Known as "William the Conqueror," William I was the first Norman monarch of England, serving as Duke of Normandy before rising to the throne of England in 1066. Due to his illegitimacy as the son of a concubine, William faced massive challenge to his power. William came to rule England through the Battle of Hastings in 1066, in which his army of Normans defeated the Anglo-Saxon forces. As King of England, William struggled to secure and maintain his power in England and the continent.