Verse 3 is the narrative shift that moves away from the chapters on Alma’s counsel to his sons; Mormon returns to the history from the large plates. As with so much of what he recorded from the large plates, it is a return “to an account of the wars between the Nephites and the Lamanites.”
Mormon introduced these wars in the eighteenth year in Alma 35:13: “And the people of Ammon departed out of the land of Jershon, and came over into the land of Melek, and gave place in the land of Jershon for the armies of the Nephites, that they might contend with the armies of the Lamanites and the armies of the Zoramites; and thus commenced a war betwixt the Lamanites and the Nephites, in the eighteenth year of the reign of the judges; and an account shall be given of their wars hereafter.” These wars were precipitated by the failure to bring the Zoramites back into the Nephite fold.
Returning to those very wars confirms that the inclusion of the counsel to Alma’s sons was a text that was somewhat out of place. Alma 35:13 serves as a conceptual exit point, and Alma 43:3 as the re-entry point, or a repetitive resumption. That technique brackets together inserted text. In this case, text was inserted from Alma’s personal record into a section otherwise taken from the large plates.
Mormon realized that the departure point was far from this reentry, and so he provides not only a reentry statement, but also the essential context that is needed to understand this particular war. Thus, verse 4 reiterates that it was the loss of the Zoramites to the Lamanites that precipitated this war. The land of Antionum had been the buffer between the land of Jershon and the Lamanites. With the Zoramites siding with the Lamanites, Jershon was exposed. Therefore, “they gathered together their armies in the land of Jershon.”