In fortifications, a cavalier is an elevation of earth of different shapes, situated ordinarily in the gorge of a bastion, bordered with a parapet, and cut into more or less embrasures, according to the capacity of the cavalier.
Cavaliers are a double defence for the faces of the opposite bastion: they defend the ditch, break the besiegers galleries, command the traverses in dry moats, scour the salient angle of the counterscarp where the besiegers have their counter-batteries, and interfere with the enemies trenches. Cavaliers are likewise very useful in defending the breach, and the retrenchments of the besieged. Research Cavalier