Osmund became bishop of Salisbury by authority of Gregory VII, and was consecrated by Archbishop Lanfranc around 3 June 1078. His diocese comprised the counties of Dorset, Wiltshire, and Berkshire, having absorbed the former bishoprics of Sherborne and Ramsbury under its incumbent Herman at the 1075 Council of London. In his "Acts of the English Bishops", William of Malmesbury describes medieval Salisbury as a fortress rather than a city, placed on a high hill, surrounded by a massive wall. Peter of Blois later referred to the castle and church as ""the ark of God shut up in the temple of Baal.""