Geographic: This Lamanite attach comes from a rather unexpected direction. The previous invasion had come through the mountain pass leading directly to Zarahemla. It may be assumed that with that event in their past, Zarahemla would be watchful over that particular entry into their lands. This invasion does not come there, however, but rather through "the wilderness side."
When the last attack was repelled, the Lamanite armies and the Amlicites fled "into the wilderness" (Alma 2:36). With this next invasion coming from the wilderness, we may speculate that at least some of the Lamanite army was able to return to its home, and mark another way from their homeland into the land of Zarahemla. In the earlier retreat, the Lamanites had fled west and north of Zarahemla (Alma 2:37). This invasion has them coming out of the wilderness upon Ammonihah, which is also north of Zarahemla. While we have no direct link to the mind of the Lamanite, it would seem rather probable that this current invasion owed its origin point to the retreat of the Lamanites from the last unsuccessful invasion.
Cultural: Mesoamerican warfare was extremely prevalent, and had many causes, only some of which were the addition of tributary cities. In this attack there is no particular attempt at creating a tributary city, but rather this is a war of annihilation. It is not a complete annihilation, however, as there are captives taken back with the Lamanites. This is not an insignificant point. The capture of prisoners during warfare is becoming extremely important among the Maya during these years (and later). Thus this particular invasion fits one of the Mesoamerican patterns. Hassig has noted that forceful destructions were often part of the need to hold power (Hassig, Ross. Aztec Warfare. University of Oklahoma Press, 1988, p. 20), and the previous defeat at the hands of the Nephites may have been sufficient reason to warrant this type of bloody retaliation.
That this is a retaliation raid, and not a war of conquest is very clear by the actions of the Lamanites. Not only do they attack and destroy the city of Ammonihah, but they take their captives and immediately begin the return. There is no attempt to gain and hold a territory, nor to set up any type of dependence. Thus the function of war was both retaliation and the collection of prisoners. When those ends were met, the army retreated.