Alfred the Great was King of Wessex from 871 to c. 886 and King of the Anglo-Saxons from c. 886 to 899. He was the youngest son of King Æthelwulf of Wessex. His father died when he was young and three of Alfred's brothers reigned in turn. Alfred took the throne after the death of his brother Æthelred and spent several years dealing with Viking invasions. He won a decisive victory in the Battle of Edington in 878 and made an agreement with the Vikings, creating what was known as Danelaw in the North of England. Alfred also oversaw the conversion of Viking leader Guthrum. He successfully defended his kingdom against the Viking attempt at conquest, and he became the dominant ruler in England. He was also the first King of the West Saxons to style himself King of the Anglo-Saxons. Details of his life are described in a work by 9th-century Welsh scholar and bishop Asser.