The Nephites gather their armies in Jershon. In one sense, this military staging area is ironic because the people of Ammon were given this locale as one deemed fairly safe from attack. The Zoramite defection and loss of control of the Antionum region changed the situation dramatically. No longer a buffer between the people of Ammon and the Lamanites, Antionum was now an operating base for the Lamanites.
Culture: Mormon almost casually states that “the Zoramites became Lamanites.” The fact that they could “become” Lamanites provides conclusive evidence that “Lamanite” no longer has anything to do with genetics or lineage. The Zoramites became Lamanites by entering into a political alliance with them. “Lamanite” is clearly a political term here.
Quite frequently, being “Lamanite” was associated with the original curse on the Lamanites and light/dark skin colors. The Zoramites, by becoming “Lamanites” would have become subject to this curse, but there is no indication that they awoke one morning to find that their skins were darker. This contrast is symbolic, not physiological. (See commentary accompanying 2 Nephi 5:21.)
Mormon creates a curious causal connection by stating that, once the Zoramites became Lamanites, “therefore” they were at war with the Nephites. Mormon’s assumption that all Lamanites were, by definition, military foes of the Nephites not only suggests ongoing tensions between the Nephites and the Lamanites, but also echoes the definition in Jacob 1:14: “But I, Jacob, shall not hereafter distinguish them by these names, but I shall call them Lamanites that seek to destroy the people of Nephi, and those who are friendly to Nephi I shall call Nephites, or the people of Nephi, according to the reigns of the kings.” Apparently, a fundamental aspect of “Lamanites” was that they “seek to destroy the people of Nephi.” The term does not specify a particular polity, but any polity that is inimical to Nephite interests.