Mormon had mentioned the Nephites’ reluctance to fight against the Lamanites (v. 22). These verses give us the Nephites’ conflicting emotions: sorrow at the bloodshed but resolution in defending their families.
Culture: Mormon notes that the Nephites are protecting themselves from “barbarous cruelty,” without specifying any details. Presumably it entailed more than battle casualties, since that type of death is not typically “barbarous.” Indeed, the Nephites would also be killing Lamanites in battle; therefore, it would be unreasonable to assume that slaying in battle is barbarous when the enemy does it but not when we do it (though all cultures do tend in that direction).
Possibly the reference to “barbarous cruelty” alludes obliquely to the Maya practice of human sacrifice preceded by lengthy and repeated sessions of torture. (See commentary accompanying Alma 14:21–22.)