The Diocese of Mercia was created by Bishop Diuma in around 656 and the see was settled in Lichfield in 669 by the then bishop, Ceadda (later Saint Chadd). At the Council of Chelsea, Bishop Higbert was raised to the rank of archbishop and given authority over the dioceses of Worcester, Leicester, Lincoln, Hereford, Elmham and Dunwich. This was due to the persuasion of King Offa of Mercia, who wanted an archbishop to rival Canterbury. On Offa's death, however, the Pope removed the archepiscopal rank and restored the dioceses to the authority of Canterbury. In 803 the Council of Clovesho accepted this decision.
During the 9th century, the diocese was devastated by the Vikings. Lichfield itself was unwalled and had become rather poor, so Bishop Peter moved the see to the fortified and wealthier Chester in 1075. His successor, Robert de Limesey, transferred it to Coventry and the diocese was renamed the Diocese of Coventry and Lichfield. At this stage it also covered Derbyshire and most of Warwickshire.
In 1539 the see was transferred back to Lichfield and the name was reversed to become the Diocese of Lichfield and Coventry. In 1918 the diocese was split when the new Diocese of Coventry was created, and again became simply the Diocese of Lichfield for the first time in eight hundred years.
This diocese took its rise in the conversion of Mercia by St. Cedd and his three companions in 652 and subsequent years.
But Lichfield, though lessened in territory, grew in political importance until the time of the ascendancy of Mercia under Offa, when that king determined to raise Lichfield as a rival to Canterbury.
The chapter at Lichfield was nevertheless maintained, and one of the early Norman bishops, Roger de Clinton, rebuilt its cathedral there, re-dedicating it to St. Chad, whose relics he there enshrined.