The Lamanites continue their war effort against the Nephites. Their king and their chief general were both Nephite dissenters. You have to wonder whether the Lamanites would have been content to leave things alone if they had not been led and inspired by men with bitterness, greed, and hatred in their souls.
The Lamanite general Coriantumr attacked the heart of the Nephite lands and their central cities rather than focus on the border cities. The Nephites did not anticipate this move.
18 And it came to pass that because of so much contention and so much difficulty in the government, that they had not kept sufficient guards in the land of Zarahemla; for they had supposed that the Lamanites durst not come into the heart of their lands to attack that great city Zarahemla.
Satan is our enemy. We sometimes focus on the perimeter thinking that in doing that we are safe while we neglect the things at the core like prayer, meditation, scripture study, and service. Doing the things that are outwardly visible to others are important (attending church meetings, for example), but it is what happens privately in the inward man that fortifies us in the war against evil.