William I (Old Norman: Williame I; circa 1028 – 9 September 1087), usually known as William the Conqueror and sometimes as William the Bastard,[a] was the first Norman King of England, reigning from 1066 until his death in 1087. Descended from Viking raiders, he had been Duke of Normandy since 1035 under the title of William II. After a long struggle to establish his power, by 1060 his hold on Normandy was secure, and he launched the Norman conquest of England in 1066. The rest of his life was marked by struggles to consolidate his hold over England and his continental lands and by difficulties with his eldest son. William was the son of the unmarried Robert I, Duke of Normandy by his mistress Herleva. His illegitimate status and his youth caused some difficulties for him after he succeeded his father, as did the anarchy that plagued the first years of his rule. During his childhood and adolescence, members of the Norman aristocracy battled each other, both for control of the child duke and for their own ends. In 1047 William was able to quash a rebellion and begin to establish his authority over the duchy, a process that was not complete until about 1060. His marriage in the 1050s to Matilda of Flanders provided him with a powerful ally in the neighbouring county of Flanders. By the time of his marriage, William was able to arrange the appointments of his supporters as bishops and abbots in the Norman church. His consolidation of power allowed him to expand his horizons, and by 1062 William was able to secure control of the neighbouring county of Maine.

William was born in 1027 or 1028 at Falaise, Normandy, probably towards the end of the latter year.[8][c] He was the only son of Robert I, Duke of Normandy, son of Duke Richard II.[d] His mother, Herleva, was the daughter of Fulbert of Falaise; Fulbert may have been a tanner or embalmer.[9] She was possibly a member of the ducal household, but did not marry Robert. Instead, she later married Herluin de Conteville, with whom she had two sons – Odo of Bayeux and Robert, Count of Mortain – and a daughter whose name is unknown.[e] One of Herleva's brothers, Walter, became a supporter and protector of William during his minority.[9][f] Robert also had a daughter, Adelaide of Normandy, by another mistress.[12] Robert, William's father, became Duke of Normandy on 6 August 1027, in succession to his elder brother Richard III, who had only succeeded to the title the previous year. Robert and his brother had been at odds over the succession, and Richard's death was very sudden. Robert was accused by some writers of killing his brother, a plausible but now unprovable charge.[13] Conditions in Normandy were unsettled, as noble families despoiled the Church and Alan III of Brittany waged war against the duchy, possibly in an attempt to take control. By 1031 Robert had gathered considerable support from noblemen, many of whom would become prominent during William's life. They included Robert's uncle, Robert the archbishop of Rouen, who had originally opposed the duke, Osbern, a nephew of Gunnor the wife of Duke Richard I, and Count Gilbert of Brionne, a grandson of Richard I.[14] After his accession, Robert continued Norman support for the English princes Edward and Alfred, who were still in exile in northern France. There are indications that Robert may have been briefly betrothed to a daughter of King Cnut, but no marriage took place. It is unclear if William would have been supplanted in the ducal succession if Robert had had a legitimate son. Earlier dukes had been illegitimate, and William's association with his father on ducal charters appears to indicate that William was considered Robert's most likely heir. In 1034 Duke Robert decided to go on pilgrimage to Jerusalem. Although some of his supporters tried to dissuade him from undertaking the journey, Robert convened a council in January 1035 and had the assembled Norman magnates swear fealty to William as his heir[15] before leaving for Jerusalem. He died in early July at Nicea, on his way back to Normandy.[15]

William left England towards the end of 1086. Following his arrival back on the continent he married his daughter Constance to Alan Fergant, the Count of Brittany, in furtherance of his policy of seeking allies against the French kings. William's son Robert, still allied with the French King Philip I, appears to have been active in stirring up trouble, enough so that William led an expedition against the French Vexin in July 1087. While seizing Mantes, William either fell ill or was injured by the pommel of his saddle.[136] He was taken to the priory of St Gervase at Rouen, where he died on 9 September 1087. Knowledge of the events preceding his death is confused because there are two different accounts. Orderic Vitalis preserves a lengthy account, complete with speeches made by many of the principals, but this is likely more of an account of how a king should die than of what actually happened. The other, the De Obitu Willelmi, or On the Death of William, has been shown to be a copy of two 9th-century accounts with names changed.[136] William left Normandy to Robert, and the custody of England was given to William's second surviving son, also called William, on the assumption that he would become king. The youngest son, Henry, received money. After entrusting England to his second son, the elder William sent the younger William back to England on 7 or 8 September, bearing a letter to Lanfranc ordering the archbishop to aid the new king. Other bequests included gifts to the Church and money to be distributed to the poor. William also ordered that all of his prisoners be released, including his half-brother Odo.[136] Disorder followed William's death; everyone who had been at his deathbed left the body at Rouen and hurried off to attend to their own affairs. Eventually, the clergy of Rouen arranged to have the body sent to Caen, where William had desired to be buried in his foundation of the Abbaye-aux-Hommes. The funeral, attended by the bishops and abbots of Normandy as well as his son Henry, was disturbed by the assertion of a citizen of Caen who alleged that his family had been illegally despoiled of the land on which the church was built. After hurried consultations the allegation was shown to be true, and the man was compensated. A further indignity occurred when the corpse was lowered into the tomb. The corpse was too large for the space, and when attendants forced the body into the tomb it burst, spreading a disgusting odour throughout the church.[137] William's grave is currently marked by a marble slab with a Latin inscription dating from the early 19th century. The tomb has been disturbed several times since 1087, the first time in 1522 when the grave was opened on orders from the papacy. The intact body was restored to the tomb at that time, but in 1562, during the French Wars of Religion, the grave was reopened and the bones scattered and lost, with the exception of one thigh bone. This lone relic was reburied in 1642 with a new marker, which was replaced 100 years later with a more elaborate monument. This tomb was again destroyed during the French Revolution, but was eventually replaced with the current marker.[138][v]