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.
Harald III of Denmark Harald III (Harald the Whetstone, Danish: "Harald Hen" ;  1040 – April 17, 1080) was King of Denmark from 1076 to 1080. Harald III was an illegitimate son of Danish king Sweyn II Estridsson, and contested the crown with some of his brothers. He was a peaceful ruler who initiated a number of reforms. Harald was married to his cousin Margareta Hasbjörnsdatter, but did not leave any heirs, and was succeeded by his brother Canute IV the Saint. Four of his half-brothers were in turn crowned Danish kings.