These verses highlight an important aspect of Mormon’s editing of the large plates. The first is that he follows the annalistic nature of the plates, that is, that events are collected chronologically, year by year. The second is that Mormon’s interest is not in peacetime, but in times of conflict.
Mormon will note that things are going well, but he doesn’t describe them. The seventy-sixth year ended in peace. That is all we know of that year, even though it is certain that there were events recorded for the year on the large plates.
The seventy-seventh year “began in peace.” Good things happened, but Mormon warns that change is coming. There was peace in the seventy-eight year, except for “a few contentions.” In the seventy-ninth year, there “began to be much strife.” Nephi and Lehi were able to calm the strife. However, the incidents are simply listed, with no elaboration. There are no great speeches or sermons, no doctrinal expositions. There is only the general peace that is more often being interrupted by contentions.