The war halts for two years. Certainly the Nephites would spend some of that time increasing their defenses, but the Lamanite/Gadianton army certainly spends it preparing for a massive assault on the Nephite lands. When the war begins, Mormon can only lament that “it is impossible for the tongue to describe… the scene of the blood and carnage.” The Nephites were in defended positions, but the Lamanite/Gadianton army had come prepared with and army that “did exceed the number of the Nephites.” It is quite certain that “did exceed” was not to be measured in a few troops, but in a rather overwhelming presence. The Lamanite/Gadianton army had been preparing for two years. This would give them time to collect a large army, and gather the supplies that would be needed for a sustained assault.
Desolation is the first city north of the narrow pass, and they take it, although with much bloodshed. Nevertheless, the Nephite losses are also great, and cost more than numerically comparable losses among the Lamanite/Gadiantons. The percentage of loss would be much higher among the Nephites.
Chronological: The three hundred and sixty sixth year would be 357 A.D.