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.
Æthelhard Æthelhard (died 12 May 805) was a Bishop of Winchester then an Archbishop of Canterbury in medieval England. Appointed by King Offa of Mercia, Æthelhard had difficulties with both the Kentish monarchs and with a rival archiepiscopate in southern England, and was deposed around 796 by King Eadberht III Præn of Kent. By 803, Æthelhard, along with the Mercian King Coenwulf, had secured the demotion of the rival archbishopric, once more making Canterbury the only archbishopric south of the Humber in Britain. Æthelhard died in 805, and was considered a saint until his cult was suppressed after the Norman Conquest in 1066.