conquests by a second defensive earthwork known as Offa's Dyke. (This enters Shropshire at Knighton, traverses moor and mountain by Llanymynech and Oswestry, in many places forming the boundary line of the county, and finally leaves it at Bronygarth and enters Denbighshire.) Danish invasions In the 9th and 10th centuries the district was frequently overrun by the Danes, who in 874 destroyed the famous priory of Wenlock, said to have been founded by St Milburga, granddaughter of King Penda of Mercia, and in 896 wintered at Quatford. In 912 Ethelfleda, the Lady of Mercia, erected a fortress at Bridgnorth against the Danish invaders, and in the following year she erected another at Chirbury. The establishment of Shropshire Mercia was mapped out into shires in the 10th century after its recovery from the Danes by Edward the Elder. The first mention of "Shropshire" in the Anglo-Saxon Chronicle occurs under 1006, when the King crossed the Thames and wintered there. In 1016 Edmund Ætheling plundered Shrewsbury and the neighbourhood. In 963 AD two towns are described in east Shropshire. These have now been identified as Newport, Plesc was described as having a High street, a stone quarry and a religious community. The name Plesc means fortified place or one with palisade, denoting it was of some importance. Thirteen years before the Norman Conquest, the Anglo-Saxon Chronicle relates that in 1053 the Welshmen slew a great many of the English wardens at Westbury, and in that year Harold ordered that any Welshman found beyond Offa's Dyke within the English pale should have his right hand cut off. Earl Godwin, Sweyn, Harold, Queen Edith, Edward the Confessor and Edwin and Morcar are all mentioned in the Domesday Survey as having held lands in the county shortly before or during the Norman Conquest. 1066 to the late Middle Ages Norman Conquest After the Norman Conquest of 1066 the principal estates in Shropshire were all bestowed on Norman proprietors, pre-eminent among whom is Roger de Montgomerie, 1st Earl of Shrewsbury, whose son Robert de Bellesme forfeited his possessions for rebelling against Henry I, when the latter bestowed the Earldom on his Queen Matilda for life. The principal landholders at the time of the Domesday Survey were the Bishop of Chester, the Bishop of Hereford, the church of St Remigius, Earl Roger, Osbern Fitz-Richard, Ralph de Mortimer, Roger de Laci, Hugh Lasne and Nicholas Medicus. Earl Roger