Question: 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?
{'answer': 'Æthelwulf', 'supporting_facts': [['Battle of Aclea', 0], ['Æthelwulf', 0], ['Æthelwulf', 1]]}