As the Israelites gathered their military forces outside the city of Gibeah, their setup revealed a very specific and focused goal for the upcoming battle. They had no intention of waging war against the entire tribe of Benjamin. Instead, their original plan was to fight only against the residents of Gibeah, the specific people who had committed terrible crimes.
Unfortunately for the Israelites, this targeted approach quickly fell apart. The rest of the tribe of Benjamin stepped in to defend the city, forcing a much larger conflict and causing heavy casualties among the Israelite army [אברבנאל].