The "Anglo-Saxon Chronicle" records that in 702 Coenred succeeded to the kingdom of the Southumbrians and that in 704 he became king of Mercia. As the "Southumbrians" were those who lived south of the Humber, Mercia's northern boundary, the two annals have proved difficult to interpret: Coenred and Æthelred may have ruled jointly for two years before Æthelred abdicated, or the chroniclers may have recorded the same event twice, once from a source that was two years in error. According to the 8th-century life of St Guthlac, Æthelred appointed Coenred as his heir despite having at least one son of his own, Ceolred. Æthelred appears to have retained influence during his nephew's reign: the "Life of St Wilfrid" relates how he summoned Coenred and made him swear to support Wilfrid in his conflict with the church hierarchy.