Verse 1 picks up the thread of a story from Alma 25:13–14 (see the comments on those verses for a possible reason for these related, but slightly different, stories). In those verses, Mormon had indicated that Lamanites had gone to war against Nephites and returned without success. The result of the failed raids is different here from the context in Alma 25:13–14. In those verses, the failure caused some of the Lamanites to join with, and become, Anti-Nephi-Lehies.
In verse 2, those raids anger those who wanted to defeat the Nephites, and they turn their anger on the Anti-Nephi-Lehies. Once again, the Anti-Nephi-Lehies are shown to be faithful to their covenants, and they do not take up arms. This sets up the crisis that will cause the Anti-Nephi-Lehies to flee to Zarahemla, as explained in the next verses.
Although Mormon continues to tell the ending of the story that he took from the record of the sons of Mosiah, which was from Alma’s personal record, he is shifting away from that record and returning to the story that had to have come from the Nephite large plates. He has not finished with Alma’s record, but is temporarily moving back to his main source of historical information. Our chapter 28, which was part of the original chapter, will see a return to Alma’s personal record for information and quotations.