Teancum is introduced to us as the leader of this army. Teancum is clearly a trusted captain under Moroni. He is successful at cutting off Morianton’s people, and he defeats them and brings them back to the camp of Moroni. Moroni is not vindictive. As he did with the Lamanite army, he takes a covenant from the people to keep the peace, and then restored them to their original lands.
Next we have the statement that the twenty fourth year of the judges has ended. This may or may not have been the final event recorded in that year, but it is the conclusion of the specific event that Mormon wanted to tell. Nevertheless, there were other important happenings in that year, and Mormon will now fill in that other historical material as the conclusion to his chapter.