Following Offa on the throne of Mercia was Coenwulf, who succeeded the great king in name and deed. He was indeed an overlord, much as Offa was, and he played the part well. He even had his own silver penny made.
Coenwulf, of course, had really succeeded Ecgfrith, Offa’s son, who managed to hold onto the crown for only 141 days. Coenwulf proving himself the better man for the throne, Ecgfrith paid for his defense of his father’s bloodline with his own blood.
Coenwulf soon went about continuing the anti-Welsh doctrine of Offa, engaging the Welsh on their own land in the 797 Battle of Rhuddlan. Fighting against a combined force from Powys and Dyfed, Coenwulf scores a convincing victory, even gaining for himself the spoils of killing Dyfed’s King Maredydd.
After this significant victory, Coenwulf continued into Wales. The next year, at a battle in Snowdonia, Coenwulf and his crack Mercian troops add Gwynedd’s King Caradog to the list of the Welsh kings killed in battle. Coenwulf’s domination of eastern Wales is nearly complete.
Not much more is mentioned in the Anglo-Saxon and Welsh chronicles of the times, for a number of years. We are left to assume that the struggles between the two peoples continued off and on. The thread of Coenwulf in Wales is taken up again in 818, when the chroniclers tell us that the Mercians raided Dyfed. (One chronicle uses the word “ravaged.”)
Coenwulf continued his campaigning in Wales until his death at Basingwerk, in 821. His target at the time: Powys.
So we can see from a simple glance at a map that Coenwulf and his Mercians were controlling a vast amount of territory at this time. In addition to most of Anglo-Saxon England (in one way or another), Mercia now controlled or could lay claim to much of Wales. The results of Coenwulf may very well be seen to have outstripped even the lofty ambitions of the great King Offa.
Coenwulf did his part for the Church as well, granting money for the establishment of churches and abbeys throughout Mercia. But such offerings to the Church did little to assuage the concerns of the common people, who were suffering the most under the Mercian yoke. The tradition of Offa, reinforced by Coenwulf, went a long way toward the viewing of Mercia as “the beast.” In just a few years more, Wessex would be seen as the instrumental of salvation from the oppression precipitated by Mercia.