Battle of Hastings

On October 14, 1066, at the Battle of Hastings, William, Duke of Normandy, and his Norman army defeated the English forces of Harold II who was killed in the battle. From the article:

"The Battle of Hastings in south-east England on 14 October 1066 saw the defeat of the Anglo-Saxon king Harold II (r. Jan-Oct 1066) by the invading Norman army led by William, Duke of Normandy (reigned from 1035). After a day of heavy fighting, the Norman cavalry eventually proved more effective than the Anglo-Saxon infantry.

William claimed the throne of England had been promised to him by Harold's predecessor, Edward the Confessor (r. 1042-1066) and he had invaded England to take by force the kingdom he considered rightfully his. Harold was killed in the battle, according to tradition, hit by an arrow to the eye and then hacked to pieces as he fell. The victor would be crowned king of England on Christmas Day of the same year and, over the next five years, his conquest of England would earn him the title of William the Conqueror. Hastings brought an end to 500 years of Anglo-Saxon rule and innumerable political, religious, and cultural changes over the coming decades as the Norman elite installed themselves throughout their new kingdom, setting up castles and creating such innovations as the Domesday Book."