Dorchester became successively the seat of two great bishoprics--the one West Saxon, the other Mercian. The first, founded by Birinus, when Wessex extended far north of the Thames, was divided seventy years later into two sees--Winchester and Sherburne. For some years the city was without bishops, owing to its insecure position during the strife between Wessex and Mercia, but later it appears as the seat of the great Mercian bishopric, retaining its jurisdiction until after the Norman conquest, when the see was transferred to Lincoln. Therefore Dorchester long enjoyed a wide celebrity and greater influence, than the city, Oxenford, which, lying at a distance of ten miles, was destined to supersede it eventually.