Mormon spent a lot of time describing the war that Chief Captain Moroni fought against the apostate-led Lamanite armies. That war ended before the end of the thirty-fifth year of the reign of the judges (Alma 62:42). This new war, began twenty-one years later; it was not the only war since the end of the previous war twenty-one years ago, but it was the one that was even more costly in the loss of Nephite territory than the previous one had been. In the earlier war, the Nephites lost territory on the west and east borders, but the center mostly remained.
In this new war, Mormon gives no details except that the Nephites lost almost all of their lands. The discussion of Nephite lands in Alma 22 had the northernmost border as the land of Bountiful, near the narrow neck of land (see Alma 22:30). In this war, the Lamanite armies pushed the Nephites off all of the lands south of the land of Bountiful. They had lost almost all of their lands.