What does Judges 20:48 mean?

With nearly the entire army of Benjamin—meaning almost all the tribe's adult men—destroyed, the combined army of the other eleven tribes of Israel turn back. But they don't return home; they sweep through the local territory with a vengeance. What began as an effort to punish a single town for atrocity has become a total war against the uncooperative tribe of Benjamin. This is the wrath of God expressed against the wickedness and rebellion of one tribe through the swords of the other tribes of His people. It is a dark day for all involved.

The Israelite soldiers move through Benjamin's territory, killing every person and animal they find and burning all the cities to the ground. In a sense, they do everything they can to wipe Benjamin from the earth. The circumstances of the following chapter cast doubt on the idea that God intended Israel to take the slaughter of Benjamin as far as they did. No mention is ever made of the Lord requiring the deaths of all the women and children of Benjamin. Nor is there a record of God commanding Israel to wipe them from the earth as if they were Canaanites. It is possible Israel has gone too far or has somehow missed the will of the Lord for Benjamin.

The next chapter makes it clear that the 600 men hiding at Rimmon (Judges 20:47) are the only Benjaminites who survived. It will also explain two national vows, made in anger, which threaten the complete extinction of that tribe.