History: This statement has no helpful parallels in Mesoamerican warfare for the period. Our best information comes from Aztec times, some six hundred years after the Book of Mormon. Between the Classic Maya period through Aztec domination (A.D. 600–1500) came an increase in the cult of sacrifice, which reached its apogee in the Aztecs. Thus, the Aztec characteristic of taking as many prisoners as possible may not be a model applicable here. The Maya did, however, prefer captives of high status, and this verse documents the capture and retention of the chief captains who were sent back to the Lamanite homeland in the land of Nephi.
The rest of the prisoners were killed, possibly as sacrifices. Even as late as Aztec times, captives during a long campaign would be sacrificed in the field. Such an act had the pragmatic advantage of freeing the attacking army from feeding and guarding so many prisoners.
In contrast, on the eastern front the Lamanites retained captives but they were stationed in fortified cities, not on the march. The western/southern front was more dynamic, and apparently the Lamanite leaders wanted to be able to move rapidly.