Judges 20:4

20:4 The Levite, the husband of the murdered woman, spoke up, “I and my concubine stopped in Gibeah in the territory of Benjamin to spend the night.

Judges 20:17

20:17 The men of Israel (not counting Benjamin) had mustered four hundred thousand sword-wielding soldiers, every one an experienced warrior.

Judges 20:36

20:36 Then the Benjaminites saw they were defeated.

The Israelites retreated before Benjamin, because they had confidence in the men they had hid in ambush outside Gibeah.

Judges 21:6

21:6 The Israelites regretted what had happened to their brother Benjamin. They said, “Today we cut off an entire tribe from Israel!