BELFREDUS, is a term used by military writers of the middle ages to signify a sort of tower erected by besiegers to overlook and command the place besieged. Belfry originally denoted a high tower, on which sentinels were placed to watch the avenues of a place, in order to prevent surprise, or to give notice of fires, by ringing a bell. The word belfry is compounded of the Teutonic bell, and freid, "peace." Belfry is also used for that part of a steeple wherein the bells are hung. This is sometimes called by old writers campanile, cloacaria, and tristegum.