According to Sylvie's observations, the reconnaissance team of the demons was usually made up of two Mad Demons and three Devilbeasts. They would patrol a set region back and forth at fixed intervals to cover a broad surveillance area with overlapping regions between the teams. It was like the "Wall of Eagles" in modern times.
Owing to the excellent field of vision of the flying demons, if the First Army were to enter the detection area, they would instantly be discovered. Roland intended to create a no-fly zone in the air, a blind zone of vision for the demons.
