After the Norman conquest in 1066, major estates in Shropshire were granted to Normans, including Roger de Montgomerie and later his son Robert de Bellême, who ordered significant constructions, particularly in Shrewsbury, the town of which he was Earl. Many defensive castles were built at this time across the county to defend against the Welsh and enable effective control of the region, including Ludlow Castle and Shrewsbury Castle. The western frontier with Wales was not finally determined until the 14th century. Also in this period, a number of religious foundations were formed, the county largely falling at this time under the Diocese of Hereford and that of Coventry and Lichfield. Some parishes in the north-west of the county in later times fell under the Diocese of St. Asaph until the disestablishment of the Church in Wales in 1920, when they were ceded to the Lichfield diocese.