthelred's family sheltered in Normandy, and his son Edward spent years in exile there before becoming king of England in 1042.
William was born at Falaise around 1028, the only son of Duke Robert I and Herleva, whose father may have been a tanner or an embalmer. She never married Robert, but later had two more sons with another husband, including Odo of Bayeux. William became duke as a boy in 1035, and nobles fought over control of him. He crushed a revolt in 1047, and by about 1060 his grip was firm. Marriage to Matilda of Flanders brought a powerful ally, and he took the neighbouring county of Maine by 1062.
Edward the Confessor, William's first cousin once removed, died childless in January 1066 after naming the English earl Harold Godwinson as king. William countered that the crown had been pledged to him long before, and that Harold himself had taken an oath to support him. He built a fleet, invaded that September, and defeated and killed Harold at Hastings on 14 October. He was crowned in London on Christmas Day, and after several failed rebellions his hold was largely secure by 1075.
His reign filled England with castles, replaced much of the old elite with Norman lords and reshaped the clergy. In 1086 he ordered the Domesday Book, recording who held land before and after the conquest. He ran his realms separately rather than as one empire, quarrelled with his eldest son Robert, and died on campaign in northern France in 1087. Normandy passed to Robert, and England to William Rufus.
Source: William the Conqueror
