William, Duke of Normandy, had decided to take by force the crown of England, which he had been denied by Harold Godwineson's enthronement in January 1066. His invasion fleet landed at Pevensey on 28th September 1066. When news reached Harold returning from his victory at Stamford Bridge in Yorkshire, he marched hurriedly southwards and arrived near Hastings overnight on 13/14 October.
Harold's position was strong, and when William attacked the English gave no ground. Indeed, it was the Norman army which broke in the belief that William had been killed, but the Duke rallied his troops and led renewed attacks. It was the apparent further retreat by the Normans, which finally lured the English away from their defensive positions and led to their downfall as the Norman troops turned on them. The battle lasted all day, but by evening King Harold was dead and his army, despite repeated stands, was broken.
The Battle of Hastings holds a special place in English history as the last English battle which lad to the conquest of the nation. It marked the opening of a new phase in English history both in terms of domestic politics and the relationship with Europe. It influenced the whole development of the ecclesiastical and political institutions of western Christendom. Its importance cannot be overstated.
Most of the battlefield is in the ownership of English Heritage and the battle is interpreted for visitors. The site of Harold's death is reputedly marked by the high altar of the Abbey at Battle.
Douglas, D C, Greenaway, G W (eds.) English Historical Documents 1042 1189