The castles of the Middle Ages, which sometimes occupied a space of many acres, were usually built on high ground, or close to a river or the sea-shore, and were almost always surrounded by a ditch or moat, which, if possible, was filled with water. Inside the moat was a high and very thick wall, generally with towers at intervals, especially at the corners, with a parapet to shelter the men fighting on the top of it, and with spaces called embrasures through which they could shoot arrows at the enemy. The principal gate was strongly defended by covering towers, and above it were holes through which melted lead, or boiling water, or hot pitch or sand could be thrown on the besiegers. The doorway was reached by a drawbridge, raised and lowered by chains, and was closed by a heavy door, or a strong grating called a portcullis. Smaller gates were the postern and the sally-port. The space inside the outer wall was known as the outer bailey, inside which was another wall, also with towers and a gate, within which were dwellings and store-houses. This was the inner bailey; and within it was the most important part of the fortress, the high tower called the keep--a building of several floors, with walls 15 or even 20 feet thick--the last place of retreat when the rest of the castle was taken. On the ground floor, which had no windows, were the well, sometimes of immense depth, the dungeon, and the store-rooms. On the next floor, which was lighted by narrow loop-holes, were the soldiers' quarters. On upper floors were the chapel and the apartments of the governor and his family. There were nearly twenty Norman and mediaeval castles in Devonshire, few of them large or elaborate from the military point of view, and some, perhaps even the majority of them, insignificant in size and simple in style. Of some of these twenty strongholds no trace remains. Almost all, of which anything survives, are ruinous and uninhabitable. And although a few have been partially restored and are now occupied as dwelling-houses, only one, that of Powderham, retains its ancient dignity, after continuous occupation that has lasted for nearly six centuries. Comparatively little is known of the history of these castles; but many of them have been the scenes of fighting, especially in Norman times, in the reign of Henry VIII and during the Civil War.