Note 181 — Chapter V · THE ORIGIN OF PRIVATE CASTLES

It is often supposed that these towers were derived from the Pretoria, or general’s quarters in the Roman castra. It is far more probable that they were derived from mural towers. The Pretorium was not originally fortified, and it was placed in the centre of the Roman camp. But one great object of the feudal keep was to have communication with the open country. The keep of Laon was certainly on the line of the walls, as Bishop Ascelin escaped from it down a rope in 989, and got away on a horse which was waiting for him. Palgrave, England and Normandy, ii., 880.