Name the King of Wessex from 839 to 858 whose father, King Egbert, defeated Beornwulf of Mercia and who himself led the Battle of Aclea between the West Saxons and the Danish Vikings?
Æthelwulf Æthelwulf (Old English for "Noble Wolf"; died 13 January 858) was King of Wessex from 839 to 858. In 825, his father, King Egbert, defeated King Beornwulf of Mercia, ending a long Mercian dominance over Anglo-Saxon England south of the Humber. Egbert sent Æthelwulf with an army to Kent, where he expelled the Mercian sub-king and was himself appointed sub-king. After 830, Egbert maintained good relations with Mercia, and this was continued by Æthelwulf when he became king in 839, the first son to succeed his father as West Saxon king since 641.
Beonna of East Anglia Beonna (also known as Beorna) was King of East Anglia from 749. He is notable for being the first East Anglian king whose coinage included both the ruler's name and his title. The end-date of Beonna's reign is not known, but may have been around 760. It is thought that he shared the kingdom with another ruler called Alberht and possibly with a third man, named Hun. Not all experts agree with these regnal dates, or the nature of his kingship: it has been suggested that he may have ruled alone (and free of Mercian domination) from around 758.