Mormon says no more about the ministrations of Alma and his sons, but notes that it was at the end of the seventeenth year of the Reign of the Judges over the people of Nephi that the Zoramites allied with the Lamanites began to prepare for war against the Nephites. The Sacred Record says:
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. (Alma 35:13)
The cause that led the Nephite armies to occupy Jershon was that the Zoramites, finding that their haughty and unjust demands would not be complied with, had exalted the Lamanites to invade the territory of the Nephites. The Lamanite forces which were commanded almost entirely by Nephite apostates, on account of their fierce hatred of their former associates, marched first into the Land of Antionum where they were joined by the Zoramites. Then the whole of the invading hosts, under a man named Zerahemnah, advanced northward towards the Land of Jershon.
This was a day of peril for the Nephites. Their enemies were much more numerous than they, and were filled with a savage thirst for blood, which was especially felt against those who were of their own race and kindred who had bowed in obedience to Heaven's command. At this juncture the Lord raised up one of the greatest heroes ever born on American soil. He was not only a military leader, but a priest and prophet, and by his inspiration and devoted courage the Nephites were for many years led to uninterrupted victory. Such was Moroni, who now, though only twenty-five years old, took the chief command of the armies of his nation.
Though the forces of the combined Lamanites and the Zoramites were much more numerous, nearly all other advantages were on the side of the Nephites. The discipline of the Nephites was better by far; the bodies of their soldiers were protected by armor, breastplates, helmets, shields, etc., and they were fighting for the sacred cause of their religion and their country, their altars and their firesides, their wives and little ones. Inspired by the justness of their cause and the extremity of their circumstances, they fought with a courage and a desperation never exceeded in all their annals.
The Lamanites, on the other hand, had no such holy impulses to nerve their arms for the combat. They were the aggressors, and were hasting to shed the blood of their brethren. Insane and infernal hatred alone inspired them for the conflict. Besides, they were ill-prepared to meet the Nephites, who had such a tactician as Moroni for their Commander-in-Chief. The descendants of Laman were simply armed with swords and cimeters, bows and arrows, slings and stones. Their bodies were naked with the exception of a skin wrapped about their loins. The Zoramites and other dissenters from the Nephites were better clothed; in dress they followed the fashion of the people from whom they sprang.