At what precise period Herefordshire passed under the Saxon yoke, and became annexed to Mercia, is unknown—probably under Creoda, early in the seventh century. The see was founded in 680, when a synod was held here under Putta, the first bishop. Sutton, or Southton, so called from its position close south of the Roman camp to which it has given its name, was at a very early period a residence of the Mercian kings. Here, in the middle of the eighth century, resided the celebrated Offa, probably during the construction of his dyke, which passes about six miles to the west; and here in 794 was committed the murder of Ethelbert, his intended son-in-law, a deed which led to the aggrandisement of the cathedral church, to which Offa’s penitential donations were largely paid. A charter of King Cœnulf, A.D. 799, mentions Hereford, as do others by Deneberht, in 802 and 803, the last recording certain “monasteria quæ olim in antiquis dictis ad Herefordensem ecclesiam præstita fuerunt.” Sutton continued a Mercian palace until the union of the seven kingdoms, under Egbert of Wessex, in 827. Edward the Elder, a great constructor of strong places, who repaired the citadel and walls of Chester in 909, is said by Grafton also to have fortified Hereford, erecting a strong castle there. His sister Ethelfleda, a still greater castle-builder than he, and to whom are due the mounds of Tutbury, Tamworth, Leicester, and some others, was the widow of Ethelred, Duke of Mercia, in 915, when the Danes had advanced by the Wye, and taken captive the Bishop of Archenfield. She attacked and defeated them before Hereford, no doubt making use of the new defences. She died shortly afterwards.