 Following a Mercian attack in 651 on the monastery at Cnobheresburg, Anna was exiled by Penda, possibly to the kingdom of the Magonsæte.After his return, East Anglia was attacked again by Penda, Anna's forces were defeated and he was killed.During the reign of his successor, Æthelhere (another brother of Æthelwold), East Anglia was eclipsed by Mercia.