Harold's predecessor, the childless Edward the Confessor (Edward), had at first probably designated William, a cousin, as his heir but on his deathbed (Jan. 5, 1066) granted the kingdom to Harold, earl of Wessex and the most powerful man in the kingdom; Harold was crowned king the next day.

On September 27 William crossed to England unopposed, with an army of 4,000 to 7,000 cavalry and infantry, disembarking at Pevensey in Sussex and moving eastward along the coast to Hastings. Harold learned of William's landing on or about October 2 and hurried southward; by October 13 Harold was approaching Hastings with about 7,000 men, many of whom were half-armed, untrained peasants. At dawn on October 14 William moved toward Harold's army, which was occupying a ridge 10 miles (16 km) northwest of Hastings. William disposed his army for attack—archers in front, infantrymen behind, and the knights in three groups to the rear. Harold's English army, lacking archers and cavalry, prepared for defense on the protected summit of the ridge. His men, too closely ranged, provided an excellent target for William's archers, who opened the Norman attack but suffered heavily from English slings and spears. William therefore threw in his cavalry, which was so badly mauled by the English infantry wielding two-handed battle-axes that it fled. William checked its flight and throughout the day launched on the English position a series of alternate cavalry charges and flights of arrows. By two feigned retreats he drew considerable numbers of Englishmen from their position and then turned and annihilated them. Gradually the English were worn down; two of Harold's brothers fell, and in the late afternoon he himself was killed when, according to the Bayeux Tapestry, he was struck in the eye by an arrow. The leaderless English fought on until dusk, then broke; after a last rally they scattered, leaving William the winner of one of the most daring gambles in history. After the battle his army moved to isolate London, where William I was crowned king on December 25.