stylistic:tone
English and continental concerns

In 1051 the childless King Edward of England appears to have chosen William as his successor. William was the grandson of Edward's maternal uncle, Richard II of Normandy.

The Anglo-Saxon Chronicle, in the "D" version, states that William visited England in the later part of 1051, perhaps to secure confirmation of the succession, or perhaps to secure aid for his troubles in Normandy. The trip is unlikely given William's absorption in warfare with Anjou at the time. Whatever Edward's wishes, it was likely that any claim by William would be opposed by Godwin, Earl of Wessex, a member of the most powerful family in England. Edward had married Edith, Godwin's daughter, in 1043, and Godwin appears to have been one of the main supporters of Edward's claim to the throne. By 1050, however, relations between the king and the earl had soured, culminating in a crisis in 1051 that led to the exile of Godwin and his family from England. During this exile, Edward offered the throne to William. Godwin returned from exile in 1052 with armed forces, and a settlement was reached between the king and the earl, restoring the earl and his family to their lands and replacing Robert of Jumièges, a Norman whom Edward had named Archbishop of Canterbury, with Stigand, the Bishop of Winchester. No English source mentions a supposed embassy by Archbishop Robert to William conveying the promise of the succession, and the two Norman sources that mention it, William of Jumièges and William of Poitiers, are not precise in their chronology of when this visit took place.

Count Herbert II of Maine died in 1062, and William, who had betrothed his eldest son Robert to Herbert's sister Margaret, claimed the county through his son. Local nobles resisted the claim, but William invaded and by 1064 had secured control of the area. William appointed a Norman to the bishopric of Le Mans in 1065. He also allowed his son Robert Curthose to do homage to the new Count of Anjou, Geoffrey the Bearded. William's western border was thus secured, but his border with Brittany remained insecure. In 1064 William invaded Brittany in a campaign that remains obscure in its details. Its effect, though, was to destabilise Brittany, forcing the duke, Conan II, to focus on internal problems rather than on expansion. Conan's death in 1066 further secured William's borders in Normandy. William also benefited from his campaign in Brittany by securing the support of some Breton nobles who went on to support the invasion of England in 1066.

Earl Godwin died in 1053. Harold succeeded to his father's earldom, and another son, Tostig, became Earl of Northumbria. Other sons were granted earldoms later: Gyrth as Earl of East Anglia in 1057 and Leofwine as Earl of Kent sometime between 1055 and 1057. Some sources claim that Harold took part in William's Breton campaign of 1064 and swore to uphold William's claim to the English throne, but no English source reports this trip, and it is unclear if it actually occurred. It may have been Norman propaganda designed to discredit Harold, who had emerged as the main contender to succeed King Edward. Meanwhile, another contender for the throne had emerged – Edward the Exile, son of Edmund Ironside and a grandson of Æthelred II, returned to England in 1057. Although he died shortly after his return, he brought with him his family, which included two daughters, Margaret and Christina, and a son, Edgar the Ætheling.

In 1065 Northumbria revolted against Tostig, and the rebels chose Morcar, the younger brother of Edwin, Earl of Mercia, as earl. Harold, perhaps to secure the support of Edwin and Morcar in his bid for the throne, supported the rebels and persuaded King Edward to replace Tostig with Morcar. Tostig went into exile in Flanders with his wife Judith, who was the daughter of Baldwin IV, Count of Flanders. Edward was ailing, and he died on 5 January 1066. It is unclear what exactly happened at Edward's deathbed. One story, deriving from the Vita Ædwardi, a biography of Edward, claims that he was attended by his wife Edith, Harold, Archbishop Stigand, and Robert FitzWimarc, and that the king named Harold as his successor. The Norman sources do not dispute that Harold was named as the next king, but they declare that Harold's oath and Edward's earlier promise of the throne could not be changed on Edward's deathbed. Later English sources stated that Harold had been elected as king by the clergy and magnates of England.