787. Synod of Chelsea: Lichfield established as third archbishopric
Ecgfrith, son of Offa of Mercia, consecrated king
The Anglo-Saxon Chronicle reports that there was a contentious synod at Chelsea, and Archbishop Jænberht lost part of his province, and Hygeberht was chosen by King Offa, and Ecgfrith was consecrated king.
The third archbishopric at Lichfield existed from the Synod of Chelsea in 787 until it was demoted back to a bishopric at the Synod of Clofesho in 803. Hygeberht was the first and only archbishop. Most of what we know about the see comes from letters written in the five years before it is abolished. Alcuin writes to Æthelheard, archbishop of Canterbury, in 798 (EHD 203), suggesting that it would be good if the unity of the (southern English) church could be restored, given that it was apparently torn asunder not out of reasonable motives but out of a desire for power. In the same year Offa's successor Coenwulf wrote to Pope Leo III (EHD 204), noting that Offa had divided the southern archdiocese in two because of his enmity against Archbishop Jænberht and the people of Kent. Pope Leo replied (EHD 205) that Offa had told the previous pope that it was the united wish of all the English people that there should be a new southern archbishopric, both because of the vast size of the country and of the expansion of the Mercian kingdom. (Pope Leo incidentally quashed Coenwulf's suggestion that the southern archdiocese be placed in London rather than restored to Canterbury; this had been a clever ploy of Coenwulf's, because while he claimed that he was trying to restore Pope Gregory's original choice for the southern see, his more pragmatic reason would be that London was much more under Mercian control than Canterbury had been.) The Pope wrote to Æthelheard of Canterbury on January 18, 802 (EHD 209), confirming the ancient privileges of the see of Canterbury, and this ruling was confirmed by the 803 Synod of Clofesho.
It seems clear then that Offa convinced Pope Hadrian that the division of the see was because Southumbrian England was too large for a single archbishopric, but that he misrepresented this as a unanimous view, and that his underlying reasons included enmity with Jænberht and the people of Kent. The fact that the Chronicle notes that Ecgfrith was consecrated king immediately after it notes the new archbishopric may suggest that the Kentish archbishop, Jænberht, refused to consecrate Ecgfrith. Jænberht might well have feared that the anointing of a Mercian prince by the archbishop of Canterbury might be seen as conferring hereditary rule over all of southern England, including Kent which had been independent until Offa re-occupied it two years previously (see Brooks, pp.119-20).
The enmity between Offa and Jænberht raises the possibility that it was Jænberht who started the rumour that surfaced in about 784 that Offa planned to dethrone the pope, as part of a plan to discredit Offa in the Papal Curia and ensure that any suggestion from the Mercian king about changing the arrangement of bishoprics should fall on deaf (or enraged) ears. (See entry on 786 for the background to this rumour, which may have helped prompt the dispatch of the papal legates to England.)
Ecgfrith was the first Anglo-Saxon whom we know to have been anointed as king (Eardwulf of Northumbria in 796 is the next known case). This anointing of the son of a reigning king during the king's lifetime follows the example of Charlemagne, who in 781 sent his two sons to be anointed by the pope (see Brooks, p.117). Offa's own example shows that the Mercian kingship was not always handed down in the immediate family (the closest common ancestor of Offa and his predecessor Æthelbald was Eowa, Penda's brother and Offa's great-great-grandfather), and he may well have felt that his son needed as much support as he could give him. After his anointing, Ecgfrith often witnesses at least two of Offa's charters as "Ecgfrith king" or even "Ecgfrith king of the Mercians" (S 129, 131) after his father's attestation, another clear sign that Offa associated his son with the royal power and intended to pass the kingship to his son. Alcuin implied in a letter written after Offa and Ecgfrith were both dead that Offa also killed many other claimants to ensure his son's succession (EHD 202), and it is clear that Alcuin regarded Ecgfrith's short reign as divine vengeance for the deaths compassed by his father.
N. Brooks, The Early History of the Church of Canterbury (Leicester: 1984)