Gibeah, being on a hill, was difficult of access to an attacking army, and gave great advantage to the defenders, who fought from higher ground, and probably defended a narrow pass, while their companions on the walls could gall the assailants with their slingstones.
Related Commentaries of Judges 20:21
Judges 20:21
21 And the children of Benjamin came forth out of Gibeah, and destroyed down to the ground of the Israelites that day twenty and two thousand men.