En route to Mechanicsburg.
These creatures appear to be constructs of great strength owned by a coalition of the Fifty Families. They are first seen ✣ as part of a unit of dragoons (mounted infantry) ordered to take Mechanicsburg by the Fifty Familes. It is reported that they are doing a great deal of damage to the countryside as they proceed.
Novel 4, p. 154, note 70 reports that these are somehow a cross between regular horses and lizards, and implies that, while powerful, they are in fact not very practical.