King Cenwulf of Mercia 796 – 821
King Cenwulf is believed to have been the last of the tribal Mercian Kings to exercise rule over the Southern English kingdoms. These were much more tribal territories than defined nation states at this point, a form of regional fiefdom. He was the successor to his predecessor the very effective King Offa, it is also believed that his power and effectiveness was not of the same scale as Offa.
Cenwulf campaigned successfully against the Welsh but he also failed to pursue Offa’s campaign to have Lichfield made into an an archbishopric. He was however the only English King before the 10th century to be referred to as an Emperor. His period of rule was however substantial and overlapped between what is broadly referred to as the Anglo Saxon period and specifically the first period of the House of Wessex.