The Battle of Aclea occurred in 851 between the West Saxons led by Æthelwulf, King of Wessex from 839 to what year, 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.
Æthelberht II of East Anglia Æthelberht (Old English: "Æðelbrihte"), also called Saint Ethelbert the King, (died 20 May 794 at Sutton Walls, Herefordshire) was an eighth-century saint and a king of East Anglia, the Anglo-Saxon kingdom which today includes the English counties of Norfolk and Suffolk. Little is known of his reign, which may have begun in 779, according to later sources, and very few of the coins issued during his reign have been discovered. It is known from the "Anglo-Saxon Chronicle" that he was killed on the orders of Offa of Mercia in 794.