 Beorhtwulf ( pronounced [ <unk> ] , meaning " bright wolf " ; also spelled Berhtwulf ; died 852 ) was King of Mercia , a kingdom of Anglo @-@ Saxon England , from 839 or 840 to 852 . His ancestry is unknown , though he may have been connected to Beornwulf , who ruled Mercia in the 820s . Almost no coins were issued by Beorhtwulf 's predecessor , Wiglaf , but a Mercian coinage was restarted by Beorhtwulf early in his reign , initially with strong similarities to the coins of Æthelwulf of Wessex , and later with independent designs . The Vikings attacked within a year or two of Beorhtwulf 's accession : the province of Lindsey was raided in 841 , and London , a key centre of Mercian commerce , was attacked the following year . Another Viking assault on London in 851 " put Beorhtwulf to flight " , according to the Anglo @-@ Saxon Chronicle ; the Vikings were subsequently defeated by Æthelwulf . This raid may have had a significant economic impact on Mercia , as London coinage is much reduced after 851 . 
