Helaman is writing after the fact, and these young men had become his sons through the rigors of the battles. They were worthy to be called sons not simply because of their age, but because of their shared closeness of purpose and effort. They arrived in Judea to find a difficult situation, which was the reason that such young men had been recruited in the first place. Not only is Judea a critical strategic location to be held, but in the wars with the Lamanites there had already been a large loss of life. The depletion of the Nephite forces was what led to these young men taking arms at the time of their adopted nation’s need.