Even though it is easy to see why some readers might suggest that the Anti-Nephi-Lehies, now known as Ammonites, were pacifists, that reading is clearly incorrect. What they were is absolutely faithful to their covenants, even when their particular covenant was different from the Nephites around them, and when it might have led to problems for the Nephites. Their desire was not to avoid fighting, but to fulfill their covenant to lay down arms. The purposes were very different.
Those differences are made clear when they suggest that they have sons who had been too young to have made the covenant. Without having made the covenant, they were not bound by it, and they were able to fight. Checking through the timetables from the time of their covenant to these sons making their own covenant to fight, these young men might have been twelve to fourteen years of age.