Social: What is described here is a resident garrison in a captured city. This is a process not unfamiliar to later Mesoamerican city-kingdoms. The captors bring in the families and live among those in the captured city. In this way, there is a presence reminding the captured city of their obligations to their conqueror. As one might imagine, while the garrison would include fighting men, the presence of families also makes them more vulnerable, and regardless of the numbers brought in, they would not outnumber the people in the tribute-city. Thus this is a political move that still relies upon conventions of honor rather than display of force. It is very possible that Alma's people could have overwhelmed this "guard" by sheer numbers. Doing so, however, would bring upon them the greater wrath of the Lamanite army, who knew now where to find them more quickly. This is a garrison of deterrence, not domination.