Verse 13 states: “when the Lamanites saw that they could not overpower the Nephites they returned again to their own land.” It is not clear how that statement relates to the death of the Amulonites. However, it was a part of the story that Mormon intended to tell. We will see the repetition of this story at the beginning of Chapter 27, verses 1 through 3. In Alma 28:10 we will learn that there were many battles between the first and fifteenth year of the reign of the judges. It appears that Mormon is attempting to connect this story with what was happening with the Nephites, but does so without sufficient details to be clear.
The converted Lamanites joined with the Anti-Nephi-Lehies and accepted their covenant of burying their weapons of war. The result was that they were truly converted. They “did observe to keep [Jehovah’s] commandments and his statues.”