53:5 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.

 53:6 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.