The return of the thwarted and angry Lamanites from destroying Ammonihah directly leads to another murderous attack on the unresisting people of Anti-Nephi-Lehi. Presumably, they were motivated, not by “anger” as much as by losing their Ammonihahite captives (Alma 16:8). Once again, their coronations plans for installing the new king were checked. An attack on their new and nearby enemies, the Anti-Nephi-Lehies, was logical; but once again, the lack of resistance foiled them, again leaving them without captives.
Mormon’s narrative does not tell us how the Lamanites solved their problem; but this second attack decided the Anti-Nephi-Lehies on leaving the land of Nephi so that they would be out of harm’s way.