Guillaume le Conquérant
Upon the death of William's cousin King Edward the Confessor of England (January 1066), William claimed the throne of England, asserting that the childless and purportedly celibate Edward had named him his heir during a visit by William (probably in 1052) and that Harold Godwinson, England's foremost magnate and brother-in-law of the late King Edward the Confessor, had reportedly pledged his support while shipwrecked in Normandy (c. 1064). Harold made this pledge while in captivity and was reportedly tricked into swearing on a saint's bones that he would give the throne to William. Even if this story is true, however, Harold made the promise under duress and so may have felt free to break it. More realistically, by the mid 1050s, Harold was effectively ruling England through the weak King Edward and was unlikely to surrender the throne to a foreign noble.
The assembly of England's leading nobles known as the Witenagemot approved Harold Godwinson’s coronation which took place on January 5, 1066 making him King Harold II of England. In order to pursue his own claim, William obtained the support of the Pope Alexander II for his cause. He assembled a Norman invasion fleet of around 600 ships and an army of 7000 men. He landed at Pevensey in Sussex on September 28, 1066 and assembled a prefabricated wooden castle near Hastings as a base. This was a direct provocation to Harold Godwinson as this area of Sussex was Harold's own personal estate, and William began immediately to lay waste to the land. It may have prompted Harold to respond immediately and in haste rather than await reinforcements in London.