Alma 53

Moroni skillfully makes use of his Lamanite prisoners to strengthen his fortifications. He uses his prisoners to build a stronghold to keep his prisoners. I love it:

5 And this city became an exceeding stronghold ever after; and in this city they did guard the prisoners of the Lamanites; yea, even within a wall which they had caused them to build with their own hands. Now Moroni was compelled to cause the Lamanites to labor, because it was easy to guard them while at their labor; and he desired all his forces when he should make an attack upon the Lamanites.
6 And it came to pass that Moroni had thus gained a victory over one of the greatest of the armies of the Lamanites, and had obtained possession of the city of Mulek, which was one of the strongest holds of the Lamanites in the land of Nephi; and thus he had also built a stronghold to retain his prisoners.

Using the enemy against themselves. That is such an awesome concept.

In this chapter again we see that the only time the Nephites lost ground in this war was when they failed to honor the Lord:

8 And now it came to pass that the armies of the Lamanites, on the west sea, south, while in the absence of Moroni on account of some intrigue amongst the Nephites, which caused dissensions amongst them, had gained some ground over the Nephites, yea, insomuch that they had obtained possession of a number of their cities in that part of the land.
9 And thus because of iniquity amongst themselves, yea, because of dissensions and intrigue among themselves they were placed in the most dangerous circumstances.

We also find that the people of Ammon were about to become a part of the covenant-breaker class of people, but they were dissuaded from this end by Helaman:

13 But it came to pass that when they saw the danger, and the many afflictions and tribulations which the Nephites bore for them, they were moved with compassion and were desirous to take up arms in the defence of their country.
14 But behold, as they were about to take their weapons of war, they were overpowered by the persuasions of Helaman and his brethren, for they were about to break the oath which they had made.

Alma 53.